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SpaceX Vehicles and Missions => SpaceX Early Days Archive Section => Topic started by: oldAtlas_Eguy on 08/09/2011 06:07 pm

Title: SpaceX: Merlin 1D thread
Post by: oldAtlas_Eguy on 08/09/2011 06:07 pm
This tread is for the posting of new information on the Merlin 1D test article and production engine. Some discussion of the posted info is also welcome. The actual Merlin 1D production engine performance is the key to the SpaceX claims of the FH capabilities. If the 1D production engine falls too far below from the design specs, FH will not be able to perform as claimed.

Here is a summary of what we know and suspect so far:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf??
Vac Thrust155klbf?(better than expected)?(expect even better)
SL isp280s??
Vac isp310s309s??
T/W160??
Chamber Pressure1420psi??
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%?
Engine weight 440kg???

As new information comes available an update of the table will be posted.
? – Unknown
[value]? – Possible value but unverified
[value] – Verified value
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: arnezami on 08/09/2011 06:44 pm
Good idea making this a separate thread.

One small correction: according to Tom Mueller (source: http://hobbyspace.com/nucleus/?itemid=31499 ) the chamber pressure is 1410 psi (not 1420).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/09/2011 07:27 pm
Good idea making this a separate thread.

One small correction: according to Tom Mueller (source: http://hobbyspace.com/nucleus/?itemid=31499 ) the chamber pressure is 1410 psi (not 1420).

Thank you.

Corrected Design chamber pressure:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf??
Vac Thrust155klbf?(better than expected)?(expect even better)
SL isp280s??
Vac isp310s309s??
T/W160??
Chamber Pressure1410psi??
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%?
Engine weight 440kg???
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/10/2011 01:38 am
The SL of 280 was something that I said totally WAG. It's just adding the 5s of the 1D design over the 1C (design, not production) of 275s. The true 1C SL isp was 266s. So at least put it between brackets.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/10/2011 03:47 pm
Ok so we don't have a Design to SL ISP just a reasonable guess:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf??
Vac Thrust155klbf?(better than expected)?(expect even better)
SL isp280s???
Vac isp310s309s??
T/W160??
Chamber Pressure1410psi??
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%?
Engine weight 440kg???

When we look closely at the numbers we don't know much. The 280s SL value is resonable because we have SL Thrust, VAC Thrust, and VAC ISP from which SL ISP can be calculated.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/10/2011 08:11 pm
My guesstimate is that your way off on the weight of the Merlin.  It should be closer to 1700-2000 pounds IMHO.
Sorry just had to do that


http://video.google.com/videoplay?docid=6461477885976703694&q=SpaceX+%28site%3Avideo.google.com+OR+site%3Ayoutube.com%29&hl=en-US


Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/10/2011 08:28 pm
My guesstimate is that your way off on the weight of the Merlin.  It should be closer to 1700-2000 pounds IMHO.
That say that it did 160:1 T/W. May be oldAtlas_Eguy should add that item to the list?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: jongoff on 08/10/2011 08:38 pm
My guesstimate is that your way off on the weight of the Merlin.  It should be closer to 1700-2000 pounds IMHO.

Nope Prober, I'm pretty sure he's actually really close there.  Merlin 1D actually took a fair bit of weight out of the 1C, though they may have had to add some weight back in when they upped the thrust.  But yeah, I'm pretty sure they didn't double the weight.  :-)

~Jon
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/10/2011 09:02 pm
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/10/2011 09:29 pm
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.


The Fastrac engine was just shy of 2000lbs.  Sorry don't see that many published weight savings.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/10/2011 09:54 pm
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.


The Fastrac engine was just shy of 2000lbs.  Sorry don't see that many published weight savings.

Fastac
Thrust (v): 60klbf
isp (v): 315s
Weight: < 2000lb
T/W > 30:1


Merlin 1D
Thrust (v): 155klbf
isp (v): 310s
Weight: 970lb
T/W: 160:1

Not much improvement, eh? I would trade 1.6% isp for that T/W difference.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/11/2011 01:12 am
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.


The Fastrac engine was just shy of 2000lbs.  Sorry don't see that many published weight savings.

Fastac
Thrust (v): 60klbf
isp (v): 315s
Weight: < 2000lb
T/W > 30:1


Merlin 1D
Thrust (v): 155klbf
isp (v): 310s
Weight: 970lb
T/W: 160:1

Not much improvement, eh? I would trade 1.6% isp for that T/W difference.

For full comparison

Merlin 1C
Thrust (v): 108klbf
isp (v): 304s
Weight: 1030lb
T/W: 105:1

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 08/11/2011 07:25 pm
There is very little public information that I am aware of, but I'm curious about the performance we might expect of a MVac 1D.

My speculation is that the expansion nozzle probably can't grow that much, when the improved expansion ratio is the source of some of the 1D's improved ISP.

How much of the ISP improvement comes from the higher chamber pressure versus greater expansion?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mlorrey on 08/12/2011 02:19 am
This in an avleak article:
http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense
Quote
Revealing several new details of the 1D, Tom Mueller, propulsion engineering vice president, says the engine is designed to produce 155,000 lb. vacuum thrust and have a chamber pressure at “the sweet spot” of roughly 1,410 psia. “We’ve also increased the nozzle expansion ratio to 16 [compared with 14.5 on the Merlin 1C],” says Mueller, who adds that the initial engine “is doing better than we hoped.” The engine is designed for an Isp (specific impulse) of 310 sec. and has a thrust-to-weight ratio of 160:1. “We took structure off the engine to make it lighter. The engine we shipped [for test] to Texas was a development engine and hopefully the production engines will be even better,” he says.

The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We’ve added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It’s going to be a 1D with the same turbopump.”
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 08/12/2011 03:10 am
This in an avleak article:
http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense
Quote
Revealing several new details of the 1D, Tom Mueller, propulsion engineering vice president, says the engine is designed to produce 155,000 lb. vacuum thrust and have a chamber pressure at “the sweet spot” of roughly 1,410 psia. “We’ve also increased the nozzle expansion ratio to 16 [compared with 14.5 on the Merlin 1C],” says Mueller, who adds that the initial engine “is doing better than we hoped.” The engine is designed for an Isp (specific impulse) of 310 sec. and has a thrust-to-weight ratio of 160:1. “We took structure off the engine to make it lighter. The engine we shipped [for test] to Texas was a development engine and hopefully the production engines will be even better,” he says.

The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We’ve added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It’s going to be a 1D with the same turbopump.”
Hm... that article leans towards the position that the new engine is LH2.

Maybe it was just on the back burner until the design for Merlin 1D was finalized?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/12/2011 07:05 am
Gwynne said SpaceX will make 100 engines total in 2011.
I'm quite at a loss here, considering the COTS-2 mission will consume only 10 engines, what will they do with the remaining 90 units? They're producing almost an order of magnitude more engines than they are consuming.

So that leads to a big question, has there been any indication Spacex is planning to sell rocket engines to any other entities?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Confusador on 08/12/2011 07:22 am
Gwynne said SpaceX will make 100 engines total in 2011.
I'm quite at a loss here, considering the COTS-2 mission will consume only 10 engines, what will they do with the remaining 90 units? They're producing almost an order of magnitude more engines than they are consuming.

So that leads to a big question, has there been any indication Spacex is planning to sell rocket engines to any other entities?

I'd want more context for that to know what she meant.  If she's counting Dracos, then each Dragon mission uses 28.  Assuming they built the engines for a couple of those, plus the MDA flight (that's still on the books, right?), plus some 1D and Super Draco development engines... 100 sounds pretty reasonable.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Pedantic Twit on 08/12/2011 07:47 am
I'd want more context for that to know what she meant.  If she's counting Dracos, then each Dragon mission uses 28.

The Falcon 9 User's Guide also includes 4 Dracos on the 2nd stage, making the total 32 for every Falcon 9 + Dragon flight.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MikeAtkinson on 08/12/2011 08:54 am
There is very little public information that I am aware of, but I'm curious about the performance we might expect of a MVac 1D.

My speculation is that the expansion nozzle probably can't grow that much, when the improved expansion ratio is the source of some of the 1D's improved ISP.

How much of the ISP improvement comes from the higher chamber pressure versus greater expansion?

The increase in MVac 1D will all come from increased expansion ratio (to a first approximation). As the exit area probably won't increase, the throat will be decreased. Merlin 1D increased expansion from 14.5 to 16, again probably by a reduction in throat area.

Higher chamber pressure allows more mass to be squeezed through the throat (hence increasing the thrust), a smaller throat area decreases the mass (hence decreasing the thrust). So for an upper stage engine it is a balancing act between thrust and Isp. Usually Isp is more important, but increasing the area ratio quickly provided diminishing returns.

The optimum is probably different for MVac 1D than the old MVac. It is impossible with the information at hand to compute exactly what that optimum will be.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ChefPat on 08/12/2011 12:27 pm
Gwynne said SpaceX will make 100 engines total in 2011.
I'm quite at a loss here, considering the COTS-2 mission will consume only 10 engines, what will they do with the remaining 90 units? They're producing almost an order of magnitude more engines than they are consuming.

So that leads to a big question, has there been any indication Spacex is planning to sell rocket engines to any other entities?
Maybe they're just ramping up for their ambitious Launch Manifest?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MikeAtkinson on 08/12/2011 01:42 pm
Gwynne said SpaceX will make 100 engines total in 2011.
I'm quite at a loss here, considering the COTS-2 mission will consume only 10 engines, what will they do with the remaining 90 units? They're producing almost an order of magnitude more engines than they are consuming.

So that leads to a big question, has there been any indication Spacex is planning to sell rocket engines to any other entities?
Maybe they're just ramping up for their ambitious Launch Manifest?

I think it more likely that they are building all the Merlin 1C they will need until they start using 1D. That allows them all of next year to reconfigure their production for 1D and ramp up production.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 08/12/2011 02:13 pm
Gwynne said SpaceX will make 100 engines total in 2011.
I'm quite at a loss here, considering the COTS-2 mission will consume only 10 engines, what will they do with the remaining 90 units? They're producing almost an order of magnitude more engines than they are consuming.

So that leads to a big question, has there been any indication Spacex is planning to sell rocket engines to any other entities?
Maybe they're just ramping up for their ambitious Launch Manifest?

I think it more likely that they are building all the Merlin 1C they will need until they start using 1D. That allows them all of next year to reconfigure their production for 1D and ramp up production.
That seems like the most likely to me.

Dracos are thrusters, not generally called "engines."
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Nate_Trost on 08/12/2011 02:19 pm
I'd want more context for that to know what she meant.  If she's counting Dracos, then each Dragon mission uses 28.

The Falcon 9 User's Guide also includes 4 Dracos on the 2nd stage, making the total 32 for every Falcon 9 + Dragon flight.

I believe the second stage only includes the dracos as part of a 'delta-v mission kit', which isn't a configuration that has flown, or will be used on the Dragon flights.

It sounds like they are currently attempting to schedule a mission to launch the bulk of the ORBCOMM satellites in the second half of 2012. One wonders if that is the mostly likely candidate for a maiden launch of a Merlin 1D equipped vehicle (along with the maiden launch of a fairing equipped F9).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/12/2011 02:52 pm
“We have built about 60 engines so far this year, and will build another 40 by year-end,” says Shotwell. Speaking at the American Institute of Aeronautics and Astronautics Joint Propulsion Conference here, Shotwell explains that the eventual “plan is to build up to 400 engines per year, that’s our target.”
I wish I knew what she really meant. 400 engines is probably 25-35 flights per year. 100 motors on the other hand probably equal 5-6 combined FH and F9 flights.

If you count the Dracos you get roughly 2 flights (F9) from 100 engines. From 400 engines you get probably around 6-7 combined FH and F9 flights (assuming they all have a dragon on top), so this sounds much more reasonable and inline with their manifest.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Hauerg on 08/12/2011 03:01 pm
“We have built about 60 engines so far this year, and will build another 40 by year-end,” says Shotwell. Speaking at the American Institute of Aeronautics and Astronautics Joint Propulsion Conference here, Shotwell explains that the eventual “plan is to build up to 400 engines per year, that’s our target.”
I wish I knew what she really meant. 400 engines is probably 25-35 flights per year. 100 motors on the other hand probably equal 5-6 combined FH and F9 flights.

If you count the Dracos you get roughly 2 flights (F9) from 100 engines. From 400 engines you get probably around 6-7 combined FH and F9 flights (assuming they all have a dragon on top), so this sounds much more reasonable and inline with their manifest.

Remember that Elon spoke of 20 flights per year, half of them Heavies.
10x1+10x3=40 cores  >> each 9 engines and you get 360 engines for the booster stages, another 20 for the second stages..... So 400 is what they HAVE to build.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: DigitalMan on 08/12/2011 03:04 pm
“We have built about 60 engines so far this year, and will build another 40 by year-end,” says Shotwell. Speaking at the American Institute of Aeronautics and Astronautics Joint Propulsion Conference here, Shotwell explains that the eventual “plan is to build up to 400 engines per year, that’s our target.”
I wish I knew what she really meant. 400 engines is probably 25-35 flights per year. 100 motors on the other hand probably equal 5-6 combined FH and F9 flights.

If you count the Dracos you get roughly 2 flights (F9) from 100 engines. From 400 engines you get probably around 6-7 combined FH and F9 flights (assuming they all have a dragon on top), so this sounds much more reasonable and inline with their manifest.

I think the probability that number includes Draco's is close to zero.  You forget they had 6 F9's in various stages of production as of a couple months ago.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ChefPat on 08/12/2011 03:15 pm
10 F9 launches + 10 FH launches = 380 engines.
400 = a small surplus that can be sandbagged for future use?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/12/2011 03:18 pm
Testing engines also count! I'm sure they had to do a few Merlin 1D tests. They will need a bunch of production for qualification testing, and then for acceptance. And they will probably count the SuperDracos (the LAS).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: DigitalMan on 08/12/2011 04:12 pm
Testing engines also count! I'm sure they had to do a few Merlin 1D tests. They will need a bunch of production for qualification testing, and then for acceptance. And they will probably count the SuperDracos (the LAS).

Yea, the avweek article linked to earlier mentioned they had done 150 test firings.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kevin-rf on 08/12/2011 05:18 pm

I think it more likely that they are building all the Merlin 1C they will need until they start using 1D. That allows them all of next year to reconfigure their production for 1D and ramp up production.

Time frame from the article:

Quote
Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward, is now underway.

So we now have a time frame for the first 1D flight ... Seven!

So will Flight 7 be in 2013 or 2014?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 08/12/2011 05:26 pm
Testing engines also count! I'm sure they had to do a few Merlin 1D tests. They will need a bunch of production for qualification testing, and then for acceptance. And they will probably count the SuperDracos (the LAS).
This isn't my industry, but isn't it within the realm of possibility that other companies may be ordering limited numbers of 1Ds for their own testing?

1C was a pretty mediocre engine and lacked features like throttling, but 1D has that plus the extremely high T/W ratio, at even lower cost. Might that be of interest to other companies in the industry?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/12/2011 05:29 pm

I think it more likely that they are building all the Merlin 1C they will need until they start using 1D. That allows them all of next year to reconfigure their production for 1D and ramp up production.

Time frame from the article:

Quote
Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward, is now underway.

So we now have a time frame for the first 1D flight ... Seven!

So will Flight 7 be in 2013 or 2014?

Assuming that Flt3 (COTS 3) is successful, they where supposed to send three CRS flt/yr. And that assumes no commercial launch. If I'm not mistaken, once the pathfinder ORBCOMM satellites flight successfully in Flt3, they might want to start sending up more.
There's another little detail. If I were NASA, and the whole ISS depended on the Dragon (if Orbital has some extra delays), I would ask them to fly a commercial Merlin 1D mission before launching the last Merlin 1C core. Just in case anything happens. I don't like to be first with anything. So, I wouldn't rule out 2012, just yet. Of course, I'm assuming everything goes fine. I would bet on first half of 2013, though.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kevin-rf on 08/12/2011 06:34 pm
So, I wouldn't rule out 2012, just yet. Of course, I'm assuming everything goes fine. I would bet on first half of 2013, though.

So when would Jim say Falcon 9 flight 7 is most likely to fly? That is probably our best guess at a realistic date ;) 

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 08/12/2011 06:59 pm
Quote
Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward, is now underway.

So we now have a time frame for the first 1D flight ... Seven!
So will Flight 7 be in 2013 or 2014?

"Flight 7" was stated a long time ago.

From the manifest "hardware arrival at launch site" is mid 2012.

2014 is consistient with the SpaceX time dilation factor. ;-)

edited to correct a silly error
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: SpacexULA on 08/12/2011 08:27 pm
So, I wouldn't rule out 2012, just yet. Of course, I'm assuming everything goes fine. I would bet on first half of 2013, though.
So when would Jim say Falcon 9 flight 7 is most likely to fly? That is probably our best guess at a realistic date ;)

Not Jim, but I would say the SpaceX time dialation factor has been on the steady shrink since Falcon 1 Flight 4, with it now being down to a matter of a few 10s of weeks.  If their string of successes continues I don't doubt late 2012-early 2013, but 1 or a string of falures and all bets are off.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/12/2011 09:48 pm
Quote
Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward, is now underway.

So we now have a time frame for the first 1D flight ... Seven!
So will Flight 7 be in 2013 or 2014?

"Flight 7" was stated a long time ago.

From the manifest "hardware arrival at launch site" is mid 2012.

2014 is consistient with the SpaceX time dilation factor. ;-)

edited to correct a silly error

FH from VAFB?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jason1701 on 08/12/2011 11:51 pm
FH from VAB?

Before Jim has a hissy fit . . IT'S VAFB!!

My guess is Q3/4 2013. :)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/13/2011 12:22 am
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.


The Fastrac engine was just shy of 2000lbs.  Sorry don't see that many published weight savings.

Fastac
Thrust (v): 60klbf
isp (v): 315s
Weight: < 2000lb
T/W > 30:1


Merlin 1D
Thrust (v): 155klbf
isp (v): 310s
Weight: 970lb
T/W: 160:1

Not much improvement, eh? I would trade 1.6% isp for that T/W difference.

Let me throw this idea out there.....the Merlin 1D borrows from the RS-83/84 with the Merlin launch experience built in.
 
 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/13/2011 03:58 pm

I think it more likely that they are building all the Merlin 1C they will need until they start using 1D. That allows them all of next year to reconfigure their production for 1D and ramp up production.

Time frame from the article:

Quote
Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward, is now underway.

So we now have a time frame for the first 1D flight ... Seven!

So will Flight 7 be in 2013 or 2014?

Assuming that Flt3 (COTS 3) is successful, they where supposed to send three CRS flt/yr. And that assumes no commercial launch. If I'm not mistaken, once the pathfinder ORBCOMM satellites flight successfully in Flt3, they might want to start sending up more.
There's another little detail. If I were NASA, and the whole ISS depended on the Dragon (if Orbital has some extra delays), I would ask them to fly a commercial Merlin 1D mission before launching the last Merlin 1C core. Just in case anything happens. I don't like to be first with anything. So, I wouldn't rule out 2012, just yet. Of course, I'm assuming everything goes fine. I would bet on first half of 2013, though.

Yes, if everything goes fine and no CRS slips CRS-3 (F9 FLT 7) would be NET Oct 2012. If a COTS 3 has to be done then a slip for F9 FLT 7 would probably move to sometime Dec 2012 or as lat as Mar 2013. Almost simultaneous with FH.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: jongoff on 08/13/2011 06:09 pm
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.


The Fastrac engine was just shy of 2000lbs.  Sorry don't see that many published weight savings.

Fastac
Thrust (v): 60klbf
isp (v): 315s
Weight: < 2000lb
T/W > 30:1


Merlin 1D
Thrust (v): 155klbf
isp (v): 310s
Weight: 970lb
T/W: 160:1

Not much improvement, eh? I would trade 1.6% isp for that T/W difference.

Let me throw this idea out there.....the Merlin 1D borrows from the RS-83/84 with the Merlin launch experience built in.

No.  Merlin-1C was already at half the weight of fastrac (just over 1000lb vs around 2000lb) and more than 50% more thrust.  Fastrac is obviously a bad comparison/reference-point.  I know they knocked some weight off of the 1C when they ditched the tube-wall nozzle.  The thrust increase is mostly from a much higher chamber pressure for 1D than 1C (something like 1700psi vs I think 1200psi).  This is still entirely a pintle-injector gas-generator driven pump-fed rocket, no staged combustion or other advanced magic.  Just good solid engineering cleverness.

~Jon
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Nomadd on 08/13/2011 07:28 pm
 Any chatter about F1e being shelved because it was planned before the M1d thrust was settled? It would be interesting to see what one designed around the d could do.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/13/2011 07:38 pm
Any chatter about F1e being shelved because it was planned before the M1d thrust was settled? It would be interesting to see what one designed around the d could do.
Apparently the F1e in freezed because the nanocubes are cheaper as secondaries on a Falcon 9. And they found a way to put multiple launches of the Orbcomm fleet per Falcon 9. They will most probably do the same for Iridium. Thus, there's little demand (they would still have to compete with Orbital), and there's all this new suppliers that want to do Suborbital for really cheap. Besides, they are way too busy with CRS/CCrew, Falcon 9/Heavy. In any case a Merlin 1D, should allow for something like 1.4tn to LEO for something like 12M, and they would have to keep open Omelek. I don't think it's a viable business given all the other developments they have. In fact, I think it will make it more difficult, since Merlin 1D allows much better Falcon 9 and Heavy performance, thus, putting them upper in the market, straight into EELV territory.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/13/2011 07:45 pm
Any chatter about F1e being shelved because it was planned before the M1d thrust was settled? It would be interesting to see what one designed around the d could do.

You will find some discussion of 1D impacts on F1 in these threads:

http://forum.nasaspaceflight.com/index.php?topic=26406.0 (http://forum.nasaspaceflight.com/index.php?topic=26406.0)

http://forum.nasaspaceflight.com/index.php?topic=14485.0 (http://forum.nasaspaceflight.com/index.php?topic=14485.0)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Zed_Noir on 08/13/2011 10:08 pm
Any chatter about F1e being shelved because it was planned before the M1d thrust was settled? It would be interesting to see what one designed around the d could do.
Apparently the F1e in freezed because the nanocubes are cheaper as secondaries on a Falcon 9. And they found a way to put multiple launches of the Orbcomm fleet per Falcon 9. They will most probably do the same for Iridium. Thus, there's little demand (they would still have to compete with Orbital), and there's all this new suppliers that want to do Suborbital for really cheap. Besides, they are way too busy with CRS/CCrew, Falcon 9/Heavy. In any case a Merlin 1D, should allow for something like 1.4tn to LEO for something like 12M, and they would have to keep open Omelek. I don't think it's a viable business given all the other developments they have. In fact, I think it will make it more difficult, since Merlin 1D allows much better Falcon 9 and Heavy performance, thus, putting them upper in the market, straight into EELV territory.

Maybe SpaceX should vacated the Omelek site and set up a SpaceX version of Sea Launch with the F1e. You could carried several F1e in the support/launch control ship for multiple launches. Guess the infrastructure requirements of the F1e is much reduce from the Zenit SL.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/13/2011 11:37 pm
You know if a F9 first stage costs around 15M$
What is the engine costs? somewhere in the neighborhood of 1M$ er engine ?
A 1d is supposed to be even lower than that.

Just made me think what is really the advantage of building a Merlin 2 if it costs 50M$ per engine...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/14/2011 12:09 am
You know if a F9 first stage costs around 15M$
What is the engine costs? somewhere in the neighborhood of 1M$ er engine ?
A 1d is supposed to be even lower than that.

Just made me think what is really the advantage of building a Merlin 2 if it costs 50M$ per engine...

It wouldn't cost 50M. Elon told Congress he could sell it to them for 50M, fixed price, if they gave him 1B for developing it. I think that he put those numbers because you can't go to Congress and tell them you'll build an EELV class rocket, and robotic capsule with return capability for 600M. If Nasa says it would cost 9B, 600M is clearly a lunatic. Besides, I'm sure that if it were made in a normal Nasa cost plus program he would have got a level of supervision, reporting and moving specifications, that would have probably put it close to 1B in development (for the Merlin 2).
I guess he thinks he can do the Merlin 2 for 500M, and use the rest to develop an HLV. In fact, he stated that he thought he could develop a Falcon XX for 1.5B, but would take 2.5B for a fixed price to cover any difficulties. Please understand that I'm only quoting, not stating that this would actually be possible.
But there's another secret here, and that makes it relevant to the Merlin 1D discussion. If you plan to launch 12 cores per year (what he stated his factory is sized for), and you already had developed the Merlin 2. Would you rather make 120 engines (9 first stage plus on second stage), with lots of commonality between 1D and 1D Vac, or would you rather have a whole new line, plus new tooling, to make 12 Merlin 2 and use the old tooling for the Merlin 1D Vac? I can assure you that it will be a lot cheaper to do the 120.
But there's another issue. Let's assume that you can chose between Raptor and Merlin 2, that each will cost about the same in DDT&E and take about the same. The Merlin 2 would be useful for a Falcon X sizes LV (but they already are developing what will be the most powerful rocket) and might give better reliability if you don't believe in engine out. But if you develop the Raptor, it will open the Falcon 9 to 60% of the GTO market, compete with EELV for planetary missions and enable the Falcon Heavy to reach the bare minimum for exploration class LV. Where would you invest your money? Tip: the former is for the glory, the latter is for the money, yet fundamental for the glory, too. That's why I believe Elon made the statement about the "huge efficiency staged combustion engine".
So yes, I believe that Merlin 1D, specially if they hit or surpass their estimations of the engine, is the stepping stone to a true mass produces LV, that will enable low enough costs to actually think of exploring. As I stated previously, it's quite probable that a staged combustion engine would give even better performance. But at what extra cost? If they already can launch anything for less than anybody else, there's no point in spending money for the sake of the highest technology. They aren't in the business of advancing the technology per se, that's NASA's. They are in advancing the applied technologies to offer the lowest cost launches.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/14/2011 01:01 am
In subcontracting out a part there are some interesting reasoning’s for doing so. Either the sub has an expertise that is needed and you lack or the part is cheaper from them than what you can make it for. The second case occurs when a supplier makes the same widgets not only for you but several other customers so that his quantities of widget X is several times what you buy allowing him to underprice even yourself making them at still pay extra for his profit added onto the cost. But in the rocket engine business the second case is extremely rare. So by building the part in-house it is cheaper solely due to not having to pay the subcontractors 20% or more profit margin on the part. Which brings us to SpaceX and the Merlin 1D.

SpaceX lacked the expertise to do the medium-large engine turbo pump they needed, so they hired someone to build it for them. Since then they acquired the expertise and with Merlin 1D that expertise is showing off not only in its improved performance but in the fact that at the outset the turbo pump will cost 10% or more less than the 1C. So of course the 1D overall will be cheaper than the 1C, how much is really a guess?

The cost for the 1C was a value backed into after subtracting other costs and best guesses. The value came out to be somewhere between $1M and $2M. More accurate than that could not be done.

So if someone has a better source for 1C costs please speak up, because mine is a guess. And a corollary to that do we have any indication how much cheaper 1D is going to be?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: go4mars on 08/14/2011 04:29 am
Just made me think what is really the advantage of building a Merlin 2 if it costs 50M$ per engine...
50 million was the price.  Not the cost.  IIRC.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/14/2011 05:14 pm
I added the M1D VAC column and a cost row to the table:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)Merlin 1D VAC
SL Thrust140klbf??-
Vac Thrust155klbf?(better than expected)?(expect even better)(155klbf)?
SL isp280s???-
Vac isp310s309s??348s( an educated WAG)?
T/W160???
Chamber Pressure1410psi???
Expansion1616?16?(this shouldn’t vary much from design)?
Throttle range70-100%70%-100%?70%-100%?70%-100%?
Engine weight 440kg???>M1D production
Costs<M1C?-?<M1CVAC?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/14/2011 05:18 pm
In subcontracting out a part there are some interesting reasoning’s for doing so. Either the sub has an expertise that is needed and you lack or the part is cheaper from them than what you can make it for. The second case occurs when a supplier makes the same widgets not only for you but several other customers so that his quantities of widget X is several times what you buy allowing him to underprice even yourself making them at still pay extra for his profit added onto the cost. But in the rocket engine business the second case is extremely rare. So by building the part in-house it is cheaper solely due to not having to pay the subcontractors 20% or more profit margin on the part. Which brings us to SpaceX and the Merlin 1D.

SpaceX lacked the expertise to do the medium-large engine turbo pump they needed, so they hired someone to build it for them. Since then they acquired the expertise and with Merlin 1D that expertise is showing off not only in its improved performance but in the fact that at the outset the turbo pump will cost 10% or more less than the 1C. So of course the 1D overall will be cheaper than the 1C, how much is really a guess?


The Merlin is something that would be very interesting to reverse engineer.    Been doing a ton of reading on Fastrac, and Merlin etc.   It’s funny how Merlin is talked about being a new design while the entire PowerPoint’s are from fastrac.  Getting off topic….

The Fastrac turbine generator weight was around 700 lbs. out of a shy 2000 lb total engine weight.  The Merlin 1C turbo pump must be a light weight.

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 08/14/2011 06:33 pm
In subcontracting out a part there are some interesting reasoning’s for doing so. Either the sub has an expertise that is needed and you lack or the part is cheaper from them than what you can make it for. The second case occurs when a supplier makes the same widgets not only for you but several other customers so that his quantities of widget X is several times what you buy allowing him to underprice even yourself making them at still pay extra for his profit added onto the cost. But in the rocket engine business the second case is extremely rare. So by building the part in-house it is cheaper solely due to not having to pay the subcontractors 20% or more profit margin on the part. Which brings us to SpaceX and the Merlin 1D.

SpaceX lacked the expertise to do the medium-large engine turbo pump they needed, so they hired someone to build it for them. Since then they acquired the expertise and with Merlin 1D that expertise is showing off not only in its improved performance but in the fact that at the outset the turbo pump will cost 10% or more less than the 1C. So of course the 1D overall will be cheaper than the 1C, how much is really a guess?


The Merlin is something that would be very interesting to reverse engineer.    Been doing a ton of reading on Fastrac, and Merlin etc.   It’s funny how Merlin is talked about being a new design while the entire PowerPoint’s are from fastrac.  Getting off topic….

The Fastrac turbine generator weight was around 700 lbs. out of a shy 2000 lb total engine weight.  The Merlin 1C turbo pump must be a light weight.

Look at this link (http://www.spaceref.com/news/viewsr.html?pid=9113) re the turbo pump for M1A back in 2003. Presumably it would have been re-engineered for regen operation in M1C - anyone have any insight how that would affect the weight?

Quote
As mentioned before, our approach is a gas generator cycle, single shaft, single turbine wheel combined LOX/kerosene pump. Like the rest of our development, all components except those used for calibration are at or near flight weight. At 150lbs, the turbo-pump may be the best ever pump in its class for thrust (max 85,000lbf vacuum) to weight.
(My highlight)

cheers, Martin

Mod Edit: do not embed images
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/14/2011 06:40 pm
http://www.barber-nichols.com/products/rocket_engine_turbopumps/default.asp (http://www.barber-nichols.com/products/rocket_engine_turbopumps/default.asp)

I was looking at the Barber-Nichols site and found that the Merlin BNI's third turbo pump seems to have more in common with the Bantum BNI's second turbo pump they built than the Fstrac BNI's first turbo pump, although the Merlin doesn't have the counter rotation feature of the Bantum.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/14/2011 06:42 pm
Thanks great pic!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/14/2011 08:08 pm
I've seen a lot of automotive turbos in my life, that looks like a beautiful piece of work and strangely not that different.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: arnezami on 08/14/2011 08:27 pm

How can a pump be so beautiful?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/14/2011 08:35 pm
Thanks great pic!

Yes thanks for the pics and links.

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/14/2011 08:39 pm
You can see from the pics how alot of the weight was reduced from the 1st Fastrac pic.

I would also note that a Regen Fastrac was done and I have the docs for it.  Want them?   Also a couple for the Bantam.



Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/14/2011 09:47 pm
Now all we need is a picture of the 1D turbo pump to compare so we can see what a SpaceX built turbo pump that is supposedly lighter looks like.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 08/14/2011 10:09 pm
Dunno if anyone has linked to it yet, but the F9 data sheet on Ed's http://www.spacelaunchreport.com (http://www.spacelaunchreport.com)  was updated on August 6, 2011 -

http://www.spacelaunchreport.com/falcon9.html (http://www.spacelaunchreport.com/falcon9.html)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Zed_Noir on 08/14/2011 10:50 pm
@oldAtlas_Eguy

Any thoughts on the maximum burntime of the Merlin-1D Vac, assuming about 50 tonnes of propellants with a separate propulsion module on top a Falcon Heavy?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/14/2011 11:45 pm
@oldAtlas_Eguy

Any thoughts on the maximum burntime of the Merlin-1D Vac, assuming about 50 tonnes of propellants with a separate propulsion module on top a Falcon Heavy?

The fuel weight is 113klb for the current US. The M1DVAC will probably burn fuel at or less than the M1D of ~500lb/s giving a minimum burn time of 226s and a possible maximum runing at 70% thrust of ~323s.

If the stage is stretched 34% so that it has 34% more fuel then the burn times would be ~303s at 100% and ~433s at 70%.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 08/15/2011 08:48 am
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.

Don't know how much this helps, but for M1C on F9b1 (with other structure):-

http://www.spacex.com/updates_archive.php?page=2009_2 (http://www.spacex.com/updates_archive.php?page=2009_2):-
Quote
Weighing in at over 7,700 kg (17,000 lbs), the thrust assembly and nine Merlin engines represents over half the dry mass of the Falcon 9 first stage.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/15/2011 03:52 pm
From this article (http://spacenews.com/profiles/110425-elon-musk.html):

Quote
What can you tell me about the upgrade under way to the Falcon 9’s Merlin-1C engine and how it will streamline production?

The hardest part of the engine to mass produce is the electro-plating of nickel cobalt on the chamber. We create this thick metal jacket that takes the primary stress of the pressure vessel and it’s plated one molecule at a time. Plating is about the slowest way you can make a metal thing. With the Merlin-1D we take a metal jacket that is explosively formed. We take a metal sheet that’s in a cylindrical form and put it in a bucket of water, effectively. Sort of a concrete pool. And you set off an explosive and the jacket just goes “boohmp” and forms to the outer side walls into a jacket shape, so you have a mold, effectively. And then you just put the jacket on the chamber and braise it on. You can do several a day. We have a fully integrated engine and it’s being test-fired right now. There’s really not a lot of question marks remaining about the Merlin-1D.

What is the capability of the Falcon 9 with the Merlin-1D vs. the Merlin-1C?

It depends on how much sandbagging you want to give on the Falcon 9 performance but it’s in the roughly 13-tons-to-low-Earth-orbit capability with the upgraded Falcon 9. The current Falcon 9 is in the 10- to 11-metric-ton class.

When will the upgraded engine fly?

The Merlin-1D will fly mid-2012. It could be a Commercial Resupply Services mission or it could be an Orbcomm mission, but it’ll be approximately flight seven.

So it does seems that he'll expects to start launching Orbcomm next year, and thus we might see Merlin 1D in 2012.
When he says sandbagging, I guess he's speaking of recovery hardware. The other small issue that might have, is that then he'll need to develop a Merlin 1D Vacuum. So 16tn is what they would have got if they had both stages at Merlin 1D specs and no recovery hardware. The other possibility, is that they would need Raptor for that.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/15/2011 04:16 pm
Don't know how much this helps, but for M1C on F9b1 (with other structure):-

http://www.spacex.com/updates_archive.php?page=2009_2 (http://www.spacex.com/updates_archive.php?page=2009_2):-
Quote
Weighing in at over 7,700 kg (17,000 lbs), the thrust assembly and nine Merlin engines represents over half the dry mass of the Falcon 9 first stage.

That's consistent with a report of the 1st stage being 32,000 lbs total.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: jnc on 08/15/2011 05:36 pm
"And then you just put the jacket on the chamber and braise it on.

That reporter triggered one of my pet peeves - my homonym alert. I assume he meant 'brazed' (http://www.thefreedictionary.com/braze) - "braised" (http://www.thefreedictionary.com/braised) is what I'd like to do to the extremities of people who make these mistakes! :-)

Noel
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kevin-rf on 08/15/2011 05:44 pm

That reporter triggered one of my pet peeves - my homonym alert. I assume he meant 'brazed' (http://www.thefreedictionary.com/braze) - "braised" (http://www.thefreedictionary.com/braised) is what I'd like to do to the extremities of people who make these mistakes! :-)

Noel


Donner, party of one?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 05:52 pm
I did some “back of the envelope calcs” that show that a drop in weight per engine of 26kg for both M1D and M1DVAC would only be a total delta V difference of 12m/s. But the ISP difference gives 256m/s total delta V difference. That DV equates to an added >2MT in payload capability. Calculations using the mass fraction and delta V equation were used. BTW that’s with no tank stretch and no higher thrust advantage so actual will be better.

So the M1D and M1DVAC no stretch F9 would have better than 12MT LEO payload capability. Exactly how much SpaceX still can only guess as well because they yet to have a M1D production engine performance values.

A M1D and M1CVAC having a 155m/s delta V advantage works out to be a payload increase over the current 9.9MT of ~0.9MT for better than 10.8MT.

Deppending on what the configuration (no stretch vs stretch and M1DVAC vs M1CVAC) and exact M1D specs you get values from just 10.8MT to 16MT. No wonder we have been getting so many different values out of SpaceX for the new F9 performance.

Edit - I meant to say an added >2MT.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/15/2011 06:01 pm
So it seems that they will putting a continuous of rocket versions, with small improvements between each other? How do they qualify that?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: apace on 08/15/2011 06:04 pm
I like this approach, small steps to make a product better and better. If NASA has done that with the Shuttle over the last 30 years, we had today a working SLS without a gap (I know, the STS is a much more complicated system than a simple rocket).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 06:14 pm
The producing of TC's and bells by explosive forming means in order to change from producing 1C to 1D a differnt form is used and obviously they already have the M1D form so they could switch from manufacturing M1C's to M1D's and back in a single week.

This is obviously not a new process for M1D but something they went to for M1C to ramp up production rates.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: edkyle99 on 08/15/2011 06:15 pm
Don't know how much this helps, but for M1C on F9b1 (with other structure):-

http://www.spacex.com/updates_archive.php?page=2009_2 (http://www.spacex.com/updates_archive.php?page=2009_2):-
Quote
Weighing in at over 7,700 kg (17,000 lbs), the thrust assembly and nine Merlin engines represents over half the dry mass of the Falcon 9 first stage.

That's consistent with a report of the 1st stage being 32,000 lbs total.

Another clue is from the following page.
http://www.spacex.com/updates_archive.php?page=121007
http://mfile.akamai.com/22165/wmv/spacex.download.akamai.com/22165/F9-Tank-Lift-Time-Lapse_Silent.asx
A video of the first tank being lifted into the big test stand in Texas has a title that includes the phrase " .... lift this 9,000 lb first stage .... ".  Note that the lift included both the primary tank structure and the thrust assembly with no Merlin engines installed.  No interstage is present either.

Note, however, that the numbers do not add up.  If the engines are "A", the thrust assembly "B", and the tank structure "C", then:

A+B = 17,000
B+C = 9,000
A+B+C = 32,000

Which doesn't solve unless B= negative 6,000 lbs, etc.

This is typical of the SpaceX information.  It seems carefully designed to not add up.

 - Ed Kyle
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/15/2011 06:17 pm
Keep in mind that's the "run tank" you're talking about, it's conceivable it's in some way different than a flight stage.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: edkyle99 on 08/15/2011 06:19 pm
Keep in mind that's the "run tank" you're talking about, it's conceivable it's more of a battleship stage than a flight stage.

That would only make sense if the mass was given as 19,000 pounds, not merely 9,000 pounds.  Then:

A (engines+plumbing) = 13,000 lbs
B (thrust assembly) = 4,000 lbs
C (tank structure) - 15,000 lbs

 - Ed Kyle
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: arnezami on 08/15/2011 06:29 pm
Which doesn't solve unless B= negative 6,000 lbs, etc.

I knew it!!! SpaceX must have invented anti-gravity along the way  ;D ;D
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 06:42 pm
Keep in mind that's the "run tank" you're talking about, it's conceivable it's more of a battleship stage than a flight stage.

That would only make sense if the mass was given as 19,000 pounds, not merely 9,000 pounds.  Then:

A (engines+plumbing) = 13,000 lbs
B (thrust assembly) = 4,000 lbs
C (tank structure) - 15,000 lbs

 - Ed Kyle

13,000 lbs results in 1444lbs per engine the value that is arrived at when using the 125klbf M1C (whishfull thinking- not grounded in reality) specs of 275s SL and 304.8s Vac and 96 T/W 1443.2lbs. This conflicts with the later flight report values that results in an engine weight of 1031lbs. so the plumbing weighs 400lbs per engine?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 06:55 pm
I went back and looked at the dates for the pics 22 Sep 2009. So the weights quoted are suspect in that was this a flight article or an engineering test article to test the nine engine cluster on the test stand?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 08/15/2011 07:03 pm
From this article (http://spacenews.com/profiles/110425-elon-musk.html):

Quote
What can you tell me about the upgrade under way to the Falcon 9’s Merlin-1C engine and how it will streamline production?

The hardest part of the engine to mass produce is the electro-plating of nickel cobalt on the chamber. We create this thick metal jacket that takes the primary stress of the pressure vessel and it’s plated one molecule at a time. Plating is about the slowest way you can make a metal thing. With the Merlin-1D we take a metal jacket that is explosively formed. We take a metal sheet that’s in a cylindrical form and put it in a bucket of water, effectively. Sort of a concrete pool. And you set off an explosive and the jacket just goes “boohmp” and forms to the outer side walls into a jacket shape, so you have a mold, effectively. And then you just put the jacket on the chamber and braise it on. You can do several a day. We have a fully integrated engine and it’s being test-fired right now. There’s really not a lot of question marks remaining about the Merlin-1D.

What is the capability of the Falcon 9 with the Merlin-1D vs. the Merlin-1C?

It depends on how much sandbagging you want to give on the Falcon 9 performance but it’s in the roughly 13-tons-to-low-Earth-orbit capability with the upgraded Falcon 9. The current Falcon 9 is in the 10- to 11-metric-ton class.

When will the upgraded engine fly?

The Merlin-1D will fly mid-2012. It could be a Commercial Resupply Services mission or it could be an Orbcomm mission, but it’ll be approximately flight seven.

So it does seems that he'll expects to start launching Orbcomm next year, and thus we might see Merlin 1D in 2012.
When he says sandbagging, I guess he's speaking of recovery hardware. The other small issue that might have, is that then he'll need to develop a Merlin 1D Vacuum. So 16tn is what they would have got if they had both stages at Merlin 1D specs and no recovery hardware. The other possibility, is that they would need Raptor for that.
I don't think that's what he meant by "sandbagging."

Here's what Wikipedia calls sandbagging:
*Deceiving someone by pretending to be weak.
*Sandbagging (racing), a driver deliberately drag races or qualifies slower than what the car can actually perform
*Sandbagging (budgeting), a manager deliberately overstates financial requirements with the intent of coming in under-budget, thus being praised.

In other words, a Falcon 9 tweaked to get the most out of the Merlin 1D would be able to do more than 13 tons to LEO.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/15/2011 07:17 pm
In other words, a Falcon 9 tweaked to get the most out of the Merlin 1D would be able to do more than 13 tons to LEO.

The FH LEO claim even without crossfeed is pretty dependant on that being the case.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 08/15/2011 07:19 pm
In other words, a Falcon 9 tweaked to get the most out of the Merlin 1D would be able to do more than 13 tons to LEO.

The FH LEO claim even without crossfeed is pretty dependant on that being the case.
You know, I don't find their figures overly-optimistic. I calculated 53mT to LEO with an excel spreadsheet a few months ago showing that it could be done with Merlin 1D, etc, and no on challenged me.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/15/2011 07:23 pm
Keep in mind that's the "run tank" you're talking about, it's conceivable it's more of a battleship stage than a flight stage.

That would only make sense if the mass was given as 19,000 pounds, not merely 9,000 pounds.  Then:

A (engines+plumbing) = 13,000 lbs
B (thrust assembly) = 4,000 lbs
C (tank structure) - 15,000 lbs

 - Ed Kyle

13,000 lbs results in 1444lbs per engine the value that is arrived at when using the 125klbf M1C (whishfull thinking- not grounded in reality) specs of 275s SL and 304.8s Vac and 96 T/W 1443.2lbs. This conflicts with the later flight report values that results in an engine weight of 1031lbs. so the plumbing weighs 400lbs per engine?

Maybe the real 1D savings is in the thrust assembly.        Looking at the history; SpaceX built the Merlin for the Falcon 1, then the F5.    It could be that they looked at the thrust assembly now,  and said we can save a ton of weight if these tubes were cut in half etc.   So the real weight savings might be the re arrangement of “plumbing” on the Merlin to have less weight within the thrust assembly.

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 07:23 pm
In other words, a Falcon 9 tweaked to get the most out of the Merlin 1D would be able to do more than 13 tons to LEO.

Yes, the ISP and thrust advantage does points to that without having to stretch the tanks.

With a 34% tank stretch It should be easy to get to 16MT.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: 2552 on 08/15/2011 07:30 pm
If the numbers in the SpaceNews were typed on a keyboard's number pad, where the 6 key is directly above the 3 key, it's possible the 13 ton number was a typo.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/15/2011 07:31 pm
In other words, a Falcon 9 tweaked to get the most out of the Merlin 1D would be able to do more than 13 tons to LEO.

The FH LEO claim even without crossfeed is pretty dependant on that being the case.
You know, I don't find their figures overly-optimistic. I calculated 53mT to LEO with an excel spreadsheet a few months ago showing that it could be done with Merlin 1D, etc, and no on challenged me.

No, I'm just saying a F9 core that can support 45-ish tonnes without crossfeed will have to do better than 13 tonnes in the single-stick configuration.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 07:36 pm
In order to do cross feed there may be a second design for the thrust assembly. One simpler and lighter for use on booster and single F9's as well as center core non-crossfeed FH's that have a fuel tap and shutoff valve to feed fuel to the central core. Then a second more complex and heavier one with fuel inlets on both sides, extra plumbing and valves. This would deffinitly make the FH crossfeed version more expensive since the central core is not common.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 07:44 pm
In other words, a Falcon 9 tweaked to get the most out of the Merlin 1D would be able to do more than 13 tons to LEO.

The FH LEO claim even without crossfeed is pretty dependant on that being the case.
You know, I don't find their figures overly-optimistic. I calculated 53mT to LEO with an excel spreadsheet a few months ago showing that it could be done with Merlin 1D, etc, and no on challenged me.

No, I'm just saying a F9 core that can support 45-ish tonnes without crossfeed will have to do better than 13 tonnes in the single-stick configuration.

13MT is related to  M1d and M1DVAC and no tank stretch but add a 34% tank stretch as specified in the FH specs and you get ~16MT per core or 48MT. Crossfeed gives ~20% increase so thats 44MT without so some loss occurs because of limitations of the delta V from the US on FH. So a non crossfeed FH would be 40-44MT depending on how much of an advantage crossfeed gves 20% or 30%.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 08/15/2011 08:37 pm
13MT is related to  M1d and M1DVAC and no tank stretch but add a 34% tank stretch as specified in the FH specs and you get ~16MT per core or 48MT. Crossfeed gives ~20% increase so thats 44MT without so some loss occurs because of limitations of the delta V from the US on FH. So a non crossfeed FH would be 40-44MT depending on how much of an advantage crossfeed gves 20% or 30%.
Interesting.

One thing I was curious about was whether the non-stretched version of F9 would continue to fly. I guess throttleability starts to look pretty important there, as it receives a very significant increase in thrust and reduction in mass. That would make for a pretty brutal max Q.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 09:42 pm
13MT is related to  M1d and M1DVAC and no tank stretch but add a 34% tank stretch as specified in the FH specs and you get ~16MT per core or 48MT. Crossfeed gives ~20% increase so thats 44MT without so some loss occurs because of limitations of the delta V from the US on FH. So a non crossfeed FH would be 40-44MT depending on how much of an advantage crossfeed gves 20% or 30%.
Interesting.

One thing I was curious about was whether the non-stretched version of F9 would continue to fly. I guess throttleability starts to look pretty important there, as it receives a very significant increase in thrust and reduction in mass. That would make for a pretty brutal max Q.

The M1D SL thrust at 70% 119klbf is greater than the M1C SL thrust of 94.8klbf.

Another tidbit is flow rates:
M1C 357lbs/s
M1D 500lbs/s 100% 350lbs/s 70% (the flow rate will be higher than this because an ISP drop will occur at throttle positions less than 100%, how much is unknown.)

This makes the M1D powered 1st stage total burn time much less than current even flying the entire time at 70%. Also even throttling back to 70% some engines will still have to be shut down to manage max g.

Interesting is the fact that 75% throttle position is 127klbf, so a design to flight capabilities can be done at that setting from liftoff until after max Q, then throttling up until max g is reached and throttling back slowly maintain at max g until 70% is reached, shutting down 2 engines and throttling back up and doing the throttle down slowly procedure again.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/15/2011 09:46 pm
The M1D SL thrust at 70% 119klbf is greater than the M1C SL thrust of 94.8klbf.

Check your math. 0.7 * 140klbf I get 98 klbf.

In fact, if the actual lowest throttle is more similar to 67% as suggested for Merlin 2, that would make the two engine pretty identical in terms of possible liftoff thrust. With the added benefit of throttling up if one of the engines dies.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 09:59 pm
The M1D SL thrust at 70% 119klbf is greater than the M1C SL thrust of 94.8klbf.

Check your math. 0.7 * 140klbf I get 98 klbf.

In fact, if the actual lowest throttle is more similar to 67% as suggested for Merlin 2, that would make the two engine pretty identical in terms of possible liftoff thrust. With the added benefit of throttling up if one of the engines dies.

I checked my spreadsheet and for some reason I had 170 not 140, a typo.

90% gives the 125klbf equivelent F9 dream vehicle value that the structure was designed to.

Interesting: Flying at 125klbf equivelent from liftoff also gives single engine out form t-0 just by throttling back up to 100% without a flight performance profile change.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 08/15/2011 10:53 pm
This makes the M1D powered 1st stage total burn time much less than current even flying the entire time at 70%. Also even throttling back to 70% some engines will still have to be shut down to manage max g.
Do you think they might fly some of the non-stretched F9s with a reduced number of engines, simply because it'll end up going so fast, so low in the atmosphere? 8x 1D @ 100% is similar thrust to 9x 1C+ @ 100%, but has higher ISP and much lower mass, and presumably cost.

Interesting is the fact that 75% throttle position is 127klbf, so a design to flight capabilities can be done at that setting from liftoff until after max Q, then throttling up until max g is reached and throttling back slowly maintain at max g until 70% is reached, shutting down 2 engines and throttling back up and doing the throttle down slowly procedure again.
hm

Throttling by killing engines would achieve a higher aggregate ISP though, wouldn't it?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/15/2011 11:42 pm
This makes the M1D powered 1st stage total burn time much less than current even flying the entire time at 70%. Also even throttling back to 70% some engines will still have to be shut down to manage max g.
Do you think they might fly some of the non-stretched F9s with a reduced number of engines, simply because it'll end up going so fast, so low in the atmosphere? 8x 1D @ 100% is similar thrust to 9x 1C+ @ 100%, but has higher ISP and much lower mass, and presumably cost.

Interesting is the fact that 75% throttle position is 127klbf, so a design to flight capabilities can be done at that setting from liftoff until after max Q, then throttling up until max g is reached and throttling back slowly maintain at max g until 70% is reached, shutting down 2 engines and throttling back up and doing the throttle down slowly procedure again.
hm

Throttling by killing engines would achieve a higher aggregate ISP though, wouldn't it?

One of the things your trying to acheive with throttling is keep the g level high but not over a certain amount to minimize gravity loss. Spacecraft 6g or less. Manned missions 3g or less. To maintain ~3g on an F9 manned flight you would have only 5 engines burning and at 70% throttle at 1st stage shutdown.

At some point the loss of ISP from throttling and the increased loss from a lower acceleration wash out. But loss of ISP in the 1st Stage is not that significant to the payload amount if it is only like 1 or 2s.

Another concern is using M1DVAC and only having a 70% minimum throttle position. What would be the lightest payload but also that the acceleration is still less than 6g?

I did a few calcs and came up with ~7000kg payload or the weight of Dragon. But what about 4000kg GEO sats?

So the M1DVAC can use the same turbopump as M1D without change, maybe, but only usable for payload >7MT.

Possibly derating it a so that <6g can be maintained for GEO sats. For a 4MT sat you would need  60% on top of the throttle position of 70%, otherwise a new turbopump that can throttle down to 40% which may not be achievable.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 08/15/2011 11:53 pm
One of the things your trying to acheive with throttling is keep the g level high but not over a certain amount to minimize gravity loss. Spacecraft 6g or less. Manned missions 3g or less. To maintain ~3g on an F9 manned flight you would have only 5 engines burning and at 70% throttle at 1st stage shutdown.

At some point the loss of ISP from throttling and the increased loss from a lower acceleration wash out. But loss of ISP in the 1st Stage is not that significant to the payload amount if it is only like 1 or 2s.

Another concern is using M1DVAC and only having a 70% minimum throttle position. What would be the lightest payload but also that the acceleration is still less than 6g?

I did a few calcs and came up with ~7000kg payload or the weight of Dragon. But what about 4000kg GEO sats?

So the M1DVAC can use the same turbopump as M1D without change, maybe, but only usable for payload >7MT.

Possibly derating it a so that <6g can be maintained for GEO sats. For a 4MT sat you would need  60% on top of the throttle position of 70%, otherwise a new turbopump that can throttle down to 40% which may not be achievable.


Couldn't you just lengthen the US? The more we look at it the less loss of increasing weight in the first stage (recovery) and second stage (GTO performance). But I would suspect that the US would be much more throttlable. I've Also thought that SpaceX could really use a third stage in the Falcon 9. Something akin the fregat or so.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/16/2011 12:17 am
One of the things your trying to acheive with throttling is keep the g level high but not over a certain amount to minimize gravity loss. Spacecraft 6g or less. Manned missions 3g or less. To maintain ~3g on an F9 manned flight you would have only 5 engines burning and at 70% throttle at 1st stage shutdown.

At some point the loss of ISP from throttling and the increased loss from a lower acceleration wash out. But loss of ISP in the 1st Stage is not that significant to the payload amount if it is only like 1 or 2s.

Another concern is using M1DVAC and only having a 70% minimum throttle position. What would be the lightest payload but also that the acceleration is still less than 6g?

I did a few calcs and came up with ~7000kg payload or the weight of Dragon. But what about 4000kg GEO sats?

So the M1DVAC can use the same turbopump as M1D without change, maybe, but only usable for payload >7MT.

Possibly derating it a so that <6g can be maintained for GEO sats. For a 4MT sat you would need  60% on top of the throttle position of 70%, otherwise a new turbopump that can throttle down to 40% which may not be achievable.


Couldn't you just lengthen the US? The more we look at it the less loss of increasing weight in the first stage (recovery) and second stage (GTO performance). But I would suspect that the US would be much more throttlable. I've Also thought that SpaceX could really use a third stage in the Falcon 9. Something akin the fregat or so.

A minimum payload weight of 4500kg and 500kg in extra dry weight for a stretched US and a 50% throttle level would work.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/16/2011 12:33 am
Anyone has a clue on what would it take to add the possibility of mid flight restart for the first stage Merlin, and how much benefit that could bring?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 08/16/2011 12:43 am
Anyone has a clue on what would it take to add the possibility of mid flight restart for the first stage Merlin, and how much benefit that could bring?

For the boost phase? Or post-staging for slowing down to ease recovery?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: sdsds on 08/16/2011 12:44 am
Would M1D performance enable e.g. a Falcon-7 configuration?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/16/2011 12:48 am
Anyone has a clue on what would it take to add the possibility of mid flight restart for the first stage Merlin, and how much benefit that could bring?

For the boost phase? Or post-staging for slowing down to ease recovery?

Maybe have 8 merlins on each core and throttle up.  Thats - the weight of three on FH
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/16/2011 01:23 am
Anyone has a clue on what would it take to add the possibility of mid flight restart for the first stage Merlin, and how much benefit that could bring?

For the boost phase? Or post-staging for slowing down to ease recovery?

For the boost phase. I think restart for stage recovery was already discussed in another thread, but it didn't go into what it would take and how it can be achieved.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 08/16/2011 01:31 am
Anyone has a clue on what would it take to add the possibility of mid flight restart for the first stage Merlin, and how much benefit that could bring?

For the boost phase? Or post-staging for slowing down to ease recovery?

For the boost phase. I think restart for stage recovery was already discussed in another thread, but it didn't go into what it would take and how it can be achieved.

But what could possibly be gained by doing that? Why would you turn off an engine and then restart it? A rocket wants to get out of the atmosphere and gravity well as soon as possible.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/16/2011 01:52 am
Well they seem to shut a couple of engines down for max Q currently. It sounds like a good idea to be able to restart them later on. Anyway, that's why I've asked this question.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 08/16/2011 02:21 am
I've Also thought that SpaceX could really use a third stage in the Falcon 9. Something akin the fregat or so.
I was thinking about that.

I bet a Super Draco with a big nozzle would make a decent engine for a hypothetical SpaceX third stage. That would add enough delta-v for a GEO circularization burn, unlimited restarts, etc. It could also probably be used as the basis for a Dragon SM and a bunch of other ideas.

Would M1D performance enable e.g. a Falcon-7 configuration?
M1C+: 125 klbf SL * 9 = 1.125 mlbf
M1D: 140 klbf SL * 8 = 1.120 mlbf (slightly less thrust, but also much lighter)

Well they seem to shut a couple of engines down for max Q currently. It sounds like a good idea to be able to restart them later on. Anyway, that's why I've asked this question.
They don't shut them down for max Q, max Q is still deep in the atmosphere and they are currently at full throttle for that.

They shut down 2 engines just before MECO because thrust increases as they leave the atmosphere, and the first stage has at that point left the vast majority of its mass behind, meaning acceleration increases significantly.

A minimum payload weight of 4500kg and 500kg in extra dry weight for a stretched US and a 50% throttle level would work.
MVac is currently significantly less thrust than the Merlin 1C+ isn't it?

They may be looking to keep the chamber pressure and ISP advantages but reduce thrust for the Vac version.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Zed_Noir on 08/16/2011 02:44 am
I've Also thought that SpaceX could really use a third stage in the Falcon 9. Something akin the fregat or so.
I was thinking about that.

I bet a Super Draco with a big nozzle would make a decent engine for a hypothetical SpaceX third stage. That would add enough delta-v for a GEO circularization burn, unlimited restarts, etc. It could also probably be used as the basis for a Dragon SM and a bunch of other ideas.


Why would SpaceX developed the hypergolic Super Draco as a 3rd stage motor when the KeroLox Kestrel  motor is available. You could just put the Falcon 1 upper stage on top of the Falcon 9 stack as is for a 3rd stage inside the current reference F9 PLF with small external solar array band.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: jnc on 08/16/2011 02:58 am
But what could possibly be gained by doing that? Why would you turn off an engine and then restart it? A rocket wants to get out of the atmosphere and gravity well as soon as possible.

To expand a bit on that brief reference to 'MaxQ', that's the point of maximum aerodynamic load on the vehicle. It's determined by a combination of air density and speed. If you minimize the loading at MaxQ, you can use a less strong struture (since if the aero shell isn't strong enough, it will implode from dynamic pressure). Less strength -> less structural mass -> more payload. More here (http://en.wikipedia.org/wiki/Max_Q).

Noel
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 08/16/2011 08:58 am
Why would SpaceX developed the hypergolic Super Draco as a 3rd stage motor when the KeroLox Kestrel  motor is available. You could just put the Falcon 1 upper stage on top of the Falcon 9 stack as is for a 3rd stage inside the current reference F9 PLF with small external solar array band.
Well, the cryogenic LOX would limit the useful life of the stage on orbit, and kestrel has limited restarts.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ChefPat on 08/16/2011 12:32 pm
10 F9 launches + 10 FH launches = 380 engines.
400 = a small surplus that can be sandbagged for future use?
I think I unintentionally started something here. :(
When I "sandbag" an item, it's usually something hard to get, so I build up a surplus of it.
Whatever the "Urban Dictionary" says is not my definition.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/16/2011 05:50 pm
In doing some evaluation of what the M1DVAC specs should meet in order for it to be usable for the most constraining case of GTO, I ended with three cases:

1) That the M1DVAC would be used on both the current US and stretched US with no derating and throttle of 50%-100%. Significant change to the turbo pump/GG.

2) That the M1DVAC would be used on both the current US and stretched US with 80% derating and throttle of 70%-100%. New throat diameter and possibly some changes to the turbo pump all to maintain the TC pressure of 1410psi.

3) That the M1DVAC would be used on only the stretched US and on current US to LEO with payloads >7MT with no derating and throttle of 70%-100%. Highest commonality and lowest cost. A sufficient inventory of M1CVAC’s to fly on GTO missions with the current US is needed until the shorter F9 is phased out.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/16/2011 05:53 pm
10 F9 launches + 10 FH launches = 380 engines.
400 = a small surplus that can be sandbagged for future use?
I think I unintentionally started something here. :(
When I "sandbag" an item, it's usually something hard to get, so I build up a surplus of it.
Whatever the "Urban Dictionary" says is not my definition.

Elon's reference to sandbagging was derating the performance spec of the F9 with M1D so that things like engine-out and 1st stage recovery by a deceleration burn would be standard features.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Ronsmytheiii on 08/16/2011 06:07 pm
from our very own Padrat:

Quote
got to watch a Merlin run...

http://twitter.com/#!/LH2Padrat
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 08/16/2011 06:12 pm
Looks like a upper stage MVac run... Assuming that is an integrated stage and not a generic tank.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Zed_Noir on 08/16/2011 06:18 pm
Why would SpaceX developed the hypergolic Super Draco as a 3rd stage motor when the KeroLox Kestrel  motor is available. You could just put the Falcon 1 upper stage on top of the Falcon 9 stack as is for a 3rd stage inside the current reference F9 PLF with small external solar array band.
Well, the cryogenic LOX would limit the useful life of the stage on orbit, and kestrel has limited restarts.

Unless the mission requires more than several US restarts and last more than a couple of days. the current F1 US is adequate for EDS role and apogee kick role. The important thing is no new development required and the stage & engine are available now.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/16/2011 06:26 pm
Looks like a upper stage MVac run... Assuming that is an integrated stage and not a generic tank.

No, that's just a tank to feed the single Merlin.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/16/2011 06:50 pm
Thanks for the pics!

Question, are all Merlin engins test fired singlely before attaching to the stages or just the M1CVAC?

I know the 1st stage is hot fired as an integrated unit, but are the M1C's test fired singlely before attachment?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/16/2011 06:57 pm
Apparently all the engines. I believe this one was also tested on VTS3:

http://www.spacex.com/assets/img/20090616_merlin.jpg
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 08/16/2011 07:00 pm
Looks like a upper stage MVac run... Assuming that is an integrated stage and not a generic tank.

No, that's just a tank to feed the single Merlin.
Merlin 1D?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris-A on 08/16/2011 07:00 pm
Gimballing tests are done on the tower. (An old video from testing was hosted somewhere)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/16/2011 07:02 pm
Merlin 1D?

No reason to believe that. I know of at least several M1c's being acceptance-tested there. Perhaps the majority of them all.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 08/16/2011 07:09 pm
Merlin 1D?

No reason to believe that. I know of at least several M1c's being acceptance-tested there. Perhaps the majority of them all.
I see. So, probably only a, say, 2-10% chance of being a Merlin 1D, considering how many Merlin 1Cs they have to prepare for acceptance testing... 9 per flight, with the first Merlin 1D flight being somewhere around flight 7, right? So, at least 27 Merlin 1Cs need to be tested, though they probably need to test the Merlin 1D longer since it's a newer engine and they're probably trying to get more data from it.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/16/2011 07:16 pm
Looks like a upper stage MVac run... Assuming that is an integrated stage and not a generic tank.

No, that's just a tank to feed the single Merlin.
Merlin 1D?

ahhhh we just need to park with a super lens to get a pic of the Merlin 1D.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/16/2011 07:25 pm
Merlin 1D?

No reason to believe that. I know of at least several M1c's being acceptance-tested there. Perhaps the majority of them all.

If they are currently manufacturing M1C's at the rate of 2 a week and they test each singly then McGerger is kept hopping just testing M1C’s, let alone the firings with stages test and development tests. That’s also a 1st stage test ever 5 weeks. If that’s the current rate of the 1st stage test firings then the 100 engines being built this year are all Merlins. If not then the 100 value stated by Ms Shotwell is some mixture of Draco's and Merlin's.

So any info on how often 1st stage test firings been occuring in the last 6 months?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/16/2011 08:05 pm
That’s also a 1st stage test ever 5 weeks.
I don't think that's right. You can't hide a F9 first stage test easily and they made a habit of announcing any such firings to the public in lieu of that November 2008 episode.

Quote
So any info on how often 1st stage test firings been occuring in the last 6 months?

As far as I can tell, just one 1st stage fired several times due to test aborts, the COTS C2 stage. Prior to that was June of last year.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/16/2011 08:10 pm
That’s also a 1st stage test ever 5 weeks.
I don't think that's right. You can't hide a F9 first stage test easily and they made a habit of announcing any such firings to the public in lieu of that November 2008 episode.

Quote
So any info on how often 1st stage test firings been occuring in the last 6 months?

As far as I can tell, just one 1st stage fired several times due to test aborts, the COTS C2 stage. Prior to that was June of last year.

So maybe 30 engines out of 100 are actually Merlins? The other 70 are Dracos?

Thats about the right ratio for three Dragon flights.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/16/2011 09:15 pm
Already been discussed in another recent thread.
Somehow we concluded the Dracos probably don't go into that figure.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 08/16/2011 09:26 pm
Are they still doing full 1st stage tests? Some posters here (Jim?) were suggesting that such tests should become rare once F9 has some flight history. They know the whole stage works together now - so they just test each engine.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: JMS on 08/16/2011 09:41 pm
The caption for the thrust assembly pictured in the latest SpaceX update (not sure which assembly it is...) says:"All nine Merlin engines have been individually tested in Texas and then returned to California for integration into the thrust assembly".
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: corrodedNut on 08/16/2011 11:10 pm
Are they still doing full 1st stage tests? Some posters here (Jim?) were suggesting that such tests should become rare once F9 has some flight history. They know the whole stage works together now - so they just test each engine.

I think the conventional wisdom is that hot-fire tests at the pad will be phased out, not the stage acceptance tests at McGregor.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/17/2011 12:33 pm
Are they still doing full 1st stage tests? Some posters here (Jim?) were suggesting that such tests should become rare once F9 has some flight history. They know the whole stage works together now - so they just test each engine.

I think the conventional wisdom is that hot-fire tests at the pad will be phased out, not the stage acceptance tests at McGregor.
Agreed, worst case scenario they have the hold before release capability.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/17/2011 12:59 pm
Agreed, worst case scenario they have the hold before release capability.

Just as everyone else.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 08/17/2011 03:09 pm
Agreed, worst case scenario they have the hold before release capability.

Just as everyone else.

I seem to recall reading that some russian LV's (like Soyuz) do not have hold before release - as soon as there is enough thrust it lifts off. But I could be wrong.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/17/2011 06:46 pm
When would M1D’s have to start into production?

Flight 7 launch would have a tentative launch date of Oct 2012.

The 1st stage arrives at Cape for Flt 7 two months prior Aug 2012.

The 1st stage goes through hotfire testing at McGregor  Jul 2012.

The M1D’s are integrated to the 1st stage Jun 2012.

The M1D’s undergo testing singly at McGregor Apr-May 2012.

If the MFC process for an M1D takes 6 months from start to a finished product where multiple engines in groups of 9 with 1-2 months separating each group then M1D production would have to start Oct 2011! Long lead items taking a year would have already been ordered/in production since Apr 2011.

Do we have any info on how long the M1C MFC process from start to a finished M1C is?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/17/2011 07:09 pm
Corollary would be that the first flight of a M1DVAC would be at about a year later Oct 2013 or Flight 13/14/15 possibly the first DragonLab if a test article has yet to have been produced.

If a M1DVAC is to be flown on the FH first flight Feb-Apr 2013 then the M1DVAC test article is already being manufactured and will begin testing shortly.

So watch for announcements of M1DVAC testing starting.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/17/2011 07:16 pm
So watch for announcements of M1DVAC testing starting.

I'll rather wait for the announcement that M1d finished qualification testing. My uneducated WAG puts that at end of this year/early next year.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: simonbp on 08/17/2011 08:06 pm
Agreed, worst case scenario they have the hold before release capability.
Just as everyone else.
I seem to recall reading that some russian LV's (like Soyuz) do not have hold before release - as soon as there is enough thrust it lifts off. But I could be wrong.

The Titans didn't, as the ICBM versions were designed to launch ASAP; the Titan II could go from key turn to launch in 58 seconds. Also, in the orbital Titan II case, you really didn't want too much hypergolic exhaust accumulating on the pad...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/17/2011 08:36 pm
Anything that uses solids doesn't have that. The shuttle obviously didn't have that. A lot of liquids don't have it too.
What I know is SpaceX stated they can abort and  relaunch within a few hours.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 08/17/2011 08:52 pm
They've already done pad abort and a rapid reset to launch; Falcon 9-Flight 1 in about 01:15,00.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 08/17/2011 08:55 pm
Corollary would be that the first flight of a M1DVAC would be at about a year later Oct 2013 or Flight 13/14/15 possibly the first DragonLab if a test article has yet to have been produced.

Or the corollary to the corollary would be the "first flight of a M1Dvac would be at about a year later Oct 2013 or Flight" ...... 7.  ;-)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 08/17/2011 09:46 pm
Agreed, worst case scenario they have the hold before release capability.
Just as everyone else.
I seem to recall reading that some russian LV's (like Soyuz) do not have hold before release - as soon as there is enough thrust it lifts off. But I could be wrong.

The Titans didn't, as the ICBM versions were designed to launch ASAP; the Titan II could go from key turn to launch in 58 seconds. Also, in the orbital Titan II case, you really didn't want too much hypergolic exhaust accumulating on the pad...

The Titans had explosive bolts
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 08/17/2011 09:50 pm
Anything that uses solids doesn't have that. The shuttle obviously didn't have that. A lot of liquids don't have it too.


False logic, nothing but PR spin..  Solids don't need it.

Shuttle did have it. The solids weren't lit until the SSMEs were good.  Same applies for Atlas and Delta. 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/17/2011 10:20 pm
Anything that uses solids doesn't have that. The shuttle obviously didn't have that. A lot of liquids don't have it too.


False logic, nothing but PR spin..  Solids don't need it.

Shuttle did have it. The solids weren't lit until the SSMEs were good.  Same applies for Atlas and Delta. 

Can you elaborate on why solids don't need it?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 08/17/2011 10:21 pm
What's to elaborate? Either they're not ignited and the rocket is sitting on the pad or they're ignited and it's going somewhere, no shutting them down.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/18/2011 01:11 am
Were wandering far off topic, not even liquid engines.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/18/2011 01:50 am
When would M1D’s have to start into production?

Flight 7 launch would have a tentative launch date of Oct 2012.

The 1st stage arrives at Cape for Flt 7 two months prior Aug 2012.

The 1st stage goes through hotfire testing at McGregor  Jul 2012.

The M1D’s are integrated to the 1st stage Jun 2012.

The M1D’s undergo testing singly at McGregor Apr-May 2012.

If the MFC process for an M1D takes 6 months from start to a finished product where multiple engines in groups of 9 with 1-2 months separating each group then M1D production would have to start Oct 2011! Long lead items taking a year would have already been ordered/in production since Apr 2011.

Do we have any info on how long the M1C MFC process from start to a finished M1C is?

Great thinking !

from what I've viewed SpaceX can manufacture around 100 engines a year.   Factor in they are "testing" new process(s) for the M1D program.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 08/18/2011 02:19 am
Anything that uses solids doesn't have that. The shuttle obviously didn't have that. A lot of liquids don't have it too.


False logic, nothing but PR spin..  Solids don't need it.

Shuttle did have it. The solids weren't lit until the SSMEs were good.  Same applies for Atlas and Delta. 

Can you elaborate on why solids don't need it?

They always ignite and achieve liftoff thrust. 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kraisee on 08/18/2011 02:29 am
Which doesn't solve unless B= negative 6,000 lbs, etc.

I knew it!!! SpaceX must have invented anti-gravity along the way  ;D ;D

Nah, that'd be Jeff Bezos! ;)   He's probably got 492 patents coming on that one...

Ross.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: padrat on 08/18/2011 12:44 pm
Sorry for the late reply. I was told that was a 1C. They did say that the stand can run all 9 at once as well.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: simonbp on 08/18/2011 04:24 pm
Presumably then for Flight 5, as the recent update on the Space X website said that all the Flight 4 engines were back in California for integration on the thrust structure.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/18/2011 04:45 pm
Do you guys think that the first flight of the 1d will feature 9 1d engines?
or might they decide to do something like put a 1d at 70% thrust in the middle and the rest of the engines being 1c ?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Nate_Trost on 08/18/2011 04:57 pm
I can't imagine they are going to mix 1C and 1D.

Where my head starts to hurt is trying to figure out if they are doing a first stage tank stretch on the initial Merlin 1D Falcon 9. It seems like the FH stages will be stretched, but I don't think we've seen confirmation that they could actually process a stretched F9 in their current hanger. Would they just fly an unstretched Merlin 1D Falcon 9 at a lower throttle and more closely match the Block 1 flight profile, or will the existing tank capacity work for a launch at 100%?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MikeAtkinson on 08/18/2011 05:10 pm
My head hurts too, thinking about it, there are lots of options.

However, I think they will go for everthing at once. This has several advantages, not least that it keeps the number of configurations manageable.

So, 9 M1D on a stretched 1st stage and a M1D Vac on a stretched second stage and a stretched hanger. Designed for 1st stage recovery using up to 15 tonnes of propellant.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 08/18/2011 05:43 pm
Which would mean 16mt to LEO, I believe Elon said the initial capability would be 13mt to LEO.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MikeAtkinson on 08/18/2011 05:46 pm
No, the 15 tonnes of propellant for recovery brings it back to about 13 tonnes to LEO (or thereabouts depending on what over recovery hardware is included and the exact spec of the upper stage).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/21/2011 06:26 pm
Are M1D’s in production yet? 

Answer to this is “unknown”.

 Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines this year. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

FLT 5 has a tentative Launch date of Apr 2012. That’s 8 months lead time for when mounting engines on the stage occurs. If this schedule is done also for FLT 7, the first M1D flight, then a flight set of 9 M1D’s tested singly and mounted to the stage would occur Feb 2012. That would imply that a full set of flight M1D’s would finish production prior to Dec 31 2011. This also seems to indicate that M1D’s are in production now.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/21/2011 10:38 pm
Are M1D’s in production yet? 

Answer to this is “unknown”.

 Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines this year. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

FLT 5 has a tentative Launch date of Apr 2012. That’s 8 months lead time for when mounting engines on the stage occurs. If this schedule is done also for FLT 7, the first M1D flight, then a flight set of 9 M1D’s tested singly and mounted to the stage would occur Feb 2012. That would imply that a full set of flight M1D’s would finish production prior to Dec 31 2011. This also seems to indicate that M1D’s are in production now.


Wouldn't you need 28 of these for FH? 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 08/22/2011 12:19 am
Are M1D’s in production yet? 

Answer to this is “unknown”.

 Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines this year. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

FLT 5 has a tentative Launch date of Apr 2012. That’s 8 months lead time for when mounting engines on the stage occurs. If this schedule is done also for FLT 7, the first M1D flight, then a flight set of 9 M1D’s tested singly and mounted to the stage would occur Feb 2012. That would imply that a full set of flight M1D’s would finish production prior to Dec 31 2011. This also seems to indicate that M1D’s are in production now.


Wouldn't you need 28 of these for FH? 

Here I am mainly talking about 1st stage engines. By the time of FH's 1st stages being readied 6 months later an addition 54 M1D's for just the 1st stages should have been completed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/22/2011 03:29 am
Are M1D’s in production yet? 

Answer to this is “unknown”.

 Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines this year. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

FLT 5 has a tentative Launch date of Apr 2012. That’s 8 months lead time for when mounting engines on the stage occurs. If this schedule is done also for FLT 7, the first M1D flight, then a flight set of 9 M1D’s tested singly and mounted to the stage would occur Feb 2012. That would imply that a full set of flight M1D’s would finish production prior to Dec 31 2011. This also seems to indicate that M1D’s are in production now.


Wouldn't you need 28 of these for FH? 

Here I am mainly talking about 1st stage engines. By the time of FH's 1st stages being readied 6 months later an addition 54 M1D's for just the 1st stages should have been completed.

oh, thought flight 7 was FH.   To change out Falcon 9 with a brand new engine would be a mistake at this time.  It sarts SpaceX at square 1 again.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/31/2011 09:22 pm
Are M1D’s in production yet? 

Answer to this is “unknown”.

 Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines this year. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

FLT 5 has a tentative Launch date of Apr 2012. That’s 8 months lead time for when mounting engines on the stage occurs. If this schedule is done also for FLT 7, the first M1D flight, then a flight set of 9 M1D’s tested singly and mounted to the stage would occur Feb 2012. That would imply that a full set of flight M1D’s would finish production prior to Dec 31 2011. This also seems to indicate that M1D’s are in production now.


Wouldn't you need 28 of these for FH? 

Here I am mainly talking about 1st stage engines. By the time of FH's 1st stages being readied 6 months later an addition 54 M1D's for just the 1st stages should have been completed.

http://www.nasa.gov/pdf/580728main_5%20-%20Suffredini%20NAC%20August%202%202011_508.pdf

saw one pic with the top of the engines shown.....when time permits, might be some very usefull info.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 09/02/2011 06:17 pm
The info in the link is related to the fact that the F9 FLT-4 M1C engines are being mounted now. So FLT-5 M1C set is probably in test now and FLT-6 MIC set is probably finishing up production now as well (the last first stage M1C's).

Summary of what we know so far:

I removed the M1D VAC column and put it into its own table:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf??
Vac Thrust155klbf?(better than expected)?(expect even better)
SL isp280s???
Vac isp310s309s??
T/W160??
Chamber Pressure1410psi??
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%?
Engine weight 440kg???
Costs<M1C?-?

Notes on manufacturing:
1) Ability to manufacture TC’s and bells at the demonstrated rate of >=2/day or ~500/year by using explosive forming.
2) Changeover from M1C of manufacturing TC’s and bells is only a matter of swapping molds. This also enables the capability to manufacture both M1CVAC and M1D’s without any significant cost penalties for this part of the process.
3) M1D’s are not in production yet?  Answer to this is “unknown”. Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

Notes on testing of test article:
1) Over 150 test fires conducted to date.
2) Testing is still ongoing?



So here is a new table just for the M1DVAC with speculative design to specs that meet these constraints:
1) Max g of 6g
2) Maximize commonality to M1D. Use of exact same turbo pump as M1D.
3) No thrust derating
4) Use only with non stretched US for payloads >7MT and for all payloads with stretched US.

EngineMerlin 1DVAC (Design)Merlin 1DVAC (Test article)Merlin 1DVAC (Production)
Vac Thrust174klbf???
Vac isp348s?(an educated WAG)??
T/W160???
Chamber Pressure1410psi???
Expansion???
Throttle range70-100%???
Engine weight >440kg???
Costs<M1CVAC?-?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: DaveH62 on 09/02/2011 10:15 pm
The info in the link is related to the fact that the F9 FLT-4 M1C engines are being mounted now. So FLT-5 M1C set is probably in test now and FLT-6 MIC set is probably finishing up production now as well (the last first stage M1C's).

Summary of what we know so far:

I removed the M1D VAC column and put it into its own table:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf??
Vac Thrust155klbf?(better than expected)?(expect even better)
SL isp280s???
Vac isp310s309s??
T/W160??
Chamber Pressure1410psi??
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%?
Engine weight 440kg???
Costs<M1C?-?

Notes on manufacturing:
1) Ability to manufacture TC’s and bells at the demonstrated rate of >=2/day or ~500/year by using explosive forming.
2) Changeover from M1C of manufacturing TC’s and bells is only a matter of swapping molds. This also enables the capability to manufacture both M1CVAC and M1D’s without any significant cost penalties for this part of the process.
3) M1D’s are not in production yet?  Answer to this is “unknown”. Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

Notes on testing of test article:
1) Over 150 test fires conducted to date.
2) Testing is still ongoing?



So here is a new table just for the M1DVAC with speculative design to specs that meet these constraints:
1) Max g of 6g
2) Maximize commonality to M1D. Use of exact same turbo pump as M1D.
3) No thrust derating
4) Use only with non stretched US for payloads >7MT and for all payloads with stretched US.

EngineMerlin 1DVAC (Design)Merlin 1DVAC (Test article)Merlin 1DVAC (Production)
Vac Thrust174klbf???
Vac isp348s?(an educated WAG)??
T/W160???
Chamber Pressure1410psi???
Expansion???
Throttle range70-100%???
Engine weight >440kg???
Costs<M1CVAC?-?

Great matrix, very helpful.
So where would this put the rocket performance? Would they be above the original estimate of 53mt for FH? Trying to understand the impact of M1DVAC and Raptor combination.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 09/02/2011 10:16 pm
To get the higher thrust etc.  How much larger will the 5 inch feed lines have to go ya think?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 09/03/2011 12:00 am
To get the higher thrust etc.  How much larger will the 5 inch feed lines have to go ya think?

On the output side of the turbo pump not much change in size because of the increase in operating preasures, but some increase would probably occur. The biggest change would be the input lines to the turbo pump to increase the volume of flow to keep from cavitating. Thrust increase is >50% so 6 inch lines a 44% increase wouldn't be a surprise.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 09/03/2011 12:06 am
So where would this put the rocket performance? Would they be above the original estimate of 53mt for FH? Trying to understand the impact of M1DVAC and Raptor combination.

FH’s 53MT performance value is using M1DVAC. So it depends on the actual ISP’s and actual thrust levels of the production engines to determine if the actual FH performance could be better or worse than the 53MT. Experience has shown that it may be a little worse than 53MT, but the comments coming out of SpaceX leads you to believe that the actual performance will be better.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 09/03/2011 11:35 am
ISTR M1C vac has lower chamber pressure than M1C SL, to optimise for Isp over thrust. Would same be true for M1D vac?

Would be good to see flown M1C figures (eg from flights) on those tables for comparison.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 09/10/2011 01:39 am
The requested M1C and M1CVAC flight values have been added to the tables for comparison.

EngineMerlin 1C (Flight)Merlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust95klbf (ref1)140klbf??
Vac Thrust108.5klbf (ref1)155klbf?(better than expected)?(expect even better)
SL isp266s (ref1)280s???
Vac isp304s (ref1)310s309s??
T/W92 (ref1)160??
Chamber Pressure1000psi?1410psi??
Expansion?1616?16?(this shouldn’t vary much from design)
Throttle range100% only70-100%70%-100%?70%-100%?
Engine weight 469kg? (calculated)440kg???
Costs>$1M?<M1C?-?

ref1) Values from SpaceX.
http://www.spacex.com/downloads/cots1-20101206.pdf (http://www.spacex.com/downloads/cots1-20101206.pdf)
 http://www.spacex.com/press.php?page=33 (http://www.spacex.com/press.php?page=33)

Notes on manufacturing:
1) Ability to manufacture TC’s and bells at the demonstrated rate of >=2/day or ~500/year by using explosive forming.
2) Changeover from M1C of manufacturing TC’s and bells is only a matter of swapping molds. This also enables the capability to manufacture both M1CVAC and M1D’s without any significant cost penalties for this part of the process.
3) M1D’s are not in production yet?  Answer to this is “unknown”. Since  FLT 5 engines have been mounted on the 1st Stage then FLT 6 engines are in test now, meaning just about all the M1C’s that will be produced have been produced, 27-36 engines. That also means M1D’s have a high probability of being in limited production now. At the end of the engineering test article testing they need a couple of production engines to do qual test on final design version.

Notes on testing of test article:
1) Over 150 test fires conducted to date.
2) Testing is still ongoing?



Table just for the M1DVAC with speculative design to specs that meet these constraints:
1) Max g of 6g
2) Maximize commonality to M1D. Use of exact same turbo pump as M1D.
3) No thrust derating
4) Use only with non stretched US for payloads >7MT and for all payloads with stretched US.

EngineMerlin 1CVAC (flight)Merlin 1DVAC (Design)Merlin 1DVAC (Test article)Merlin 1DVAC (Production)
Vac Thrust92.5klbf (ref1)174klbf???
Vac isp336s (ref1)348s?(an educated WAG)??
T/W<92?160???
Chamber Pressure1000psi?1410psi???
Expansion????
Throttle range70-100%?70-100%???
Engine weight >469kg?>440kg???
Costs>$1M?<M1CVAC?-?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Salo on 09/26/2011 05:21 am
Quote
2.1.1 Grasshopper RLV
2.1.1.1 Description
The Grasshopper RLV consists of a Falcon 9 Stage 1 tank, a Merlin-1D engine, four steel landing legs, and a steel support structure. Carbon overwrapped pressure vessels (COPVs), which are filled with either nitrogen or helium, are attached to the support structure. The Merlin- 1D engine has a maximum thrust of 122,000 pounds. The overall height of the Grasshopper RLV is 106 feet, and the tank height is 85 feet.
Source (http://www.faa.gov/about/office_org/headquarters_offices/ast/media/20110922%20SpaceX%20Grasshopper%20Draft%20EA.Final.pdf)

What happened? This is less then Merlin-1C+ maximum thrust.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: beancounter on 09/26/2011 06:45 am
Quote
2.1.1 Grasshopper RLV
2.1.1.1 Description
The Grasshopper RLV consists of a Falcon 9 Stage 1 tank, a Merlin-1D engine, four steel landing legs, and a steel support structure. Carbon overwrapped pressure vessels (COPVs), which are filled with either nitrogen or helium, are attached to the support structure. The Merlin- 1D engine has a maximum thrust of 122,000 pounds. The overall height of the Grasshopper RLV is 106 feet, and the tank height is 85 feet.
Source (http://www.faa.gov/about/office_org/headquarters_offices/ast/media/20110922%20SpaceX%20Grasshopper%20Draft%20EA.Final.pdf)

What happened? This is less then Merlin-1C+ maximum thrust.

Could be they've now stopped production of the 1C and scaled back the 1D for this vehicle!?  Just a WAG!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: tegla on 09/26/2011 07:36 am
What happened? This is less then Merlin-1C+ maximum thrust.
Maybe it's a modified version, where they improved throttleability at the cost of max thrust?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Crispy on 09/26/2011 11:52 am
Small point: Consistent units please! (you've got kg and lbf)
Preferably metric, but that's just me.
And the rest of the world :p
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 09/26/2011 03:23 pm
I understand your pain at a mixture of English and Metric units but thrust has always been given in lbf for a historical comparison of engine size. That is why that measure is in lbf. The other measures are easier to handle in metric except for chamber pressure which is another of those historical reference problems. When the sources give values [SpaceX] the units are usually the way that they show in the table. There is also a PR value in using the units that are used, which is one reason that there is such a mix of units. Using lbf for thrust gives a larger value making the engine appear better as well as using kg for weight making it appear lighter. Newton’s is beginning to catch on for thrust but Pascal’s are not for some reason. If you wish you can update the table to show the Metric values in parenthesis for thrust and chamber pressure.

On another subject the Grasshopper M1D specs in the Government document can be a multitude of reasons why it shows 122klbf.
1) The engine actually used is a refurbished test article, which makes a sort of sense, don’t throw anything away if you can reuse it.
2) The request for permit that included the Grasshopper definition could have been submitted before M1D testing got started very far and the value listed is the first confirmed thrust value for the engine.
3) They were always going to use a throttled down M1D in the tests to reduce flight dynamics controllability problems.
4) The engine has a high likelihood of being a skirtless M1DVAC configuration which could as well have a lower SL thrust than a regular M1D on purpose.

So none of these can be discarded or accepted until more information about when the request was filled and what actual engine is being used.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 09/26/2011 05:08 pm
4) The engine has a high likelihood of being a skirtless M1DVAC configuration which could as well have a lower SL thrust than a regular M1D on purpose.

This is an excellent point.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mr. mark on 10/14/2011 06:02 pm
First pic from McGregor test.-Spacex Facebook
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 10/14/2011 08:47 pm
Merlin 1C (from http://www.spacex.com/falcon9.php) vs this image of the Merlin 1D at approximately the same scale.  (Merlin 1C image mirrored to put exhaust on right side.)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: SpacexULA on 10/14/2011 09:25 pm
I know Merlin 1D is regen cooled, but the nozzle looks more like an ablative that any regen cooled nozzle I have ever seen... Where are the pipes/ripples in the nozzle?

It looks a lot more like the Merlin 1A than the 1C, anyone know where you can find a nice 1A test stand picture?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mmeijeri on 10/14/2011 09:29 pm
First pic from McGregor test.-Spacex Facebook

Heh, looks like a museum of modern art!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 10/14/2011 09:36 pm
I know Merlin 1D is regen cooled, but the nozzle looks more like an ablative that any regen cooled nozzle I have ever seen... Where are the pipes/ripples in the nozzle?

It looks a lot more like the Merlin 1A than the 1C, anyone know where you can find a nice 1A test stand picture?
If I'm not mistaken, it's the same technique of the NK-33. Instead of pipes they put corrugated metal brazed to an outer and inner lining. Look at the modern Russian engines. None have pipes.
BTW, NEW test stand.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: M_Puckett on 10/14/2011 09:36 pm
I know Merlin 1D is regen cooled, but the nozzle looks more like an ablative that any regen cooled nozzle I have ever seen... Where are the pipes/ripples in the nozzle?

It looks a lot more like the Merlin 1A than the 1C, anyone know where you can find a nice 1A test stand picture?

Mabey is is a channel wall design.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 10/14/2011 11:30 pm
Appearances can be deceiving, but it certainly looks like Merlin 1D design has been simplified compared to the 1C.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 10/14/2011 11:52 pm
I know Merlin 1D is regen cooled, but the nozzle looks more like an ablative that any regen cooled nozzle I have ever seen... Where are the pipes/ripples in the nozzle?

It looks a lot more like the Merlin 1A than the 1C, anyone know where you can find a nice 1A test stand picture?
If I'm not mistaken, it's the same technique of the NK-33. Instead of pipes they put corrugated metal brazed to an outer and inner lining. Look at the modern Russian engines. None have pipes.
BTW, NEW test stand.

The nozzle shape is a tad different (maybe  larger).  Would like to know what test model of D or how long ago this was taken.
That glowing piping is also a dead give away.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: peter-b on 10/15/2011 12:01 am
That glowing piping is also a dead give away.

What do you make of it? I don't know a lot about these engines...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 10/15/2011 12:21 am
The piping isn't glowing - it looks like reflected light from the flames below.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 10/15/2011 01:06 am
Definitely a “clean” looking engine, but a picture of both sides of both engines would be better to make that determination.

Do we have a picture of the other side of the M1C?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 10/15/2011 01:59 am
The piping isn't glowing - it looks like reflected light from the flames below.

still think its glowing, compare it to the other parts.  Also lookbehind the part it looks like a heat shield.
Possible: part is same material as Merlin Vac
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jason1701 on 10/15/2011 02:02 am
Definitely a “clean” looking engine, but a picture of both sides of both engines would be better to make that determination.

Do we have a picture of the other side of the M1C?

Here:

For comparison, here's 1a:


Mode Edit: Do not embed imaged
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 10/15/2011 02:05 am
That glowing piping is also a dead give away.

What do you make of it? I don't know a lot about these engines...

Looks like a very simple way to get more pressure.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: starsilk on 10/15/2011 02:47 am
First pic from McGregor test.-Spacex Facebook

Heh, looks like a museum of modern art!

it reminds me of some of the 'Imperial' sets from (original) Star Wars. I think its the inward angled part of the 'ceiling'.

very neat looking picture..
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lee Jay on 10/15/2011 03:00 am
The piping isn't glowing - it looks like reflected light from the flames below.

still think its glowing,

If it were glowing, the whole thing would be glowing and not just the bottom.  It's a reflection.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: alexw on 10/15/2011 03:52 am
First pic from McGregor test.-Spacex Facebook
Heh, looks like a museum of modern art!
   Ha, so it does! See you at the Guggenheim.
       -Alex
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Ronsmytheiii on 10/15/2011 04:15 am
The piping isn't glowing - it looks like reflected light from the flames below.

still think its glowing,

If it were glowing, the whole thing would be glowing and not just the bottom.  It's a reflection.

The pipe could be hot from channeling the preburn exhaust, which would be pretty hot in itself.  That would explain why that pipe is glowing and not the others.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Pedantic Twit on 10/15/2011 04:25 am
I hate to be a downer, but compare it to this picture (http://www.spacex.com/images/Merlin_1C_Falcon_1_engine.jpg), this picture (http://www.spacex.com/00Graphics/Images/F9Update0807/10%20Merlin%20at%20DarpaTech.jpg) or this picture (http://media.photobucket.com/image/merlin%20rocket%20engine/NellaSelim/merlinvac.jpg) from a similar angle.
It's a very reflective insulated section of pipe.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 10/15/2011 12:57 pm
I hate to be a downer, but compare it to this picture (http://www.spacex.com/images/Merlin_1C_Falcon_1_engine.jpg), this picture (http://www.spacex.com/00Graphics/Images/F9Update0807/10%20Merlin%20at%20DarpaTech.jpg) or this picture (http://media.photobucket.com/image/merlin%20rocket%20engine/NellaSelim/merlinvac.jpg) from a similar angle.
It's a very reflective insulated section of pipe.

Precisely. Guaranteed to be running LOX through, which is why there's also vapor generated there and sucked toward the flame trench.

Also have to echo what others have said, this stand does look artsy.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 10/15/2011 03:55 pm
The test stand looks to be purpose built for rapid acceptance testing of M1D engines. Since the stand is a dual test stand it would be designed to be able to do one test per stand per work day, 2 firings in one day, in order to test 400 engines in 1 year. I wonder if there is a cart that rolls up under the mount so that the engine can be bolted on or removed quickly and easily.

They would need a different stand for M1DVAC engines if tested with the extension.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 10/15/2011 04:01 pm
Why would they need a different test stand for M1Dvac ?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 10/15/2011 04:05 pm
They would need a different stand for M1DVAC engines if tested with the extension.

I don't think they can test them with the extension without a vacuum chamber. They already have two stands for MVac, one for the engine and another for the stage acceptance firing. That's probably adequate given how they'd need 9x fewer MVac tests done.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: arnezami on 10/15/2011 04:48 pm
I think the most significant difference is the absence of the "Nozzle Fuel Return Lines" and a nozzle that doesn't look regeneratively cooled, but must be.

The "Fuel Main Valve" cannot be seen, but must be behind the chamber/nozzle in the 1d picture.

See diagram below.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 10/16/2011 09:49 pm
You seem to be correct that the "Nozzle Fuel Return Lines" no longer exist in the form they were on the M1C. That means that the Nozzle regen cooling on the M1D is vastly different from the M1C. One of the changes that removes weight, complexity and costs. But the TC regen may still be similar or the same as it was for M1C.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 10/16/2011 11:29 pm
I'm not sure, but corrugated metal sandwitched between two layers, allows you to have the inner channels for cooling, and the outer channels for return.
It's true that the expansion ratio went from 14.5 to 16. But the nozzle seems a lot more "steep". I'm wondering if this is not an effect of keeping a constant channel profile area. In other words, if you cut the nozzel from below, you'd see an inner layer, a sawtooth like channels, and an outer layer. So the fuel cools when passing through the "inner" triangles, and returns through the "outer" triangles. But to keep the same area, the triangles have to get very "steep" towards the throat. So, the external profile would get more "steep", too. I don't know if my word are clear.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: brtbrt on 10/16/2011 11:59 pm
I'm not sure, but corrugated metal sandwitched between two layers, allows you to have the inner channels for cooling, and the outer channels for return.
It's true that the expansion ratio went from 14.5 to 16. But the nozzle seems a lot more "steep". I'm wondering if this is not an effect of keeping a constant channel profile area. In other words, if you cut the nozzel from below, you'd see an inner layer, a sawtooth like channels, and an outer layer. So the fuel cools when passing through the "inner" triangles, and returns through the "outer" triangles. But to keep the same area, the triangles have to get very "steep" towards the throat. So, the external profile would get more "steep", too. I don't know if my word are clear.

It might be hard to bend a corrugated shape into the complex 3D shape of the nozzle. In the past, there have been pictures of a SpaceX copper chamber/nozzle having cooling channels machined into it. This might be what's going on on the M1D. And the outer layer is either electro-deposited, brazed, or welded on top. Just a guess.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 10/17/2011 12:04 am
In addition to two surprisingly large cameras, there is a ring above the engine with eight lines pointed approximately at the turbopump.  Does anyone have any idea what they are?

PS As someone from a place with some half century old buildings and test equipment, the new, purpose-built test chamber looks particularly sleek and clean. 8)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 10/17/2011 12:07 am
In addition to two surprisingly large cameras, there is a ring above the engine with eight lines pointed approximately at the turbopump.  Does anyone have any idea what they are?
Those remind me of the cooling hoses on a mill. But I'd speculate that are part of a fire suppression system, just in case.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 10/17/2011 01:03 am
It might be hard to bend a corrugated shape into the complex 3D shape of the nozzle. In the past, there have been pictures of a SpaceX copper chamber/nozzle having cooling channels machined into it. This might be what's going on on the M1D. And the outer layer is either electro-deposited, brazed, or welded on top. Just a guess.
I think they mentioned they were switching from electro deposition to explosive forming.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: joek on 10/17/2011 01:52 am
I think they mentioned they were switching from electro deposition to explosive forming.

IIRC that was for the thrust chamber; no mention of the nozzle(?).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 10/17/2011 03:50 am
I think they mentioned they were switching from electro deposition to explosive forming.

IIRC that was for the thrust chamber; no mention of the nozzle(?).

was 3 a week or was that a month made.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: DigitalMan on 10/17/2011 04:06 am
I think they mentioned they were switching from electro deposition to explosive forming.

IIRC that was for the thrust chamber; no mention of the nozzle(?).

was 3 a week or was that a month made.

There was an article that had indicated several per day.  I don't see how they could reach their target of 400 engines per year if they could only do 3 per week.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: 2552 on 10/17/2011 04:32 am
That would be this article from April 25:

http://spacenews.com/profiles/110425-elon-musk.html
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 10/17/2011 11:43 am
It might be hard to bend a corrugated shape into the complex 3D shape of the nozzle. In the past, there have been pictures of a SpaceX copper chamber/nozzle having cooling channels machined into it. This might be what's going on on the M1D. And the outer layer is either electro-deposited, brazed, or welded on top. Just a guess.
The benefit of a "corrugated" structure, is two fold. First, is naturally stronger, so you can do it lighter. If I'm not mistaken, it only works if you fill the outer passages with some liquid at a similar pressure of the inner passages. So it sort of forces you to use it for cooling liquid return, saving a lot of plumbing.
There's an easy and fast way to do the complicated corrugated forming, and that's with a huge hydraulic press. Make two dies, put a disk of your favorite maraging steel, or whatever you decide to use, and press a button. Of course it will require a significant investment in tooling, but then you could produce many corrugated parts per day. If you add a couple of dies, you could use the same machine for the inner and outer layers. Then, it's only a problem of stacking the three parts and putting it in the brazing oven. Expensive down payment, but extremely cheap to produce afterwards. What's more, it very low overhead.
If the union at the "vertices" could be spin welded, they could save all that and just weld the parts. A lot more work, though. But also a lot more flexible for development.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: brtbrt on 10/17/2011 02:23 pm
It might be hard to bend a corrugated shape into the complex 3D shape of the nozzle. In the past, there have been pictures of a SpaceX copper chamber/nozzle having cooling channels machined into it. This might be what's going on on the M1D. And the outer layer is either electro-deposited, brazed, or welded on top. Just a guess.
The benefit of a "corrugated" structure, is two fold. First, is naturally stronger, so you can do it lighter. If I'm not mistaken, it only works if you fill the outer passages with some liquid at a similar pressure of the inner passages. So it sort of forces you to use it for cooling liquid return, saving a lot of plumbing.
There's an easy and fast way to do the complicated corrugated forming, and that's with a huge hydraulic press. Make two dies, put a disk of your favorite maraging steel, or whatever you decide to use, and press a button. Of course it will require a significant investment in tooling, but then you could produce many corrugated parts per day. If you add a couple of dies, you could use the same machine for the inner and outer layers. Then, it's only a problem of stacking the three parts and putting it in the brazing oven. Expensive down payment, but extremely cheap to produce afterwards. What's more, it very low overhead.
If the union at the "vertices" could be spin welded, they could save all that and just weld the parts. A lot more work, though. But also a lot more flexible for development.

So it looks like the outer shell is explosively formed. According to Elon (in the Apr 25article: http://spacenews.com/profiles/110425-elon-musk.html ):

"....
The hardest part of the engine to mass produce is the electro-plating of nickel cobalt on the chamber. We create this thick metal jacket that takes the primary stress of the pressure vessel and it’s plated one molecule at a time. Plating is about the slowest way you can make a metal thing. With the Merlin-1D we take a metal jacket that is explosively formed. We take a metal sheet that’s in a cylindrical form and put it in a bucket of water, effectively. Sort of a concrete pool. And you set off an explosive and the jacket just goes “boohmp” and forms to the outer side walls into a jacket shape, so you have a mold, effectively. And then you just put the jacket on the chamber and braise it on. You can do several a day. We have a fully integrated engine and it’s being test-fired right now. There’s really not a lot of question marks remaining about the Merlin-1D.
..."

But there's nothing on the core of the chamber or the nozzle, or any intermediate corrugated shapes.

From further back, however, here are two images of Merlin-1C from 2006 (h/t Jon Goff @ Selenian Boondocks: http://selenianboondocks.com/2006/10/spacex-comstac-briefing/):

http://photos1.blogger.com/photoInclude/blogger/1613/496/1600/Merlin1C_HeadEnd.jpg
http://photos1.blogger.com/photoInclude/blogger/1613/496/1600/Merlin1C_Chamber.jpg

So it's at least plausible that the core is milled, and an explosively formed outer jacket is then brazed on top of it.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 10/17/2011 03:32 pm
The corrugated was a speculation on my part. That's the trick the Russians used for the 130:1 T/W on the NK33, and if you look at the engine:
(http://upload.wikimedia.org/wikipedia/commons/thumb/a/ad/Aerojet_AJ26_Rocket_Engine_Arrives_at_Stennis.jpg/640px-Aerojet_AJ26_Rocket_Engine_Arrives_at_Stennis.jpg)
It also has that clean look.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kch on 10/17/2011 04:06 pm

So it looks like the outer shell is explosively formed. According to Elon (in the Apr 25article: http://spacenews.com/profiles/110425-elon-musk.html ):

"....
The hardest part of the engine to mass produce is the electro-plating of nickel cobalt on the chamber. We create this thick metal jacket that takes the primary stress of the pressure vessel and it’s plated one molecule at a time. Plating is about the slowest way you can make a metal thing. With the Merlin-1D we take a metal jacket that is explosively formed. We take a metal sheet that’s in a cylindrical form and put it in a bucket of water, effectively. Sort of a concrete pool. And you set off an explosive and the jacket just goes “boohmp” and forms to the outer side walls into a jacket shape, so you have a mold, effectively. And then you just put the jacket on the chamber and braise it on. You can do several a day. We have a fully integrated engine and it’s being test-fired right now. There’s really not a lot of question marks remaining about the Merlin-1D.
..."


"Braise"?  LOL -- makes it sound like they're really *cooking* now:

http://en.wikipedia.org/wiki/Braising

... or might Elon have actually meant this?

http://en.wikipedia.org/wiki/Brazing

"Caerfal proffraedign is impotant!"  ;)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 10/17/2011 05:38 pm
With three separate molds the inner, the corrugated channels, and the outer a Nozzle or TC can be quickly fabricated very precisely using a precise mold and explosive forming. That would be a total of six forming operations and six molds to make one engine. The molds would be a milled hard thick metal backed by a cement jacket to keep the mold from changing shape during forming. You would do multiple forming’s using one mold over several days say three days resulting in 9 copies then swap molds and do the next. In 18 days you could make 9 complete TC and Nozzles easily or about 150 to 180 engines a year per one forming tank. The six pieces would fit together easily.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 10/17/2011 05:44 pm
Would M1d be the first U.S. engine to use this approach pioneered by Russians?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 10/17/2011 06:39 pm
With three separate molds the inner, the corrugated channels, and the outer a Nozzle or TC can be quickly fabricated very precisely using a precise mold and explosive forming. That would be a total of six forming operations and six molds to make one engine. The molds would be a milled hard thick metal backed by a cement jacket to keep the mold from changing shape during forming. You would do multiple forming’s using one mold over several days say three days resulting in 9 copies then swap molds and do the next. In 18 days you could make 9 complete TC and Nozzles easily or about 150 to 180 engines a year per one forming tank. The six pieces would fit together easily.

Yes, the only real cost is the mold design.  Once you have that perfect the rest is gravy.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 11/21/2011 05:12 pm
I don't know if all this (http://www.facebook.com/media/set/?set=a.10150402259399424.386613.75755694423&type=3&l=abb4e2a02b) was really meant to go public so enjoy it while it lasts.

Behold, a developmental Merlin 1D:
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: 2552 on 11/21/2011 05:21 pm
I don't know if all this (http://www.facebook.com/media/set/?set=a.10150402259399424.386613.75755694423&type=3&l=abb4e2a02b) was really meant to go public so enjoy it while it lasts.

Behold, a developmental Merlin 1D:

Nice! Where is this from?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 11/21/2011 05:23 pm
I don't know if all this (http://www.facebook.com/media/set/?set=a.10150402259399424.386613.75755694423&type=3&l=abb4e2a02b) was really meant to go public so enjoy it while it lasts.

Behold, a developmental Merlin 1D:

Nice! Where is this from?

Looks like it was from the "open house" this last Saturday @ McGregor, TX.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: peter-b on 11/21/2011 05:35 pm
How much of that wiring harness is likely to be test instrumentation, and how much will stay on the production engine?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 11/21/2011 05:36 pm
Captured for posterity ;)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jason1701 on 11/21/2011 05:42 pm
How much of that wiring harness is likely to be test instrumentation, and how much will stay on the production engine?

Much of it is likely for testing, especially where you see tape.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 11/21/2011 06:11 pm
I don't know if all this (http://www.facebook.com/media/set/?set=a.10150402259399424.386613.75755694423&type=3&l=abb4e2a02b) was really meant to go public

I guess it was because this (and a couple of others) have been added to SpaceX facebook page (http://www.facebook.com/media/set/?set=a.10150964581395131.767931.353851465130&type=1).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Salo on 11/21/2011 07:15 pm
http://www.facebook.com/media/set/?set=a.10150964581395131.767931.353851465130&type=1
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 11/21/2011 07:17 pm
Interesting how janky it looks compared to the clean Merlin (presumably 1C) they have for show:
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 11/21/2011 07:19 pm
That M1c was stripped of everything but the most major piping.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kevin-rf on 11/21/2011 08:30 pm
The 1D is also covered in kapton tape, for I assume test sensors.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 11/21/2011 08:35 pm
A bit of image processing for a side-by-side....
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 11/21/2011 08:43 pm
Thanks for the pics. They look great. :)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Kaputnik on 11/21/2011 09:28 pm
The GG exhaust looks much, much bigger on the 1D- is the turbopump a new design?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 11/21/2011 09:35 pm
It's supposed to be an upgraded pump, that's the whole point of the Merlin 1D. I'm not sure the pump itself looks larger, but the exhaust pipe is definitely noticeably thicker than on 1C.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 11/21/2011 09:39 pm
A close-up/gamma-adjusted pic showing the pump & exhaust.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: apace on 11/21/2011 09:44 pm
A close-up/gamma-adjusted pic showing the pump & exhaust.

Why you don't use the original sized version of the photo?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 11/21/2011 09:57 pm
Sorry - used to sizing for low bandwidth people.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: spectre9 on 11/22/2011 04:01 am
I don't know if all this (http://www.facebook.com/media/set/?set=a.10150402259399424.386613.75755694423&type=3&l=abb4e2a02b) was really meant to go public so enjoy it while it lasts.

Behold, a developmental Merlin 1D:

Thanks for a pic with detail  ;D

Low res stuff is horrible and uninteresting to me. Not sure if others share this opinion but when you can't see the small details pics are just plain and boring.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RobLynn on 11/23/2011 09:17 am
How is the aft half of the nozzle cooled?  Does the fuel pass down to bottom then then back up or is it passively cooled?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jason1701 on 01/03/2012 08:47 pm
RobLynn, I believe the channels are built into the wall of the 1D nozzle rather than built over it.

Check out this image:
http://media.wacotrib.com/images/625-spacex.jpg (http://media.wacotrib.com/images/625-spacex.jpg)
I'm pretty sure he's standing outside the beautiful 1D test stand.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: go4mars on 01/03/2012 09:09 pm
low bandwidth people.
lol. 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 05/21/2012 04:25 pm
It’s been awhile since we had any new information related to the M1D’s.

With Elon’s latest statement on the first flight of the longer F9 v1.1 being Flight #6 instead of the previous much much older statement that it would be Flight #7 for the first M1D F9 flown, this is only an indication that the production schedule for M1D’s has not slipped but the flight schedule has slipped significantly so that Flight #6 will be NET sometime 2013. This allows the pad infrastructure and the F9 build schedule to replace the F9 v1.0 build of core # 6 with a build of a F9 v1.1 core.

The question still is will this vehicle use a M1D VAC or a M1C VAC? There is still little or no information of the M1DVAC progress.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Norm38 on 05/21/2012 05:29 pm
Guess they could hedge their bets and use the M1D only for the first stage where there's engine redundancy, and use the M1C for the 2nd stage until they have at least one full M1D flight under their belt.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 05/21/2012 05:31 pm
Guess they could hedge their bets and use the M1D only for the first stage where there's engine redundancy, and use the M1C for the 2nd stage until they have at least one full M1D flight under their belt.
There may not be enough commonality between Merlin and Merlin vacuum for that to be worthwhile.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 05/21/2012 05:34 pm
It’s been awhile since we had any new information related to the M1D’s.

With Elon’s latest statement on the first flight of the longer F9 v1.1 being Flight #6 instead of the previous much much older statement that it would be Flight #7 for the first M1D F9 flown, this is only an indication that the production schedule for M1D’s has not slipped but the flight schedule has slipped significantly so that Flight #6 will be NET sometime 2013. This allows the pad infrastructure and the F9 build schedule to replace the F9 v1.0 build of core # 6 with a build of a F9 v1.1 core.

The question still is will this vehicle use a M1D VAC or a M1C VAC? There is still little or no information of the M1DVAC progress.

I don't know if this info is still accurate (http://hobbyspace.com/nucleus/?itemid=31499 (http://hobbyspace.com/nucleus/?itemid=31499)):-

Quote
There will be a vacuum version of the 1D for the Falcon Heavy second stage.
(My highlight)

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 05/21/2012 08:09 pm
It’s been awhile since we had any new information related to the M1D’s.

With Elon’s latest statement on the first flight of the longer F9 v1.1 being Flight #6 instead of the previous much much older statement that it would be Flight #7 for the first M1D F9 flown, this is only an indication that the production schedule for M1D’s has not slipped but the flight schedule has slipped significantly so that Flight #6 will be NET sometime 2013. This allows the pad infrastructure and the F9 build schedule to replace the F9 v1.0 build of core # 6 with a build of a F9 v1.1 core.

The question still is will this vehicle use a M1D VAC or a M1C VAC? There is still little or no information of the M1DVAC progress.

I don't know if this info is still accurate (http://hobbyspace.com/nucleus/?itemid=31499 (http://hobbyspace.com/nucleus/?itemid=31499)):-

Quote
There will be a vacuum version of the 1D for the Falcon Heavy second stage.
(My highlight)

cheers, Martin

My calculations show the M1Cvac is under powered to push 53mt even lofted.  If you scale the M1D estimated performance (500lb/s) then you get ~171,000 lbf with an expansion ratio high enough to make the exit the same diameter as the M1C.  This setup comes to 53mt with almost no margin (less then 1% fuel remaining).  (These are my made up numbers and don't reflect what SpaceX is or will do)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 05/21/2012 08:12 pm
Can you figure out what happens if you replace 1 x M1D and its large nozzle with 2 x M1D with substantially shorter nozzles (but still expanded over sea level M1D)?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 05/21/2012 08:19 pm
My calculations show the M1Cvac is under powered to push 53mt even lofted.  If you scale the M1D estimated performance (500lb/s) then you get ~171,000 lbf with an expansion ratio high enough to make the exit the same diameter as the M1C.  This setup comes to 53mt with almost no margin (less then 1% fuel remaining).  (These are my made up numbers and don't reflect what SpaceX is or will do)
Presumably the core stage will burn out not just higher but a lot faster than would be the case of a Falcon 9.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: starsilk on 05/21/2012 09:02 pm
My calculations show the M1Cvac is under powered to push 53mt even lofted.  If you scale the M1D estimated performance (500lb/s) then you get ~171,000 lbf with an expansion ratio high enough to make the exit the same diameter as the M1C.  This setup comes to 53mt with almost no margin (less then 1% fuel remaining).  (These are my made up numbers and don't reflect what SpaceX is or will do)
Presumably the core stage will burn out not just higher but a lot faster than would be the case of a Falcon 9.

I calculate the FH SI burn out is 137.8 km altitude, 5319 m/s inertial, 5.4 deg flight path angle.
I calculate the FH S0 burn out is 50.5 km altitude, 2397 m/s inertial, 20.8 deg flight path angle.
Cross Feed Active with 6 cross feeding (8 gives lower performance)

that's interesting. there was quite some comment a while ago because it is not terribly clear from Elon's statements whether all the engines on the center core will be cross fed, or just the three next to each booster (ie 6). if you're getting better performance in simulation from 6 instead of 8 (9?), perhaps that question is answered..
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris-A on 05/21/2012 09:22 pm
I believe Elon said 6 engines on the center core are cross feed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: charliem on 05/22/2012 01:07 am
My calculations show the M1Cvac is under powered to push 53mt even lofted.  If you scale the M1D estimated performance (500lb/s) then you get ~171,000 lbf with an expansion ratio high enough to make the exit the same diameter as the M1C.  This setup comes to 53mt with almost no margin (less then 1% fuel remaining).  (These are my made up numbers and don't reflect what SpaceX is or will do)
Presumably the core stage will burn out not just higher but a lot faster than would be the case of a Falcon 9.

I calculate the FH SI burn out is 137.8 km altitude, 5319 m/s inertial, 5.4 deg flight path angle.
I calculate the FH S0 burn out is 50.5 km altitude, 2397 m/s inertial, 20.8 deg flight path angle.
Cross Feed Active with 6 cross feeding (8 gives lower performance)
IIRC Elon stated that for FH when the boosters separate the core still has its tanks 90% full. That doesn't look possible if cross-feed is only for 6 engines.

I agree about one thing, the Merlin 1C-vac seems seriously underpowered to take 53 mT of payload, plus at least the same for a fueled second stage, to orbit.

That kind of thrust looks only reasonable if at ignition the stage is already near orbital velocity, if not gravity losses would be too high.

The first and a half stage of FH is going to have to provide most of the delta-v.

I've also done a few trajectory integrations and they seem to confirm this. If staging happens at an inertial speed under 5 km/s, the second stage spends most of its delta-v fighting gravity, and does not reach orbit.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: dcporter on 05/22/2012 01:39 am
Speculation at the time was that the six outer cores were to be crossfed while the middle three would be throttled, allowing for the 90% figure.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: charliem on 05/22/2012 02:22 am
Speculation at the time was that the six outer cores were to be crossfed while the middle three would be throttled, allowing for the 90% figure.
That'd mean throttling down the 3 center engines to 40%, and the announced throttle capacity for Merlin-1D is 70%-100%.

Moreover throttling down at sea level has another drawback, you loose Isp.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Norm38 on 05/22/2012 03:05 am
The center 3 would likely be at max thrust for liftoff, maybe throttling back well before max Q to help ease through.  And at less thrust, lower ISP is less of a problem.

And wouldn't throttling back to 40% on a launch be an ideal test of the grasshopper's deep throttling requirements?  That's going to be at sea level and low ISP also, right?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 05/27/2012 02:43 am
With three separate molds the inner, the corrugated channels, and the outer a Nozzle or TC can be quickly fabricated very precisely using a precise mold and explosive forming. That would be a total of six forming operations and six molds to make one engine. The molds would be a milled hard thick metal backed by a cement jacket to keep the mold from changing shape during forming. You would do multiple forming’s using one mold over several days say three days resulting in 9 copies then swap molds and do the next. In 18 days you could make 9 complete TC and Nozzles easily or about 150 to 180 engines a year per one forming tank. The six pieces would fit together easily.


And this would of course provide an engine that is still regen cooled?

Certainly is deceiving from a precursory glance.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 05/27/2012 02:46 am
A bit of image processing for a side-by-side....

One thing is for sure, unless the full production engine looks different, I am really going to miss that shiny stainless steel look :(
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 05/27/2012 02:49 am
It’s been awhile since we had any new information related to the M1D’s.

With Elon’s latest statement on the first flight of the longer F9 v1.1 being Flight #6 instead of the previous much much older statement that it would be Flight #7 for the first M1D F9 flown, this is only an indication that the production schedule for M1D’s has not slipped but the flight schedule has slipped significantly so that Flight #6 will be NET sometime 2013. This allows the pad infrastructure and the F9 build schedule to replace the F9 v1.0 build of core # 6 with a build of a F9 v1.1 core.

The question still is will this vehicle use a M1D VAC or a M1C VAC? There is still little or no information of the M1DVAC progress.


Good question.

I myself was wondering if perhaps it would use any  mvac engine at all.

What if raptor is further along (it has been kept rather under wraps) and they just use that?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris-A on 05/27/2012 05:43 am
A good clue with that question would be the installation of any H2 infrastructure at McGregor. The recently updated video seems to show nothing. Raptor is objectively still paper.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 05/27/2012 06:23 am
Are we certain that his talking of alternative fuels doesn't also include alternative non-cryo oxidizers?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Halidon on 05/27/2012 08:23 am
Raptor for v1.1 seems very unlikely. With M1D in production, their propulsion R&D focus now appears to be on Super Draco. Raptor may be next in line, but then again there's that "next generation rocket" which may need a BME.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: QuantumG on 05/27/2012 09:04 am
LH2 rocket development takes about a decade.. how long has Blue Origin been working on theirs now? And in the end you get a whole new set of operational problems.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Kaputnik on 05/27/2012 09:07 am
Are we certain that his talking of alternative fuels doesn't also include alternative non-cryo oxidizers?

Why would they do that? Just to be willfully different?

AFAIK LOX is as high performance as you can get (short of Fluorine) and is a very mature technology with its only downside being its storage life on orbit. If longer on-orbit storage is a requirement, they need to use hypergolics, which they already are doing.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: rklaehn on 05/27/2012 09:14 am
It’s been awhile since we had any new information related to the M1D’s.

With Elon’s latest statement on the first flight of the longer F9 v1.1 being Flight #6 instead of the previous much much older statement that it would be Flight #7 for the first M1D F9 flown, this is only an indication that the production schedule for M1D’s has not slipped but the flight schedule has slipped significantly so that Flight #6 will be NET sometime 2013. This allows the pad infrastructure and the F9 build schedule to replace the F9 v1.0 build of core # 6 with a build of a F9 v1.1 core.

The question still is will this vehicle use a M1D VAC or a M1C VAC? There is still little or no information of the M1DVAC progress.


Good question.

I myself was wondering if perhaps it would use any  mvac engine at all.

What if raptor is further along (it has been kept rather under wraps) and they just use that?

I think the published payload for falcon heavy matches very well with what has been announced, so there is no need to assume any secret development programs.

Falcon 9 is ~10t to LEO. Using Merlin 1D they are able to stretch the stages to get about 15t to LEO. If you combine three of them with a slightly larger upper stage you get to 45t. If you do cross-feed and shut off the boosters earlier and turn the whole thing into a parallel staged three stage vehicle, you get a modest increase to 53t.

I think that spacex will focus on reusability before accelerating raptor development. For LEO raptor is really not worth it at all. For GTO it would give a significant increase, but given that falcon heavy has double the payload capacity of every conceivable payload in the next years, what for? Where raptor really makes a big difference is for interplanetary trajectories. But even in spacex time we are a decade away from that.

Besides, I really think that reusability is much more important. Hydrogen gets you a factor of 2 more payload to TMI, with all sorts of operational hassles. Reusability has the potential to reduce the cost by one or even two orders of magnitude.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: sanman on 05/27/2012 09:40 am

I think the published payload for falcon heavy matches very well with what has been announced, so there is no need to assume any secret development programs.

Falcon 9 is ~10t to LEO. Using Merlin 1D they are able to stretch the stages to get about 15t to LEO. If you combine three of them with a slightly larger upper stage you get to 45t. If you do cross-feed and shut off the boosters earlier and turn the whole thing into a parallel staged three stage vehicle, you get a modest increase to 53t.

I think that spacex will focus on reusability before accelerating raptor development. For LEO raptor is really not worth it at all. For GTO it would give a significant increase, but given that falcon heavy has double the payload capacity of every conceivable payload in the next years, what for? Where raptor really makes a big difference is for interplanetary trajectories. But even in spacex time we are a decade away from that.

Besides, I really think that reusability is much more important. Hydrogen gets you a factor of 2 more payload to TMI, with all sorts of operational hassles. Reusability has the potential to reduce the cost by one or even two orders of magnitude.

While I'm glad that Musk has strong ambitions for taking humanity to Mars, I hope that he doesn't get his head so far in the clouds that his feet aren't solidly on the ground. The main market for the conceivable future is for LEO/GTO. He should mainly focus on this market and use it to reduce costs and refine his technologies, so that these improvements will facilitate an eventual market for Mars spaceflight. It's nice that SpaceX is thinking about doing Red Dragon for NASA, but it seems really premature of them to be thinking about Mars as an independently sustainable business market.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 05/28/2012 12:41 am
A good clue with that question would be the installation of any H2 infrastructure at McGregor. The recently updated video seems to show nothing. Raptor is objectively still paper.
They just bought an old hydrogen tank from NASA.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: just-nick on 05/31/2012 09:46 pm
My calculations show the M1Cvac is under powered to push 53mt even lofted.  If you scale the M1D estimated performance (500lb/s) then you get ~171,000 lbf with an expansion ratio high enough to make the exit the same diameter as the M1C.  This setup comes to 53mt with almost no margin (less then 1% fuel remaining).  (These are my made up numbers and don't reflect what SpaceX is or will do)
Presumably the core stage will burn out not just higher but a lot faster than would be the case of a Falcon 9.

I calculate the FH SI burn out is 137.8 km altitude, 5319 m/s inertial, 5.4 deg flight path angle.
I calculate the FH S0 burn out is 50.5 km altitude, 2397 m/s inertial, 20.8 deg flight path angle.
Cross Feed Active with 6 cross feeding (8 gives lower performance)

What are you using for these simulations?

 --N
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: just-nick on 05/31/2012 10:25 pm
What are you using for these simulations?

 --N

I wrote it using excel and a lot of math.  ;)
You are kidding, right? About the Excel? If not, I really need to raise the game on my Excel trajectory simulation efforts!

--N
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/01/2012 03:19 pm
I think the more appropriate place to discuss simulations on F9 v1.1 performance, dry weights comparisons (except for engine and thrust structure which is driven by the engine design), and propellant loads should be done in the F9 v1.1 thread.

I appreciate the interest in the M1D performance and what that means to the F9 v1.1 but beyond short discussions of what M1D and M1DVAC means to performance, detailed discussions of this nature is not what the thread is about.

THANK YOU :)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/02/2012 10:32 pm
I agree.  I removed my posts that did not contribute to the M1D conversation.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/03/2012 06:49 pm
I agree.  I removed my posts that did not contribute to the M1D conversation.

Thank you.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MikeAtkinson on 06/07/2012 09:18 pm
Looks like we can fill in a few more numbers:



Sea Level Thrust :   147,000 lbf
Vacuum Thrust:   161,000 lbf
Sea Level Isp:   282s
Vacuum Isp:   311s
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Zed_Noir on 06/07/2012 09:25 pm
Looks like we can fill in a few more numbers:



Sea Level Thrust :   147,000 lbf
Vacuum Thrust:   161,000 lbf
Sea Level Isp:   282s
Vacuum Isp:   311s

What is the source for the data?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: 2552 on 06/07/2012 09:31 pm
http://www.spacex.com/falcon9.php
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 06/07/2012 09:37 pm
Looks like we can fill in a few more numbers:



Sea Level Thrust :   147,000 lbf
Vacuum Thrust:   161,000 lbf
Sea Level Isp:   282s
Vacuum Isp:   311s


Is this supposed to be for M1D?

I thought that was going to be ~160 ish sea level?

Meh, probably got it mixed up with something else.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris-A on 06/07/2012 09:48 pm
The engine thrust to weight ratio is no longer listed, if you noticed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 06/07/2012 09:56 pm
I thought that was going to be ~160 ish sea level?
They had previously said it was going to be ~140ish sea level.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 06/07/2012 10:15 pm
I thought that was going to be ~160 ish sea level?
They had previously said it was going to be ~140ish sea level.

Like I said, I think I got that number from something else.

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/08/2012 01:14 am
Summary of what we know so far:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf?147klbf
Vac Thrust155klbf?(better than expected)161klbf
SL isp280s??282s
Vac isp310s309s?311s
T/W160??
Chamber Pressure1410psi??
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%?
Engine weight 440kg???
Costs<M1C?-?


EngineMerlin 1DVAC (Design)Merlin 1DVAC (Test article)Merlin 1DVAC (Production)
Vac Thrust174klbf???
Vac isp348s?(an educated WAG)??
T/W160???
Chamber Pressure1410psi???
Expansion??117
Throttle range70-100%???
Engine weight >440kg???
Costs<M1CVAC?-?

Note is that there was an expansion ratio value for the engine on the second stage section in the new F9 description for the M1DVAC of 117:1.

The really interesting thing is that it beats all of our expectations for both thrust and ISP. Thrust is higher by 5%.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 06/08/2012 02:27 am
The really interesting thing is that it beats all of our expectations for both thrust and ISP. Thrust is higher by 5%.
Also, assuming most of the growth came from tweaking the turbines and pressures and not adding structure, the T/W ratio is probably more like 165:1. :o
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: krytek on 06/08/2012 06:34 am
The really interesting thing is that it beats all of our expectations for both thrust and ISP. Thrust is higher by 5%.
Also, assuming most of the growth came from tweaking the turbines and pressures and not adding structure, the T/W ratio is probably more like 165:1. :o
Just as well it could be they had to add some mass to the engine to get that extra 5%. i.e the T/W ratio might be lower now, which would explain why they didn't list it. Really hoping that's not the case though.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Joel on 06/08/2012 10:08 am
The really interesting thing is that it beats all of our expectations for both thrust and ISP. Thrust is higher by 5%.
Also, assuming most of the growth came from tweaking the turbines and pressures and not adding structure, the T/W ratio is probably more like 165:1. :o
Just as well it could be they had to add some mass to the engine to get that extra 5%. i.e the T/W ratio might be lower now, which would explain why they didn't list it. Really hoping that's not the case though.

Don't think so. According to Tom Mueller: "We took structure off the engine to make it lighter".
http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1 (http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 06/08/2012 10:12 am
The really interesting thing is that it beats all of our expectations for both thrust and ISP. Thrust is higher by 5%.
Also, assuming most of the growth came from tweaking the turbines and pressures and not adding structure, the T/W ratio is probably more like 165:1. :o
Just as well it could be they had to add some mass to the engine to get that extra 5%. i.e the T/W ratio might be lower now, which would explain why they didn't list it. Really hoping that's not the case though.

Don't think so. According to Tom Mueller: "We took structure off the engine to make it lighter".
http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1 (http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1)
He's talking about the delta between the 140 klbf Mueller discussed in that article and the updated 147 klbf SpaceX has disclosed now. I guessed they did it without making the engine much heavier than the test article, krytek correctly points out I could be wrong.

Edit: wrong poster
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Zed_Noir on 06/08/2012 11:15 am
@oldAtlas_Eguy

Just wondering if the new turbo-pump for the M-1D would be the same for the M-1D Vac?

Would a more powerful (about 6% to 12%) turbo-pump be worthwhile to stretch the M-1D performance further. Also the same query about the M-1D Vac.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 06/08/2012 11:54 am
See http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=2 (http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=2):-
Quote
The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We've added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It's going to be a 1D with the same turbopump.”



Note is that there was an expansion ratio value for the engine on the second stage section in the new F9 description for the M1DVAC of 117:1.

That article is nearly 10 months old, but the first highlight suggests M1D vac may be introduced on FH rather than F9v1.1. Perhaps it means the requirement is driven by the larger payload on FH?

What's the expansion ratio of M1C vac? Are we sure it's not 117:1, and M1D vac will be introduced later?



Just wondering if the new turbo-pump for the M-1D would be the same for the M-1D Vac?

See second highlight above.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 06/08/2012 11:57 am
oldAtlas_Eguy,

might be worth you updating the Original Post with the latest stats, as a reference? Perhaps retain the original values but also the table updates.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/08/2012 12:26 pm
See http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=2 (http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=2):-
Quote
The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We've added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It's going to be a 1D with the same turbopump.”



Note is that there was an expansion ratio value for the engine on the second stage section in the new F9 description for the M1DVAC of 117:1.

That article is nearly 10 months old, but the first highlight suggests M1D vac may be introduced on FH rather than F9v1.1. Perhaps it means the requirement is driven by the larger payload on FH?

What's the expansion ratio of M1C vac? Are we sure it's not 117:1, and M1D vac will be introduced later?



Just wondering if the new turbo-pump for the M-1D would be the same for the M-1D Vac?

See second highlight above.

cheers, Martin

I have found that Falcon 9v1.1 works fine with the M1Cvac but the Falcon Heavy will need more thrust for max payload on SII.

I would expect them to use their stock of M1Cvac (if they have a stock pile) on the V1.1 and then switch to the M1Dvac.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/08/2012 03:06 pm
There is some implication in the wording of SpaceX's F9 description web page that the M1D and M1DVAC only differ by a gimbaling GG exhaust and the ablative expansion skirt. If that is true then that also means that the M1D has the in-flight cartridge start ports on it. So that making the first stage be able to do 2 restarts in-flight is an inherant existing capability of the M1D.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 06/08/2012 03:14 pm
The really interesting thing is that it beats all of our expectations for both thrust and ISP. Thrust is higher by 5%.
Also, assuming most of the growth came from tweaking the turbines and pressures and not adding structure, the T/W ratio is probably more like 165:1. :o
Just as well it could be they had to add some mass to the engine to get that extra 5%. i.e the T/W ratio might be lower now, which would explain why they didn't list it. Really hoping that's not the case though.

Don't think so. According to Tom Mueller: "We took structure off the engine to make it lighter".
http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1 (http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1)

old info....  see we have changes as we go.

"All Falcon 9 flights up to and including the sixth will be powered by the kerosene/liquid oxygen 95,000-lb.-thrust Merlin 1C, with the Merlin 1C-Vac derivative powering the upper stage. Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward"
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/08/2012 03:25 pm
The really interesting thing is that it beats all of our expectations for both thrust and ISP. Thrust is higher by 5%.
Also, assuming most of the growth came from tweaking the turbines and pressures and not adding structure, the T/W ratio is probably more like 165:1. :o
Just as well it could be they had to add some mass to the engine to get that extra 5%. i.e the T/W ratio might be lower now, which would explain why they didn't list it. Really hoping that's not the case though.

Don't think so. According to Tom Mueller: "We took structure off the engine to make it lighter".
http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1 (http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_08_2011_p27-354586.xml&p=1)

old info....  see we have changes as we go.

"All Falcon 9 flights up to and including the sixth will be powered by the kerosene/liquid oxygen 95,000-lb.-thrust Merlin 1C, with the Merlin 1C-Vac derivative powering the upper stage. Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward"


This really only speaks to the fact that the M1D production schedule has held while the launch schedule has slipped, making the intro of the M1D which was scheduled for fall 2012 deliveries of cores for launches in 2013. Launch of core #006 is now in 2013 instead of the 2011 prediction that it would take place in 2012 which would have meant that it would have had to use M1C engines.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/12/2012 02:30 pm
If the 1D is going to be used to slow down the stage for landing without parachutes, doesn't that mean it's going to have to be restarted while falling open nozzle first through the atmosphere? Either that or it's going to have to be kept running during the descent.

Unless the nozzle is quite under-expanded, won't the exhaust become unstable if the ambient plus dynamic pressure builds up to much over 1atm?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/12/2012 02:38 pm
If the 1D is going to be used to slow down the stage for landing without parachutes, doesn't that mean it's going to have to be restarted while falling open nozzle first through the atmosphere? Either that or it's going to have to be kept running during the descent.

Unless the nozzle is quite under-expanded, won't the exhaust become unstable if the ambient plus dynamic pressure builds up to much over 1atm?

That is an interesting idea, but I have never heard anything about thrust changes during max Q due to lower pressure, but higher dynamic pressure acting on the nozzles.  Would love to hear from someone with experience if this is an issue.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/12/2012 03:07 pm
If the 1D is going to be used to slow down the stage for landing without parachutes, doesn't that mean it's going to have to be restarted while falling open nozzle first through the atmosphere? Either that or it's going to have to be kept running during the descent.

Unless the nozzle is quite under-expanded, won't the exhaust become unstable if the ambient plus dynamic pressure builds up to much over 1atm?

That is an interesting idea, but I have never heard anything about thrust changes during max Q due to lower pressure, but higher dynamic pressure acting on the nozzles.  Would love to hear from someone with experience if this is an issue.
During launch the nozzles are facing downstream so aren't exposed to positive dynamic pressure. Due to flow separation at the base of the vehicle they're probably in a lower pressure area, although the exhaust itself tend to keep the pressure up.

If the reentry is engine first however, the situation is reversed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/12/2012 03:45 pm
Actually, if the reentry engine is the center one, it's probably going to be right at the stagnation point, so the pressure will be even higher than the average Q over the entire base.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/12/2012 03:58 pm
Actually, if the reentry engine is the center one, it's probably going to be right at the stagnation point, so the pressure will be even higher than the average Q over the entire base.
During a nominal entry for the suborbital trajectory you're going to want the stage at least angle toward the side to increase frontal area.  They can always start the engine while angled and then pitch to the desired angle for slowing down.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/12/2012 04:41 pm
Actually, if the reentry engine is the center one, it's probably going to be right at the stagnation point, so the pressure will be even higher than the average Q over the entire base.
During a nominal entry for the suborbital trajectory you're going to want the stage at least angle toward the side to increase frontal area.  They can always start the engine while angled and then pitch to the desired angle for slowing down.
I'm not sure what your point is. To slow the stage, the thrust has to be opposite the velocity so the engine would be facing directly into the air stream.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/12/2012 04:44 pm
Actually, if the reentry engine is the center one, it's probably going to be right at the stagnation point, so the pressure will be even higher than the average Q over the entire base.
During a nominal entry for the suborbital trajectory you're going to want the stage at least angle toward the side to increase frontal area.  They can always start the engine while angled and then pitch to the desired angle for slowing down.
I'm not sure what your point is. To slow the stage, the thrust has to be opposite the velocity so the engine would be facing directly into the air stream.
If you can supply altitude, velocity, pitch, and dynamic pressure at ignition then we can go over the numbers.  At no time in my model was thrust directly into the flight path angle since my original trajectory was designed to be short of the pad to account for a failure to restart.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MikeAtkinson on 06/12/2012 05:05 pm
Going back to drag again.

Are your models taking into account the drag from the landing legs?

It strikes me that they could be designed to provide significant drag, but that would be at the front for base first re-entry which I think makes it aerodynamically unstable.

[edit: posted in the wrong thread, replies in the reusable rocket thread please (http://forum.nasaspaceflight.com/index.php?topic=27748.0)]
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/12/2012 06:36 pm
Actually, if the reentry engine is the center one, it's probably going to be right at the stagnation point, so the pressure will be even higher than the average Q over the entire base.
During a nominal entry for the suborbital trajectory you're going to want the stage at least angle toward the side to increase frontal area.  They can always start the engine while angled and then pitch to the desired angle for slowing down.
I'm not sure what your point is. To slow the stage, the thrust has to be opposite the velocity so the engine would be facing directly into the air stream.
If you can supply altitude, velocity, pitch, and dynamic pressure at ignition then we can go over the numbers.  At no time in my model was thrust directly into the flight path angle since my original trajectory was designed to be short of the pad to account for a failure to restart.
Sure, I'm using this calculator: https://engineering.purdue.edu/AAE450s/trajectories/Point%20Mass%20Lifting%20Earth%20Entry%20Trajectory%20-%20Time%20Integration.xls (https://engineering.purdue.edu/AAE450s/trajectories/Point%20Mass%20Lifting%20Earth%20Entry%20Trajectory%20-%20Time%20Integration.xls) from Purdue, and starting at 70km, 70 degree angle, 1500 m/s velocity and an end on entry with Cd .8 and Cl 0.

The stagnation pressure exceeds 1Atm at about 26km, 1800m/s, 73 degrees, Q is about half, 58kN/m^2, deceleration .7G. It never gets below this for the rest of the return without braking.

The max stagnation pressure without braking is 680kN/m^2 at about 8.8km, 1250m/s, 74 degrees, Q 360kN/m^2, deceleration 9.3G.

If you think changing the pitch will significantly change these numbers, please provide the pitch angle, altitude, velocity, Q, Cd and Cl you're using.

I'm still wondering if anyone knows what the implications are for starting and operating an engine in a high dynamic pressure environment would be. Are they going to do something like the SSME narrowing the end of the nozzle to avoid problems with over expansion?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/12/2012 07:12 pm
Actually, if the reentry engine is the center one, it's probably going to be right at the stagnation point, so the pressure will be even higher than the average Q over the entire base.
During a nominal entry for the suborbital trajectory you're going to want the stage at least angle toward the side to increase frontal area.  They can always start the engine while angled and then pitch to the desired angle for slowing down.
I'm not sure what your point is. To slow the stage, the thrust has to be opposite the velocity so the engine would be facing directly into the air stream.
If you can supply altitude, velocity, pitch, and dynamic pressure at ignition then we can go over the numbers.  At no time in my model was thrust directly into the flight path angle since my original trajectory was designed to be short of the pad to account for a failure to restart.
Sure, I'm using this calculator: https://engineering.purdue.edu/AAE450s/trajectories/Point%20Mass%20Lifting%20Earth%20Entry%20Trajectory%20-%20Time%20Integration.xls (https://engineering.purdue.edu/AAE450s/trajectories/Point%20Mass%20Lifting%20Earth%20Entry%20Trajectory%20-%20Time%20Integration.xls) from Purdue, and starting at 70km, 70 degree angle, 1500 m/s velocity and an end on entry with Cd .8 and Cl 0.

The stagnation pressure exceeds 1Atm at about 26km, 1800m/s, 73 degrees, Q is about half, 58kN/m^2, deceleration .7G. It never gets below this for the rest of the return without braking.

The max stagnation pressure without braking is 680kN/m^2 at about 8.8km, 1250m/s, 74 degrees, Q 360kN/m^2, deceleration 9.3G.

If you think changing the pitch will significantly change these numbers, please provide the pitch angle, altitude, velocity, Q, Cd and Cl you're using.

I'm still wondering if anyone knows what the implications are for starting and operating an engine in a high dynamic pressure environment would be. Are they going to do something like the SSME narrowing the end of the nozzle to avoid problems with over expansion?

http://forum.nasaspaceflight.com/index.php?topic=27748.msg914446#msg914446

583 seconds

pitch angle - 25 DEG
flight path angle - -89.7 deg
altitude - 3.4KM
velocity - 109 M/S
Q = 5,207 kpa
Cd = .75 per your request
Cl = zero, your not going to get lift from a cylinder
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/12/2012 07:12 pm
There is some implication in the wording of SpaceX's F9 description web page that the M1D and M1DVAC only differ by a gimbaling GG exhaust and the ablative expansion skirt....
Are you sure you don't mean /radiative/ expansion skirt, like all the Falcon 1 and Falcon 9 launches have had for the second stage? Ablative isn't very appropriate for the expansion part.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/12/2012 07:26 pm
There is some implication in the wording of SpaceX's F9 description web page that the M1D and M1DVAC only differ by a gimbaling GG exhaust and the ablative expansion skirt....
Are you sure you don't mean /radiative/ expansion skirt, like all the Falcon 1 and Falcon 9 launches have had for the second stage? Ablative isn't very appropriate for the expansion part.

Your correct its radiatively cooled.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/12/2012 07:40 pm
http://forum.nasaspaceflight.com/index.php?topic=27748.msg914446#msg914446

583 seconds

pitch angle - 25 DEG
flight path angle - -89.7 deg
altitude - 3.4KM
velocity - 109 M/S
Q = 5,207 kpa
Cd = .75 per your request
Cl = zero, your not going to get lift from a cylinder
That's a bit cryptic. The post you mentioned was dealing with an out of control un-powered flat sideways entry, this discussion is about an in control braking entry, presumably with engine pointing forward.

You show the velocity at 3.4km as 109m/s. That's significantly below terminal velocity so how did it get down to that without running the engine? If you're suggesting a sidewise reentry, how would it be controlled to prevent tumbling, not to mention being broken up, as all the first stages to the present have been?

Anyway, if you want to discuss reentry attitudes, let's go back to the Reuseability thread. My question was, and is, about how the 1D nozzle design would work.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/12/2012 08:01 pm
http://forum.nasaspaceflight.com/index.php?topic=27748.msg914446#msg914446

583 seconds

pitch angle - 25 DEG
flight path angle - -89.7 deg
altitude - 3.4KM
velocity - 109 M/S
Q = 5,207 kpa
Cd = .75 per your request
Cl = zero, your not going to get lift from a cylinder
That's a bit cryptic. The post you mentioned was dealing with an out of control un-powered flat sideways entry, this discussion is about an in control braking entry, presumably with engine pointing forward.

You show the velocity at 3.4km as 109m/s. That's significantly below terminal velocity so how did it get down to that without running the engine? If you're suggesting a sidewise reentry, how would it be controlled to prevent tumbling, not to mention being broken up, as all the first stages to the present have been?

Anyway, if you want to discuss reentry attitudes, let's go back to the Reuseability thread. My question was, and is, about how the 1D nozzle design would work.

Our original discussion was really "what happens if the engine doesn't ignite to slow down and land, and where will the debris land in relationship to the landing pad".  I am trying to find out what environment your trying to start a M1D engine to see what the nozzle has to work with.  This is related to this thread, and not the recovery as this is an engine issue.
In my example ignition would be at Mach .33.  The velocity in my example came from your argument that CD is a fixed number, and the Cd for a cylinder is ~.75.  I ran the same numbers with a Cd of 1 and found it was at 104m/s instead of 109 m/s.  Calculating terminal velocity from those conditions at that time came up to 99 m/s.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/12/2012 08:13 pm

You show the velocity at 3.4km as 109m/s. That's significantly below terminal velocity so how did it get down to that without running the engine? If you're suggesting a sidewise reentry, how would it be controlled to prevent tumbling, not to mention being broken up, as all the first stages to the present have been?

In my example ignition would be at Mach .33.  The velocity in my example came from your argument that CD is a fixed number, and the Cd for a cylinder is ~.75.  I ran the same numbers with a Cd of 1 and found it was at 104m/s instead of 109 m/s.  Calculating terminal velocity from those conditions at that time came up to 99 m/s.
OK, so where would the control force come from to maintain that pitch, and how would it avoid being broken up?

I answered this more fully here: http://forum.nasaspaceflight.com/index.php?topic=27748.msg915423#msg915423 (http://forum.nasaspaceflight.com/index.php?topic=27748.msg915423#msg915423) as I really think this should not be hashed out in this thread. We're talking about how reentry would work, not how the engine would work.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/12/2012 08:27 pm
Zero angle of attack along the long axis.  No more questions, you can extract your answers from the graphs.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: RDoc on 06/13/2012 01:07 am
Zero angle of attack along the long axis.  No more questions, you can extract your answers from the graphs.
The numbers in the charts are only consistent with an engine first reentry. Using the Purdue speadsheet shows the stage hitting the ground at about 570 m/s with Q at 186kPa and stagnation pressure at 392kPa, so there's still a question of how the engine would run at those pressures.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/13/2012 04:52 pm
Another Merlin 1D test image I came across on The Internets:
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris-A on 06/13/2012 07:49 pm
That image is different from the SpaceX FB page, so it is new.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/13/2012 08:52 pm
That image is different from the SpaceX FB page, so it is new.

Yes its from the opposite side.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/13/2012 08:58 pm
Yes its from the opposite side.

No, it's from the same side as the other M1D firing pic that exists, same test stand actually, only this one in daytime.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/13/2012 10:47 pm
Yes its from the opposite side.

No, it's from the same side as the other M1D firing pic that exists, same test stand actually, only this one in daytime.

See the M1D picture in the F9 page on the SpaceX site, it has the turbo pump and GG exhaust on the left and this picture has it on the right.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/13/2012 10:54 pm
After looking at the two pictures up close the one on the F9 page looks like it may be a M1CVAC and not an M1D. So you may be right that there is only one picture so far of a M1D in this facility.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 06/13/2012 11:06 pm
Really? What picture? Because the M1C Vac looks *quite* different - noone would mistake it for a plain M1C or M1D.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 06/13/2012 11:55 pm
Really? What picture? Because the M1C Vac looks *quite* different - noone would mistake it for a plain M1C or M1D.
I think Muller stated for AW that they would be using a straight Merlin 1D with a nozzle extension on the US. No Merlin 1E. At least he did said same turbopump.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: corrodedNut on 06/14/2012 12:48 am
See the M1D picture in the F9 page on the SpaceX site, it has the turbo pump and GG exhaust on the left and this picture has it on the right.

The picture on the F9 page is a Merlin1C, the turbopump is on the left, but it's to the front. The Merlin1D has the same config. The turbopump is on the right (from the POV of the camera) but it's to the back. Compared to M1C's tube wall nozzle, the smooth D is unmistakable.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 06/14/2012 03:08 am
Did we get close to a weight for the 1D?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/14/2012 11:39 am
Did we get close to a weight for the 1D?


Only a calculated one of 440kg from the the stated 155klbf VAC thrust and the T/W of 160:1 by Muller April 2011.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: gospacex on 06/14/2012 11:44 am
Why turbine exhaust tube is so long? It's a dead weight...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Silmfeanor on 06/14/2012 12:00 pm
Why turbine exhaust tube is so long? It's a dead weight...

no it's not...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 06/14/2012 12:38 pm
Why turbine exhaust tube is so long? It's a dead weight...

See first two Atlas launches
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: jnc on 06/14/2012 03:34 pm
See first two Atlas launches

To expand on that, for those who are curious, the first two Atlas test flights in 1957 (4A and 6A) failed because "the base heat shield was completely inadequate and they needed to redirect the turbine exhaust .. to keep hot gasses and radiated heat away from the interior of the skirt". (Chuck Walker, Joel Powell, "The Story of Atlas", pg. 145)

Noel
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 06/14/2012 04:05 pm
Why turbine exhaust tube is so long? It's a dead weight...

See first two Atlas launches

saw one about the same size on the H-1
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mto on 06/14/2012 04:37 pm
See first two Atlas launches

To expand on that, for those who are curious,...
Thank you for the explanation :)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: bocephus419 on 06/16/2012 02:11 am
Interesting pic from the spaceflightnow coverage of the Bolden visit.  Looks like the sign says:
"THE ALL NEW M1D PRODUCTION FLOOR LAYOUT"
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mr. mark on 06/16/2012 02:36 am
Interesting pic from the spaceflightnow coverage of the Bolden visit.  Looks like the sign says:
"THE ALL NEW M1D PRODUCTION FLOOR LAYOUT"

(http://www.spaceflightnow.com/news/n1206/14bolden/20.jpg)

Ah... not sure if this is a 1c or 1d. visually it looks more like 1c.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 06/16/2012 03:16 am
That is *certainly* a Merlin 1C.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: clarkeo on 06/16/2012 04:13 am
but the picture on the board is of a 1D with a layout of how the factory floor is set up. Would be very interesting to see this at a higher resolution!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris-A on 06/16/2012 04:22 am
Isn't hot-linking images not allowed, per forum rules? ;)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: bocephus419 on 06/16/2012 06:34 am
That is *certainly* a Merlin 1C.

To clarify, I'm referring to the sign to the lower left of the Merlin 1C:

"THE ALL NEW M1D PRODUCTION FLOOR LAYOUT"
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 06/16/2012 12:37 pm
Not to throw of the discussion, but to me, the Merlin "fineness" ratio seems higher than lets say an H-1.  Or even an RS-27.  Because of this perception, its power is deceiving. Booster engines are suppose to be squat and big (H-1, RS-68, F-1, etc) and upperstage engines are suppose to be slender with a big bell, the Agena Hustler, J-2 on S-IVB, Delta II second stage, etc
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: sdsds on 06/16/2012 08:52 pm
A cluster of nine Merlins, though, would look rather squat and big!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: HMXHMX on 06/16/2012 09:21 pm
Not to throw of the discussion, but to me, the Merlin "fineness" ratio seems higher than lets say an H-1.  Or even an RS-27.  Because of this perception, its power is deceiving. Booster engines are suppose to be squat and big (H-1, RS-68, F-1, etc) and upperstage engines are suppose to be slender with a big bell, the Agena Hustler, J-2 on S-IVB, Delta II second stage, etc

At least a third of this of Merlin 1C length comes from the structure.  Most previous engines aren't shown with the thrust structure attached (for example, consider H-1 and Saturn 1B).  That's portably due to the fact that engine and airframe manufacturers have been historically separate, and SpaceX is one of the few examples where they are the same entity.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: simonbp on 06/17/2012 05:20 am
Yeah, if you look from the top of the chamber to the end of the nozzle, Merlin looks a lot more like comparable RP-1 nozzles (H-1, S-3D, RS-27, etc).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Swatch on 06/25/2012 02:37 pm
Not to throw of the discussion, but to me, the Merlin "fineness" ratio seems higher than lets say an H-1...

How I choose to interpret this...

Jim thinks Merlin is a 'fine' engine!

:P
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/25/2012 03:02 pm
Not to throw of the discussion, but to me, the Merlin "fineness" ratio seems higher than lets say an H-1...

How I choose to interpret this...

Jim thinks Merlin is a 'fine' engine!

:P

Jim is correct the M1D is both a high performance and very economical engine. Usually its either one or the other not both.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mto on 06/25/2012 06:35 pm
SpaceX Testing: Merlin 1D Engine Firing

http://www.youtube.com/watch?v=976LHTpnZkY&feature=plcp

"SpaceX's Merlin 1D engine has achieved a full mission duration firing and multiple restarts at target thrust and specific impulse (Isp). The engine firing was for 185 seconds with 147,000 pounds of thrust, the full duration and power required for a Falcon 9 rocket launch. The tests took place at SpaceX's rocket development facility in McGregor, Texas. The Merlin 1D builds on the proven technology of the Merlin engines used on the first three flights of Falcon 9, including the recent historic mission to the International Space Station"
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Silmfeanor on 06/25/2012 07:12 pm
SpaceX Testing: Merlin 1D Engine Firing


First impressions:
They shortened the Gas Generator exhaust a lot - or moved it up.
The black exhaust is hitting the nozzle for sure.
There really is a big diffirence in nozzles compared to Merlin 1C- This one looks very smooth.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/25/2012 07:36 pm
This is a new configuration.
They got rid of the "quadrapod" (legacy of Falcon1)

This is a good hint SpaceX is going to redesign the thrust assembly for v1.1
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/25/2012 07:44 pm
SpaceX Testing: Merlin 1D Engine Firing


First impressions:
They shortened the Gas Generator exhaust a lot - or moved it up.
The black exhaust is hitting the nozzle for sure.
There really is a big diffirence in nozzles compared to Merlin 1C- This one looks very smooth.

The exhaust pipe has changed AT LEAST 3 or 4 times. I wonder if they are having problems with them or just ... trying to see if they can shave some weight.

I liked the old style nozzles :P they remind me of the F1 and J2 nozzles. The new one is probably better mind you. Hopefully thinning it out doesn't result in any splitting issues. Which SpaceX has had once before.

You can really tell where they got all these weight improvements from. Here is to hoping it doesn't explode :D
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/25/2012 07:47 pm
Another two views:
First one: attachment points of reaction rods are clearly lower than old version, and rods more vertical.
Second one: rods are shorter
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Silmfeanor on 06/25/2012 07:50 pm
Looks like the entire engine has less - as Jim put it -Merlin "fineness" ratio. - They seem to be compressing the thrust structure, moving the gas generator more parallel to the engine chamber, shortening the complete structure.
This might reflect in estimates about stages, especially if the same is true for 1D vacuum.

Or am I just seeing things? It looks shorter to me, especially if you remove the plumbing in the test stand. The thrust chamber is immediatly below the attachment point for the reaction rods, and the GG is to the side of it...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: edkyle99 on 06/25/2012 08:08 pm
I'm trying to imagine 27 of these starting up and firing together.   

 - Ed Kyle
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/25/2012 08:18 pm
I'm trying to imagine 27 of these starting up and firing together.   

 - Ed Kyle
Even 9 would be pretty impressive. Firing 9 Merlin 1Ds at once has not yet happened (ie for the inaugural Falcon 9 v1.1 first stage acceptance test), but I'm following this guy from Waco, Texas who should tweet when they do (it's so loud that surrounding Texans have to be informed before a test with all 9 at once):
https://twitter.com/JoeScience
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris Bergin on 06/25/2012 08:22 pm
I'm trying to imagine 27 of these starting up and firing together.   

 - Ed Kyle

HA! I just thought the same thing, now I'm catching up with the day and watched the video.

Got to do an article for this. Won't be telling you all anything new, but when we're thinking about the future, we need baseline articles to reference back to. This will be one of those.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/25/2012 08:30 pm
This was part of a press release

Vacuum T/W ratio of over 150, flight #6 in 2013 so VAFB will see no launches this year (as expected).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/25/2012 08:34 pm
This was part of a press release

Vacuum T/W ratio of over 150, flight #6 in 2013 so VAFB will see no launches this year (as expected).
Okay, so absolutely no chance of 4 launches this year (which was already essentially known). We might see hardware at VAFB, though...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/25/2012 08:45 pm
SpaceX got rid of the "quadrapod", reduced the reaction rods to 2 (from 4).
BTW, I see no actuators on the 2 remaining reaction rods.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: SpacexULA on 06/25/2012 08:50 pm
Seeing that single engine firing makes me miss Falcon 1.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/25/2012 08:55 pm
Seeing that single engine firing makes me miss Falcon 1.

I bet Falcon 9 v1.1 will cure your nostalgia, and FH will give you a lot of euphoria
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: daver on 06/25/2012 09:31 pm
SpaceX Testing: Merlin 1D Engine Firing

http://www.youtube.com/watch?v=976LHTpnZkY&feature=plcp

"SpaceX's Merlin 1D engine has achieved a full mission duration firing and multiple restarts at target thrust and specific impulse (Isp). The engine firing was for 185 seconds with 147,000 pounds of thrust, the full duration and power required for a Falcon 9 rocket launch. The tests took place at SpaceX's rocket development facility in McGregor, Texas. The Merlin 1D builds on the proven technology of the Merlin engines used on the first three flights of Falcon 9, including the recent historic mission to the International Space Station"

 :o Talk about rollin coal.  Sweet!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 06/25/2012 09:37 pm
Seeing that single engine firing makes me miss Falcon 1.


Same, Falcon 1 was a nice bird.


Aside from that, really like the new engine. Looks like significant improvements to the engine compared to 1C, seems like a far more stable burn, also higher velocity burn, by comparison to the 1 C videos.

Now I want to see em fly! 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/25/2012 09:57 pm
Isp is only about 10% higher. The main changes are a drastic reduction in weight, a huge increase in chamber pressure (knock on wood), increased expansion ratio (14.5 to 16) and the ability to throttle.

If it comes out close to specs it will be the highest thrust:weight vehicle in the world.

I'm sure they know what they are doing but I hope they don't have to test their engine out capability. Higher pressures, less weight is a brave combo.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 06/25/2012 10:01 pm
Isp is only about 10% higher. The main changes are a drastic reduction in weight, a huge increase in chamber pressure (knock on wood), increased expansion ratio (14.5 to 16) and the ability to throttle.

If it comes out close to specs it will be the highest thrust:weight vehicle in the world.

I'm sure they know what they are doing but I hope they don't have to test their engine out capability. Higher pressures, less weight is a brave combo.

I'll have more confidence personally on the chamber pressure after I see 9 engine firing. Also wondering if they are going to do 256-300 sec firings on these or not.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/25/2012 10:04 pm
Isp is only about 10% higher. The main changes are a drastic reduction in weight, a huge increase in chamber pressure (knock on wood), increased expansion ratio (14.5 to 16) and the ability to throttle.

If it comes out close to specs it will be the highest thrust:weight vehicle in the world.

I'm sure they know what they are doing but I hope they don't have to test their engine out capability. Higher pressures, less weight is a brave combo.

I'll have more confidence personally on the chamber pressure after I see 9 engine firing. Also wondering if they are going to do 256-300 sec firings on these or not.

They have to for prepping for flyback. Also, multiple restarts.

Hopefully the grasshopper will give them a lot of practice... Assuming the follow armadillo aerospace and test everything ... a lot. Seems that the computer programmer types are fans of testing.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 06/25/2012 10:10 pm
Isp is only about 10% higher. The main changes are a drastic reduction in weight, a huge increase in chamber pressure (knock on wood), increased expansion ratio (14.5 to 16) and the ability to throttle.

If it comes out close to specs it will be the highest thrust:weight vehicle in the world.

I'm sure they know what they are doing but I hope they don't have to test their engine out capability. Higher pressures, less weight is a brave combo.

I'll have more confidence personally on the chamber pressure after I see 9 engine firing. Also wondering if they are going to do 256-300 sec firings on these or not.

They have to for prepping for flyback. Also, multiple restarts.

Hopefully the grasshopper will give them a lot of practice... Assuming the follow armadillo aerospace and test everything ... a lot. Seems that the computer programmer types are fans of testing.


Before you do a flyback booster, grasshopper, or any of these things you test the engines on the test stand first. That is what I was referring to: essentially how much more testing will be done on these before they fly, and what does it consist of.

Prior to Falcon 9 flight 1 there were many engine tests both individually for each engine and all 9.

But you are correct, additional vehicle testing by proxy using these engines will gives us more data.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/25/2012 10:16 pm
This is the part SpaceX eliminated.
It was a residual of the old Falcon 1 thrust arrangement.
And this is an aswer also where SpaceX saved weight
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 06/25/2012 10:34 pm
A wide angle view of the same test, from the SpaceX update page.

This shows a better view of the thrust structure (or lack thereof) on the Merlin 1D.

EDIT: comparing the turbopump exhaust to the M1C diagram above, the exhaust itself appears to be virtually unchanged from the 1C.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/26/2012 12:57 am
A wide angle view of the same test, from the SpaceX update page.

This shows a better view of the thrust structure (or lack thereof) on the Merlin 1D.

EDIT: comparing the turbopump exhaust to the M1C diagram above, the exhaust itself appears to be virtually unchanged from the 1C.

http://www.b14643.de/Spacerockets_2/Diverse/U.S._Rocket_engines/Merlin-1D.jpg

http://www.spacex.com/images/Merlin_1C_Falcon_1_engine.jpg

http://www.spacex.com/00Graphics/Images/F9Update0807/09%20Merlin%20test.jpg

It changes plenty :P
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: JBF on 06/26/2012 01:41 am
A wide angle view of the same test, from the SpaceX update page.

This shows a better view of the thrust structure (or lack thereof) on the Merlin 1D.

EDIT: comparing the turbopump exhaust to the M1C diagram above, the exhaust itself appears to be virtually unchanged from the 1C.

http://www.b14643.de/Spacerockets_2/Diverse/U.S._Rocket_engines/Merlin-1D.jpg

http://www.spacex.com/images/Merlin_1C_Falcon_1_engine.jpg

http://www.spacex.com/00Graphics/Images/F9Update0807/09%20Merlin%20test.jpg

It changes plenty :P

That first link is protected.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: jiggawo on 06/26/2012 01:57 am
The engine definitely still has a "quadpod" thrust structure. There are two visible legs, one directly in front of the camera, and one to the left.


A wide angle view of the same test, from the SpaceX update page.

This shows a better view of the thrust structure (or lack thereof) on the Merlin 1D.

EDIT: comparing the turbopump exhaust to the M1C diagram above, the exhaust itself appears to be virtually unchanged from the 1C.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/26/2012 02:37 am
That first link is protected.

Errr... Go through http://www.b14643.de/Spacerockets_2/Diverse/U.S._Rocket_engines/engines.htm
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: go4mars on 06/26/2012 03:37 am
Grasshopper suddenly seems an innocuous name...

To summarize this update:
Elon has the coolest hobby of any billionaire I've heard of.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: 8900 on 06/26/2012 05:22 am
http://www.spacex.com/press.php?page=20120625 (http://www.spacex.com/press.php?page=20120625)

Abstract:
An upgraded Merlin engine designed to boost the lift capacity of SpaceX's Falcon 9 rocket has completed a full mission duration test firing in Texas, the company announced Monday.
The Merlin 1D engines will first see flight on Falcon 9 Flight 6, expected to launch in 2013.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris Bergin on 06/26/2012 05:39 am
I'm trying to imagine 27 of these starting up and firing together.   

 - Ed Kyle

HA! I just thought the same thing, now I'm catching up with the day and watched the video.

Got to do an article for this. Won't be telling you all anything new, but when we're thinking about the future, we need baseline articles to reference back to. This will be one of those.

And done (with an AJ-26 test fire included):

http://www.nasaspaceflight.com/2012/06/spacex-merlin-1d-orbital-fire-aj-26-engine/
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/26/2012 05:40 am
The engine definitely still has a "quadpod" thrust structure. There are two visible legs, one directly in front of the camera, and one to the left.



No, the engine has it no more.
Big difference is that "quadrapod" now is part of the test stand.
Now it is something like a test stand fixture, it will disappear on the launch mount.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 06/26/2012 08:36 am
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified.

VAC Thrust / T/W  =  engine weight
155,000lbf / 160:1 = 968.75lb or 440kg

The one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.

Did we get close to a weight for the 1D?

Only a calculated one of 440kg from the the stated 155klbf VAC thrust and the T/W of 160:1 by Muller April 2011.

Note that the latest update now backs the T:W down slightly to "over 150", and confirms it relates to vac thrust:-

This was part of a press release

Vacuum T/W ratio of over 150...

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: a_langwich on 06/26/2012 11:15 am

http://www.b14643.de/Spacerockets_2/Diverse/U.S._Rocket_engines/Merlin-1D.jpg

http://www.spacex.com/images/Merlin_1C_Falcon_1_engine.jpg

http://www.spacex.com/00Graphics/Images/F9Update0807/09%20Merlin%20test.jpg

It changes plenty :P

To my untrained eyes it looks like the turbopump assembly is beefier, which seems pretty reasonable for an engine with increased thrust.

Why is the bell smooth?  It's still regen cooled, but I don't see the circumferential rings...what are they doing there?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/26/2012 11:27 am
Why is the bell smooth?  It's still regen cooled, but I don't see the circumferential rings...what are they doing there?

Channel wall nozzle. Another improvement of Russian origin. See RD-170, 180, etc.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Crispy on 06/26/2012 11:57 am
Are they using the corrugation method, or milled channels? I can't find a reference...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/26/2012 12:00 pm
I thought I read corrugated somewhere, but I may just be imagining things.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: dasmoth on 06/26/2012 12:17 pm
I thought I read corrugated somewhere, but I may just be imagining things.

Several previous posts here have talked about the use of explosive hydroforming in the M1D, for both the chamber and nozzle.  I assume that counts as corrugated channels.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: 2552 on 06/26/2012 01:25 pm
I thought I read corrugated somewhere, but I may just be imagining things.

Several previous posts here have talked about the use of explosive hydroforming in the M1D, for both the chamber and nozzle.  I assume that counts as corrugated channels.

That's from here (http://spacenews.com/profiles/110425-elon-musk.html):

Quote
What can you tell me about the upgrade under way to the Falcon 9’s Merlin-1C engine and how it will streamline production?

The hardest part of the engine to mass produce is the electro-plating of nickel cobalt on the chamber. We create this thick metal jacket that takes the primary stress of the pressure vessel and it’s plated one molecule at a time. Plating is about the slowest way you can make a metal thing. With the Merlin-1D we take a metal jacket that is explosively formed. We take a metal sheet that’s in a cylindrical form and put it in a bucket of water, effectively. Sort of a concrete pool. And you set off an explosive and the jacket just goes “boohmp” and forms to the outer side walls into a jacket shape, so you have a mold, effectively. And then you just put the jacket on the chamber and braise it on. You can do several a day. We have a fully integrated engine and it’s being test-fired right now. There’s really not a lot of question marks remaining about the Merlin-1D.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Crispy on 06/26/2012 01:48 pm
Yeah, I found that. But reading carefully, it only describes the production of the *outer* layer, which would be a smooth-faced surface. Can explosive hydroforming be used for the middle, corrugated layer, whilst maintaining good tolerance on all the fine detail?

The statement that the previous method was plating makes me more curious. It implies that the channels in the 1C chamber/nozzle are on the *inside* face of the central layer. If they were on the outside, then the plating process would just fill in the channels, instead of leaving them open.

I don't expect all these details to be known, tbh. I doubt SpaceX wants to share every last detail of their manufacturing process with their competitors.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/26/2012 03:46 pm
Why is the bell smooth?  It's still regen cooled, but I don't see the circumferential rings...what are they doing there?

Channel wall nozzle. Another improvement of Russian origin. See RD-170, 180, etc.

:P So what you are saying is... next steps: staged combustion, multichamber and 12x more thrust?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/26/2012 03:58 pm
Absolutely. That is *precisely* what I'm saying...  ::)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/26/2012 04:51 pm
Isp is only about 10% higher. The main changes are a drastic reduction in weight, a huge increase in chamber pressure (knock on wood), increased expansion ratio (14.5 to 16) and the ability to throttle.

If it comes out close to specs it will be the highest thrust:weight vehicle in the world.

I'm sure they know what they are doing but I hope they don't have to test their engine out capability. Higher pressures, less weight is a brave combo.

I'll have more confidence personally on the chamber pressure after I see 9 engine firing. Also wondering if they are going to do 256-300 sec firings on these or not.

They have to for prepping for flyback. Also, multiple restarts.

Hopefully the grasshopper will give them a lot of practice... Assuming the follow armadillo aerospace and test everything ... a lot. Seems that the computer programmer types are fans of testing.


Before you do a flyback booster, grasshopper, or any of these things you test the engines on the test stand first. That is what I was referring to: essentially how much more testing will be done on these before they fly, and what does it consist of.

Prior to Falcon 9 flight 1 there were many engine tests both individually for each engine and all 9.

But you are correct, additional vehicle testing by proxy using these engines will gives us more data.
I'm pretty sure you'll see acceptance testing of each individual engine (don't know if it'll be full duration), plus a full duration acceptance test of the stage itself and all 9 engines at McGregor before the rocket flies (and quite likely a shorter test or two beforehand, plus the usual 2 second hot-fire test on the pad). ALL Falcon 9s have done that so far (including the CRS-1 Falcon 9 sitting at the Cape right now, though it hasn't done the 2 second hot fire, yet), so it seems to be SpaceX's standard operating procedure at this point. That may change in the future (i.e. shorter acceptance tests), but I have absolutely no doubt they'll do just as much testing for the first v1.1 vehicle.

This is a lot more testing than is usually done for an expendable launch vehicle. Stage Acceptance tests haven't been standard operating procedure for most groups since the Saturn launch vehicle, according to what I've been told.

This is probably why SpaceX's first 3 Falcon 9 launches have done so well, in spite of the historical improbability of the first 3 launches of a new launch vehicle being all successful. (They also do full acceptance testing of the upper stage, but not in a vacuum, so without the nozzle extension.) It's a pretty good model, IMHO, for any groups wishing to develop a new launch vehicle.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 06/26/2012 04:58 pm
The only reason to shorten acceptance tests in the future is a concern that a full duration test somehow increases the odds of failure on flight.

This of course will directly contradict any claim for reusability.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: spacetraveler on 06/26/2012 05:00 pm
They are probably more rigorous in the testing than most because SpaceX wants to carry people on the Falcon 9, and they know that rockets blowing up is not very conducive to the safety perception or political will needed to make that happen.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/26/2012 05:06 pm
The only reason to shorten acceptance tests in the future is a concern that a full duration test somehow increases the odds of failure on flight.

This of course will directly contradict any claim for reusability.
Not at all the only reason. Others in the industry I've talked to seem to think they may not always do such acceptance tests as they do now. Doing more tests also costs more time and money.

These are currently (and will remain, until Grasshopper is finished) expendable launch vehicles. Many of the components can be reused many times. The engines can be reportedly (and some have been, reportedly) used for 10-20 firings. But there are other components as well that might need monitoring.

It's not free to do these acceptance tests. They plan on getting to 8 launches per year in 2013 (I think it'll be wonderful to get 5 or 6, IMHO... 8 is a pretty high goal). At that point, saving a week or even a couple days at McGregor makes a significant difference to the final schedule.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 06/26/2012 05:37 pm
Less tests is cheaper, but what I was saying is that shorter tests - not so much.

As for less tests -

Right now they are at their infancy.  "If you think too much testing is expensive, try too little testing"...  That's an obvious statement of course, but for what testing gives them (their biggest enemy is lack of confidence by the market) it's cheap.

Even at one launch a month, if the testing crew and the fabrication crew are separate, I don't see the conflict.  Even if they have to build another test stand.

Once they get to reusability, of course, each flight is the test of the next flight, and they can increase flight rates w/o increasing test rates.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/26/2012 05:40 pm
Less tests is cheaper, but what I was saying is that shorter tests - not so much.

As for less tests -

Right now they are at their infancy.  "If you think too much testing is expensive, try too little testing"...  That's an obvious statement of course, but for what testing gives them (their biggest enemy is lack of confidence by the market) it's cheap.

Even at one launch a month, if the testing crew and the fabrication crew are separate, I don't see the conflict.  Even if they have to build another test stand.

Once they get to reusability, of course, each flight is the test of the next flight, and they can increase flight rates w/o increasing test rates.

Hey, I'm just repeated the opinion others in the industry have expressed. SpaceX does a lot more acceptance testing than almost anyone else has done recently, even for new launch vehicles. I tend to think it's a very good choice to do so much testing.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 06/26/2012 05:54 pm
I'm shooting at the message, not the messenger  :)

Not really shooting, either - just opining - they were just opining too...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 06/26/2012 06:17 pm
The only reason to shorten acceptance tests in the future is a concern that a full duration test somehow increases the odds of failure on flight.

This of course will directly contradict any claim for reusability.

Not at all the only reason. Others in the industry I've talked to seem to think they may not always do such acceptance tests as they do now. Doing more tests also costs more time and money.

I presume F9 #004 (Spx-1) has gone through this process, and it would seem to make sense for F9 #005 to do the same, since it's the last of the v1.0s.

It would make sense for the early v1.1s to do the same, as a substantially upgraded config.



It's not free to do these acceptance tests. They plan on getting to 8 launches per year in 2013 (I think it'll be wonderful to get 5 or 6, IMHO... 8 is a pretty high goal). At that point, saving a week or even a couple days at McGregor makes a significant difference to the final schedule.

AIUI, engines are built at Hawthorne, shipped to McGregor for testing, shipped back to Hawthorne, assembled onto a stage, shipped back to McGregor, tested as a stage, then shipped to KSC.

I'm wondering why they couldn't ship stages to McGregor without engines, then fit them, test the stage, and ship onwards. After all, they were all set to perform an engine swap at KSC on F9 #003 in a couple of days.

ISTM the tests are worth it if they avoid a launch failure, repeating the comments above.

That's the open question - would it? Perhaps the important metric is whether less testing would be balanced by more expensive insurance.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/26/2012 06:27 pm
Yes, Falcon 9 Flight 4 has been acceptance tested already.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Joel on 06/26/2012 07:16 pm
:P So what you are saying is... next steps: staged combustion, multichamber and 12x more thrust?

Sorry for a stupid question, but are there any examples of GG engines that have evolved into SC? Could SpX use the Merlin 1D as a basis for a SC engine or would they have to start from a clean sheet?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/26/2012 08:01 pm
Falcon 9 v1.1 with scaled pic of Merlin 1D new version.
Fits nicely....
That picture wasn't so meaningless....
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 06/26/2012 08:06 pm
How does it fit? I'm sorry, but that tells us nothing about the accuracy of that picture. Practically ANY engine could be photoshopped in there like you did, and look like "it fits!".
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: dwightlooi on 06/26/2012 08:11 pm
:P So what you are saying is... next steps: staged combustion, multichamber and 12x more thrust?

Sorry for a stupid question, but are there any examples of GG engines that have evolved into SC? Could SpX use the Merlin 1D as a basis for a SC engine or would they have to start from a clean sheet?

I guess you can use the chamber and nozzle, but the pumps and gas generators will have to be new. This, for all practical purpose makes it a new engine.

The real question is why do you want a staged combustion engine? For about 20 seconds higher Isp? Sometimes it is easier and cheaper to build a slightly bigger rocket -- or in the case of the falcon 9 one with 12% more thrust and extended 1st stage tanks -- than it is to build a more complex, more finicky and higher performance engine.

Aluminum is cheap. Fuel is cheap. Efficiency and payload fraction performance often isn't as important as payload capacity itself. Bigger, simpler and less efficient and often be cheaper per pound to orbit. For years, NASA and many others have been chasing after performance and efficiency, when the effort really should have been directed at building the cheapest vehicle that will take a given payload size into orbit and beyond.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 06/26/2012 08:19 pm
If you think so... ::)

Here's proof. Look, I pasted in both an F-1 and SSME engine. They both fit! Amazing!  ;D

My *point*, which you seem to have missed, is that these kinds of 'pasting' exercises are pointless without hard and accurate dimension figures.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/26/2012 08:24 pm

Here's proof. Look, I pasted in both an F-1 and SSME engine. They both fit! Amazing!  ;D

My *point*, which you seem to have missed, is that these kinds of 'pasting' exercises are pointless without hard and accurate dimension figures.
I see the SSME will fit if they have now moved to a 20' core, and the F-1 will fit if they moved to a 40' core.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/26/2012 08:30 pm
@Lars_J
You did a really amazing thing... :D
Much more better than mine... :o

Seriously, I can't see your point.
I put in it the new merlin 1D with the new attachment points, not a random engine...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 06/26/2012 08:32 pm
That picture was CAD-derived.  I know of no graphic designer that on a whim will shift the engine configuration on an image given to him by engineering.  And then hide it later under another image.  It's a contrived scenario...  The much simpler explanation is that they've been given that image as is.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 06/26/2012 08:34 pm
How about you simply wait until F9 V 1.1 begins acceptance testing?

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Joel on 06/26/2012 08:36 pm
The real question is why do you want a staged combustion engine?

Clearly Musk wants a staged combustion engine. But it could of course be used only for the upper stage. But that's the topic of other threads in this forum.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 06/26/2012 08:53 pm
:P So what you are saying is... next steps: staged combustion, multichamber and 12x more thrust?

Sorry for a stupid question, but are there any examples of GG engines that have evolved into SC? Could SpX use the Merlin 1D as a basis for a SC engine or would they have to start from a clean sheet?
Everything is different. You can't. The temperature and pressure of the chamber is very different (compare the 1400psi of he Merlin 1D to the 3,850psi of the RD-191), the gas generator circuit is completely different, the turbopump requirements are completely different, I can't think of much more than actuators as common.
Regarding the necessity of SC, it generally is better for higher energy orbits. So, it's usually more important for US than for first stage applications. Ultimately, though, the whole issue is if you can make a business case. As it is now, and if they can keep the Falcon Heavy price. There will be very little market's that the F9/FH combo wouldn't be competitive. So as of now, I don't really see a need for extra investment on SC.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 06/26/2012 09:03 pm
@FinalFrontier Sorry if I hurted you... bold mine

This tread is for the posting of new information on the Merlin 1D test article and production engine. Some discussion of the posted info is also welcome. The actual Merlin 1D production engine performance is the key to the SpaceX claims of the FH capabilities. If the 1D production engine falls too far below from the design specs, FH will not be able to perform as claimed.

Here is a summary of what we know and suspect so far:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf??
Vac Thrust155klbf?(better than expected)?(expect even better)
SL isp280s??
Vac isp310s309s??
T/W160??
Chamber Pressure1420psi??
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%?
Engine weight 440kg???

As new information comes available an update of the table will be posted.
? – Unknown
[value]? – Possible value but unverified
[value] – Verified value



Waiting for others real updates now...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: JBF on 06/26/2012 09:48 pm
From the start of the video we know the 1D test article thrust is 147klbf.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 06/26/2012 10:08 pm
How about you simply wait until F9 V 1.1 begins acceptance testing?


we sure the 9 engines havn't been tested as yet?    We don't know when the videos were taken, only when the info is released.

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/26/2012 10:10 pm
How about you simply wait until F9 V 1.1 begins acceptance testing?

we sure the 9 engines havn't been tested as yet?

Core #5 hasn't even been fired yet.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 06/26/2012 10:14 pm
Ultimately, though, the whole issue is if you can make a business case.

This is the source of a lot of misunderstanding IMO.

SpaceX is not trying to be a ULA clone.

The right observation is:  Ultimately, does it make sense to the grand plan of going to Mars.

Even if a certain engine is less than ideal for Earth orbits, but is useful for Mars and can work for (and thus be paid for) doing LEO or GEO work, then they will do it.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/26/2012 10:41 pm
Summary of what we know so far:

EngineMerlin 1D (Design)Merlin 1D (Test article)Merlin 1D (Production)
SL Thrust140klbf?147klbf
Vac Thrust155klbf?(better than expected)161klbf
SL isp280s??282s
Vac isp310s309s?311s
T/W160?150+
Chamber Pressure1410psi? 1410psi?
Expansion1616?16?(this shouldn’t vary much from design)
Throttle range70-100%70%-100%?70%-100%
Engine weight 440kg??485kg?
Costs<M1C?-<M1C


EngineMerlin 1DVAC (Design)Merlin 1DVAC (Test article)Merlin 1DVAC (Production)
Vac Thrust174klbf???
Vac isp348s?(an educated WAG)??
T/W160???
Chamber Pressure1410psi???
Expansion??>117?(this was the MVAC value)
Throttle range70-100%???
Engine weight >440kg???
Costs<M1CVAC?-?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: FinalFrontier on 06/26/2012 10:45 pm
That's for the new numbers Atlas.

Where did you get the extra 45kg weight for M1D production from?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/26/2012 10:46 pm
On the standpoint of costs for doing engine testing:

It will cost you about the same for doing 2 to 4 tests a week as it would to do 2 tests a month. The difference primarily being prop and water costs. Your overhead is the about the same (personnel and facilities).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/26/2012 10:49 pm
That's for the new numbers Atlas.

Where did you get the extra 45kg weight for M1D production from?

161,000lbf -> 73,181kgf/(151kgf/kg) = 485kg

The more than 150 T/W implies > 150 but < 155 or probably about 151.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/26/2012 11:02 pm
I'm trying to imagine 27 of these starting up and firing together.   

 - Ed Kyle

HA! I just thought the same thing, now I'm catching up with the day and watched the video.

Got to do an article for this. Won't be telling you all anything new, but when we're thinking about the future, we need baseline articles to reference back to. This will be one of those.

And done (with an AJ-26 test fire included):

http://www.nasaspaceflight.com/2012/06/spacex-merlin-1d-orbital-fire-aj-26-engine/

Thanks Chris for the great article. :)

Nitpicks: 27 M1D's 100% SL of 147,000lbf is 3,969,000lbf and at vac at 100% would be 4,347,000lbf.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 06/27/2012 01:10 am
I'm trying to imagine 27 of these starting up and firing together.

HA! I just thought the same thing, now I'm catching up with the day and watched the video.

Got to do an article for this. Won't be telling you all anything new, but when we're thinking about the future, we need baseline articles to reference back to. This will be one of those.

And done (with an AJ-26 test fire included):

http://www.nasaspaceflight.com/2012/06/spacex-merlin-1d-orbital-fire-aj-26-engine/

Thanks Chris for the great article. :)

Nitpicks: 27 M1D's 100% SL of 147,000lbf is 3,969,000lbf and at vac at 100% would be 4,347,000lbf.

Plume infringement?

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 06/27/2012 12:48 pm
Nitpicks: 27 M1D's 100% SL of 147,000lbf is 3,969,000lbf and at vac at 100% would be 4,347,000lbf.

Plume infringement?

Old thrust data for M1D (140 klbf). There is no plume interaction at sea level to account for the 3.8 Mlbf vs 4.0 Mlbf difference.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: 2552 on 06/27/2012 02:15 pm
https://twitter.com/elonmusk/status/217973460348047360

Quote from: Elon Musk
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/27/2012 02:24 pm
https://twitter.com/elonmusk/status/217973460348047360

Quote from: Elon Musk
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams


That seems to be a confirmation that the weight is ~485-490kg.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 06/27/2012 04:35 pm
https://twitter.com/elonmusk/status/217973460348047360

Quote from: Elon Musk
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams

That seems to be a confirmation that the weight is ~485-490kg.

Assuming "ton" = "tonne" (or metric ton).

If ton = 2000 lbs, then half-a-ton is 455 kg! But I still think you're right - SpaceX does seem to use metric for most things except engine thrust.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 06/27/2012 04:44 pm
SpaceX does seem to use metric for most things except engine thrust.
We don't know that. Only that they publish on lbf. The 140klbg does a very round 5.6MN, and the new 147klbf goes to almost exactly 3.8MN. I know that SpaceX has been known for some very generous rounding. But I suspect that internally they use metric exclusively. After all, Elon learned to use the metric system first.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MikeAtkinson on 06/27/2012 04:44 pm
https://twitter.com/elonmusk/status/217973460348047360

Quote from: Elon Musk
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams

That seems to be a confirmation that the weight is ~485-490kg.

Assuming "ton" = "tonne" (or metric ton).

If ton = 2000 lbs, then half-a-ton is 455 kg! But I still think you're right - SpaceX does seem to use metric for most things except engine thrust.

cheers, Martin

But he isn't trying to be accurate here, look at the other side of the equation "several Hoover Dams" - hardly accurate is it. All we can say from this statement is that it is within maybe 10% of "half a ton" where ton could mean tonne.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/27/2012 05:04 pm
https://twitter.com/elonmusk/status/217973460348047360

Quote from: Elon Musk
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams

That seems to be a confirmation that the weight is ~485-490kg.

Assuming "ton" = "tonne" (or metric ton).

If ton = 2000 lbs, then half-a-ton is 455 kg! But I still think you're right - SpaceX does seem to use metric for most things except engine thrust.

cheers, Martin

But he isn't trying to be accurate here, look at the other side of the equation "several Hoover Dams" - hardly accurate is it. All we can say from this statement is that it is within maybe 10% of "half a ton" where ton could mean tonne.

T/W of 150 with vac thrust of 161klbf makes the upper weight number of 488kg, 160 T/W would be 457kg, so the bounds on the weight seem to be
457kg < engine weight < 488kg.

Stating that the T/W is more than 150 but not saying more than 160 means that it is somewhere between those two, possibly the upper value is 155 if rounding is used. 2 digit accuracy values.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 06/27/2012 06:46 pm
Things to keep in mind: Would a staged combustion engine weigh more or less than a gas generator engine?

Merlin 1D (GG) now has the highest (vacuum) T/W ratio of any engine, even higher than the NK-33.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 06/27/2012 07:03 pm
Things to keep in mind: Would a staged combustion engine weigh more or less than a gas generator engine?

Merlin 1D (GG) now has the highest (vacuum) T/W ratio of any engine, even higher than the NK-33.
From what I've seen explained, the SC engine needs higher strength (due to higher temperature and pressure), but uses smaller diameter diameters, for equal thrust. And since you have the material (i.e. weight) needs decreasing cubically but diameters only decrease to the square, it's quite possible that you'll end up pretty close.
Let's remember that the NK-33 is a 45 years old engine. And still it's 130T/W vs more then 150T/W for the Merlin 1D. I don't know if you could apply some tricks of the Merlin 1D to improve the T/W of the NK-33. But I guess it's not necessary impossible to get similar (say, 10%) T/W. How much T/W (and thus fmp) are you willing to sacrifice for the increased isp, that depends heavily on your overall requirements.
What I can say, is that SC is a lot more expensive to develop than GG.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 06/27/2012 07:16 pm
Things to keep in mind: Would a staged combustion engine weigh more or less than a gas generator engine?

Merlin 1D (GG) now has the highest (vacuum) T/W ratio of any engine, even higher than the NK-33.

From what I've seen explained, the SC engine needs higher strength (due to higher temperature and pressure), but uses smaller diameter diameters, for equal thrust. And since you have the material (i.e. weight) needs decreasing cubically but diameters only decrease to the square, it's quite possible that you'll end up pretty close.
Let's remember that the NK-33 is a 45 years old engine. And still it's 130T/W vs more then 150T/W for the Merlin 1D. I don't know if you could apply some tricks of the Merlin 1D to improve the T/W of the NK-33. But I guess it's not necessary impossible to get similar (say, 10%) T/W. How much T/W (and thus fmp) are you willing to sacrifice for the increased isp, that depends heavily on your overall requirements.
What I can say, is that SC is a lot more expensive to develop than GG.

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mvpel on 06/28/2012 03:26 am
The statement that the previous method was plating makes me more curious. It implies that the channels in the 1C chamber/nozzle are on the *inside* face of the central layer. If they were on the outside, then the plating process would just fill in the channels, instead of leaving them open.

I don't expect all these details to be known, tbh. I doubt SpaceX wants to share every last detail of their manufacturing process with their competitors.

Check out patent 5,473,817 (http://www.google.com/patents/US5473817), by Schnoor and Surls of United Technologies. It describes the technique for explosive forming of combustion chamber cooling channels quite nicely. It makes reference to another patent, 3,208,132, which describes an explosive forming/brazing process, but the newer patent eliminates the need for brazing or welding. You form the outer wall by filling the outside channels with wax, leaving the ridges exposed, then electro-forming the outer surface onto the ridges. Once you melt out the wax, you have your fully formed coolant channels.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: dwightlooi on 06/28/2012 04:53 am

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin

Before we even talk about the performance benefits of a Staged Combustion cycle and if it decreases reliability and safety margins, I think we should why we want to totally change the design of the Merlin in exchange for about 20 Isp. In short, why do we want more performance?

The F9 already has payload capacity of the EELVs. The FH already beats them by a factor of 2. That 20 Isp may get you another 2 tons of lift in an F9 and up to 5 on the FH. Really, does have 15 tons instead of 13 and/or 58 instead of 53 help SpaceX expand their launch manifest in any tangible way? If not, why isn't a simpler, safer, cheaper to build engine preferable to one with higher performance?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: CapitalistOppressor on 06/28/2012 10:27 am

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin

Before we even talk about the performance benefits of a Staged Combustion cycle and if it decreases reliability and safety margins, I think we should why we want to totally change the design of the Merlin in exchange for about 20 Isp. In short, why do we want more performance?

The F9 already has payload capacity of the EELVs. The FH already beats them by a factor of 2. That 20 Isp may get you another 2 tons of lift in an F9 and up to 5 on the FH. Really, does have 15 tons instead of 13 and/or 58 instead of 53 help SpaceX expand their launch manifest in any tangible way? If not, why isn't a simpler, safer, cheaper to build engine preferable to one with higher performance?


This post is OT, as pointed out by Martin, but as long as we are living dangerously . . .

The "New Methane SC" thread discusses this issue exhaustively while making a persuasive case that the proposed SC engine will burn CH3.

http://forum.nasaspaceflight.com/index.php?topic=26995.0

First of all, Elon has said that he is getting ready to announce a new high efficiency SC engine, so as is normally the case what we think he should do doesn't matter.  If you take him at his word he is working on an SC engine for something.

Second, SPX answered an Air Force RFP with a proposal for a Methane powered high performance engine that they were working on, and which also could be a SC engine.

Third, SPX launchers would all get a big performance increase GTO and BEO with a high isp vac stage.  What you think SPX needs is not what Elon thinks it needs.  Elon badly wants to retire on Mars.  He is not doing that with a M1d vac upper stage.

Fourth, its not clear at all that you achieve only a 20isp improvement with a CH4 SC engine.  Threadstimates range up to a nigh impossible 400isp for vac operations, but a lot of smart money thinks 380 vac looks achievable along with a 355ish first stage.

Fifth, a lot of thread guesstimates point to the re-usability advantages of a CH4 SC engine in the context of Grasshopper.  Recent Russian test data support this line of thinking.  Elon <3's re-usability, because once he retires on Mars he wants you to be able to join him and that just can't happen unless he achieves his re-usability goals.

However, in terms of SpaceX current business you are basically right.  M1d on F9v1.1 and FH seem to service most/all of the current launch market, and (claims to) does it at (advertised) world beating prices. 

If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: dwightlooi on 06/29/2012 02:02 am
 
If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.

There are two ways to look at this...

(1) If that engine costs say $500 million to develop and probably a little more to produce, it may make more sense to simply use the money to give the customers of the next 50 launches a $10 million discount. That's 4~6 years worth and will firmly establish the company as the player to beat in the industry.

(2) Another way to look at it however is that SpaceX has hired the minds and made the capital investments to design, develop and qualify rocket engines. Unless they want to immediately layoff their hard won talent pool, they will have to keep them on the payroll. This becomes a fix cost whether they use them to develop a new rocket engine or not. A large part of the development cost of a new engine hence will become an overhead they will have to pay whether they do anything with it or not.

But, if it's me, Super Draco and the launch escape application has way higher priority than upgrading the main propulsion engine(s) for the Falcon family. Beyond that, Super Draco can and should be developed into a long endurance engine. Long endurance meaning that it can be fired for 1~2 hours continuously. If you want to go to mars and come back, you need something that can sit in space for up to a year, then fire for that 0.9 km/s mars capture burn, possibly another 1.4km/s for MCO-LMO transition and another 1.4 km/s for earth return. A mission like that will probably need to burn tens of tons of propellant and it'll have to be truly storable propellant (nothing using LOX). You don't need a big engine -- big engines are heavy and need heavy thrust structures. You are just as well served with a tiny engine with a decent Isp burning for a long time. You can burn an RCS class thruster for days, but as the burn time gets ridiculous the thermal problems become questionable for ablatives. However, a Super Draco class thruster burning for 2~3 hours during an insertion burn is not unreasonable.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/29/2012 05:15 am
 
If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.

There are two ways to look at this...

(1) If that engine costs say $500 million to develop and probably a little more to produce, it may make more sense to simply use the money to give the customers of the next 50 launches a $10 million discount. That's 4~6 years worth and will firmly establish the company as the player to beat in the industry.

(2) Another way to look at it however is that SpaceX has hired the minds and made the capital investments to design, develop and qualify rocket engines. Unless they want to immediately layoff their hard won talent pool, they will have to keep them on the payroll. This becomes a fix cost whether they use them to develop a new rocket engine or not. A large part of the development cost of a new engine hence will become an overhead they will have to pay whether they do anything with it or not.

But, if it's me, Super Draco and the launch escape application has way higher priority than upgrading the main propulsion engine(s) for the Falcon family. Beyond that, Super Draco can and should be developed into a long endurance engine. Long endurance meaning that it can be fired for 1~2 hours continuously. If you want to go to mars and come back, you need something that can sit in space for up to a year, then fire for that 0.9 km/s mars capture burn, possibly another 1.4km/s for MCO-LMO transition and another 1.4 km/s for earth return. A mission like that will probably need to burn tens of tons of propellant and it'll have to be truly storable propellant (nothing using LOX). You don't need a big engine -- big engines are heavy and need heavy thrust structures. You are just as well served with a tiny engine with a decent Isp burning for a long time. You can burn an RCS class thruster for days, but as the burn time gets ridiculous the thermal problems become questionable for ablatives. However, a Super Draco class thruster burning for 2~3 hours during an insertion burn is not unreasonable.

IF FH meets price and payload targets and doesn't explode. They will be far cheaper than any of their competition. Why discount? I mean, unless they have extra rockets just laying around. Either way, they will be launching at the same rate: as fast as they can build them. The flexibility between F9 and FH means that they can easily move to fit the market.

Better to spend all that $ on his reusability ambitions. Build another grasshopper if it makes it work faster. Design a more deeply throttled engine. As well, his Mars ambitions. ISRU, landers, w/e the heck other mass of technology needed for mars. This keeps his talent pool.

Superdraco fired for 2 hours is 164,000kg of hypergols unless my math was terribly wrong. Even if there were a rocket that could put such a large spaceship into orbit.... The US would never allow it. Shit is dangerous. A leak would be like a small nuclear bomb going off.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: dwightlooi on 06/29/2012 06:14 am
Superdraco fired for 2 hours is 164,000kg of hypergols unless my math was terribly wrong. Even if there were a rocket that could put such a large spaceship into orbit.... The US would never allow it. crap is dangerous. A leak would be like a small nuclear bomb going off.

Actually that's about right if you want a 2 man mission to mass. You'll need about 30 tons in LMO -- that includes a 20 tons for the earth return stack, the rest you leave behind. It takes about 144 tons of MMH/N2O4 to put about 75 tons on TMI from LEO. 75 tons is necessary if you want to put about 30 tons into LMO because you need to lose about 2.3km/s to get from TMI to LMO. So you'll be burning about 140~150 tons of hypergolics in nearly 2-hour burn if you use a Draco class engine.

As for putting that in orbit, it is not any more or less acceptable than launching a Titan with its 163 ton core booster loaded with 155 tons of Hypergolics. The difference is that you won't actually light it until it's in LEO where there are no collaterals to hurt if you blow up.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Idiomatic on 06/29/2012 07:21 am
Superdraco fired for 2 hours is 164,000kg of hypergols unless my math was terribly wrong. Even if there were a rocket that could put such a large spaceship into orbit.... The US would never allow it. crap is dangerous. A leak would be like a small nuclear bomb going off.

Actually that's about right if you want a 2 man mission to mass. You'll need about 30 tons in LMO -- that includes a 20 tons for the earth return stack, the rest you leave behind. It takes about 144 tons of MMH/N2O4 to put about 75 tons on TMI from LEO. 75 tons is necessary if you want to put about 30 tons into LMO because you need to lose about 2.3km/s to get from TMI to LMO. So you'll be burning about 140~150 tons of hypergolics in nearly 2-hour burn if you use a Draco class engine.

As for putting that in orbit, it is not any more or less acceptable than launching a Titan with its 163 ton core booster loaded with 155 tons of Hypergolics. The difference is that you won't actually light it until it's in LEO where there are no collaterals to hurt if you blow up.

I think if they are doing a mars shot it will be all new rockets and engines with not very much overlap from what we have now.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 06/29/2012 08:42 pm
Please keep it on the M1D. There are other threads for speculations on Dracos usage.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: CapitalistOppressor on 06/29/2012 11:15 pm
(2) Another way to look at it however is that SpaceX has hired the minds and made the capital investments to design, develop and qualify rocket engines. Unless they want to immediately layoff their hard won talent pool, they will have to keep them on the payroll. This becomes a fix cost whether they use them to develop a new rocket engine or not. A large part of the development cost of a new engine hence will become an overhead they will have to pay whether they do anything with it or not.

^^  This is a critical point that still manages to understate its case. 

It's not just that they have an amazing development team that either gets used, gets wasted (and attrited away) or gets laid off.  It's that I don't think Elon Musk will ever stop investing in propulsion innovation.  Elon Musk is not just some corporate suit who looks at the bottom line and starts carving away with his pen knife.

The man styles himself as CTO, Chief Designer, etc.  He absolutely fancies himself as an engineer/designer and the last thing he wants to do is get rid of the engineering team that actually allows him to innovate. 

Personally, I think it would take the impending failure of his company to shut down his development team.  Once he finishes M1d (shameless plug for thread legitimacy) he will shift his team to something new, and process will continue for as long as he controls the company.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 06/29/2012 11:26 pm
T/W of 150 with vac thrust of 161klbf makes the upper weight number of 488kg, 160 T/W would be 457kg, so the bounds on the weight seem to be
457kg < engine weight < 488kg.

Stating that the T/W is more than 150 but not saying more than 160 means that it is somewhere between those two,....

That's MY kind of tea leaf reading.  Quite believable.

And you other guys, please take you staged combustion, hydrolox and other questions elsewhere.  This thread is for M1D Updates.  It's not "living dangerously" to go OT. It's living discourteously.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 06/30/2012 12:58 am
Not an update on the engine, but starting my next CAD project.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cordor on 06/30/2012 08:44 pm

I believe that the higher pressures in SC mean an engine is less likely to fail in a benign way. To the extent that F9/FH have engine out, it would possibly be compromised by a switch to SC.

However, this is OT for updates on 1D.

cheers, Martin

Before we even talk about the performance benefits of a Staged Combustion cycle and if it decreases reliability and safety margins, I think we should why we want to totally change the design of the Merlin in exchange for about 20 Isp. In short, why do we want more performance?

The F9 already has payload capacity of the EELVs. The FH already beats them by a factor of 2. That 20 Isp may get you another 2 tons of lift in an F9 and up to 5 on the FH. Really, does have 15 tons instead of 13 and/or 58 instead of 53 help SpaceX expand their launch manifest in any tangible way? If not, why isn't a simpler, safer, cheaper to build engine preferable to one with higher performance?


This post is OT, as pointed out by Martin, but as long as we are living dangerously . . .



a persuasive case that the proposed SC engine will burn CH3.

http://forum.nasaspaceflight.com/index.php?topic=26995.0


Third, SPX launchers would all get a big performance increase GTO and BEO with a high isp vac stage.  What you think SPX needs is not what Elon thinks it needs.  Elon badly wants to retire on Mars.  He is not doing that with a M1d vac upper stage.


Fifth, a lot of thread guesstimates point to the re-usability advantages of a CH4 SC engine in the context of Grasshopper.  Recent Russian test data support this line of thinking.  Elon <3's re-usability, because once he retires on Mars he wants you to be able to join him and that just can't happen unless he achieves his re-usability goals.

However, in terms of SpaceX current business you are basically right.  M1d on F9v1.1 and FH seem to service most/all of the current launch market, and (claims to) does it at (advertised) world beating prices. 

If they execute on FH and get their flight rate up while maintaining (advertised) prices they win.  But even in that scenerio, getting a high isp vac engine would provide a dramatic boost in performance for both rockets.

1. Mars is an ultimate goal, but it's not part of spacex business, not yet. Right now, spacex needs positive cash flow, after that they need to bring the cost down, which is F9R for. Expensive high performance engine doesn't fit in at all.

2. Even if they are going to Mars, today. They are not going to do apollo style rocket and spacecraft. YOU CAN'T PACK 5 billionaires in a confined space for 6 months PERIOD that's no way to do businese. More likely, they will use FH to carry 30~40 ppl to LEO, from there, they will dock and aboard Interplanetary Spacecraft with private compartments, another FH will carry supplies onboard. And then the Interplanetary Spacecraft fire up it's ion thruster all the way to Mars.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: arnezami on 06/30/2012 09:44 pm
Not an update on the engine, but starting my next CAD project.
Great!

Keep in mind though that according to the very latest photo's the turbopump has significantly changed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 07/01/2012 12:00 am
Not an update on the engine, but starting my next CAD project.
Great!

Keep in mind though that according to the very latest photo's the turbopump has significantly changed.
My drawing reflects the engine as of their open house at McGregor.  As soon as we have better photos I will get the turbo pump fixed.  At least I didn't waste time on the thrust structure, which has changed as well.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: aero on 07/03/2012 05:27 pm
Did anyone ever post the value of Bulk Density for the Merlin D?

It seems a little tricky to estimate due to the various densities given for RP-1.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: charliem on 07/04/2012 05:20 pm
Did anyone ever post the value of Bulk Density for the Merlin D?

It seems a little tricky to estimate due to the various densities given for RP-1.

This document from 1962 might give you an idea: http://atlasbases.homestead.com/Analysis_of_RP-1_Fuel_Density_-_SAWE0323.pdf

I don't think the specifications have changed much since.

Basically it says that Air Force standard RP-1 density is 807.5 kg/m3 (at 60şF).

It also gives a formula to compensate for temperature and a composition variations. Says nothing about pressure though, so I suppose those numbers are for 1 bar.

At 76şF, the Cape Canaveral anual average, mean density is a bit lower, 800.8 kg/m3.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: aero on 07/04/2012 05:53 pm
OK, that helps. Now, do we know what the RP-1/LOX ratio is?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: charliem on 07/04/2012 06:36 pm
OK, that helps. Now, do we know what the RP-1/LOX ratio is?

I have not found any numbers for 1D but there are clues about 1C in here (http://sites.wff.nasa.gov/code250/docs/expansion_ea/Appendix_A_MARS_Final_EA.pdf").

From the LOX and RP-1 tank capacities mentioned on page A-3, 15586 kg and 7159 kg, the O/F ratio should be about 2.21

For Merlin 1D it might be a different though.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 07/04/2012 08:02 pm
OK, that helps. Now, do we know what the RP-1/LOX ratio is?

I have not found any numbers for 1D but there are clues about 1C in here (http://sites.wff.nasa.gov/code250/docs/expansion_ea/Appendix_A_MARS_Final_EA.pdf").

From the LOX and RP-1 tank capacities mentioned on page A-3, 15586 kg and 7159 kg, the O/F ratio should be about 2.21

For Merlin 1D it might be a different though.


The main chamber is probably ~2.27.  I can't find the source for that one directly so don't quote me on it, but I think I got if from a SpaceX interview or publication for the M1C and assumed that the M1D is the same. 
The tank ratio will be slightly different since the gas generator will be run fuel rich compared to the main chamber.  Although not a huge difference, but will probably account for some extra RP-1 in the tank.

The Merlin 2 presentation (I know they are not doing it as of now) had that one at a 2.4 ratio.

I may be blowing steam with my information from above, but its all I have and its what I model my engine from the information published so far.

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Maciej Olesinski on 07/04/2012 08:52 pm
Not sure if anyone noticed but this can be viewed in 3d
http://www.youtube.com/watch?v=976LHTpnZkY
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ChefPat on 07/05/2012 12:52 pm
Not sure if anyone noticed but this can be viewed in 3d
I keep a pair of 3D glasses on my desk just for pix like that. Thanks for the heads up.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: billh on 08/23/2012 02:23 am
I just noticed something interesting near the bottom of the second page in this article on smallsats:

http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_20_2012_p31-486488.xml

"To produce the motors, CRP uses a computer-aided design (CAD) file containing the motor's shape, and electronically divides it into layers for the 3-D printing. Space Exploration Technologies Corp. (SpaceX) uses the same technique to manufacture tiny impellers and other parts for its Merlin rocket engines from titanium powder, according to a SpaceX spokesman."
[Emphasis mine.]

I don't recall hearing before that SpaceX was using 3-D printing in their engine manufacturing. Is anybody else doing this? It sounds pretty bleeding edge. Could they really be manufacturing turbopump impeller blades that way? The required tolerances are awfully fine.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Chris-A on 08/23/2012 02:26 am
For building molds?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: billh on 08/23/2012 02:35 am
That wouldn't be the most straightforward reading of it, but I suppose that's possible. I don't think the molds would be titanium. I think the blades would be titanium.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 08/23/2012 02:35 am
I just noticed something interesting near the bottom of the second page in this article on smallsats:

http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_20_2012_p31-486488.xml

"To produce the motors, CRP uses a computer-aided design (CAD) file containing the motor's shape, and electronically divides it into layers for the 3-D printing. Space Exploration Technologies Corp. (SpaceX) uses the same technique to manufacture tiny impellers and other parts for its Merlin rocket engines from titanium powder, according to a SpaceX spokesman."
[Emphasis mine.]

I don't recall hearing before that SpaceX was using 3-D printing in their engine manufacturing. Is anybody else doing this? It sounds pretty bleeding edge. Could they really be manufacturing turbopump impeller blades that way? The required tolerances are awfully fine.
Yeah, I think other people are doing it that way. the tolerances are good enough for blade shape (though I wouldn't be surprised if they did another polishing step or something like that). And no, I don't think it's just for molds, though it's possible they can't use it for the most strenuous parts of the rocket engine (which might want single-crystal fancy alloys or something like that).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: go4mars on 08/23/2012 05:11 am
I don't recall hearing before that SpaceX was using 3-D printing in their engine manufacturing....Could they really be manufacturing turbopump impeller blades that way?
I've seen their machine and what it makes.  It was explained to me as a good way to have engineers fast-track parts.  Make it on your computer, hit print, then walk over in a little while and see if it fits/works.  Make adjustments as necessary.  Just little stuff (at least back when I was in there).  Really cool. 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 08/23/2012 02:33 pm
I just noticed something interesting near the bottom of the second page in this article on smallsats:

http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_08_20_2012_p31-486488.xml

"To produce the motors, CRP uses a computer-aided design (CAD) file containing the motor's shape, and electronically divides it into layers for the 3-D printing. Space Exploration Technologies Corp. (SpaceX) uses the same technique to manufacture tiny impellers and other parts for its Merlin rocket engines from titanium powder, according to a SpaceX spokesman."
[Emphasis mine.]

I don't recall hearing before that SpaceX was using 3-D printing in their engine manufacturing. Is anybody else doing this? It sounds pretty bleeding edge. Could they really be manufacturing turbopump impeller blades that way? The required tolerances are awfully fine.

Boeing was doing some of this when they owned Rocketdyne.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: docmordrid on 08/25/2012 07:00 am
3D metal printing has become a 'really big deal' recently with the development of laser / plasma sintering of the layers, fusing theclayers into a solid part.

The quality is very high, as was evidenced last year in Europe when a woman received a pronted titanium jaw prosthesis. Thing is, the process can be used with many alloys and metal ceramics. Times, they are a changin'
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 09/30/2012 10:47 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

Does this match the expected thrust for M1D vac?

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 09/30/2012 10:50 pm
Sounds high, but if you take published M1d thrust and Isp numbers and assuming it uses the same chamber and has the same mass flow as regular M1d, that seems to work out to about 343 sec Isp. Pretty much the target for the original MVac.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: GBpatsfan on 09/30/2012 10:57 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

Does this match the expected thrust for M1D vac?

cheers, Martin
From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust:   161,000 lbf
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Zed_Noir on 09/30/2012 11:40 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

Does this match the expected thrust for M1D vac?

cheers, Martin
From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust:   161,000 lbf

Think that's for the regular version of the Merlin 1-D.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 10/01/2012 05:09 pm
Thanks for the update.

Updated table to show the possible Test article? vac thrust value for 80mt.

EngineMerlin 1DVAC (Design)Merlin 1DVAC (Test article)Merlin 1DVAC (Production)
Vac Thrust174klbf?176klbf??
Vac isp348s?(an educated WAG)??
T/W160???
Chamber Pressure1410psi???
Expansion??>117?(this was the MVAC value)
Throttle range70-100%???
Engine weight >440kg???
Costs<M1CVAC?-?

There are still a lot of unknowns but this is the best validation of the estimates we have had so far.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Prober on 10/01/2012 06:45 pm
Old Atlas, know I shouldn't be thinking this but....

What would you get if the 1.1D Vac was fired at SL?   That F12 is still bugging me. 

Edit:   good place to learn something anyhow.


Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 10/01/2012 07:26 pm
Old Atlas, know I shouldn't be thinking this but....

What would you get if the 1.1D Vac was fired at SL?   That F12 is still bugging me. 

Edit:   good place to learn something anyhow.



I am not OldAtlas_Eguy, but here is my estimated data.

Sea Level - 168 seconds - 87,253 lbf
Design - 336 seconds - 174,674 lbf (used in my simulation to change ISP by altitude)
Vacuum - 345 seconds 179,310 lbf

Estimated nozzle exit pressure is 0.74 psi.  Flow seperation at sea level would be very bad and probably kill the isp lower then 168 seconds estimated.


* Estimated data by MODEMEAGLE
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: WHAP on 10/02/2012 03:55 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

Does this match the expected thrust for M1D vac?

cheers, Martin
From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust:   161,000 lbf

Think that's for the regular version of the Merlin 1-D.

Why are people sure Elon meant 80 tonnes when he wrote 80 tons?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kch on 10/02/2012 04:09 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

Does this match the expected thrust for M1D vac?

cheers, Martin
From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust:   161,000 lbf

Think that's for the regular version of the Merlin 1-D.

Why are people sure Elon meant 80 tonnes when he wrote 80 tons?

They're "seeing" what they want to see -- it happens a lot.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 10/02/2012 04:10 pm
As long as it is within 10 percent or so, I doubt he cares.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 10/02/2012 04:39 pm
South Africa after 1977 was fully metric only, so this is the measument system environment in which Elon Musk grew up. He left South Africa in 1988. The default "ton" definition to someone who used only metric and very little English measurments would be the metric ton.

http://ukma.org.uk/south-african-experience (http://ukma.org.uk/south-african-experience)

So the interpretation of metric ton for this tweet has a foundation.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 10/02/2012 05:01 pm
My numbers are about a year old and based on scaling the M1D with a vacuum optimized nozzle.  If I was within 10% of the final data then I figured I was doing good.  I also used lower thrust data in my simulations and found FH could reach orbit with almost 70% of my estimated data.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: iamlucky13 on 10/02/2012 11:48 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: go4mars on 10/02/2012 11:57 pm
It also could be read the other way...  That they tested it at 80.  Not that it's rating is for 80. 
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 10/03/2012 12:07 am
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.
If you look in the background you will see a flex below the turbo pump.  Notice the dark streaks in the exhaust.  Compare it to the F-1 and the only conclusion is the turbo pump exhaust is pumped into the nozzle.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: neilh on 10/03/2012 12:18 am
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.

This is a totally random uneducated guess, but would the ring make sense as a mounting point for a retractable nozzle?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 10/03/2012 07:11 am
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.

If you look in the background you will see a flex below the turbo pump.  Notice the dark streaks in the exhaust.  Compare it to the F-1 and the only conclusion is the turbo pump exhaust is pumped into the nozzle.

Isn't the turbo-pump exhaust shown at the left of the pic, rather than being diverted into the nozzle? This would need to remain separate if v1.1 us is going to use the same roll control as v1.0.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 10/03/2012 10:15 am
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.

If you look in the background you will see a flex below the turbo pump.  Notice the dark streaks in the exhaust.  Compare it to the F-1 and the only conclusion is the turbo pump exhaust is pumped into the nozzle.

Isn't the turbo-pump exhaust shown at the left of the pic, rather than being diverted into the nozzle? This would need to remain separate if v1.1 us is going to use the same roll control as v1.0.

cheers, Martin
I could be wrong, been know to happen from time to time.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MATTBLAK on 10/03/2012 10:20 am
A rare admission around here!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 10/03/2012 11:14 am
Isn't the turbo-pump exhaust shown at the left of the pic, rather than being diverted into the nozzle? This would need to remain separate if v1.1 us is going to use the same roll control as v1.0.

Not necessarily. F9 US has to have cold gas RCS anyway for coast period attitude control, prop settling, etc. You don't need GG exhaust for roll control if you're confident the engine operation itself won't introduce large roll torques (although this assumption can bite you in the rear), bigger than RCS can handle and/or deplete the propellant.

MVac already demonstrated that any roll torques it produced were fairly small and yet the lower regen part of the nozzle was tube-wall design which makes the exhaust swirl a little. M1D flavor should be free from even that effect so it should impart very little roll torque.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Crispy on 10/03/2012 11:43 am
How does the shape of the regen channels affect the motion of the exhaust? I can understand how acceleration of propellant flow through the channels can create a torque, but how can it influence the exhaust?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: corrodedNut on 10/03/2012 11:58 am
...the lower regen part of the nozzle was tube-wall design...

I'm not sure about that. It seems that both Merlin C and D Vac are solely channel wall. Although the new MvacD extension has yet to be seen, assuming they are the same, there's no active cooling on the nozzle extentions, aside from the new GG exhaust injector.

edit: wrong picture, fixed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 10/03/2012 02:51 pm
I could be wrong, been know to happen from time to time.

I don't think you're wrong this time. There's what appears (to me) to be insulation on the lower conduit. My guess is that this is done to prevent cooling of the flowing gasses, which would have created unrealistic test conditions.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 10/03/2012 07:21 pm

If you look in the background you will see a flex below the turbo pump.  Notice the dark streaks in the exhaust.  Compare it to the F-1 and the only conclusion is the turbo pump exhaust is pumped into the nozzle.

I agree with you; for sure the manifold has sensors (thermocouples?) for something flowing inside.
Also it seems tapered from left of the image to the right.

I second also Ugordan's conclusions about roll control, considering that SpaceX has data from three flights to validate their models.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 10/03/2012 07:40 pm
It seems that both Merlin C and D Vac are solely channel wall.

Hmm, you're probably right.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: iamlucky13 on 10/03/2012 08:57 pm

If you look in the background you will see a flex below the turbo pump.  Notice the dark streaks in the exhaust.  Compare it to the F-1 and the only conclusion is the turbo pump exhaust is pumped into the nozzle.

I agree with you; for sure the manifold has sensors (thermocouples?) for something flowing inside.
Also it seems tapered from left of the image to the right.

I second also Ugordan's conclusions about roll control, considering that SpaceX has data from three flights to validate their models.

I agree on the roll control...requirements could certainly be within the limits of a reasonable cold gas system.

I can't say the "only conclusion" however is that they're mixing the turbopump exhaust in the nozzle extension. That was the answer that jumped out at me most immediately when seeing the big ring and the darker exhaust but a couple things surprise me about this;

1.) The current nozzle extension is apparently fine just being radiatively cooled niobium.

2.) It's a relatively substantial difference between the vacuum and atmospheric configurations of the -1D.

3.) It doesn't taper around the circumference like the scrollcase manifold on the F-1, which isn't necessarily required, but would help distribute the exhaust evenly.

4.) I haven't previously heard any rumors about switching to cold gas roll control on the upper stage, except in connection with brand new engines like Raptor. On the other hand, I briefly forgot the 2nd stage already has a cold gas system, so it's not like it would be completely new...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 10/03/2012 09:08 pm
@iamlucky 13
It seems to me that the manifold does taper around the circonference; right side is smaller, and we can't see behind.
About nozzle extension maybe (maybe!) they could change material; titanium is 50% lighter than niobium with not so smaller high temp strenght.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: simonbp on 10/04/2012 12:47 am
South Africa after 1977 was fully metric only, so this is the measument system environment in which Elon Musk grew up. He left South Africa in 1988. The default "ton" definition to someone who used only metric and very little English measurments would be the metric ton.

http://ukma.org.uk/south-african-experience (http://ukma.org.uk/south-african-experience)

So the interpretation of metric ton for this tweet has a foundation.

Except there isn't such a thing as a "metric ton" of force, just a metric tonne of mass (1000 kg precisely). Force/mass confusion is a common deficiency of American engineers...

He almost certainly got the number from his engineers, most of whom are American, and would have expressed it in US short tons of force (2000 pounds-force), so the thrust is about 160,000 pounds-force or 711 kN.

Ed Kyle's estimate of the mass of v1.1 the upper stage is 78.1 tonnes = 86.1 short tons. So, what Elon's tweet really says is that the upper stage has a thrust/weight just less than one at ignition. That's all it needs to be, and you don't want it too much higher or the burnout acceleration will be too high for the crew.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: QuantumG on 10/04/2012 01:15 am
Except there isn't such a thing as a "metric ton" of force, just a metric tonne of mass (1000 kg precisely). Force/mass confusion is a common deficiency of American engineers...

It's not a confusion, it's shorthand.. and it's not just American engineers.

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: bocephus419 on 10/04/2012 02:30 am
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.

This is a totally random uneducated guess, but would the ring make sense as a mounting point for a retractable nozzle?

While we're making uneducated guesses, I bet they chose to dump the turbo pump exhaust into the main nozzle in order to make it sleek enough to be retractable.  I don't see an exhaust nozzle in spacex's reusability video nor do I see where they would put one: http://spacex.com/multimedia/videos.php?id=2
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 10/04/2012 06:38 pm
Except there isn't such a thing as a "metric ton" of force, just a metric tonne of mass (1000 kg precisely). Force/mass confusion is a common deficiency of American engineers...

It's not a confusion, it's shorthand.. and it's not just American engineers.


+1
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 10/04/2012 07:08 pm
While we're making uneducated guesses, I bet they chose to dump the turbo pump exhaust into the main nozzle in order to make it sleek enough to be retractable.  I don't see an exhaust nozzle in spacex's reusability video nor do I see where they would put one: http://spacex.com/multimedia/videos.php?id=2
Don't try to read too many details into that video, the vision behind it isn't less than 5 years in the future for the first stage and 8 for the second stage.
For example the squared configuration for first stage engines has already been surpassed.
My "uneducated" guess is SpaceX ducted the turbo pump exaust into the main nozzle to:
-Gain a little bit ISP (as MeekGee says, the duct seems insulated, but for enthalpy conservation, not for test issues)
-Have a "relatively" cold flow (like F1) to use something less exotic (and heavy) than Niobium
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: newspacer on 10/04/2012 10:13 pm
Don't read too much into the bottom of this picture. It is a setup for test. They can't test the actual nozzle because it would be super over expanded at sea level. The thing in the pic is probably a stub skirt for test.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: JBF on 10/05/2012 11:18 am
Don't read too much into the bottom of this picture. It is a setup for test. They can't test the actual nozzle because it would be super over expanded at sea level. The thing in the pic is probably a stub skirt for test.

Remember they do have a vacuum chamber for testing these versions.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 10/05/2012 11:25 am
Remember they do have a vacuum chamber for testing these versions.

Not for MVac.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: JBF on 10/05/2012 01:15 pm
Remember they do have a vacuum chamber for testing these versions.

Not for MVac.
[/quote

My mistake I was thinking of the dracos.  Heh I wonder how big a setup you would need to actually test an MVac. Heat dissipation alone would be tough.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: iamlucky13 on 10/05/2012 04:32 pm
Don't read too much into the bottom of this picture. It is a setup for test. They can't test the actual nozzle because it would be super over expanded at sea level. The thing in the pic is probably a stub skirt for test.

It appears to be ended at the flange where the vacuum nozzle extension attaches, which I believe is consistent with past tests.

And just having a stub nozzle would not explain the large instrumented ring at the base or the apparently darker exhaust.

Although it surprised me as I said, I'm having trouble talking myself out of the conclusion they're dumping the turbo exhaust into nozzle and using something else for roll control.

@iamlucky 13
It seems to me that the manifold does taper around the circonference; right side is smaller, and we can't see behind.
About nozzle extension maybe (maybe!) they could change material; titanium is 50% lighter than niobium with not so smaller high temp strenght.

It's hard to tell with the shadowing. It may taper a bit, but not as significantly as the F-1 does. Again, this isn't critical, but one would expect a slower flow coming from the end of the manifold than the start, meaning uneven cooling, slight thrust imbalance, etc...but if it's easier to manufacture...

I also don't see the insulation.

By the way, I stumbled upon some really detailed images of how the nozzle of the F-1 is constructed here for comparison:
http://heroicrelics.org/info/f-1/f-1-thrust-chamber.html

Nothing really revealing, and obviously the brazed tubes in the F-1 are different than the Merlin's channel wall construction, but still gives some interesting details to compare and contrast.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 10/05/2012 05:13 pm
@iamlucky 13
sorry for the wording, I was not clear; the duct seems to me something like double wall (insulated), beefier in the middle and thinner on the flanges.
If you compare with F1, you see that flanges are bigger diameter than the duct (as normal for a single wall duct).
The double wall means also it's more difficult to see the taper.
About uneven distribution of flow I guess that sensors on duct are precisely to see temperature and flow.

Anyway I hope to see soon some more pics (or info).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Joffan on 10/05/2012 05:32 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.

I thought it might be some kind of stabilization (weighting/damping) for the stub nozzle due to the missing vacuum extension section. With some instruments to assess vibration embedded, as a further speculation.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 10/05/2012 06:51 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.

If you look in the background you will see a flex below the turbo pump.  Notice the dark streaks in the exhaust.  Compare it to the F-1 and the only conclusion is the turbo pump exhaust is pumped into the nozzle.

Isn't the turbo-pump exhaust shown at the left of the pic, rather than being diverted into the nozzle? This would need to remain separate if v1.1 us is going to use the same roll control as v1.0.

cheers, Martin

I could be wrong, been know to happen from time to time.

I thought the area I've surrounded in black was the gas generator exhaust.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: modemeagle on 10/05/2012 07:14 pm
Copied from the "general" thread:-
First picture of the Merlin 1D-Vac:

https://twitter.com/elonmusk/status/252528724602400768
Quote
Elon Musk ‏@elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ

I asked in the general thread, but my question was buried in the big long argument about T-shirts...  ::)

...what's the big ring around the base of the nozzle? The regen manifold is visible separately above it, so I know it's not that.

If you look in the background you will see a flex below the turbo pump.  Notice the dark streaks in the exhaust.  Compare it to the F-1 and the only conclusion is the turbo pump exhaust is pumped into the nozzle.

Isn't the turbo-pump exhaust shown at the left of the pic, rather than being diverted into the nozzle? This would need to remain separate if v1.1 us is going to use the same roll control as v1.0.

cheers, Martin

I could be wrong, been know to happen from time to time.

I thought the area I've surrounded in black was the gas generator exhaust.

cheers, Martin

Not sure what that is; angle would be off as it would produce roll.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 10/05/2012 07:27 pm
Modemeagle saw it correctly, the flex is under the GG-turbo pump assembly, in the right place for the exaust.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Hooperball on 10/05/2012 07:56 pm
Flexible coupling (expansion joint) to allow for thermal expansion in the GG piping.

S
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Hooperball on 10/05/2012 08:02 pm
GG gas is obviously being dumped into the nozzle extension which isn't present in this test.

S
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 10/06/2012 02:27 am
Modemeagle saw it correctly, the flex is under the GG-turbo pump assembly, in the right place for the exaust.

OK, thanks.

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 10/06/2012 12:11 pm
This sounds comparable to the J-2X, which does something similar, and has a pretty advanced Isp target for GG.

Is there any way to guess the Isp & thrust benefits on the kerolox M1D?

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 10/06/2012 01:19 pm

Is there any way to guess the Isp & thrust benefits on the kerolox M1D?

cheers, Martin
Difficult crunch numbers, without hard design numbers for the engine.
But vacuum nozzle extension doesn't grow indefinitely for two reasons:
-obviously, mass of the extension grows
-second, friction increases on the increased surface
Dumping your gg exaust into the nozzle you can keep the high speed flow far from the wall, using an already slower, less energetic flow.
One hint is SpaceX already has numbers from two different nozzle extension configurations (the famous tin snip repair).
From that numbers they can evaluate the nozzle performance.
Anyway, I would not absolutely dismiss bocephus419 suggestion:
"they chose to dump the turbo pump exhaust into the main nozzle in order to make it sleek enough to be retractable"
Not going to bet on it, but possible.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: simonbp on 10/06/2012 04:29 pm
Would any of the changes make it easier or more difficult to to switch over to CH4? CH4 burns hotter, and so presumably have a higher chamber pressure per Newton of thrust.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: go4mars on 10/06/2012 05:32 pm
If the gg exhaust can be actively controlled (which part(s) of the ring chamber manifold it goes through to the main chamber), it can act as a low mass thrust vectoring iris nozzle.  If most of the gg exhaust is directed to one port, for example, then it would very slightly change the thrust angle.  I mentioned that a few months ago.  But I agree that thermal expansion might be an additional reason for the segmented design.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Hooperball on 10/06/2012 06:19 pm
How many stages are in the new Spacex built turbo-pump turbine? Its possible that part of the GG gas (before turbine nozzle) or a 1st stage or 2nd stage turbine bleed could be used for roll control while the lower pressure turbine exhaust is used for nozzle extension cooling. This could explain what looks like exhaust on the left in the picture.

How much thrust does the M1C tubo-pump exhaust produce? A couple thousand lbs? How much is needed for roll control on the second stage? A couple hundred?

I speculate the segmented "hot gas manifold"  could be the result of ease of manufacture but all the other plumbing appears to be smooth single segments. Its possible with this being a test article that the segments are shielding to more accurately measure thermal properties (piping surface temperatures and therefore pressures) in the smooth single piece hot gas manifold underneath without interrupting flow characteristics.

S

 

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 10/08/2012 03:16 pm
(snip)How much thrust does the M1C tubo-pump exhaust produce? A couple thousand lbs? How much is needed for roll control on the second stage? A couple hundred?
(snip)
S

Durring the second stage burn on yesterday's CRS-1 launch, the roll control seemed to be activated at about seven second intervals.  This was much more frequent, many more times, than on the three previous flights.  It would be interesting to see if this effects the implimentation of M1-D vac and second stage roll control.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 10/08/2012 04:23 pm
(snip)How much thrust does the M1C tubo-pump exhaust produce? A couple thousand lbs? How much is needed for roll control on the second stage? A couple hundred?
(snip)
S

Durring the second stage burn on yesterday's CRS-1 launch, the roll control seemed to be activated at about seven second intervals.  This was much more frequent, many more times, than on the three previous flights.  It would be interesting to see if this effects the implimentation of M1-D vac and second stage roll control.
I think it might be because there's a built-in biasing for when the roll control isn't engaged... In other words, it can only turn left hard, so they build in a bias towards the right, so if you want to go roughly straight, you have to turn left regularly (and if you want to go right, you just don't turn left). That way, they don't have to add another mechanism to make it turn right.

...and they perhaps increased the bias for this flight, allowing them a little greater control over the roll rate (in the biased direction).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 10/11/2012 03:02 am
Has anyone heard the number of starts that can be done by the Vacuum version of the Merlin 1D?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 10/18/2012 06:32 pm
Has anyone heard the number of starts that can be done by the Vacuum version of the Merlin 1D?

The max capability other than the obvious of 2 is not known but a value of 3 has been speculated based on being able to do some missions that would need 3 burns.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: pechisbeque on 10/28/2012 09:26 pm
Found this video on Facebook.

A short duration Merlin 1D Testing:
http://www.facebook.com/photo.php?v=10100751381781895
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: mlindner on 10/29/2012 01:26 pm
Has anyone heard the number of starts that can be done by the Vacuum version of the Merlin 1D?

The max capability other than the obvious of 2 is not known but a value of 3 has been speculated based on being able to do some missions that would need 3 burns.

I forget where I heard it, but I remember either reading or hearing from a friend who interned at SpaceX that they can restart regular Merlins up to 6-7 times.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: MP99 on 10/29/2012 06:17 pm
Has anyone heard the number of starts that can be done by the Vacuum version of the Merlin 1D?

The max capability other than the obvious of 2 is not known but a value of 3 has been speculated based on being able to do some missions that would need 3 burns.

I forget where I heard it, but I remember either reading or hearing from a friend who interned at SpaceX that they can restart regular Merlins up to 6-7 times.

Does that perhaps mean they can be ground started 6-7 times during their lifetime, including tests at McGregor?

M1C doesn't restart at all, and I don't think we've heard a number that high for Merlin Vac, either??

cheers, Martin
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 10/29/2012 08:43 pm
Has anyone heard the number of starts that can be done by the Vacuum version of the Merlin 1D?

The max capability other than the obvious of 2 is not known but a value of 3 has been speculated based on being able to do some missions that would need 3 burns.

I forget where I heard it, but I remember either reading or hearing from a friend who interned at SpaceX that they can restart regular Merlins up to 6-7 times.

Does that perhaps mean they can be ground started 6-7 times during their lifetime, including tests at McGregor?

M1C doesn't restart at all, and I don't think we've heard a number that high for Merlin Vac, either??

cheers, Martin
Merlin 1C can supposedly last for about 10 flight durations.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: IRobot on 10/29/2012 11:44 pm
Side question: what deteriorates between engine restarts? And how hard is to reset it to original conditions if they start reusing them?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 10/30/2012 12:26 am
Side question: what deteriorates between engine restarts? And how hard is to reset it to original conditions if they start reusing them?
They already reuse them. They fire each engine at least three times before launch.

Merlin 1D is made for greater reuse.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: guckyfan on 10/30/2012 06:28 am
Side question: what deteriorates between engine restarts? And how hard is to reset it to original conditions if they start reusing them?
They already reuse them. They fire each engine at least three times before launch.

Merlin 1D is made for greater reuse.

I believe you speak of different things. I rephase the question I believe IRobot tried to ask, if you don't mind.

What capability of an engine is required for several restarts in one flight? What is required to reset that ability to max before launch after several test burns have been done?

This is unrelated or only losely related to the question on reusability or total burn time.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Crispy on 10/30/2012 11:32 am
What capability of an engine is required for several restarts in one flight? What is required to reset that ability to max before launch after several test burns have been done?
Ignition charges.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: guckyfan on 10/30/2012 12:21 pm
What capability of an engine is required for several restarts in one flight? What is required to reset that ability to max before launch after several test burns have been done?
Ignition charges.

Thanks. So there is a number of charges on the engine and each restart consumes one.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: IRobot on 10/30/2012 12:54 pm
That's it? Nothing deteriorates? So when an engine fails to start, what happened? Can another attempt be made, provided there are more ignition charges?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: john smith 19 on 10/30/2012 01:07 pm
What capability of an engine is required for several restarts in one flight? What is required to reset that ability to max before launch after several test burns have been done?

This paper
http://www.ulalaunch.com/site/docs/publications/IVF-Space-2012.pdf
on this thread

http://forum.nasaspaceflight.com/index.php?topic=29757.90

Discusses the sort of issues.

I don't know if Merlin uses uses pyrotechnics (starter cartridges) or pyrophors (liquid that burns on contact with O2) but both would be poor choices for a reusable design. The obvious choice would be a "spark assisted ignitor" IE a spark plug fed by a small LOX/HC flow like a miniature rocket engine in the chamber.

Note the results of the ULA work were that the *real* limit on re-starts was set by how much He was available to do tank re-pressurisation. This would probably apply to the Spacex upper stage as well. Spacex described their stage designs as "Semi-pressure stabilised" so tank pressure before engine start is probably quite important and RP1 is a liquid so simply pumping some heat into the tank to vaporise it won't work like LH2 (at least not at any *reasonable* temperature you'd want to use). You *could* tap some of the GG exhaust and if you got the water out you'd have roughly CO2 which would be a gas at these temps and AFAIK have a *much* lower density than any RP1 vapor.

OTOH were they to switch to a fuel that was a cryogen like LO2 they could use a system like the ULA integrated fluids approach. With pressurisation, propellant settling and power generation taken care of you can have as many starts as needed till you run *completely* out of propellants.

Good enough for Mars? IDK but certainly for escape burns to the Moon.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Crispy on 10/30/2012 01:18 pm
The publicly available information is for the 1C, which uses pyrophor (triethylaluminium-triethylborane). I can't find anything on the 1D.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 10/30/2012 01:30 pm
That's it? Nothing deteriorates? So when an engine fails to start, what happened? Can another attempt be made, provided there are more ignition charges?
No, there is more:
Tank pressurants,
and related - stage battery life and attitude control propellant.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 10/30/2012 01:47 pm
That's it? Nothing deteriorates? So when an engine fails to start, what happened? Can another attempt be made, provided there are more ignition charges?
No, there is more:
Tank pressurants,
and related - stage battery life and attitude control propellant.
Thermal conditioning, too!
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: guckyfan on 10/30/2012 02:53 pm
Very interesting infos.

When I formulated my question I thought of the narrower requirements of the engine itself reigniting. That got much clearer now for me even if we don't know, what exactly SpaceX is doing. However the other conditions like tank pressure, attitude control, battery lifetime are interesting too.

I don't know if Merlin uses uses pyrotechnics (starter cartridges) or pyrophors (liquid that burns on contact with O2) but both would be poor choices for a reusable design. The obvious choice would be a "spark assisted ignitor" IE a spark plug fed by a small LOX/HC flow like a miniature rocket engine in the chamber.

So if this kind of ignition is chosen, a series of short burns would be possible for orbit corrections. If it all happens in a short timeframe the other conditions would probably not become critical.

But there is one more point. For the engine to reignite the fuel needs to be where the turbopump sucks it in. So a method would be needed to supply some initial fuel to the engine until thrust gets the whole amount of fuel where it is needed.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Joel on 10/30/2012 03:14 pm
Tank pressurants ... stage battery life

Does that speak in favor of using methane if you need several restarts? I mean, you don't need any pressurant with methane in the tank, right? And batteries could be replaced by (methane) fuel cells.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: baldusi on 10/30/2012 03:37 pm
Tank pressurants ... stage battery life

Does that speak in favor of using methane if you need several restarts? I mean, you don't need any pressurant with methane in the tank, right? And batteries could be replaced by (methane) fuel cells.

Only H2 is started with sparks. Until now nobody did it for RP-1. I suspect it could be possible for CH4. Regarding the pressurant, you could re heat the CH4. But then you'd need a heat source. A constant one since you are tying to keep a vapor pressure. He would still rule, since it would keep it's pressure at CH4 liquid temperature.
Obviously it depends on how much time are you expecting for the mission, 2hr? 8hr? 24hrs? one week? one year? Until you define the required time you can't find solid technical solutions.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 10/30/2012 03:40 pm
Tank pressurants ... stage battery life

Does that speak in favor of using methane if you need several restarts? I mean, you don't need any pressurant with methane in the tank, right? And batteries could be replaced by (methane) fuel cells.

Can't say that.  Centaur uses He.  The design has to be integrated.  Fuel cells have drawbacks like what do you do with the water.  See ULA IFV.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 10/30/2012 03:43 pm
That's it? Nothing deteriorates? So when an engine fails to start, what happened? Can another attempt be made, provided there are more ignition charges?
No, there is more:
Tank pressurants,
and related - stage battery life and attitude control propellant.
Thermal conditioning, too!

Spin up gas too?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jim on 10/30/2012 03:44 pm

But there is one more point. For the engine to reignite the fuel needs to be where the turbopump sucks it in. So a method would be needed to supply some initial fuel to the engine until thrust gets the whole amount of fuel where it is needed.

That is the attitude control system for the stage.  Between burns, the stage still has to be controlled.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 10/30/2012 04:42 pm
What capability of an engine is required for several restarts in one flight? What is required to reset that ability to max before launch after several test burns have been done?
Ignition charges.
Thanks. So there is a number of charges on the engine and each restart consumes one.
We had heard a number of two or three for the M1C-Vac.
I was wondering which it was, and if it would be the same or increased for the M1D-Vac.  Whether or not they can all be used given the other constraints in only answerable on a case by case basis with much more knowledge than we seem to have.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: john smith 19 on 10/30/2012 05:16 pm
But there is one more point. For the engine to reignite the fuel needs to be where the turbopump sucks it in. So a method would be needed to supply some initial fuel to the engine until thrust gets the whole amount of fuel where it is needed.
This is a "settling" burn. The development of a small engine (that could run on gaseous *or* liquid propellants in the injectors) was the *first* priority to do this on the Centaur stage. *Everything* becomes easier when the gas makes a large bubble at one end and the remaining propellant is over the feed pipes. It takes a surprisingly small acceleration to do this.

You are strongly suggested to read the paper listed.
http://www.ulalaunch.com/site/docs/publications/IVF-Space-2012.pdf

*all* the items other posters have mentioned are discussed.

You might also look at the Agena storable liquid stage that also did on orbit starts. This used "sumps" in the base of the tanks to hold fluid over the feed pipes by surface tension. Tapering the exit pipes has also been tested as a way to encourage propellants to stay trapped in the pipes ready for a re-start.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 12/01/2012 08:14 pm
Channel wall nozzle (several more in b/g) for the Merlin 1D in production: http://www.flickr.com/photos/jurvetson/8233308933
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 12/17/2012 06:44 pm
New image posted on SpaceX' FB an hour ago:
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: go4mars on 12/17/2012 07:51 pm
The only thing missing from that familiar scene is Geordi LaForge. 

reminiscent of the dilithium chamber.  To me. 

As you were.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 12/17/2012 08:11 pm
New image posted on SpaceX' FB an hour ago:

What are we seeing here?
That looks like the turbopump on the right but there is no visible exhaust.  In this frame from a video of a Merlin 1D engine firing, the turbopump exhaust is large and dark.  I don't see anything like this anywhere in the image.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ugordan on 12/17/2012 08:16 pm
I think it's a start transient, Melin 1C tests occasionally showed a shortlived absence of dark exhaust from the GG. Notice the ice particles shaken off from above which is why I think this was taken very shortly after ignition.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 12/17/2012 08:44 pm
Maybe the green reflex on the upper frame is due to the TEB ignition.
BTW, same POV of this other picture.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: oldAtlas_Eguy on 12/18/2012 02:09 pm
Thanks for the new picture.

You can see the faint exhaust from the GG even though it is very clear. The better the mixture ratio for the GG the clearer the exhaust.

Maybe they use an O2 sensor like a car engine to manipulate the GG mixture ratio right to the edge. That would give better performance for the GG and the Merlin engine in general.

edit spelling
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: kevin-rf on 12/18/2012 02:19 pm
What would methane look like?

Still the greenness (TEB?) of the frame makes me think it's a startup pic...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: woods170 on 12/18/2012 02:50 pm
What would methane look like?

Still the greenness (TEB?) of the frame makes me think it's a startup pic...
Likely. Notice all those ice particles flying off near the top of the engine...
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Comga on 12/18/2012 03:10 pm
Still the greenness (TEB?) of the frame makes me think it's a startup pic...

But only that ring is green.  In the videos of ignition for the Falcon 9 the TEA-TEB green frame is concentrated below the engine.  Surely if there was that bright green flame it would have colored other surfaces green, too.

It hard to imagine tuning the turbopump so that its exhaust is perfectly clear.
The falling debris does look like a transient, but perhaps it's not a start-up. 
Is there a spit second after the turbopump shuts down where the engine keeps burning? 
Does anyone have any information they can share on the shut-down transients, sequence, durations, etc?
Could this be the boiling regen fuel "burp" ignighting?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: hrissan on 12/18/2012 05:16 pm
Thanks for the new picture.

You can see the faint exhaust from the GG even though it is very clear. The better the mixture ratio for the GG the clearer the exhaust.

Maybe they use an O2 sensor like a car engine to manipulate the GG mixture ratio right to the edge. That would give better performance for the GG and the Merlin engine in general.
Stohiometric combustion is very hot and will destroy the turbine. Running oxygen rich gives very aggressive (though not so hot) exhaust and will destroy the turbine. They usually run fuel rich and select ratio according to the maximum temperature the turbine can safely endure.

Can this be Merlin 1D running on Methane? :)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 12/18/2012 05:30 pm
Or, they're just piping the exhaust into the engine.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 12/18/2012 05:36 pm
My two cents:
-startup pic,
-GG not yet ignited, spinning with compressed gas (the faint exaust oldAtlas_Eguy noticed)
-green reflex visible only on the frame because the green plume is already expanding some meters down the hole.

Overall, nice pic. Good details of new arrangement of turbopump (RP1 pump clearly visible), clear view of new reaction rod (opposite side of the turbopump), some wirings removed (probably sensors for development).
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 12/18/2012 06:17 pm
The green color is weird.  All I can say, FWIW, is that the color of the inner ring matches very well the color of the grass outside, visible on the middle right.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 12/18/2012 06:34 pm

Stohiometric combustion is very hot and will destroy the turbine. Running oxygen rich gives very aggressive (though not so hot) exhaust and will destroy the turbine. They usually run fuel rich and select ratio according to the maximum temperature the turbine can safely endure.

Can this be Merlin 1D running on Methane? :)

I agree completely on turbine feed.
About running on Methane.... ;D
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: butters on 12/18/2012 06:41 pm
Isn't that an M1DVac? My understanding is that the M1D GG exhausts to ambient, whereas the M1DVac GG exhaust is ducted into the nozzle extension.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 12/18/2012 06:52 pm
Isn't that an M1DVac? My understanding is that the M1D GG exhausts to ambient, whereas the M1DVac GG exhaust is ducted into the nozzle extension.
This is the only pic we have of M1DVac; nozzle is really larger and different (obviously missing the radiatively cooled extension)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: corrodedNut on 12/18/2012 06:56 pm
You can see in the previously released video (at about .11 sec on the clock) that there is a momentary lack of visible exhaust just after startup:

http://www.youtube.com/watch?v=976LHTpnZkY

Title: Re: SpaceX: Merlin 1D Updates thread
Post by: douglas100 on 12/18/2012 11:03 pm
Isn't that an M1DVac? My understanding is that the M1D GG exhausts to ambient, whereas the M1DVac GG exhaust is ducted into the nozzle extension.

Then how do they do roll control?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Robotbeat on 12/18/2012 11:52 pm
Isn't that an M1DVac? My understanding is that the M1D GG exhausts to ambient, whereas the M1DVac GG exhaust is ducted into the nozzle extension.

Then how do they do roll control?
Perhaps they'll just use thrusters.

... besides, they don't ALWAYS do roll control... ;)
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: meekGee on 12/19/2012 12:31 am
You can see in the previously released video (at about .11 sec on the clock) that there is a momentary lack of visible exhaust just after startup

It's when they shift gear
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 03/14/2013 11:03 pm
The '11 years of SpaceX' video had a close-up of a Merlin 1D: (production version?)

https://www.youtube.com/watch?v=ujX6CuRELFE&feature=youtu.be

It certainly looks less complicated (on the outside at least) than the M1C.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: billh on 03/14/2013 11:32 pm
It certainly looks less complicated (on the outside at least) than the M1C.

Well, of course, they're still building it.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 03/14/2013 11:33 pm
It certainly looks less complicated (on the outside at least) than the M1C.

Well, of course, they're still building it.

No, it isn't just that. Compare the 1C with the 1D (an image from earlier in the thread) - Now imagine that engine without the test sensor and wiring for that:

From the '11 years' thread:
A couple of interesting images.

If someone wants to splice those two factory floor images and the 3 interstage images together, be my guest. I don't have the software for doing it.

your shot0033 - that's a Merlin 1D I think? It looks...smooth.

I was wondering what that was myself. It almost doesn't look like metal. Is it a training model for teaching engine assembly?

Look at the image below - The M1D has a different, less shiny surface texture.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: bubbagret on 03/15/2013 12:29 am
Look at the image below - The M1D has a different, less shiny surface texture.
That was an old test picture. Here is the "M1D" test article on the right compared to a more recent engine on the left. Notice the old M1D picture more resembles an M1C with a sandwich nozzle. The thrust mounts, turbo and throat are considerably changed on the new engine.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Lars_J on 03/15/2013 12:43 am
Yes, the turbopump exhaust is different, and a bunch of the early test sensor wires are gone. That left engine certainly is a very good match for the image from the new '11th anniversary' video..
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: simonbp on 03/15/2013 04:25 pm
Look at the image below - The M1D has a different, less shiny surface texture.
That was an old test picture. Here is the "M1D" test article on the right compared to a more recent engine on the left. Notice the old M1D picture more resembles an M1C with a sandwich nozzle. The thrust mounts, turbo and throat are considerably changed on the new engine.

Yeah, 1D does look a lot cleaner. And with a shorter turbohead and mount, which I guess was part of the motivation for the redesigned thrust structure on v1.1.

Anyone when the first v1.1 is supposed to arrive at VAFB, thus allowing our first glimpse at the actual flight hardware?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: guckyfan on 03/15/2013 04:39 pm
Does the turbopump exhaust really go into the engine bell? That left picture looks like it.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: Jason1701 on 03/15/2013 04:41 pm
Does the turbopump exhaust really go into the engine bell? That left picture looks like it.

No, the pipe that appears to come out of it is actually behind. M1DVac probably does, though.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: pippin on 03/15/2013 04:57 pm
M1DVac does? Ho do they do roll control then?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: R7 on 03/15/2013 05:10 pm
RCS
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: bubbagret on 03/15/2013 05:11 pm
M1DVac does? Ho do they do roll control then?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: pippin on 03/15/2013 05:14 pm
That's not M1DVac, that's M1CVac

@R7 Do we _know_ that? Any sources? Sorry, didn't follow everything here.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: cambrianera on 03/15/2013 05:16 pm
M1DVac does? Ho do they do roll control then?
Not yet known, but may be with cold gas thrusters.
In the last two F9 flights the GG exaust was limited to only one side movement, and in CRS-2 there were very few corrections.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: R7 on 03/15/2013 05:18 pm
@R7 Do we _know_ that?

What other option is there?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: douglas100 on 03/15/2013 05:29 pm
Sorry if I'm missing something, but where is the evidence that MDvac turbopump exhaust isn't used for roll control?
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: corrodedNut on 03/15/2013 05:31 pm
Sorry if I'm missing something, but where is the evidence that MDvac turbopump exhaust isn't used for roll control?
One page back:

http://forum.nasaspaceflight.com/index.php?topic=26388.msg993109#msg993109
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: bubbagret on 03/15/2013 05:56 pm
Sorry if I'm missing something, but where is the evidence that MDvac turbopump exhaust isn't used for roll control?
One page back:

http://forum.nasaspaceflight.com/index.php?topic=26388.msg993109#msg993109

That's the picture I made the assumption from. It appears that there is an extension of some kind from the turbine exhaust housing on the left, that could be for the RCS nozzle. Maybe. maybe not. We will know for sure when the next launch occurs.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: ArbitraryConstant on 03/15/2013 07:44 pm
Maybe it vents most of the turbogas into the nozzle but can open valves to bleed a little for roll control.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: joek on 03/15/2013 08:02 pm
Post moved to SpaceX Falcon 9 v1.1 (http://forum.nasaspaceflight.com/index.php?topic=28882.msg1026750#msg1026750) thread.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: hrissan on 03/15/2013 08:30 pm
Maybe it vents most of the turbogas into the nozzle but can open valves to bleed a little for roll control.
Looks like rather simple and good solution.

By the way should they measure the rolling forces when acceptance-testing the engines? Otherwise how do they know the amount of roll control they have will be enough to counter the engine rolling? :)
Title: Re: SpaceX: Merlin 1D thread
Post by: Chris Bergin on 03/15/2013 08:58 pm
This hasn't been an update thread for a while, so changed the thread title. But this has to be on Merlin 1D.
Title: Re: SpaceX: Merlin 1D thread
Post by: oldAtlas_Eguy on 03/16/2013 01:46 pm
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.
Title: Re: SpaceX: Merlin 1D Updates thread
Post by: douglas100 on 03/16/2013 08:48 pm
Sorry if I'm missing something, but where is the evidence that MDvac turbopump exhaust isn't used for roll control?
One page back:

http://forum.nasaspaceflight.com/index.php?topic=26388.msg993109#msg993109

That's the picture I made the assumption from. It appears that there is an extension of some kind from the turbine exhaust housing on the left, that could be for the RCS nozzle. Maybe. maybe not. We will know for sure when the next launch occurs.

Thank you. That was the picture that led me to ask the question. I agree with you that the question is open.
Title: Re: SpaceX: Merlin 1D thread
Post by: Prober on 03/17/2013 04:45 pm
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.

Maybe a possible 1E will come out of the long wait of the 1D?
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 03/17/2013 05:43 pm
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.

Maybe a possible 1E will come out of the long wait of the 1D?
that is a long wait?
Title: Re: SpaceX: Merlin 1D thread
Post by: Comga on 03/17/2013 06:53 pm
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.

Maybe a possible 1E will come out of the long wait of the 1D?

Even the "Is  Falcon 1E dead?" thread (http://forum.nasaspaceflight.com/index.php?topic=24333.msg702893#msg702893) is dead.  (No, he's just resting.  Dead!  Dead, I tell you!)

There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets.  I was disappointed.  They "built it" but "they did not come".   The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.
Title: Re: SpaceX: Merlin 1D thread
Post by: Jason1701 on 03/17/2013 07:59 pm
A Falcon 1-size vehicle will not help them get to Mars, nor at this stage is it particularly useful for developing technologies for larger vehicles.
Title: Re: SpaceX: Merlin 1D thread
Post by: deltaV on 03/17/2013 08:27 pm
A couple of questions about the vacuum 1D:

(1) Why go to the trouble of dumping the gas generator exhaust in the main nozzle instead of just giving the gas generator exhaust a nozzle extension to improve its area ratio? This suggests to me that there are beneficial interactions between the gas generator exhaust and the main combustion chamber exhaust; if so what are they? One possibility is that the combined exhausts could mix and burn up some of the solid carbon in the (very fuel-rich) gas generator exhaust. Or maybe the gas generator exhaust helps keep the nozzle extension cool?

(2) Would it make sense to add a little oxygen to the fuel-rich gas generator exhaust to reheat it? The idea is to bring the gas generator exhaust closer to the ideal mixture ratio.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/17/2013 08:32 pm
A couple of questions about the vacuum 1D:

(1) Why go to the trouble of dumping the gas generator exhaust in the main nozzle instead of just giving the gas generator exhaust a nozzle extension to improve its area ratio? This suggests to me that there are beneficial interactions between the gas generator exhaust and the main combustion chamber exhaust; if so what are they? One possibility is that the combined exhausts could mix and burn up some of the solid carbon in the (very fuel-rich) gas generator exhaust. Or maybe the gas generator exhaust helps keep the nozzle extension cool?

(2) Would it make sense to add a little oxygen to the fuel-rich gas generator exhaust to reheat it? The idea is to bring the gas generator exhaust closer to the ideal mixture ratio.

Not an expert here, but think of a jet-engine with bypass - add cold air to the expanding exhaust, as long as it is compressed.  Or not.  Just guessing.
Title: Re: SpaceX: Merlin 1D thread
Post by: cambrianera on 03/17/2013 08:48 pm
A couple of questions about the vacuum 1D:

(1) Why go to the trouble of dumping the gas generator exhaust in the main nozzle instead of just giving the gas generator exhaust a nozzle extension to improve its area ratio? This suggests to me that there are beneficial interactions between the gas generator exhaust and the main combustion chamber exhaust; if so what are they? One possibility is that the combined exhausts could mix and burn up some of the solid carbon in the (very fuel-rich) gas generator exhaust. Or maybe the gas generator exhaust helps keep the nozzle extension cool?

(2) Would it make sense to add a little oxygen to the fuel-rich gas generator exhaust to reheat it? The idea is to bring the gas generator exhaust closer to the ideal mixture ratio.

GG exaust is really cooler than the main exaust; F1 had a similar arrangement to keep at a reasonable temperature the stainless steel nozzle. Titanium has a high temperature strenght similar to stainless steel, but half the density (and less than half the density of niobium). I guess SpaceX is going to change the material of the radiatively cooled extension.

Another advantage I guess is that in a flow you always have a boundary layer on a surface, causing friction and loss of energy; injecting the GG exhaust in the nozzle you make a sort of "sliding layer" that minimize the energy losses in the main exhaust.

About your second question I guess no, seems a complication with minimum advantage.

Excerpt from: http://history.msfc.nasa.gov/saturn_apollo/documents/F-1_Engine.pdf

Title: Re: SpaceX: Merlin 1D thread
Post by: corrodedNut on 03/17/2013 10:27 pm
IIRC, there was an issue during development of the original MerlinVac that was described as nozzle heating that was higher than expected (or something to that effect), and the solution was to "de-tune" the engine. I took that to mean that some performance was traded for reliability/safety or schedule. Perhaps they anticipated/encountered this issue with MerlinDVac and the permanent solution is using GG exhaust for cooling the nozzle extension. If so, GG exhaust may be more valuable as coolant (for maximum performance) than as roll control.

Also, I wouldn't be surprised if the new 2nd stage uses Dracos for part of its RCS as well as propellant settling and GTO missions.
Title: Re: SpaceX: Merlin 1D thread
Post by: ArbitraryConstant on 03/17/2013 11:14 pm
If so, GG exhaust may be more valuable as coolant (for maximum performance) than as roll control.
They can bleed some of the GG exhaust for roll control. Other rockets do it.
Title: Re: SpaceX: Merlin 1D thread
Post by: deltaV on 03/18/2013 01:12 am
Thanks cambrianera!
Title: Re: SpaceX: Merlin 1D thread
Post by: Jason1701 on 03/18/2013 01:34 am
IIRC, there was an issue during development of the original MerlinVac that was described as nozzle heating that was higher than expected (or something to that effect), and the solution was to "de-tune" the engine. I took that to mean that some performance was traded for reliability/safety or schedule. Perhaps they anticipated/encountered this issue with MerlinDVac and the permanent solution is using GG exhaust for cooling the nozzle extension. If so, GG exhaust may be more valuable as coolant (for maximum performance) than as roll control.

Also, I wouldn't be surprised if the new 2nd stage uses Dracos for part of its RCS as well as propellant settling and GTO missions.

Pretty sure 1.1 US uses cold gas thrusters. (First stage does too.)
Title: Re: SpaceX: Merlin 1D thread
Post by: ArbitraryConstant on 03/18/2013 03:36 am
Pretty sure 1.1 US uses cold gas thrusters. (First stage does too.)
Grasshopper uses cold gas, but it seems unlikely in the extreme the first stage will, at least on the way up.
Title: Re: SpaceX: Merlin 1D thread
Post by: Prober on 03/18/2013 11:49 am
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.

Maybe a possible 1E will come out of the long wait of the 1D?

Even the "Is  Falcon 1E dead?" thread (http://forum.nasaspaceflight.com/index.php?topic=24333.msg702893#msg702893) is dead.  (No, he's just resting.  Dead!  Dead, I tell you!)

There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets.  I was disappointed.  They "built it" but "they did not come".   The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.

No I'm saying that maybe that the F9 might use a 1E engine?
Title: Re: SpaceX: Merlin 1D thread
Post by: Jason1701 on 03/18/2013 12:14 pm
1E engine? No such thing.
Title: Re: SpaceX: Merlin 1D thread
Post by: docmordrid on 03/18/2013 04:24 pm
Someone correct me if I'm wrong, but IIRC they specifically excluded any post-D Merlin 1's some time ago.
Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 03/18/2013 04:53 pm
Someone correct me if I'm wrong, but IIRC they specifically excluded any post-D Merlin 1's some time ago.
I think they stated something like "there's not going to be a Merlin 1E, the upper stage will use the same Merlin 1D. No new turbopumps". So it's not clear that there won't be a Merlin 1E eventually. Just that v1.1 + Heavy will use 1Ds. Apparently Merlin Vac (the one on v1.0) had a different turbopump. But I'm just quoting from memory.
Title: Re: SpaceX: Merlin 1D thread
Post by: Chris Bergin on 03/20/2013 03:08 pm
I'll write it up, but here's the presser!

SpaceX’s Merlin 1D Engine Achieves Flight Qualification

 

Hawthorne, CA – Space Exploration Technologies’ (SpaceX) Merlin 1D engine has achieved flight qualification, a major milestone for the next generation Merlin engine. Through a 28 test qualification program, the Merlin 1D accumulated 1,970 seconds of total test time, the equivalent run time of over 10 full mission durations, and is now fully qualified to fly on the Falcon 9 rocket.

 

The program included four tests at or above the power (147,000 pounds of thrust) and duration (185 seconds) required for a Falcon 9 rocket launch. The Merlin 1D engine was also tested at propellant inlet and operating conditions that were well outside the bounds of expected flight conditions.

 

SpaceX's testing program demonstrated a ratio of 4:1 for critical engine life parameters such as firing duration and restart capacity to the engine's expected flight requirements. The industry standard is 2:1. 

 

“The Merlin 1D successfully performed every test throughout this extremely rigorous qualification program,” said Elon Musk, SpaceX CEO and chief designer. “With flight qualification now complete, we look forward to flying the first Merlin 1D engines on Falcon 9’s Flight 6 this year.”

 

The Merlin 1D builds on the technology of the Merlin engines used on the first five flights of Falcon 9. With nine Merlin 1Ds on the first stage, the Falcon 9 rocket will produce nearly 1.5 million pounds of thrust in a vacuum. The Merlin 1D has a vacuum thrust-to-weight ratio exceeding 150, the best of any liquid rocket engine in history. This enhanced design makes the Merlin 1D the most efficient booster engine ever built, while still maintaining the structural and thermal safety margins needed to carry astronauts. Additionally, the new engine is designed for improved manufacturability by using higher efficiency processes, increased robotic construction and reduced parts count.

 

Testing took place at SpaceX's rocket development facility in McGregor, Texas.
Title: Re: SpaceX: Merlin 1D thread
Post by: 2552 on 03/20/2013 03:26 pm
https://twitter.com/SpaceX/status/314410250574897152

Quote
SpaceX ‏@SpaceX
SpaceX’s Merlin 1D engine achieves flight qualification: spacex.com/press.php?page=20130320 (http://spacex.com/press.php?page=20130320) … pic.twitter.com/wDS61CKaZS (http://pic.twitter.com/wDS61CKaZS)
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/20/2013 04:05 pm
https://twitter.com/SpaceX/status/314410250574897152

Quote
SpaceX ‏@SpaceX
SpaceX’s Merlin 1D engine achieves flight qualification: spacex.com/press.php?page=20130320 (http://spacex.com/press.php?page=20130320) … pic.twitter.com/wDS61CKaZS (http://pic.twitter.com/wDS61CKaZS)


Bigger version of the image: https://pbs.twimg.com/media/BF0CdQPCIAAL0_y.jpg:orig
When you grab twitter images instead of having :large on the suffix, change to :orig to get the original resolution, often larger.
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 03/20/2013 04:10 pm
When you grab twitter images instead of having :large on the suffix, change to :orig to get the original resolution, often larger.

Thanks, that's a good tip!
Title: Re: SpaceX: Merlin 1D thread
Post by: russianhalo117 on 03/20/2013 04:35 pm
1E engine? No such thing.
Yes, you are correct in that it currently does not exist. But it has been mentioned previously a couple of time before that another Merlin-1x (my guess is probably a 1E designation) block series would be designed before starting Merlin-2 R&D Programme. That was almost a couple of years ago when I heard the above mentioned. So at this time this is just theoretical since I have found nothing new as of late to further back this.
Title: Re: SpaceX: Merlin 1D thread
Post by: Prober on 03/20/2013 04:50 pm
1E engine? No such thing.
Yes, you are correct in that it currently does not exist. But it has been mentioned previously a couple of time before that another Merlin-1x (my guess is probably a 1E designation) block series would be designed before starting Merlin-2 R&D Programme. That was almost a couple of years ago when I heard the above mentioned. So at this time this is just theoretical since I have found nothing new as of late to further back this.

my guess is that the is just a 1D in name only and should be a 1E or 1F by now.
Title: Re: SpaceX: Merlin 1D thread
Post by: JBF on 03/20/2013 04:51 pm
Interesting the exhaust of the gas generator is even shorter then the earlier pictures.
Title: Re: SpaceX: Merlin 1D thread
Post by: Chris Bergin on 03/20/2013 04:52 pm
Will give this a standlone to allow for the update threads to stay clear of too much chat.

http://www.nasaspaceflight.com/2013/03/falcon-9-boost-merlin-1d-engine-achieves-milestone/
Title: Re: SpaceX: Merlin 1D thread
Post by: Jason1701 on 03/20/2013 05:05 pm
1E engine? No such thing.
Yes, you are correct in that it currently does not exist. But it has been mentioned previously a couple of time before that another Merlin-1x (my guess is probably a 1E designation) block series would be designed before starting Merlin-2 R&D Programme. That was almost a couple of years ago when I heard the above mentioned. So at this time this is just theoretical since I have found nothing new as of late to further back this.

It was my understanding that Raptor, a methane engine with thrust equivalent to ~5 Merlins, had superseded Merlin 2.
Title: Re: SpaceX: Merlin 1D thread
Post by: russianhalo117 on 03/20/2013 06:48 pm
1E engine? No such thing.
Yes, you are correct in that it currently does not exist. But it has been mentioned previously a couple of time before that another Merlin-1x (my guess is probably a 1E designation) block series would be designed before starting Merlin-2 R&D Programme. That was almost a couple of years ago when I heard the above mentioned. So at this time this is just theoretical since I have found nothing new as of late to further back this.

It was my understanding that Raptor, a methane engine with thrust equivalent to ~5 Merlins, had superseded Merlin 2.
I am not entirely positive about the status of Raptor except that USAF wants SpaceX to use their development laboratory so USAF can research and collect additional data about CH4 propellant in rocket engines for their Next Generation Engine programme, but that was from awhile ago to my knowledge.
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 03/20/2013 06:50 pm
There's pretty good evidence Raptor is actively under development, in the 600,000-700,000 lbf thrust class. This would make it much more powerful per chamber than the RD-180.
Title: Re: SpaceX: Merlin 1D thread
Post by: Prober on 03/20/2013 06:53 pm
careful don't take the thread in a different direction.
Title: Re: SpaceX: Merlin 1D thread
Post by: Borklund on 03/20/2013 07:00 pm
https://twitter.com/SpaceX/status/314410250574897152

Quote
SpaceX ‏@SpaceX
SpaceX’s Merlin 1D engine achieves flight qualification: spacex.com/press.php?page=20130320 (http://spacex.com/press.php?page=20130320) … pic.twitter.com/wDS61CKaZS (http://pic.twitter.com/wDS61CKaZS)


Bigger version of the image: https://pbs.twimg.com/media/BF0CdQPCIAAL0_y.jpg:orig
When you grab twitter images instead of having :large on the suffix, change to :orig to get the original resolution, often larger.

This might be a stupid question, but I'd like to know why the two engines in the picture look different from eachother?
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 03/20/2013 07:02 pm
The one on the right looks like it has been fired already.
Title: Re: SpaceX: Merlin 1D thread
Post by: hrissan on 03/20/2013 07:10 pm
28 tests
1,970 seconds of total test time

four tests at or above the power (147,000 pounds of thrust) and duration (185 seconds).

ratio of 4:1 for firing duration and restart capacity to the engine's expected flight requirements
It means that in restart test Merlin 1D was restarted 8 or even 12 times (2 restarts are required for F9R, but SpaceX may anticipate third restart will be needed). Impressive!

Also, of four "supertests", one must be long test with 185*4=740 seconds at 100% thrust, one of nominal duration, but insane thrust (110%?), what are the probable other two "supertests"? Other combinations of larger thrust and longer duration?

Edit: no one would be offended if I guess the exact thrust was tested to be 146.973372 pounds?
Title: Re: SpaceX: Merlin 1D thread
Post by: Borklund on 03/20/2013 07:13 pm
The one on the right looks like it has been fired already.
Not just that, but the wiring differs and there's different colouration on different parts, some parts look structurally different etc.
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 03/20/2013 07:20 pm
They look pretty much the same to me, to be honest. Some of that wiring is for test purposes. The discoloration of the turbopump exhaust pipe was what suggested to me the engine on the right was fired.
Title: Re: SpaceX: Merlin 1D thread
Post by: hrissan on 03/20/2013 08:10 pm
Bigger version of the image: https://pbs.twimg.com/media/BF0CdQPCIAAL0_y.jpg:orig
On the left engine, the yellow-ended pipes must be Acetylene burners ready to create an environment "well outside expected operations conditions" or just simulating other adjacent hot Merlins. Any ideas on how much Watts those burners can produce?

SpaceX must have completed "shrapnel" tests also. I doubt they blown up complete working Merlin on depicted test stand. Most probably they have separate test rig where they blow up partially assembled Merlins by exploding HE in combustion chamber and turbopump?
Title: Re: SpaceX: Merlin 1D thread
Post by: Jason1701 on 03/20/2013 08:30 pm
Video:
http://www.youtube.com/watch?v=Zj0851Wkm9c
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/20/2013 09:05 pm
Video:

Is it just me or at the image at 0:05 is that caked with soot? That thing must have gone through a lot of firings....
Title: Re: SpaceX: Merlin 1D thread
Post by: MP99 on 03/20/2013 09:43 pm
Video:

Is it just me or at the image at 0:05 is that caked with soot? That thing must have gone through a lot of firings....

It certainly looks black, but I'm not sure it's soot that's doing that - it's evenly applied all the way up to the top of the thrust chamber. It looks more like it was intentionally coated, perhaps?

cheers, Martin
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 03/20/2013 09:45 pm

On the left engine, the yellow-ended pipes must be Acetylene burners ready to create an environment "well outside expected operations conditions" or just simulating other adjacent hot Merlins. Any ideas on how much Watts those burners can produce?


No, more like firex nozzles
Title: Re: SpaceX: Merlin 1D thread
Post by: corrodedNut on 03/20/2013 10:49 pm
I don't understand, how is 75 seconds "full duration"?

 "...1,970 seconds of total test time, the equivalent run time of over 10 full mission durations..."

Divide 1970 seconds by ten get you a duration of about 3 minutes 28 sec, which seems more like it.
Title: Re: SpaceX: Merlin 1D thread
Post by: Jason1701 on 03/20/2013 10:56 pm
I don't understand, how is 75 seconds "full duration"?

 "...1,970 seconds of total test time, the equivalent run time of over 10 full mission durations..."

Divide 1970 seconds by ten get you a duration of about 3 minutes 28 sec, which seems more like it.

Perhaps the test was supposed to be 75 seconds, and the engine fired for that "full duration."
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 03/20/2013 11:43 pm
I don't understand, how is 75 seconds "full duration"?

Does anything in the video actually indicate that this was supposed to be a video of a full duration testing, or are you just inferring it?
Title: Re: SpaceX: Merlin 1D thread
Post by: Soralin on 03/21/2013 12:33 am
I don't understand, how is 75 seconds "full duration"?

Does anything in the video actually indicate that this was supposed to be a video of a full duration testing, or are you just inferring it?
About 1 second in, in the lower left, it has "75 seconds (full duration)"  I guess it was referring to the full duration of the test, or something, rather than that of the first stage.
Title: Re: SpaceX: Merlin 1D thread
Post by: GBpatsfan on 03/21/2013 02:26 am
Video:

Did anyone else notice the engine gimbal at ~17 seconds.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/21/2013 02:55 am
About 1 second in, in the lower left, it has "75 seconds (full duration)"  I guess it was referring to the full duration of the test, or something, rather than that of the first stage.

Yup, it's a bit weird.  Most tests do indeed last exactly their full duration.

Maybe 75 seconds is the fly-back burn?  But that doesn't make much sense as a test.
Title: Re: SpaceX: Merlin 1D thread
Post by: joek on 03/21/2013 03:04 am
Maybe 75 seconds is the fly-back burn?  But that doesn't make much sense as a test.
It might make sense if it's a restart test. (edit: that is, a restart followed by a nominal burn, for whatever you want to define as "nominal"; since we don't know what transpired before or after, hard to tell.)
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/21/2013 03:59 am
you're right, it could be that, but since it's not in vacuum, is there really meaning to running it at the exact duration?  But yeah, you have to decide on something, might as well be that duration.
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 03/21/2013 04:03 am
you're right, it could be that, but since it's not in vacuum, is there really meaning to running it at the exact duration?  But yeah, you have to decide on something, might as well be that duration.

What this obsession with the run-time in this video? Do you think there's some dark SpaceX conspiracy where the M1D is secretly unable to run for the full mission duration burns?

Clearly there is several levels of testing, with different durations. Production engines do not get burned for a full 3-6 minutes before being accepted.
Title: Re: SpaceX: Merlin 1D thread
Post by: blazotron on 03/21/2013 04:13 am
you're right, it could be that, but since it's not in vacuum, is there really meaning to running it at the exact duration?  But yeah, you have to decide on something, might as well be that duration.

Full duration probably just means the test was not cut off earlier than the planned duration on a redline.

The corners-of-the-box testing such as propellant inlet pressure sweeps may require test durations that do not actually correspond to an anticipated in-flight duration for the liftoff burn or any restart burns.  They would likely still count the start and run time in their totals as long as the engine was operated in manner flight-like enough to generate representative stress on the engine and experience a full thermal cycle.
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 03/21/2013 08:23 am
Did anyone else notice the engine gimbal at ~17 seconds.

Yes.
Title: Re: SpaceX: Merlin 1D thread
Post by: Okie_Steve on 03/22/2013 02:58 pm
I found the mention of testing above rated thrust intriguing. Spacex is designing for reuse and stresses how their design margins are above normal accepted practice. How far could one expect to push a 1D above nominal in a worst-case scenerio where reuse is abandonded for a given set of engines in order to avoid loss of mission? After all, if you lose the mission you probably lose the engines too. I would expect that a 1% increase in thrust would be pretty safe while a 100% increase would be pretty fatal. What does the curve look like and would it be reasonable to actually plan for using "over thrust" on cargo missions in some situations?
Title: Re: SpaceX: Merlin 1D thread
Post by: 2552 on 03/22/2013 03:10 pm
In an engine out scenario, to keep the same level of overall thrust to avoid gravity losses, the other 8 engines would need to go to 112.5% rated thrust, or 165,375lbs sea level thrust.
Title: Re: SpaceX: Merlin 1D thread
Post by: Kaputnik on 03/22/2013 03:14 pm
This is probably more a general rocket engine question, but how do you actually go about pushing a rocket to a higher thrust level? Presumably there is a limit on the mass flow rate which the GG/turbine will suck in, before you'd need to redesign with larger components.
Title: Re: SpaceX: Merlin 1D thread
Post by: aero on 03/22/2013 04:11 pm
In an engine out scenario, to keep the same level of overall thrust to avoid gravity losses, the other 8 engines would need to go to 112.5% rated thrust, or 165,375lbs sea level thrust.

That does not follow - You are overlooking the longer burn time of the remaining engines. Further, you can't conclude that the remaining fuel will be enough to run the engines at the higher thrust level until MECO. What I think happens is that the engines continue to run until the revised MECO (planned for the engine out contingency) then the US uses its reserve to reach orbit.
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 03/22/2013 04:15 pm
In an engine out scenario, to keep the same level of overall thrust to avoid gravity losses, the other 8 engines would need to go to 112.5% rated thrust, or 165,375lbs sea level thrust.

That does not follow - You are overlooking the longer burn time of the remaining engines. Further, you can't conclude that the remaining fuel will be enough to run the engines at the higher thrust level until MECO. What I think happens is that the engines continue to run until the revised MECO (planned for the engine out contingency) then the US uses its reserve to reach orbit.
The post says "to avoid gravity losses..."
Title: Re: SpaceX: Merlin 1D thread
Post by: 2552 on 03/22/2013 04:40 pm
8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/22/2013 04:43 pm
What I think happens is that the engines continue to run until the revised MECO (planned for the engine out contingency) then the US uses its reserve to reach orbit.

Doesn't work that way. You can't plan every possible run time for every possible time in which an engine is lost. More likely it's using its internal GPS + inertial guidance to judge where it is and re-figures out based on its current thrust how much longer it needs to thrust to get there.
Title: Re: SpaceX: Merlin 1D thread
Post by: aero on 03/22/2013 05:57 pm
What I think happens is that the engines continue to run until the revised MECO (planned for the engine out contingency) then the US uses its reserve to reach orbit.

Doesn't work that way. You can't plan every possible run time for every possible time in which an engine is lost. More likely it's using its internal GPS + inertial guidance to judge where it is and re-figures out based on its current thrust how much longer it needs to thrust to get there.

OK. Feedback control is usually better than open loop control anyway.
Title: Re: SpaceX: Merlin 1D thread
Post by: peter-b on 03/22/2013 06:09 pm
OK. Feedback control is usually better than open loop control anyway.

Jim was insisting that the Falcon 9 must use open loop control a few months ago when people were discussing relights, engine out, or something like that, but I think SpaceX's public statements suggest fairly definitively that the F9 uses closed-loop control and continually recalculates its trajectory etc. on the fly...
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 03/22/2013 07:59 pm

Jim was insisting that the Falcon 9 must use open loop control a few months ago when people were discussing relights, engine out, or something like that, but I think SpaceX's public statements suggest fairly definitively that the F9 uses closed-loop control and continually recalculates its trajectory etc. on the fly...

Never said that.  All launch vehicles use close loop.  If this was in regard to the COTS-1 canceled restart, then the point was that there are limited branches for a vehicle to follow, since there are limited data sources.

First stage is usually open loop (fly to depletion) and upperstages use close loop.
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 03/22/2013 08:05 pm
What I think happens is that the engines continue to run until the revised MECO (planned for the engine out contingency) then the US uses its reserve to reach orbit.

Doesn't work that way. You can't plan every possible run time for every possible time in which an engine is lost. More likely it's using its internal GPS + inertial guidance to judge where it is and re-figures out based on its current thrust how much longer it needs to thrust to get there.

That is exactly how it works.  The "revised" MECO is propellant depletion of the first stage and the US does use reserve to make up.  Boosters burn until they deplete and US figure out what is needed to complete the mission.

Not talking RLV's or boosters that return.
Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 03/22/2013 08:11 pm
8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?
What if the way to increase the thrust is to change the O/F ratio?
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 03/22/2013 08:16 pm
8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?
What if the way to increase the thrust is to change the O/F ratio?

Not good if you are going to throttle a lot - you want oxidizer and fuel to be depleted at the same time.
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/22/2013 08:17 pm

Jim was insisting that the Falcon 9 must use open loop control a few months ago when people were discussing relights, engine out, or something like that, but I think SpaceX's public statements suggest fairly definitively that the F9 uses closed-loop control and continually recalculates its trajectory etc. on the fly...

Never said that.  All launch vehicles use close loop.  If this was in regard to the COTS-1 canceled restart, then the point was that there are limited branches for a vehicle to follow, since there are limited data sources.

First stage is usually open loop (fly to depletion) and upperstages use close loop.

Is there any advantage, besides less complexity, in using open loop on the first stage? SpaceX has a standard of using the same flight computer between different stages. This would imply to me that both would be closed loop. There is also nothing preventing them from starting initailly from the pad in open loop and switching to closed loop part way through lower stage launch.

Edit: for readability.
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 03/22/2013 11:10 pm
Better performance margin if you fly to depletion for the first stage... Otherwise, you're leaving some margin behind when you stage.
Title: Re: SpaceX: Merlin 1D thread
Post by: Okie_Steve on 03/22/2013 11:28 pm
8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?
Spacex advertises engine out capability. Falcon 9 successfully recovered from an engine out by burning longer on the other 8 engines as designed so I would not expect Spacex to risk the 112.5% trick in as similar case, especially if they plan to recover/reuse the engines, but what about losing 2 engines at an inopportune time where longer burn and slower ascent would not hack it. Would 7 @ 112.5% be worth trying if there was reason to believe the engines could probably hack those conditions *once* and stay close enough to profile to prevent loss of mission? Think in terms of red lining a racing engine. You can probably get away with exceeding the red line once, but don't try it on a regular basis. All of this is modulo the question of how much can they overboost and what does the failure probability look like when doing so.

I remember reading somewhere about the possibility of extra heavy Falcon something payload that would not have engine out capacity. If that's true it seems like an overboost "Hail Mary" attempt would have very little down side vs pushing the big red button and making little bitty payload pieces. Those are the sorts of conditions I was thinking about. Again, probably only for cargo (non-crew) flight.
Title: Re: SpaceX: Merlin 1D thread
Post by: iamlucky13 on 03/22/2013 11:45 pm

Jim was insisting that the Falcon 9 must use open loop control a few months ago when people were discussing relights, engine out, or something like that, but I think SpaceX's public statements suggest fairly definitively that the F9 uses closed-loop control and continually recalculates its trajectory etc. on the fly...

Never said that.  All launch vehicles use close loop.  If this was in regard to the COTS-1 canceled restart, then the point was that there are limited branches for a vehicle to follow, since there are limited data sources.

First stage is usually open loop (fly to depletion) and upperstages use close loop.

Is there any advantage, besides less complexity, in using open loop on the first stage? SpaceX has a standard of using the same flight computer between different stages. This would imply to me that both would be closed loop. There is also nothing preventing them from starting initailly from the pad in open loop and switching to closed loop part way through lower stage launch.

Edit: for readability.

Open loop is not really an advantage per se, but modern controllers are programmable. SpaceX could install the same controller in both stages, but simply apply open loop logic to the first stage MECO.

Many modern controllers are also modular* so you can add I/O units as needed, or produced in families of varying capabilities but the same interfaces, programming, etc so your engineers are working with the same basic system in either case, without paying for excess capacity.

All of which I thought was irrelevant: doesn't the Falcon just have one (redundant) control system on the 2nd stage controlling the whole vehicle?

And keep in mind Jim was just talking about the MECO logic unless I misunderstood him. You've still got pitch/yaw/roll plus thrust level to deal with, and those themselves are outcomes of the controlled movements of the actuators, valves, etc. I assume that most or all of those are under closed loop control.


* Off-topic thought - talking about modular systems gave me a thought - If SpaceX had a customer who wanted a sufficiently-below capacity launch, they could potentially save money on engines by leaving one or two off and short-fueling the first stage to lower the weight. Falcon 9.8, 9.7, maybe even 9.6?

Yeah, yeah...I know somebody is going to tell me this was discussed before, please let it die. Time to go browsing through old threads. I'm really not trying to derail this one.
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/23/2013 01:40 am
Better performance margin if you fly to depletion for the first stage... Otherwise, you're leaving some margin behind when you stage.

No reason to not fly to depletion, agreed. There is no reason that flying to depletion excludes having a closed loop system measuring acceleration and engine status and throttling as needed.
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/23/2013 01:44 am
All of which I thought was irrelevant: doesn't the Falcon just have one (redundant) control system on the 2nd stage controlling the whole vehicle?

First I've heard of this. I was under the impression they have a computer per stage. Each one is triply redundant (with each element having two computers each voting against each other) linux based embedded system.

At the very least we know they have a computer per stage in F9 v1.1.
Title: Re: SpaceX: Merlin 1D thread
Post by: LouScheffer on 03/23/2013 11:54 am
Would 7 @ 112.5% be worth trying if there was reason to believe the engines could probably hack those conditions *once* and stay close enough to profile to prevent loss of mission? Think in terms of red lining a racing engine. You can probably get away with exceeding the red line once, but don't try it on a regular basis. All of this is modulo the question of how much can they overboost and what does the failure probability look like when doing so.
Of course this is worth trying if the alternative is certain doom.  As the accident report said where a pilot did not simply jam the throttles full forward, when redline thrust was not enough:  "Who was he trying to save the engines for?  The accident investigators?"
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 03/23/2013 11:57 am
At the very least we know they have a computer per stage in F9 v1.1.

We know this from where?
Title: Re: SpaceX: Merlin 1D thread
Post by: Silmfeanor on 03/23/2013 12:00 pm
At the very least we know they have a computer per stage in F9 v1.1.

We know this from where?


This follows from the fact that they'll try restarts on the frst stage, and the 2nd stage needs guidance aswell. So, a minimum of 1 computer per stage.
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 03/23/2013 12:07 pm
For the restart tests, yes, they'll need guidance for the first stage, but it doesn't follow from that that every v1.1 has/will have 2 sets of computers. Certainly not 2 complete sets of triple string computers as mlindner is asserting. I would be surprised if the restart tests use anything more than single string on the 1st stage.
Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 03/23/2013 01:38 pm
8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?
What if the way to increase the thrust is to change the O/F ratio?

Not good if you are going to throttle a lot - you want oxidizer and fuel to be depleted at the same time.
That was my point. That even with increased thrust on an engine out situation you might not end with the same MECO point. You might be oxidizer limited, for example. I'm not stating one way or the other since I ignore who the Merlin 1D throttles. But I'm stating that flat out same situation might not happen.
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 03/23/2013 04:39 pm
For the restart tests, yes, they'll need guidance for the first stage, but it doesn't follow from that that every v1.1 has/will have 2 sets of computers. Certainly not 2 complete sets of triple string computers as mlindner is asserting. I would be surprised if the restart tests use anything more than single string on the 1st stage.
Well, the first v1.1 will have two sets of computers (redundancy level really doesn't matter too much in this discussion), and they likely plan to do similar tests on later flights before going entirely to their future recovery plan. So why would you design multiple different types of v1.1, one with two computers another with one? The differences in avionics integration would make it not worth it, the differences in software, etc. The cost of the hardware itself wouldn't be that great compared to the cost of having multiple versions of the avionics set. Once it's designed for two computers, they wouldn't go back without a major change.
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 03/23/2013 04:48 pm
That's like saying they put parachutes in the first F9 so why not keep putting them in all other vehicles as well, to avoid multiple configurations. Recovery systems had logic as well. 1st stage guidance and 2nd stage guidance shouldn't really be linked in a way that it counts as an integration problem if you *remove* 1st stage guidance when you don't need it. It's supposed to kick in only after staging and be completely inactive until then. At least that's what the customers would like, I'd think.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/23/2013 05:12 pm
Elon said they want to start recovering stages by 2015

Before they fly those, they'd want to experiment with re-entering standard F9 1.1 stages, as many times as possible.

If those were dedicated tests, then "possible" means "financially possible" and so maybe 2-3 times tops.

But if they can get those tests for free by making the standard 1.1 as close ot the F9R as possible, why not?

They might even collect some of the hardware to get a statistical picture of post-launch damage, and since they'll likely not be able to recover the first few experiments, I think the next year and a half worth of F9 launches will be mostly with recovery attempts.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/23/2013 05:31 pm
That's like saying they put parachutes in the first F9 so why not keep putting them in all other vehicles as well, to avoid multiple configurations. Recovery systems had logic as well. 1st stage guidance and 2nd stage guidance shouldn't really be linked in a way that it counts as an integration problem if you *remove* 1st stage guidance when you don't need it. It's supposed to kick in only after staging and be completely inactive until then. At least that's what the customers would like, I'd think.

And actually, looking back about a couple of month, we had a fierce argument here where I argued that they should standardize the pitch-over/restart/avionics hardware on all 1.1s, to facilitate testing.

As always it was the case of "you don't know anything", "cool-aid", and "customers won't allow it" - since they hate configuration changes.

So we had a trade-off: SpaceX wants to experiment with reentry, customers want a stable configuration.

Now that we know (btw, was it ever corroborated?  I think it is still a single-source bit of knowledge) that the first flight will already carry all of the hardware, there's no longer a trade-off - everyone wants the same thing.

As for the first stage avionics, I wouldn't make them "turn on" after separation.  If they're not driving the combined stack, I'd at least make them fully awake, keeping track of all the data, and in independent communication with the ground - again, to get as much development done as early as possible, which is what SpaceX has always been doing.
Title: Re: SpaceX: Merlin 1D thread
Post by: joek on 03/23/2013 05:49 pm
So we had a trade-off: SpaceX wants to experiment with reentry, customers want a stable configuration.

Customers want to reduce risk.  A stable configuration is one way; greater margins is another way.
Title: Re: SpaceX: Merlin 1D thread
Post by: cambrianera on 03/23/2013 05:52 pm
Off topic.
Please go on the right topic: http://forum.nasaspaceflight.com/index.php?topic=21923.0
Title: Re: SpaceX: Merlin 1D thread
Post by: russianhalo117 on 03/24/2013 12:47 am
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.

Maybe a possible 1E will come out of the long wait of the 1D?

Even the "Is  Falcon 1E dead?" thread (http://forum.nasaspaceflight.com/index.php?topic=24333.msg702893#msg702893) is dead.  (No, he's just resting.  Dead!  Dead, I tell you!)

There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets.  I was disappointed.  They "built it" but "they did not come".   The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.
F1 programme Merlin-1C's were transferred to the F9 programme quite a while ago, so the answer to the beginning of post is a confirmed no.
Title: Re: SpaceX: Merlin 1D thread
Post by: llanitedave on 03/24/2013 01:35 am
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.

Maybe a possible 1E will come out of the long wait of the 1D?

Even the "Is  Falcon 1E dead?" thread (http://forum.nasaspaceflight.com/index.php?topic=24333.msg702893#msg702893) is dead.  (No, he's just resting.  Dead!  Dead, I tell you!)

There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets.  I was disappointed.  They "built it" but "they did not come".   The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.
F1 programme Merlin-1C's were transferred to the F9 programme quite a while ago, so the answer to the beginning of post is a confirmed no.

I don't think the question was about the Falcon 1E, but about about a possible Merlin 1E, a hypothetical follow-on to the Merlin 1D.

I don't know if they're going to be happy with that engine and make it mainstream for a while, or if they have a continuous development program going on with it.
Title: Re: SpaceX: Merlin 1D thread
Post by: spectre9 on 03/24/2013 01:40 am
Has a Merlin 1D ever failed (exploded) in testing?

If one did would SpaceX disclose it?

Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/24/2013 02:18 am
Has a Merlin 1D ever failed (exploded) in testing?

If one did would SpaceX disclose it?
"If engines are not exploding, you are not testing hard enough" ?
Title: Re: SpaceX: Merlin 1D thread
Post by: 8900 on 03/24/2013 02:50 am
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.

Maybe a possible 1E will come out of the long wait of the 1D?

Even the "Is  Falcon 1E dead?" thread (http://forum.nasaspaceflight.com/index.php?topic=24333.msg702893#msg702893) is dead.  (No, he's just resting.  Dead!  Dead, I tell you!)

There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets.  I was disappointed.  They "built it" but "they did not come".   The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.
F1 programme Merlin-1C's were transferred to the F9 programme quite a while ago, so the answer to the beginning of post is a confirmed no.

I don't think the question was about the Falcon 1E, but about about a possible Merlin 1E, a hypothetical follow-on to the Merlin 1D.

I don't know if they're going to be happy with that engine and make it mainstream for a while, or if they have a continuous development program going on with it.
As far as I know there is no plan of (Merlin) 1E, no one has talked about it so I assume it doesn't exist
There are talks of Elon abut Merlin 2 (large engine, one is enough to power the F9 first stage but the rocket will also lose engine out capability) and Raptor cryogenic upper stage, maybe what he means is Merlin 2 instead of 1E
Title: Re: SpaceX: Merlin 1D thread
Post by: Okie_Steve on 03/24/2013 02:57 am
"If engines are not exploding, you are not testing hard enough" ?
Yep, failure tells you where the boundaries really are as opposed to where you *think* they are. I don't expect Spacex to tell us where those boundaries are either since current appearances to the contrary they might decide to iterate to a Merlin 1E at some point if it looks worth while enough. In any case they don't want to give away any competitive advantages. Which comes back to the question of how far might it be possible to push a kero-lox engine like the Merlin 1D in a do-or-die situation? Anyone have any guess based on prior art? If the answer is 1-2% vs 10-20% the number of useful scenerios changes greatly.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/24/2013 03:05 am
Regarding a hypothetical Merlin 1E, maybe someone remembers - were there any rumors about the 1D before it was revealed?  If yes, how long before?

I wouldn't be surprised if they iterated again, since a) re-usability is coming and they want engines to last many cycles and b) they will soon start having engines recovered after flight, and there will a lot to learn from them towards future iterations.

EDIT: D, not E.
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 03/24/2013 05:40 am
Regarding a hypothetical Merlin 1E, maybe someone remembers - were there any rumors about it before it was revealed?  If yes, how long before?

What? There have been no 1E rumors.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/24/2013 07:14 am
Sorry - see Edit above...
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/24/2013 07:54 am
I'm not sure how all this discussion about a non-existant Merlin 1E came about... There have been _zero_ rumors about a Merlin 1E so let's stop talking about something that we have heard _nothing_ about it even existing. This is even worse than talking about the MCT which we barely only know the acronym for (but not what the letters stand for).

More so it look like Merlin 2 has been abandoned as well, unlikely to happen. Raptor is no longer a cryogenic upper stage, but now a methane stage-agnostic high thrust engine. (It honestly appears the concepts for Merlin 2 (higher thrust Merlin 1) and Raptor (high ISP upper stage) have been combined into one engine under the name Raptor.) SpaceX obviously changes even what names refer to over time, so there is no point on latching on to a name that doesn't even exist yet (Merlin 1E)...
Title: Re: SpaceX: Merlin 1D thread
Post by: spectre9 on 03/24/2013 08:22 am
Rocketdyne engines have been tested to failure and that information has been made public.

SpaceX can do what they like I guess. Sometimes the secrecy is a bit annoying.
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/24/2013 08:30 am
Rocketdyne engines have been tested to failure and that information has been made public.

SpaceX can do what they like I guess. Sometimes the secrecy is a bit annoying.

I asked a friend who interned at SpaceX McGregor last summer about if he had heard of them shrapnel testing any engines by testing them till they blew. He hadn't. That doesn't confirm or deny though, just a data point.
Title: Re: SpaceX: Merlin 1D thread
Post by: Comga on 03/24/2013 03:24 pm
Regarding a hypothetical Merlin 1E, maybe someone remembers - were there any rumors about the 1D before it was revealed?  If yes, how long before?

What? There have been no 1E rumors.

Actually, it is the opposite of rumors about SpaceX developing another evolution of the Merlin 1D.  I haven't found it but do recall a statement from SpaceX or Musk himself that there would be NO Merlin 1E.  And we heard about the 1D way, way back in the days of Falcon 1.  The Falcon 1E was based on SpaceX moving from the Merlin 1C to the 1D.

(Sorry if I misinterpreted an earlier post of "1E" to mean the rocket, which was planned, rather than the engine, which has not been planned or announced. I try to be quite explicit above.)
Title: Re: SpaceX: Merlin 1D thread
Post by: krytek on 03/24/2013 03:40 pm
Regarding a hypothetical Merlin 1E, maybe someone remembers - were there any rumors about the 1D before it was revealed?  If yes, how long before?

What? There have been no 1E rumors.


Actually, it is the opposite of rumors about SpaceX developing another evolution of the Merlin 1D.  I haven't found it but do recall a statement from SpaceX or Musk himself that there would be NO Merlin 1E.  And we heard about the 1D way, way back in the days of Falcon 1.  The Falcon 1E was based on SpaceX moving from the Merlin 1C to the 1D.

(Sorry if I misinterpreted an earlier post of "1E" to mean the rocket, which was planned, rather than the engine, which has not been planned or announced. I try to be quite explicit above.)
It was Gwynne Shotwell. She was directly asked about it, and the answer was that there will be no 1E.
Currenty the 'rumors' hint at a light hydrocabon staged combustion engine.
Title: Re: SpaceX: Merlin 1D thread
Post by: cleonard on 03/24/2013 05:41 pm
Spacex seems to change the letter only when a rather large change is made to the engine.  There is a big change between the 1C and the 1D.  If SpaceX decides that a redesign is necessary, then we will see the 1E.  From what we have heard this is not yet the case so no 1E has been announced.

That doesn't mean that there are no changes going on.  I'd wager that there have been many incremental changes to the 1D design during the testing process. 

I do wonder if they have done any test to failures at over 100% thrust or just how long the engine will run at 100%. 
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 03/24/2013 05:50 pm
I get the feeling their convention is that the number (Merlin 1c, d, etc, Falcon 9 v1.0, v1.1) is an indication of product class and heritage. This isn't that weird. Look at how much the RL-10 has changed or the AJ-10 over the decades. Incredibly different, same initial number and name.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/24/2013 07:18 pm
'sactly - that's all I said - that as they learn more about what post-flight engines look like, and as they get ready for F9R, there might be another revision, whether it's called "E" or not. Not exactly an earth shaking conditional prediction...

Any info on Raptor is irrelevant to this, since it's not replacing the Merlin anytime soon.

Title: Re: SpaceX: Merlin 1D thread
Post by: MP99 on 03/24/2013 07:28 pm
Regarding a hypothetical Merlin 1E, maybe someone remembers - were there any rumors about the 1D before it was revealed?  If yes, how long before?

What? There have been no 1E rumors.
Actually, it is the opposite of rumors about SpaceX developing another evolution of the Merlin 1D.  I haven't found it but do recall a statement from SpaceX or Musk himself that there would be NO Merlin 1E.  And we heard about the 1D way, way back in the days of Falcon 1.  The Falcon 1E was based on SpaceX moving from the Merlin 1C to the 1D.

(Sorry if I misinterpreted an earlier post of "1E" to mean the rocket, which was planned, rather than the engine, which has not been planned or announced. I try to be quite explicit above.)

It was Gwynne Shotwell. She was directly asked about it, and the answer was that there will be no 1E.
Currenty the 'rumors' hint at a light hydrocabon staged combustion engine.

Clipped from http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense (http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense), Aug 2011:-

Quote
Revealing several new details of the 1D, Tom Mueller, propulsion engineering vice president, says the engine is designed to produce 155,000 lb. vacuum thrust and have a chamber pressure at “the sweet spot” of roughly 1,410 psia. “We’ve also increased the nozzle expansion ratio to 16 [compared with 14.5 on the Merlin 1C],” says Mueller, who adds that the initial engine “is doing better than we hoped.” The engine is designed for an Isp (specific impulse) of 310 sec. and has a thrust-to-weight ratio of 160:1. “We took structure off the engine to make it lighter. The engine we shipped [for test] to Texas was a development engine and hopefully the production engines will be even better,” he says.

The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We’ve added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It’s going to be a 1D with the same turbopump.”
(My highlight)

Note, also, that Gwynne was mentioned in the earlier part of the same article.

cheers, Martin
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/24/2013 07:29 pm
Clipped from http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense (http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense), Aug 2011:-

This URL is broken. Goes to "Page Not Found"
Title: Re: SpaceX: Merlin 1D thread
Post by: MP99 on 03/24/2013 09:09 pm
Clipped from http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense (http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense), Aug 2011:-

This URL is broken. Goes to "Page Not Found"

Yup, AvWeek only seem to put the articles up for a short while (presumably to advertise the magazines) before taking them down again.

That's why I said "clipped from" (and only pasted sections that were quotes from Tom Mueller). Evernote is your friend.

(Actually, I have a love / hate relationship with Evernote, but this it's good for.)

cheers, Martin
Title: Re: SpaceX: Merlin 1D thread
Post by: Nomadd on 03/24/2013 09:41 pm
 I wonder if "able to throttle them all" means "will throttle them all. Don't you get a better isp at full throttle?  Then again, all engines running would help engine out numbers some.
Title: Re: SpaceX: Merlin 1D thread
Post by: LegendCJS on 03/24/2013 10:09 pm
I wonder if "able to throttle them all" means "will throttle them all. Don't you get a better isp at full throttle?  Then again, all engines running would help engine out numbers some.

It is possible to fly a more efficient trajectory by taking advantage of the continuous spectrum of thrust offered by throttle capability than to deal with step changes in thrust from turning engines off.  All throttling will at least be symmetrical to avoid differential thrust causing a torque that requires counter steering. 

If, in the past thrust levels went from 9 arbitrary units to 7 units by shutting two engines off, then with 70% throttle capability, they would only have to throttle the outer 8 to 75% while keeping the middle engine at 100% to achieve the same 7 arbitrary units of thrust, but this assumes that the throttle-able 1Ds provide the same thrust at full rating as the 1Cs, which we know isn't true. 

It all depends on the details, but 1Ds make a lot more thrust than 1Cs, and therefore probably all engines must throttle deeply to have the same acceleration limits on the rocket for the same payload as previous 1C powered flight.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/25/2013 12:40 am
btw - is it even a given that when you throttle down, the ISP remains constant?

The requirement to throttle for landing is for a very brief maneuver, so ISP is not of prime importance.

So the solution might not be suitable for the long initial burn.

Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 03/25/2013 12:41 pm
btw - is it even a given that when you throttle down, the ISP remains constant?

The requirement to throttle for landing is for a very brief maneuver, so ISP is not of prime importance.

So the solution might not be suitable for the long initial burn.
Quite difficult that you'd keep isp the same. Even the RD-180 loses some 3 to 5 seconds when throttling. And that's probably one of the most efficient engines ever.
Title: Re: SpaceX: Merlin 1D thread
Post by: krytek on 03/25/2013 12:56 pm
btw - is it even a given that when you throttle down, the ISP remains constant?

The requirement to throttle for landing is for a very brief maneuver, so ISP is not of prime importance.

So the solution might not be suitable for the long initial burn.
Quite difficult that you'd keep isp the same. Even the RD-180 loses some 3 to 5 seconds when throttling. And that's probably one of the most efficient engines ever.
Yes but is Isp equal to fuel consumption?
Maybe the Isp drops but the engines use less fuel due to lower thrust.
Title: Re: SpaceX: Merlin 1D thread
Post by: kevin-rf on 03/25/2013 01:29 pm
Yes but is Isp equal to fuel consumption?
Maybe the Isp drops but the engines use less fuel due to lower thrust.

Think of ISP has fuel efficiency.

Dropping the ISP is the same as saying your car dropped from 30 mpg to 20 mpg. You used more fuel to go the same distance.
Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 03/25/2013 01:33 pm
Yes but is Isp equal to fuel consumption?
Maybe the Isp drops but the engines use less fuel due to lower thrust.

Think of ISP has fuel efficiency.

Dropping the ISP is the same as saying your car dropped from 30 mpg to 20 mpg. You used more fuel to go the same distance.

Technically, you used more propellent mass units per unit of thrust. You obviously use less propellant overall since you are throttling.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 03/25/2013 01:49 pm
So it might be better to turn off motors rather than to throttle them, since your ISP remains optimal.  Of course you can only throttle this way by steps of 11%, but you can combines the methods for a smooth throttle and small loss of efficiency
Title: Re: SpaceX: Merlin 1D thread
Post by: douglas100 on 03/25/2013 03:12 pm
Maybe. It'll be interesting to see what the actually do on the first flight. There may be factors other than Isp to consider.
Title: Re: SpaceX: Merlin 1D thread
Post by: llanitedave on 03/25/2013 03:45 pm
CASSIOPE is a small payload, so they should have plenty of reserve to play with.
Title: Re: SpaceX: Merlin 1D thread
Post by: sheltonjr on 03/25/2013 07:39 pm
If somebody could answer a question for me, I did a search but could not find anything specific, maybe it is obvious.

As the Gas generator turbopump is a critical part of the engine. When did SpaceX start to develop and build their own turbopumps for their engines?

I thought I read the Merlin 1D turbopump was built in-house. What about the Merlin 1C and the Merlin on the Falcon 1?

Title: Re: SpaceX: Merlin 1D thread
Post by: sublimemarsupial on 03/25/2013 07:52 pm
M1A,M1C and MVacC used turbopumps from Barber-Nichols. M1D was the first to be built in-house. MVacD uses the same pump as M1D.
Title: Re: SpaceX: Merlin 1D thread
Post by: krytek on 03/31/2013 04:40 pm
Saw an interesting interview with Andrew Nelson from Xcor
The guys claims rocket turbo pumps cost between $500k and $2M.
Anyone ever saw a price quote for M1C/M1D turbo pumps or cares to make an educated guess?
Title: Re: SpaceX: Merlin 1D thread
Post by: ArbitraryConstant on 03/31/2013 05:19 pm
Anyone ever saw a price quote for M1C/M1D turbo pumps or cares to make an educated guess?
We've speculated from time to time. It doesn't seem possible that a full up Merlin 1D costs even $1M.

We've heard the stories about all the 3D printers and CNC machines SpaceX has. I think a lot of the old school engines have a lot more manual processes that bring up their cost quite a bit.
Title: Re: SpaceX: Merlin 1D thread
Post by: HMXHMX on 03/31/2013 07:28 pm
Saw an interesting interview with Andrew Nelson from Xcor
The guys claims rocket turbo pumps cost between $500k and $2M.
Anyone ever saw a price quote for M1C/M1D turbo pumps or cares to make an educated guess?

The FASTRAC pump, which is physically very similar to SpaceX Merlin pumps, cost about $320K, with a projected learning curve reduction to $196K.  I would expect current 1D pumps to cost perhaps $150K fully burdened.
Title: Re: SpaceX: Merlin 1D thread
Post by: Elmar Moelzer on 03/31/2013 08:43 pm
The FASTRAC pump, which is physically very similar to SpaceX Merlin pumps, cost about $320K, with a projected learning curve reduction to $196K.  I would expect current 1D pumps to cost perhaps $150K fully burdened.
That sounds reasonable to me.
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/31/2013 09:24 pm
Saw an interesting interview with Andrew Nelson from Xcor
The guys claims rocket turbo pumps cost between $500k and $2M.
Anyone ever saw a price quote for M1C/M1D turbo pumps or cares to make an educated guess?

The FASTRAC pump, which is physically very similar to SpaceX Merlin pumps, cost about $320K, with a projected learning curve reduction to $196K.  I would expect current 1D pumps to cost perhaps $150K fully burdened.

From my understanding I thought that only M1C and earlier pumps were made by Barber-Nichols. Would not this imply a significant price drop considering SpaceX traded into developing the M1D turbo in-house?
Title: Re: SpaceX: Merlin 1D thread
Post by: HMXHMX on 03/31/2013 10:20 pm
Saw an interesting interview with Andrew Nelson from Xcor
The guys claims rocket turbo pumps cost between $500k and $2M.
Anyone ever saw a price quote for M1C/M1D turbo pumps or cares to make an educated guess?

The FASTRAC pump, which is physically very similar to SpaceX Merlin pumps, cost about $320K, with a projected learning curve reduction to $196K.  I would expect current 1D pumps to cost perhaps $150K fully burdened.

From my understanding I thought that only M1C and earlier pumps were made by Barber-Nichols. Would not this imply a significant price drop considering SpaceX traded into developing the M1D turbo in-house?

I have no insight into SpaceX costs, or how they account for the unit cost of an article.  These figures are from the late 1990s, from NASA MSFC.  B-N was the vendor at the time.  Since SpaceX's production rate will be much, much higher, a lower cost per unit is likely.
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 03/31/2013 10:26 pm
Saw an interesting interview with Andrew Nelson from Xcor
The guys claims rocket turbo pumps cost between $500k and $2M.
Anyone ever saw a price quote for M1C/M1D turbo pumps or cares to make an educated guess?

The FASTRAC pump, which is physically very similar to SpaceX Merlin pumps, cost about $320K, with a projected learning curve reduction to $196K.  I would expect current 1D pumps to cost perhaps $150K fully burdened.

From my understanding I thought that only M1C and earlier pumps were made by Barber-Nichols. Would not this imply a significant price drop considering SpaceX traded into developing the M1D turbo in-house?

I have no insight into SpaceX costs, or how they account for the unit cost of an article.  These figures are from the late 1990s, from NASA MSFC.  B-N was the vendor at the time.  Since SpaceX's production rate will be much, much higher, a lower cost per unit is likely.

Thanks for the info. Having someone who worked extensively in the industry is handy.

On the production rate note, turbopumps are very much out of my area of knowledge, but are there any special materials used in their construction as in turbine blades? Or are they usually made out of a single material type for the entire turbopump?
Basically what I'm trying to get at is what components are the main cost drivers inside a turbopump? What makes it so much more expensive than say a turbopump used in high performance cars?
Title: Re: SpaceX: Merlin 1D thread
Post by: QuantumG on 03/31/2013 10:52 pm
How reusable was the FASTRAC pump?
Title: Re: SpaceX: Merlin 1D thread
Post by: cambrianera on 03/31/2013 10:56 pm
are there any special materials used in their construction as in turbine blades? Or are they usually made out of a single material type for the entire turbopump?
Basically what I'm trying to get at is what components are the main cost drivers inside a turbopump? What makes it so much more expensive than say a turbopump used in high performance cars?

Turbine blades are high temp low creep alloys (typical are nickel alloys)
Pump impellers and casings can be aluminium (or other materials, depending on pressure and construction constraints).
Main factor for cost is production rate. Turbochargers for high performance gasoline cars have similar (not same, but similar) requirements, the production cost (not price) is around 1K $ (and the fact that the piece is smaller sometimes makes things more complicate).
Title: Re: SpaceX: Merlin 1D thread
Post by: cambrianera on 03/31/2013 11:01 pm
How reusable was the FASTRAC pump?


Highly reusable; the engine had a ablative liner to be replaced between flights on the X-34 demonstrator.
http://en.wikipedia.org/wiki/Orbital_Sciences_X-34
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 03/31/2013 11:08 pm
How reusable was the FASTRAC pump?


Highly reusable; the engine had a ablative liner to be replaced between flights on the X-34 demonstrator.
http://en.wikipedia.org/wiki/Orbital_Sciences_X-34

Anything that uses ablative materials should not be classified as "highly reusable".
Title: Re: SpaceX: Merlin 1D thread
Post by: cambrianera on 03/31/2013 11:32 pm
The turbopump had no ablative material inside.
The turbopump was deemed highly reusable hardware.

By the way, far heavier than merlin TP.
Title: Re: SpaceX: Merlin 1D thread
Post by: HMXHMX on 04/01/2013 04:16 am
The turbopump had no ablative material inside.
The turbopump was deemed highly reusable hardware.

By the way, far heavier than merlin TP.

FASTRAC was an engine that was meant as a learning experience for younger NASA MSFC engineers, who had no experience developing (or managing the development of) a pump-fed engine.  While it had terrible t/w, as I recall worse than the A-4 powerplant, the design of the pump became a predecessor for several new rocket engine turbopumps, and put Barber-Nichols on the map, as well.  (The poor t/w wasn't due to TPA, but due to the ablative TPA primarily.)
Title: Re: SpaceX: Merlin 1D thread
Post by: cambrianera on 04/01/2013 07:32 am
For those interested in FASTRAC & Merlin TPA, nice pics at the beginning of this topic.
http://forum.nasaspaceflight.com/index.php?topic=26388.msg793205#msg793205
Title: Re: SpaceX: Merlin 1D thread
Post by: manboy on 04/24/2013 04:30 pm
Clipped from http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense (http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense), Aug 2011:-

This URL is broken. Goes to "Page Not Found"
http://web.archive.org/web/20111116095606/http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defense
Title: Re: SpaceX: Merlin 1D thread
Post by: cambrianera on 04/24/2013 04:54 pm
A doubt I had (and can't answer).
M1D is throttleable and SpaceX plans to leverage throttleability at the end of the first stage burn, instead of turning off two engines.
When this thing surfaced some consideration were done if this is negative in terms of ISP (throttling normally is bad for ISP).

But M1D has an underexpanded nozzle at altitude; isn't possible that throttling makes the nozzle less underexpanded (gaining some ISP).
Furthermore throttle can be done sending less propellant to the TPA preburner, increasing the percentage of propellant passing in the CC.

Any thought?
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 04/24/2013 05:02 pm
But M1D has an underexpanded nozzle at altitude; isn't possible that throttling makes the nozzle less underexpanded (gaining some ISP).

That just means your Isp loss due to throttling won't be as bad.

When you kill 2 engines after hitting a G limit (4.5G or whatever it is on F9), your accel immediately drops to 7/9 of that G limit. With throttling, you could keep the accel right at the G limit so the Isp hit of throttling might actually be offset by slightly lower gravity losses - higher overall acceleration and quicker propellant depletion.

The Isp hit due to throttling is likely to be a non-issue.
Title: Re: SpaceX: Merlin 1D thread
Post by: ClaytonBirchenough on 05/05/2013 04:55 pm
Is the only difference between a Merlin 1D and a Merlin 1D Vac the nozzle extension on the latter?
Title: Re: SpaceX: Merlin 1D thread
Post by: deltaV on 05/05/2013 05:55 pm
Is the only difference between a Merlin 1D and a Merlin 1D Vac the nozzle extension on the latter?
No there are other differences. For example the M1D gas generator exhaust has a separate nozzle and the M1D Vac gas generator exhausts into the main nozzle F-1 style.
Title: Re: SpaceX: Merlin 1D thread
Post by: ClaytonBirchenough on 05/05/2013 06:12 pm
Is the only difference between a Merlin 1D and a Merlin 1D Vac the nozzle extension on the latter?
No there are other differences. For example the M1D gas generator exhaust has a separate nozzle and the M1D Vac gas generator exhausts into the main nozzle F-1 style.

Thanks. It was probably relatively easy to convert Merlin 1D into Merlin 1D VAC though, right?
Title: Re: SpaceX: Merlin 1D thread
Post by: Prober on 05/05/2013 07:19 pm
Is the only difference between a Merlin 1D and a Merlin 1D Vac the nozzle extension on the latter?
No there are other differences. For example the M1D gas generator exhaust has a separate nozzle and the M1D Vac gas generator exhausts into the main nozzle F-1 style.

maybe, we have only seen "tease" photos up to now.
 
Title: Re: SpaceX: Merlin 1D thread
Post by: sdsds on 05/05/2013 11:07 pm
It was probably relatively easy to convert Merlin 1D into Merlin 1D VAC though, right?

My phrasing of the question would be, "How much more did it cost to create both variants, over what it would have cost to create only the sea-level variant?"

My guess is that they actually saved money, compared with the other likely option of continuing Merlin 1C Vac production!
Title: Re: SpaceX: Merlin 1D thread
Post by: beancounter on 05/06/2013 05:06 am
Just throwing this one out there to see if anyone has any ideas.

Apologies if it's been discussed previously however it seems that SpaceX require some form of high energy upper stage to increase the throw mass of their payloads.  Would adding another one or two M1Dv engines do the same as a single say Raptor?  I imagine you'd need to stretch the tanks a bit but that shouldn't be insurmountable.
Am I missing something obvious to rocket scientists that makes this a 'stupid' question?
Thanks.
Title: Re: SpaceX: Merlin 1D thread
Post by: QuantumG on 05/06/2013 05:17 am
It's not a stupid question.. but the answer isn't obvious. There is some advantage to adding more thrust to an upper stage, due to the Oberth effect, but it is minor compared to improving ISP.. so, it's only really a sensible tradeoff between comparable engines. Improving ISP of an upper stage gives you an exponential improvement, which can be "spent" in making the stage more bulky in order to hold the more bulky propellants, for a net win.
Title: Re: SpaceX: Merlin 1D thread
Post by: beancounter on 05/06/2013 05:45 am
It's not a stupid question.. but the answer isn't obvious. There is some advantage to adding more thrust to an upper stage, due to the Oberth effect, but it is minor compared to improving ISP.. so, it's only really a sensible tradeoff between comparable engines. Improving ISP of an upper stage gives you an exponential improvement, which can be "spent" in making the stage more bulky in order to hold the more bulky propellants, for a net win.

Ok thanks.  Had a quick look at this effect.  Interesting and clearly not intuitive.  I need to think about this a bit.  Raptor is, I believe, a far higher isp engine than the Merlin and this is what provides the upper stage with the improved throw ability, not simply more engines?
Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 05/06/2013 01:16 pm
Also, adding thrust means worsening your fmp (if you don't enlarge the whole stage). A worse fmp is just as critical as isp. And adding a second engine usually means a smaller nozzle.
For purely orbital maneuvers, isp trumps thrust almost every time. As stated before, you have the Oberth Effect, and the more T/W the more your maneuver approaches an instant impulse, which might be more critical on certain application. But for uppers stages, the general rule is that thrust is not critical unless you are sub orbital. Thus, highly capable second stages, like the Centaur or DIVUS, could take the fmp hit of a second RL10, and improve their LEO performance, because of the gravity losses, but for higher energy orbits, the performance is worse with two engines, since the suborbital time is much less.
In general, the Falcon 9 US has a lot of T/W, but that's the consequence of using a 9 to 1 engine relationship. And with the Merlin 1C, the Vac version had less thrust than the first stage version. Since the 1D is the same engine (turbopump, chamber, etc.) with a better nozzle expansion, the Vac version will be more powerful than the first stage version. This might worsen the high energy performance of the Falcon 9, but might be needed for the Falcon Heavy.
Title: Re: SpaceX: Merlin 1D thread
Post by: beancounter on 05/07/2013 01:00 am
Also, adding thrust means worsening your fmp (if you don't enlarge the whole stage). A worse fmp is just as critical as isp. And adding a second engine usually means a smaller nozzle.
For purely orbital maneuvers, isp trumps thrust almost every time. As stated before, you have the Oberth Effect, and the more T/W the more your maneuver approaches an instant impulse, which might be more critical on certain application. But for uppers stages, the general rule is that thrust is not critical unless you are sub orbital. Thus, highly capable second stages, like the Centaur or DIVUS, could take the fmp hit of a second RL10, and improve their LEO performance, because of the gravity losses, but for higher energy orbits, the performance is worse with two engines, since the suborbital time is much less.
In general, the Falcon 9 US has a lot of T/W, but that's the consequence of using a 9 to 1 engine relationship. And with the Merlin 1C, the Vac version had less thrust than the first stage version. Since the 1D is the same engine (turbopump, chamber, etc.) with a better nozzle expansion, the Vac version will be more powerful than the first stage version. This might worsen the high energy performance of the Falcon 9, but might be needed for the Falcon Heavy.

Sorry, you lost me in the first sentence:  'fmp'?  Also the 2nd stage should be able to handle the width of 2 engines without nozzle diameter reduction - shouldn't it?
Thanks.
Title: Re: SpaceX: Merlin 1D thread
Post by: CuddlyRocket on 05/07/2013 02:44 am
A second engine doubles the total thrust, which means you'll accelerate quicker, but it also doubles the rate you use the propellant, which means you can't fire the engines for as long. These effectively cancel out, but you're also carrying the additional weight of the extra engine, so performance is poorer.

Because you have more thrust, you could extend the stage and carry more propellant, but this reduces your acceleration. Also, the first stage now has more mass to carry and this reduces that stage's performance.

There's plenty of room on a Falcon 9 for additional engines, as the diameter of the two stages are the same. The fact that there is only one second stage engine, despite SpaceX's fondness for redundancy, tells you something.
Title: Re: SpaceX: Merlin 1D thread
Post by: beancounter on 05/07/2013 06:41 am
A second engine doubles the total thrust, which means you'll accelerate quicker, but it also doubles the rate you use the propellant, which means you can't fire the engines for as long. These effectively cancel out, but you're also carrying the additional weight of the extra engine, so performance is poorer.

Because you have more thrust, you could extend the stage and carry more propellant, but this reduces your acceleration. Also, the first stage now has more mass to carry and this reduces that stage's performance.

There's plenty of room on a Falcon 9 for additional engines, as the diameter of the two stages are the same. The fact that there is only one second stage engine, despite SpaceX's fondness for redundancy, tells you something.
Ok thanks for that.  More to think about.
Title: Re: SpaceX: Merlin 1D thread
Post by: simonbp on 05/07/2013 06:51 am
But, it's not a Kestrel. You don't need much thrust, but you still want the thrust/weight to be greater than about 0.25 to cancel out the gravity and drag losses.

If you ever see an RL-10, it's a pretty small little engine, especially without any nozzle extensions. Centaur and DCSS get away with using a single one for GTO flights both because of the low thrust requirements and and the low mass of the hydrogen fuel.
Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 05/07/2013 05:13 pm
Also, adding thrust means worsening your fmp (if you don't enlarge the whole stage). A worse fmp is just as critical as isp. And adding a second engine usually means a smaller nozzle.
For purely orbital maneuvers, isp trumps thrust almost every time. As stated before, you have the Oberth Effect, and the more T/W the more your maneuver approaches an instant impulse, which might be more critical on certain application. But for uppers stages, the general rule is that thrust is not critical unless you are sub orbital. Thus, highly capable second stages, like the Centaur or DIVUS, could take the fmp hit of a second RL10, and improve their LEO performance, because of the gravity losses, but for higher energy orbits, the performance is worse with two engines, since the suborbital time is much less.
In general, the Falcon 9 US has a lot of T/W, but that's the consequence of using a 9 to 1 engine relationship. And with the Merlin 1C, the Vac version had less thrust than the first stage version. Since the 1D is the same engine (turbopump, chamber, etc.) with a better nozzle expansion, the Vac version will be more powerful than the first stage version. This might worsen the high energy performance of the Falcon 9, but might be needed for the Falcon Heavy.

Sorry, you lost me in the first sentence:  'fmp'?  Also the 2nd stage should be able to handle the width of 2 engines without nozzle diameter reduction - shouldn't it?
Thanks.
Fuel Mass Percentage, i.e. you need the extra dry weight of the second engine, TVC and associated plumbing, APU, etc. Thus, the percentage of fuel for the total mass of the stage worsen significantly. And in a second stage, if gravity losses are not critical, an extra kilogram of upper stage weight means one less kilogram of payload.
Title: Re: SpaceX: Merlin 1D thread
Post by: Okie_Steve on 06/28/2013 08:48 pm
There was some discussion on another thread about the difference between running engines dry and shutting down with some small abount of propellant in the lines and pumps, which got me to wondering.

What is the likely failure mode if you run a kero-lox turbopump engine like the Merlin-1D dry? I've always assumed it would be the turbos going overspeed and self destructing, but I don't really know. Maybe it's something else? And, is RUD pretty much guaranteed, likely or just possible in this scenerio?
Title: Re: SpaceX: Merlin 1D thread
Post by: Jcc on 06/28/2013 11:24 pm
There was some discussion on another thread about the difference between running engines dry and shutting down with some small abount of propellant in the lines and pumps, which got me to wondering.

What is the likely failure mode if you run a kero-lox turbopump engine like the Merlin-1D dry? I've always assumed it would be the turbos going overspeed and self destructing, but I don't really know. Maybe it's something else? And, is RUD pretty much guaranteed, likely or just possible in this scenerio?

For one, RP-1 is used to cool the nozzle, though I don't know if there would be enough time for it to overheat. For two, it also is used for hydraulic fluid to gimble the engine. Again, maybe not critical if it is about to conk out anyway. If the tank loses pressure maybe it can deform.

As far as the turbo pump, that won't be driven without fuel, the question is would there be a reservoir of fuel for the turbo pump when the stream it is pumping runs dry.

Also with a multi-engine system, you can have unpredictable forces if some engines cut when others continue for a while.
Title: Re: SpaceX: Merlin 1D thread
Post by: simonbp on 06/30/2013 08:30 pm
Yeah, I doubt you could even run them actually dry; the control system is too smart for that. Rather, you'd run them until the control system determines that the stage has hit a predetermined low fuel safety point and does controlled shutdown of the engines.
Title: Re: SpaceX: Merlin 1D thread
Post by: Okie_Steve on 06/30/2013 10:33 pm
That was the point of the original question about running dry. What *BAD* thing will happen and how probable is it? I had not considered the multi-engine case and can see the problem with differential shutdown there. I was thinking more of single engine upper stage or maybe center stage on a returning first stage if the F9R works out. There is apparently not much propellent left at auto shutdown. What sort of small gain might there be to running dry to maybe prevent loss of vehicle/mission at the risk of possible loss of vehicle/mission if it comes apart. Clearly it's not done, probably for a very good reason, just wondering what/why. Specifically for kero-lox engines like the Merlin-1d. Hydrogen-oxygen or methane-oxygen might very well be different.
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 06/30/2013 10:39 pm
That was the point of the original question about running dry. What *BAD* thing will happen and how probable is it? I had not considered the multi-engine case and can see the problem with differential shutdown there. I was thinking more of single engine upper stage or maybe center stage on a returning first stage if the F9R works out. There is apparently not much propellent left at auto shutdown. What sort of small gain might there be to running dry to maybe prevent loss of vehicle/mission at the risk of possible loss of vehicle/mission if it comes apart. Clearly it's not done, probably for a very good reason, just wondering what/why. Specifically for kero-lox engines like the Merlin-1d. Hydrogen-oxygen or methane-oxygen might very well be different.
q

It is the same for all of them.  Unloaded turbopumps do not behave very well.  The vehicle doesn't know when this happens and wouldn't take the necessary steps that would normally happen after commanded shutdown (a shutdown from a depletion signal is still a commanded shutdown).   There is little gain, since the amount of propellant is only a few seconds of burn time.
Title: Re: SpaceX: Merlin 1D thread
Post by: sanman on 07/01/2013 03:50 am
To me, unloaded pumps / pumps running on dry means cavitation damage.

If your pumps cavitate, then they get damaged - metal hitting metal, instead of hitting liquid.
Title: Re: SpaceX: Merlin 1D thread
Post by: R7 on 07/01/2013 11:09 am
Running the pump dry is not exactly same as cavitation, latter happens when pump is fed fluid but not fast enough or at high enough pressure, causing voids on impeller blades where fluid pressure suddenly drops below vapor pressure. When the voids later collapse that eats the metal.

What happens when rocket engine runs dry depends on things like what cycle it employs, how the pumps are arranged (single axis, separate, boost pumps etc), which of the propellants runs dry first (unlikely that you get perfect PU to finish both exactly the same time), are propellants used for lubrication etc.

When uncontrollably run dry there may also be issues with pressures decaying in the propellant lines and injector in the wrong way, possibly leading to things flowing wrong direction, mixing and burning in the wrong place.
Title: Re: SpaceX: Merlin 1D thread
Post by: Prober on 07/01/2013 02:24 pm
That was the point of the original question about running dry. What *BAD* thing will happen and how probable is it? I had not considered the multi-engine case and can see the problem with differential shutdown there. I was thinking more of single engine upper stage or maybe center stage on a returning first stage if the F9R works out. There is apparently not much propellent left at auto shutdown. What sort of small gain might there be to running dry to maybe prevent loss of vehicle/mission at the risk of possible loss of vehicle/mission if it comes apart. Clearly it's not done, probably for a very good reason, just wondering what/why. Specifically for kero-lox engines like the Merlin-1d. Hydrogen-oxygen or methane-oxygen might very well be different.
q

It is the same for all of them.  Unloaded turbopumps do not behave very well.  The vehicle doesn't know when this happens and wouldn't take the necessary steps that would normally happen after commanded shutdown (a shutdown from a depletion signal is still a commanded shutdown).   There is little gain, since the amount of propellant is only a few seconds of burn time.

and in some systems the fluids are also used for lubrication.   
Title: Re: SpaceX: Merlin 1D thread
Post by: Heinrich on 07/01/2013 03:53 pm
It is the same for all of them.  Unloaded turbopumps do not behave very well.  The vehicle doesn't know when this happens and wouldn't take the necessary steps that would normally happen after commanded shutdown (a shutdown from a depletion signal is still a commanded shutdown).   There is little gain, since the amount of propellant is only a few seconds of burn time.

You're reasoning the wrong way round. If there would be no disadvantage of running it dry, that would be a reason not to put low level cut-off switches onto the tank. Any instrumented system can fail, and you don't want to inadvertantly shutdown halfway on your trip uphill.

-

On an earth based pump (I'm process engineer, not a rocket scientist): first it'll start cavitating due to the lower amount of static pressure above the pump. This will lead to impeller damage and vibrations, but since this will last very shortly before it'll be totally empty this would not be a big problme. (cavitation only is a problem when running it for longer periods of time)

Secondly, once ALL the liquid is gone there's gas entering the casing of the pump. Since a pump cannot transfer gas, the last bit of liquid will slosh around. This will give major vibrations, serious impeller damage (impeller hitting casing) and overheating.
For reusable engines: start ordering a new pump.
The vibrations will most likely hurt you during separation?? Also you'll get some serious hickups in the combustion chambers. Again hurting a clean stage separation?
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 07/01/2013 04:19 pm
It is the same for all of them.  Unloaded turbopumps do not behave very well.  The vehicle doesn't know when this happens and wouldn't take the necessary steps that would normally happen after commanded shutdown (a shutdown from a depletion signal is still a commanded shutdown).   There is little gain, since the amount of propellant is only a few seconds of burn time.

You're reasoning the wrong way round. If there would be no disadvantage of running it dry, that would be a reason not to put low level cut-off switches onto the tank. Any instrumented system can fail, and you don't want to inadvertantly shutdown halfway on your trip uphill.

-

On an earth based pump (I'm process engineer, not a rocket scientist): first it'll start cavitating due to the lower amount of static pressure above the pump. This will lead to impeller damage and vibrations, but since this will last very shortly before it'll be totally empty this would not be a big problme. (cavitation only is a problem when running it for longer periods of time)

Secondly, once ALL the liquid is gone there's gas entering the casing of the pump. Since a pump cannot transfer gas, the last bit of liquid will slosh around. This will give major vibrations, serious impeller damage (impeller hitting casing) and overheating.
For reusable engines: start ordering a new pump.
The vibrations will most likely hurt you during separation?? Also you'll get some serious hickups in the combustion chambers. Again hurting a clean stage separation?

No, that is not what I am saying
a.  The low level sensors have redundancy and are enabled by timers. 
b.  I was stating that launch vehicle need some type of low level sensors regardless of running dry, so that the guidance knows what to do next.

Rocket turbopump is running at 6000 rpm and at 4000hp moving propellant at 5000 gpm.  The turbine is spinning much faster.   The pumps and turbine are going to come apart.

The time from low level to empty is a matter of seconds.  The placement of the sensors is dictated by the amount of time it takes to orderly shutdown the engine plus a small margin. 
Title: Re: SpaceX: Merlin 1D thread
Post by: Roy_H on 07/01/2013 04:32 pm
I am not a rocket engineer either, but I can't imagine a run dry system that wouldn't do damage one way or another. What happens if the oxygen runs out before the kerosene, giving too rich a mixture or the other way around with dwindling fuel and full oxygen running hotter?

How do they guarantee full fuel supply during re-start in a weightless environment where the fuel could be distributed anywhere in the tank, and not necessarily at the pump inlet?
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 07/01/2013 04:44 pm

How do they guarantee full fuel supply during re-start in a weightless environment where the fuel could be distributed anywhere in the tank, and not necessarily at the pump inlet?

There are settling thrusters for that
Title: Re: SpaceX: Merlin 1D thread
Post by: sublimemarsupial on 07/01/2013 04:45 pm

On an earth based pump (I'm process engineer, not a rocket scientist): first it'll start cavitating due to the lower amount of static pressure above the pump. This will lead to impeller damage and vibrations, but since this will last very shortly before it'll be totally empty this would not be a big problme. (cavitation only is a problem when running it for longer periods of time)

Secondly, once ALL the liquid is gone there's gas entering the casing of the pump. Since a pump cannot transfer gas, the last bit of liquid will slosh around. This will give major vibrations, serious impeller damage (impeller hitting casing) and overheating.
For reusable engines: start ordering a new pump.


Jim said it before I could, but a rocket engine turbopump is close to an order of magnitude above any "earth pump" in energy density - any sort of impeller damage or rotordynamic instability caused by running the pump dry will absolutely cause a RUD of the pump, probably taking the rest of the engine with it.

With regards to cavitation, it is a much more serious issue in turbopumps than you seem to realize. The tremendously high rotational speeds necessarily lead to high flow incidence angles on the blade leading edges which almost inevitably lead to pressures below the fluid vapor pressure on the blade suction side, triggering cavitation. It is not simply a small transient issue; cavitation can happened in steady state pump operation. The resulting cavities can decay benignly if the blades and casing are well designed, or if not they can collapse violently causing major low-cycle fatigue issues and leading to extensive impeller damage and a RUD, including LOV and LOM: this very thing happened to the Japanese H-II rocket in 1999, specifically in the LH2 pump. There are also many poorly understood unsteady cavitation modes which see cavities propagating from blade to blade and causing cyclic loading on the rotor shafts asynchronous with the shaft speed which may couple with shaft or other pump structural component natural frequencies. Empirical studies on these "rotating cavitation" modes have found design methods to alleviate them, but their root causes in the fluid dynamic sense have yet to be determined. Bottom line, cavitation is very very hard to deal with in a rocket turbopump.
Title: Re: SpaceX: Merlin 1D thread
Post by: Heinrich on 07/01/2013 04:52 pm
@Marsupial: with "longer epriods of time"I meant more than the couple of seconds (?) between low cut-off level and totally running dry".


No, that is not what I am saying
a.  The low level sensors have redundancy and are enabled by timers. 
b.  I was stating that launch vehicle need some type of low level sensors regardless of running dry, so that the guidance knows what to do next.


Interesting, gives me some extra questions, but I won't bring this Merlin 1D thread further O/T. :-|
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 07/01/2013 04:54 pm
I am not a rocket engineer either, but I can't imagine a run dry system that wouldn't do damage one way or another. What happens if the oxygen runs out before the kerosene, giving too rich a mixture or the other way around with dwindling fuel and full oxygen running hotter?


The issue isn't the thrust chamber, it is last in line for the propellant. 
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 07/01/2013 05:20 pm

How do they guarantee full fuel supply during re-start in a weightless environment where the fuel could be distributed anywhere in the tank, and not necessarily at the pump inlet?

There are settling thrusters for that

Does anyone know what they used to settle the propellants on the flown F9 upper stages? At least one of the missions did a restart, but it did not appear to have Draco thrusters... Was some sort of cold gas thruster (from tank venting) used?
Title: Re: SpaceX: Merlin 1D thread
Post by: edkyle99 on 07/01/2013 05:23 pm
I am not a rocket engineer either, but I can't imagine a run dry system that wouldn't do damage one way or another. What happens if the oxygen runs out before the kerosene, giving too rich a mixture or the other way around with dwindling fuel and full oxygen running hotter?
They use "propellant utilization" systems to solve this problem.  The systems monitor the fuel and oxidizer and slightly meter one (I believe) to guarantee a near simultaneous empty tank condition.  This is done by varying the propellant mixture ratio slightly.  This is a key system for any liquid propellant rocket, and has been since at least Peenemunde, and even Goddard understood that such systems would be required.

 - Ed Kyle
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 07/01/2013 05:31 pm

Does anyone know what they used to settle the propellants on the flown F9 upper stages? At least one of the missions did a restart, but it did not appear to have Draco thrusters... Was some sort of cold gas thruster (from tank venting) used?

GN2 thrusters with dedicated tanks for attitude control and settling
Title: Re: SpaceX: Merlin 1D thread
Post by: mmeijeri on 07/01/2013 08:36 pm
It is the same for all of them.  Unloaded turbopumps do not behave very well.  The vehicle doesn't know when this happens and wouldn't take the necessary steps that would normally happen after commanded shutdown (a shutdown from a depletion signal is still a commanded shutdown).   There is little gain, since the amount of propellant is only a few seconds of burn time.

I can't find it right now, but I remember reading a ULA paper about a test of an RL-10 that was successfully run to depletion and then continued to run on the remaining gaseous propellant at low thrust.
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 07/01/2013 09:04 pm
It is the same for all of them.  Unloaded turbopumps do not behave very well.  The vehicle doesn't know when this happens and wouldn't take the necessary steps that would normally happen after commanded shutdown (a shutdown from a depletion signal is still a commanded shutdown).   There is little gain, since the amount of propellant is only a few seconds of burn time.

I can't find it right now, but I remember reading a ULA paper about a test of an RL-10 that was successfully run to depletion and then continued to run on the remaining gaseous propellant at low thrust.

RL-10 unique because of its expander cycle
Title: Re: SpaceX: Merlin 1D thread
Post by: guckyfan on 07/03/2013 01:18 pm
I saw this on the SpaceX website.

http://www.spacex.com/press.php?page=20130320

Quote
SpaceX's testing program demonstrated a ratio of 4:1 for critical engine life parameters such as firing duration and restart capacity to the engine's expected flight requirements. The industry standard is 2:1.

Could someone explain what that 4:1 refers to? Does it mean the engine is expected to be able to do four flights when reused? That would be a very low value for a reusable engine.

Thanks.

Title: Re: SpaceX: Merlin 1D thread
Post by: MP99 on 07/03/2013 02:06 pm
I saw this on the SpaceX website.

http://www.spacex.com/press.php?page=20130320

Quote
SpaceX's testing program demonstrated a ratio of 4:1 for critical engine life parameters such as firing duration and restart capacity to the engine's expected flight requirements. The industry standard is 2:1.

Could someone explain what that 4:1 refers to? Does it mean the engine is expected to be able to do four flights when reused? That would be a very low value for a reusable engine.

Thanks.

The claim is that "industry standard" is not to use an engine beyond half of the demonstrated lifetime.

If they stick to that standard, then they will exceed 2:1 ratio if they fly an engine more than twice.

cheers, Martin
Title: Re: SpaceX: Merlin 1D thread
Post by: pippin on 07/03/2013 02:25 pm
Or they have to do longer demonstration firings
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 07/03/2013 02:47 pm
Indeed, it probably is designed for more reuse, just not demonstrated.
Title: Re: SpaceX: Merlin 1D thread
Post by: meekGee on 07/03/2013 03:17 pm
I actually think the 1D won't be the engine on a true reusable rocket, except maybe on first few launches.

Two reasons:
1) At least as far as we know, or as far as was demonstrated, its lifetime is far too short.

2) SpaceX will have learned a lot from recovering the first 1Ds - first from the ocean (maybe) and then after the first RTLS flights.  There's absolutely no way that they won't use that data to do another revision cycle.  (unless all the data says "you've done everything perfect and there's nothing to improve on" - which is highly unlikely)

Title: Re: SpaceX: Merlin 1D thread
Post by: ClaytonBirchenough on 07/03/2013 03:32 pm
I actually think the 1D won't be the engine on a true reusable rocket, except maybe on first few launches.

Two reasons:
1) At least as far as we know, or as far as was demonstrated, its lifetime is far too short.

2) SpaceX will have learned a lot from recovering the first 1Ds - first from the ocean (maybe) and then after the first RTLS flights.  There's absolutely no way that they won't use that data to do another revision cycle.  (unless all the data says "you've done everything perfect and there's nothing to improve on" - which is highly unlikely)



Probably minor modifications that reduce coking and improve performance slightly will be made. I can't imagine SpaceX doing another kerolox engine anytime soon...
Title: Re: SpaceX: Merlin 1D thread
Post by: R7 on 07/03/2013 04:35 pm
The claim is that "industry standard" is not to use an engine beyond half of

Which is dubious. Is there even such "standard", it's not as if new American booster engines pop up like mushrooms every other day. What was the latest before Merlin, RS-68? It's used for 259 seconds, max flight was set to 1200 seconds, certification 1800 seconds and longest demonstrated in test was close to 4000 seconds. So PWR Aerojet Rocketdyne could brag demonstrating 15:1 ratio.
Title: Re: SpaceX: Merlin 1D thread
Post by: Swatch on 07/03/2013 05:37 pm
I can vouch that there are specifications out there that specifies a life requirement on space vehicle and engine systems.  When most people/companies refer to a 'industry standard', they are referring to any one of a number of specifications that have been released by NASA, the military, SAE, etc.

That being said, standards can often contradict or superset/subset other standards, but, in the end, companies can push life-cycle testing as long as they'd like, there's no real penalty for 'over-certifying' a piece of engineering. :)
Title: Re: SpaceX: Merlin 1D thread
Post by: Joffan on 07/03/2013 10:56 pm
there's no real penalty for 'over-certifying' a piece of engineering. :)

...except the time, effort and materials penalties of actually doing the excess tests, of course, and less obviously the risk penalty of incurring a late-lifetime failure that dents user confidence unnecessarily.

But - if and when the tests are completed successfully - you are right. Nobody is going to complain about extra tests having been done.
Title: Re: SpaceX: Merlin 1D thread
Post by: baldusi on 07/04/2013 01:07 am
there's no real penalty for 'over-certifying' a piece of engineering. :)

...except the time, effort and materials penalties of actually doing the excess tests, of course, and less obviously the risk penalty of incurring a late-lifetime failure that dents user confidence unnecessarily.

But - if and when the tests are completed successfully - you are right. Nobody is going to complain about extra tests having been done.
Exept your stockholders whom financed the extra work and cost for an over engineered rocket.
Title: Re: SpaceX: Merlin 1D thread
Post by: dcporter on 07/04/2013 01:54 pm
I can vouch that there are specifications out there that specifies a life requirement on space vehicle and engine systems.  When most people/companies refer to a 'industry standard', they are referring to any one of a number of specifications that have been released by NASA, the military, SAE, etc.

That being said, standards can often contradict or superset/subset other standards, but, in the end, companies can push life-cycle testing as long as they'd like, there's no real penalty for 'over-certifying' a piece of engineering. :)

Except, IIRC for occasionally losing an engine on your way to the space station.
Title: Re: SpaceX: Merlin 1D thread
Post by: llanitedave on 07/05/2013 01:50 am
there's no real penalty for 'over-certifying' a piece of engineering. :)

...except the time, effort and materials penalties of actually doing the excess tests, of course, and less obviously the risk penalty of incurring a late-lifetime failure that dents user confidence unnecessarily.

But - if and when the tests are completed successfully - you are right. Nobody is going to complain about extra tests having been done.
Exept your stockholders whom financed the extra work and cost for an over engineered rocket.

Yeah, just like the NASA financial managers who are so upset by the fact the the Mars Exploration Rovers they funded didn't die on time.

Oh, wait...
Title: Re: SpaceX: Merlin 1D thread
Post by: dkovacic on 07/05/2013 09:09 am
I have looked at the recently tweeted photo of the Merlin 1D (see https://twitter.com/SpaceX/status/350350191439794176/photo/1 ), and it appears much simpler in the number of parts and the structure than Merlin 1C or others. I know that the shiny cover can hide a lot of things/complexity, but it seems to me as a striking design difference of Merlin 1D compared to other liquid rocket engines.

Another odd thing is that the external cooling pipe reaches only to the engine throat, and there are no visible lines in the nozzle for the coolant. Is it possible that the engine bell uses some kind of ablative cooling and the regenerative cooling is used only for the chamber and the throat?

And the third principle of design - Merlin 1D is "human sized", which obviously makes manual assembly and servicing much simpler than in bigger engines like SSME or F-1. It seems to me that most of the engine parts (except the bell, turbopump and the chamber) are light enough to be picked up and assembled by one or two persons. Is this by chance/luck or real design principle?

Does this setup of 1D include the turbopump in the shown assembly?


Here are few examples to illustrate the difference:

Merlin 1C which already looks "cleaner" design than other engines:
http://d3j5vwomefv46c.cloudfront.net/photos/large/569286128.jpg?1335655945 http://www.kcet.org/socal/departures/landofsunshine/assets/images/Tom%20Mueller%20Arrival%20Story%20Merlin%20engines.jpg

J-2: http://www.google.hr/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=O8mlyTPCtvoaOM&tbnid=AqZ5sFIY9GXcaM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.daviddarling.info%2Fencyclopedia%2FJ%2FJ-2.html&ei=nYXWUcP8EpHIsgaX8YGYDQ&bvm=bv.48705608,d.bGE&psig=AFQjCNGJpRIHJicycWogaXLLjiH0RbUC4Q&ust=1373099443769598

F-1: http://www.americaspace.com/wp-content/uploads/2013/01/718980main_IMG_7022_cropped_946-710-500x322.jpg

RS-68: http://upload.wikimedia.org/wikipedia/commons/thumb/4/4d/RS-68_rocket_engine_test.jpg/300px-RS-68_rocket_engine_test.jpg

AJ-26: https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTmWlPBqxnOh9VlMgXFQOv3AGBEoIpGoX0xpLOGG4lZa3b0_WkT


Title: Re: SpaceX: Merlin 1D thread
Post by: smoliarm on 07/05/2013 09:16 am
I have looked at the recently tweeted photo of the Merlin 1D (see https://twitter.com/SpaceX/status/350350191439794176/photo/1 ), and it appears much simpler in the number of parts and the structure than Merlin 1C or others. ...
...


That's because these particular engines are incomplete. They do not have GG installed yet, check earlier posts in this thread.
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 07/05/2013 12:02 pm
Another odd thing is that the external cooling pipe reaches only to the engine throat, and there are no visible lines in the nozzle for the coolant. Is it possible that the engine bell uses some kind of ablative cooling and the regenerative cooling is used only for the chamber and the throat?


It uses channel wall cooling and not tubes, lines would not be visible.
Title: Re: SpaceX: Merlin 1D thread
Post by: AnjaZoe on 07/05/2013 02:45 pm
The claim is that "industry standard" is not to use an engine beyond half of

Which is dubious. Is there even such "standard", it's not as if new American booster engines pop up like mushrooms every other day. What was the latest before Merlin, RS-68? It's used for 259 seconds, max flight was set to 1200 seconds, certification 1800 seconds and longest demonstrated in test was close to 4000 seconds. So PWR Aerojet Rocketdyne could brag demonstrating 15:1 ratio.

Not to mention the SSME ;-)

Compare the total firing time of the engines during the qualification between Merlin 1D (1970 seconds) to RS-68 (18000 seconds) and the Vulcain 1 (90000 seconds).

If the engines would really be tested so much more than "industry standard", why do they have shown a reliability so far of not more than 96%? (correct me if I'm wrong, 2 failures out of 50)

Zoe
Title: Re: SpaceX: Merlin 1D thread
Post by: PreferToLurk on 07/05/2013 03:40 pm
The claim is that "industry standard" is not to use an engine beyond half of

Which is dubious. Is there even such "standard", it's not as if new American booster engines pop up like mushrooms every other day. What was the latest before Merlin, RS-68? It's used for 259 seconds, max flight was set to 1200 seconds, certification 1800 seconds and longest demonstrated in test was close to 4000 seconds. So PWR Aerojet Rocketdyne could brag demonstrating 15:1 ratio.

Not to mention the SSME ;-)

Compare the total firing time of the engines during the qualification between Merlin 1D (1970 seconds) to RS-68 (18000 seconds) and the Vulcain 1 (90000 seconds).

If the engines would really be tested so much more than "industry standard", why do they have shown a reliability so far of not more than 96%? (correct me if I'm wrong, 2 failures out of 50)

Zoe

I believe the ratio of 4:1 is about design strength vs expected maximum flight loads, not qualification time vs flight time?  Besides, the 4:1 is for 1D which is supposed to be more robust than the 1C which is the one that flight failed.

All the test firing in the world can't protect against a manufacture/materials flaw. (Although other types of testing can, which they are now doing) That's one failure.  Whats the other?  Corroded nut?  That wasn't a 1C.  The oxidizer rich shutdown?  I'm blanking on the second one.   

The 1C also flew on 3 Falcon 1 flights (first stage only) giving it a reliability rate of 98.1% (53 flight firings, 1 failure).
Title: Re: SpaceX: Merlin 1D thread
Post by: blazotron on 07/05/2013 05:54 pm
The claim is that "industry standard" is not to use an engine beyond half of

Which is dubious. Is there even such "standard", it's not as if new American booster engines pop up like mushrooms every other day. What was the latest before Merlin, RS-68? It's used for 259 seconds, max flight was set to 1200 seconds, certification 1800 seconds and longest demonstrated in test was close to 4000 seconds. So PWR Aerojet Rocketdyne could brag demonstrating 15:1 ratio.

Not to mention the SSME ;-)

Compare the total firing time of the engines during the qualification between Merlin 1D (1970 seconds) to RS-68 (18000 seconds) and the Vulcain 1 (90000 seconds).

If the engines would really be tested so much more than "industry standard", why do they have shown a reliability so far of not more than 96%? (correct me if I'm wrong, 2 failures out of 50)

Zoe

Can you provide references for these numbers for RS-69 and Vulcain?  These must be cumulative engine time probably on many engines through development, certification, and possibly flight engine acceptance.  The number for Merlin 1D is just the qualification testing, presumably on a single engine and isn't really a valid comparison. Also, their claim of 4:1 presumably also encompasses all of the fairly extensive acceptance testing they do on a typical engine in addition to the actual burn time in flight, since they said they actually performed more than 10 mission durations of runtime equivalent in the qualification.
Title: Re: SpaceX: Merlin 1D thread
Post by: R7 on 07/05/2013 08:46 pm
Can you provide references for these numbers for RS-69 and Vulcain?

Here's for RS-68: http://www.lpre.de/resources/articles/PropulsionForThe21stCentury-RS-68.pdf

Title: Re: SpaceX: Merlin 1D thread
Post by: Davinator on 07/06/2013 11:05 am
Stay on topic please!
Title: Re: SpaceX: Merlin 1D thread
Post by: Nomadd on 07/06/2013 01:37 pm

If the engines would really be tested so much more than "industry standard", why do they have shown a reliability so far of not more than 96%? (correct me if I'm wrong, 2 failures out of 50)

Zoe
I count 1 out of 50 for five F9 missions. Unless you count the F1s, and the first failed one wasn't an M1C.
Title: Re: SpaceX: Merlin 1D thread
Post by: AnjaZoe on 07/08/2013 08:23 am
The claim is that "industry standard" is not to use an engine beyond half of

Which is dubious. Is there even such "standard", it's not as if new American booster engines pop up like mushrooms every other day. What was the latest before Merlin, RS-68? It's used for 259 seconds, max flight was set to 1200 seconds, certification 1800 seconds and longest demonstrated in test was close to 4000 seconds. So PWR Aerojet Rocketdyne could brag demonstrating 15:1 ratio.

Not to mention the SSME ;-)

Compare the total firing time of the engines during the qualification between Merlin 1D (1970 seconds) to RS-68 (18000 seconds) and the Vulcain 1 (90000 seconds).

If the engines would really be tested so much more than "industry standard", why do they have shown a reliability so far of not more than 96%? (correct me if I'm wrong, 2 failures out of 50)

Zoe

Can you provide references for these numbers for RS-69 and Vulcain?  These must be cumulative engine time probably on many engines through development, certification, and possibly flight engine acceptance.  The number for Merlin 1D is just the qualification testing, presumably on a single engine and isn't really a valid comparison. Also, their claim of 4:1 presumably also encompasses all of the fairly extensive acceptance testing they do on a typical engine in addition to the actual burn time in flight, since they said they actually performed more than 10 mission durations of runtime equivalent in the qualification.

Iirc those numbers are from the various ESA publications over the time. Quite interesting to see how the testing progressed. You will probably find other references on the web as well, probably the german space site of Bernd Leitenberger will have some information as well.

Zoe
Title: Re: SpaceX: Merlin 1D thread
Post by: Robotbeat on 07/08/2013 06:34 pm

If the engines would really be tested so much more than "industry standard", why do they have shown a reliability so far of not more than 96%? (correct me if I'm wrong, 2 failures out of 50)

Zoe
I count 1 out of 50 for five F9 missions. Unless you count the F1s, and the first failed one wasn't an M1C.
Indeed, the one other "failure" was on shutdown, which would have made recovery (probably) impossible but didn't otherwise affect the mission. So, 1 failure out of 53, or 1 out of 48 since the upper stage is a significantly different engine. About 98%.

BTW, where's that one thread where we did some modeling of failure rates vs number of engines vs engine-out capability?
Title: Re: SpaceX: Merlin 1D thread
Post by: AnjaZoe on 07/09/2013 05:37 am
Oh yes, I forgot, Space-X doesn't have failures, they have "anomalies". ;-)

Zoe
Title: Re: SpaceX: Merlin 1D thread
Post by: beancounter on 07/09/2013 06:58 am
Oh yes, I forgot, Space-X doesn't have failures, they have "anomalies". ;-)

Zoe
Well there's been a whole thread around what was a failure and what wasn't.  My view only is that a failure is a LOM such as the recent Proton launch, whereas an anomoly doesn't result in LOM rather in SpaceX case, reduced capability  :)
Title: Re: SpaceX: Merlin 1D thread
Post by: kalif3000 on 07/09/2013 07:48 am
Quote
...probably the german space site of Bernd Leitenberger will have some information as well.

Zoe

I have read his articles, too. No doubt, his site is THE source for details on engines, rockets, probes and many other aspects of spaceflight in German. But it felt like he has a personal issue with SpaceX and constantly tries to "prove" how bad SpaceX really is. He often does that using doubious examples and i.e. tries to say 'How dare SpaceX say that is possible while 60 years of spaceflight show its not!'
His articles simply don't seem as objective as his articles about the products from the traditional spaceflight industry.

I remember that he mocked how SpaceX just shortened the nozzle of the Falcon 9 second stage and how 'real' rocket companies would take that serously, ground the rocket and perform endless tests instead of just launching it when deemed save. He fails to see how this approach is a much needed break from the endlessly bureaucratic way of doing spaceflight and he fails to aknowledge that it workes well.

So, unless he gives a clear source I would advice against takeing his word for it.

Quote
Can you provide references for these numbers for RS-69 and Vulcain?  These must be cumulative engine time probably on many engines through development, certification, and possibly flight engine acceptance.  The number for Merlin 1D is just the qualification testing, presumably on a single engine and isn't really a valid comparison. Also, their claim of 4:1 presumably also encompasses all of the fairly extensive acceptance testing they do on a typical engine in addition to the actual burn time in flight, since they said they actually performed more than 10 mission durations of runtime equivalent in the qualification.

I suspect the same. I couldn't find any sources other than his site. 90000 seconds sounds like a lot just for certification testing.
Title: Re: SpaceX: Merlin 1D thread
Post by: AnjaZoe on 07/09/2013 07:54 am
Oh yes, I forgot, Space-X doesn't have failures, they have "anomalies". ;-)

Zoe
Well there's been a whole thread around what was a failure and what wasn't.  My view only is that a failure is a LOM such as the recent Proton launch, whereas an anomoly doesn't result in LOM rather in SpaceX case, reduced capability  :)

Does LOM also account for second(ary) payloads? :)

Zoe
Title: Re: SpaceX: Merlin 1D thread
Post by: AnjaZoe on 07/09/2013 07:58 am
Quote
...probably the german space site of Bernd Leitenberger will have some information as well.

Zoe

I have read his articles, too. No doubt, his site is THE source for details on engines, rockets, probes and many other aspects of spaceflight in German. But it felt like he has a personal issue with SpaceX and constantly tries to "prove" how bad SpaceX really is. He often does that using doubious examples and i.e. tries to say 'How dare SpaceX say that is possible while 60 years of spaceflight show its not!'
His articles simply don't seem as objective as his articles about the products from the traditional spaceflight industry.

I remember that he mocked how SpaceX just shortened the nozzle of the Falcon 9 second stage and how 'real' rocket companies would take that serously, ground the rocket and perform endless tests instead of jus launching it when deemed save. He fails to see how this approach is a much needed break from the endlessly bureaucratic way of doing spaceflight and he fails to aknowledge that it workes well.

So, unless he gives a clear source I would advice against takeing his word for it.

Of course his site is biased, as is just about every site you will find on the internet. Probably one could call the ESA publications biased as well... On the other hand, his sources are usually well founded.

Assuming some of the folks here are engineers, it shouldn't be too hard to read various sources and then estimate the average; in other words, the truth usually lies between all claims of the extreme sides.

Zoe
Title: Re: SpaceX: Merlin 1D thread
Post by: R7 on 07/09/2013 09:17 am
vulcain tests:

http://arc.aiaa.org/doi/abs/10.2514/6.1999-2616  (behind pay wall)

http://www.flightglobal.com/FlightPDFArchive/1992/1992%20-%200198.PDF
Title: Re: SpaceX: Merlin 1D thread
Post by: Lars_J on 07/09/2013 03:48 pm
Oh yes, I forgot, Space-X doesn't have failures, they have "anomalies". ;-)

Zoe
Well there's been a whole thread around what was a failure and what wasn't.  My view only is that a failure is a LOM such as the recent Proton launch, whereas an anomoly doesn't result in LOM rather in SpaceX case, reduced capability  :)

Does LOM also account for second(ary) payloads? :)

Zoe

If you happen to live in a binary or black/white world, then potentially. Read up on some past threads regarding the CRS-1 mission - this has been discussed to death.
Title: Re: SpaceX: Merlin 1D thread
Post by: Port on 07/09/2013 04:18 pm
Quote
...probably the german space site of Bernd Leitenberger will have some information as well.

Zoe

I have read his articles, too. No doubt, his site is THE source for details on engines, rockets, probes and many other aspects of spaceflight in German. But it felt like he has a personal issue with SpaceX and constantly tries to "prove" how bad SpaceX really is. He often does that using doubious examples and i.e. tries to say 'How dare SpaceX say that is possible while 60 years of spaceflight show its not!'
His articles simply don't seem as objective as his articles about the products from the traditional spaceflight industry.

I remember that he mocked how SpaceX just shortened the nozzle of the Falcon 9 second stage and how 'real' rocket companies would take that serously, ground the rocket and perform endless tests instead of jus launching it when deemed save. He fails to see how this approach is a much needed break from the endlessly bureaucratic way of doing spaceflight and he fails to aknowledge that it workes well.

So, unless he gives a clear source I would advice against takeing his word for it.

Of course his site is biased, as is just about every site you will find on the internet. Probably one could call the ESA publications biased as well... On the other hand, his sources are usually well founded.

Assuming some of the folks here are engineers, it shouldn't be too hard to read various sources and then estimate the average; in other words, the truth usually lies between all claims of the extreme sides.

Zoe

I just spend some awful lot of time sifting through his site.
Once in a while I could not help myself but smile of how hardcore-biased he lays out certain facts (or decides not to mention some).

Funny enough most of the ESA and NASA-related stuff was well written and researched and way more neutral than I could have managed to write up.
I think it's a little bit sad regarding the otherwise near perfect (you know how we Germans are ;)) neutral sum up of space related news/facts for German readers :/

If you read his section about the M1A-D you should get the general sense of where the problem was, at least the facts laid out there are correct - while the interpretation should be taken with a grain of salt.
The final assessment of the rout cause can be read up somewhere here
http://forum.nasaspaceflight.com/index.php?topic=29130.1560

for whatever reason he missed to mention it :)
Title: Re: SpaceX: Merlin 1D thread
Post by: llanitedave on 07/09/2013 06:49 pm

Assuming some of the folks here are engineers, it shouldn't be too hard to read various sources and then estimate the average; in other words, the truth usually lies between all claims of the extreme sides.

Zoe

Not really.  There is no law of average truth, and extreme claims don't cancel each other out.  Finding the truth takes independent and rigorous investigation, regardless of competing claims.  You can form conclusions by whichever method you see fit, but you shouldn't label them "truth".
Title: Re: SpaceX: Merlin 1D thread
Post by: mlindner on 07/10/2013 07:29 am

Assuming some of the folks here are engineers, it shouldn't be too hard to read various sources and then estimate the average; in other words, the truth usually lies between all claims of the extreme sides.

Zoe

Not really.  There is no law of average truth, and extreme claims don't cancel each other out.  Finding the truth takes independent and rigorous investigation, regardless of competing claims.  You can form conclusions by whichever method you see fit, but you shouldn't label them "truth".

Indeed. If you develop a good engineering bullsh*t meter it is relatively easy to throw out what people say when it conflicts with other information, even if its on the internet. Just be sure the standards you are measuring it against are good. Otherwise its bullsh*t in, bullsh*t out.
Title: Re: SpaceX: Merlin 1D thread
Post by: AnjaZoe on 07/10/2013 08:07 am

Assuming some of the folks here are engineers, it shouldn't be too hard to read various sources and then estimate the average; in other words, the truth usually lies between all claims of the extreme sides.

Zoe

 You can form conclusions by whichever method you see fit, but you shouldn't label them "truth".

That's not what I said.

Zoe
Title: Re: SpaceX: Merlin 1D thread
Post by: justineet on 07/20/2013 09:11 pm
I have looked at the recently tweeted photo of the Merlin 1D (see https://twitter.com/SpaceX/status/350350191439794176/photo/1 ), and it appears much simpler in the number of parts and the structure than Merlin 1C or others. ...
...


That's because these particular engines are incomplete. They do not have GG installed yet, check earlier posts in this thread.


This seems like an incomplete engine....I don't see the turbo-pump and the exhaust manifold which will  be fixed on top with certain parts sitting along the side of the engine.....
Title: Re: SpaceX: Merlin 1D thread
Post by: fatjohn1408 on 07/25/2013 03:10 pm
Is there already a vacuum version of this engine that will be used on the upper stage or will the upper stages still use the 1C vacuum.

If there is one how do they compare?
Title: Re: SpaceX: Merlin 1D thread
Post by: Jim on 07/25/2013 03:16 pm
It is a D version
Title: Re: SpaceX: Merlin 1D thread
Post by: Davidthefat on 07/28/2013 09:25 pm
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR

The reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.
Title: Re: SpaceX: Merlin 1D thread
Post by: Hauerg on 07/28/2013 10:03 pm
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR
...

IIRC IT has been posted or linked.
Title: Re: SpaceX: Merlin 1D thread
Post by: Maciej Olesinski on 07/28/2013 11:04 pm
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR
...

IIRC IT has been posted or linked.

I haven't seen it yet. Thanks
Title: Re: SpaceX: Merlin 1D thread
Post by: justineet on 07/29/2013 02:26 am
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR

The reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.

The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..
Title: Re: SpaceX: Merlin 1D thread
Post by: Davidthefat on 07/29/2013 02:34 am
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR

The reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.

The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..

The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.


edit: unless they shortened it dramatically.

Well, I'll be... It does seem they have shortened it significantly from the last revision.
Title: Re: SpaceX: Merlin 1D thread
Post by: justineet on 07/29/2013 02:48 am
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR

The reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.

The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..

The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.


edit: unless they shortened it dramatically.

Well, I'll be... It does seem they have shortened it significantly from the last revision.

Yes I think it's both the turbopump and exhaust manifold assembly ur looking at. It looks like significantly shorter and wider than the 1c exhaust pipe.
Title: Re: SpaceX: Merlin 1D thread
Post by: justineet on 07/29/2013 10:06 pm
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR

The reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.

The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..

The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.


edit: unless they shortened it dramatically.

Well, I'll be... It does seem they have shortened it significantly from the last revision.


Can compare it with the 1C in the picture below...quite shorter..overall I think more compact and smaller..

http://www.popularmechanics.com/cm/popularmechanics/images/WZ/spacex-factory-06-0112-lgn-87860333.jpg
Title: Re: SpaceX: Merlin 1D thread
Post by: Davidthefat on 07/29/2013 11:50 pm
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR

The reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.

The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..

The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.


edit: unless they shortened it dramatically.

Well, I'll be... It does seem they have shortened it significantly from the last revision.


Can compare it with the 1C in the picture below...quite shorter..overall I think more compact and smaller..

http://www.popularmechanics.com/cm/popularmechanics/images/WZ/spacex-factory-06-0112-lgn-87860333.jpg

This picture shows the M1Ds ready for static testing, with its shorter exhaust. http://i.imgur.com/lj9zTrL.jpg (http://i.imgur.com/lj9zTrL.jpg)
Title: Re: SpaceX: Merlin 1D thread
Post by: justineet on 07/30/2013 01:05 am
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR

The reason why the fuel line is bent in is to allow for more space when the engine is gimballed. AFAIK, this is pretty much the completed engines ready to be mounted on the octagon shaped structure in the back; I think only the fuel and oxidizer lines and wires have to be installed to interface with the main fuel tanks. The turbopump assembly seems to be missing the exhaust pipe and the hydraulic actuators.

The first one on the foreground is the most complete...u can see the exhaust manifold/pipe to the side of the combustion chamber..

The pipe that extends from that is missing. What you are seeing is the turbopump assembly; yes, the exhaust manifold that's downstream from the turbine is there, but not the actual pipe. The actual pipe converges slightly to form a nozzle at the tip.


edit: unless they shortened it dramatically.

Well, I'll be... It does seem they have shortened it significantly from the last revision.


Can compare it with the 1C in the picture below...quite shorter..overall I think more compact and smaller..

http://www.popularmechanics.com/cm/popularmechanics/images/WZ/spacex-factory-06-0112-lgn-87860333.jpg

This picture shows the M1Ds ready for static testing, with its shorter exhaust. http://i.imgur.com/lj9zTrL.jpg (http://i.imgur.com/lj9zTrL.jpg)

Yes there are some significant changes in terms of form. The combustion chamber seems also to be different from the 1C. The 1C has a funnel shape while the 1D looks like a small barrel...kinda of a small beer keg..
Title: Re: SpaceX: Merlin 1D thread
Post by: GalacticIntruder on 07/30/2013 09:16 pm
Is the M1D Vac really 801kN? That is a big boost, more than I was expecting anyway. No ISP mentioned though.

Or, is it marketing hype?
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 07/30/2013 09:28 pm
Same chamber and mass flow rate as the sea-level Merlin 1D and a nozzle optimized for vacuum. Higher Isp and higher thrust are directly related here.
Title: Re: SpaceX: Merlin 1D thread
Post by: sublimemarsupial on 07/30/2013 09:31 pm
From the new spaceX website "SpaceX's Merlin vacuum engine has the highest vaccum specific impulse (isp)--a measure of engine efficiency--of any American liquid oxygen/kerosene engine with a vaccum isp of 340 seconds"
Title: Re: SpaceX: Merlin 1D thread
Post by: PreferToLurk on 07/30/2013 09:54 pm
From the new spaceX website "SpaceX's Merlin vacuum engine has the highest vaccum specific impulse (isp)--a measure of engine efficiency--of any American liquid oxygen/kerosene engine with a vaccum isp of 340 seconds"

Interesting, wikipedia, sourcing a spacex press release, claims the M1c Vac had an ISP of 342 seconds. But of course the link is now dead with the site redesign...

So did the old engine really out-ISP the new engine?  It obviously delivers a lot more thrust, but it seems odd that they would trade ISP away for the second stage engine.
Title: Re: SpaceX: Merlin 1D thread
Post by: pippin on 07/30/2013 09:57 pm
It might use a shorter nozzle, they had to redesign that, didn't they?
Or the 342s was the original wishful-thinking figure
Title: Re: SpaceX: Merlin 1D thread
Post by: ugordan on 07/30/2013 10:06 pm
Interesting, wikipedia, sourcing a spacex press release, claims the M1c Vac had an ISP of 342 seconds.

COTS-C1 press kit said M1c-Vac had 336 s Isp, IIRC.
Title: Re: SpaceX: Merlin 1D thread
Post by: Arthree on 07/31/2013 04:43 am
801 kN with the same mass flow rate as M1D would imply ~346s, which I believe was the number floating around previously.

(801 kN/716 kN)*311 s = 348 s
(801 kN/654 kN)*282 s = 345 s
Title: Re: SpaceX: Merlin 1D thread
Post by: malu5531 on 08/21/2013 07:29 pm
(801 kN/716 kN)*311 s = 348 s
(801 kN/654 kN)*282 s = 345 s

I believe the vac thrust of Merlin 1D is ~741 kN, from spacex.com; 1500000 lbf / 9 ~ 166.5 klbf ~ 741 kN.

Instead of 311s for Vac ISP for Merlin 1D (non Vac), we use 320;
Merlin 1D Vac ISP: 1500000/1323000 * 282 = 319.73 (total Vac/SL thrust, from spacex.com)

This would also make the calculation match better;
(801 kN/741 kN)*319.73 s = 345.6 s
(801 kN/654 kN)*282 s = 345.4 s

Difference probably due to rounding.
Title: Re: SpaceX: Merlin 1D thread
Post by: Arthree on 08/22/2013 03:00 am
(801 kN/716 kN)*311 s = 348 s
(801 kN/654 kN)*282 s = 345 s

I believe the vac thrust of Merlin 1D is ~741 kN, from spacex.com; 1500000 lbf / 9 ~ 166.5 klbf ~ 741 kN.

Instead of 311s for Vac ISP for Merlin 1D (non Vac), we use 320;
Merlin 1D Vac ISP: 1500000/1323000 * 282 = 319.73 (total Vac/SL thrust, from spacex.com)

This would also make the calculation match better;
(801 kN/741 kN)*319.73 s = 345.6 s
(801 kN/654 kN)*282 s = 345.4 s

Difference probably due to rounding.

There are varying figures for the performance of M1D.  Before the page was updated, it listed the vacuum Isp as 311s and thrust as 161000 lbs (720kN).  The Falcon Heavy M1D page on spacex.com (http://www.spacex.com/news/2013/04/12/falcon-heavy-merlin-engines) lists it now as having 309s and 161000 lbs (716kN), and the F9 version (http://www.spacex.com/news/2013/03/26/merlin-engines) confirms it (without a mention of Isp).

320s seems exceptionally high, far above what it was predicted to have (310s) when it was designed, and the SL Isp doesn't seem to have changed.  I would guess that the numbers posted on the F9/FH pages (1,500,000 lbs/6672 kN per core) are either rounding errors or wishful thinking on SpaceX's part.

Or they somehow managed 9 more seconds of vacuum Isp without affecting SL performance.
Title: Re: SpaceX: Merlin 1D thread
Post by: IRobot on 08/22/2013 07:21 am
Doesn't it depend on the stage? AFAIK, the 2nd stage Merlin 1D is optimized for vacuum, with larger nozzle.
Title: Re: SpaceX: Merlin 1D thread
Post by: aga on 08/22/2013 08:46 am
the 2nd stage merlin is optimized for vacuum and its isp = 340 s
source: http://www.spacex.com/falcon9 - you can see the info, when you click the "inside the interstage" blue text
Title: Re: SpaceX: Merlin 1D thread
Post by: malu5531 on 08/22/2013 09:25 am
I would guess that the numbers posted on the F9/FH pages (1,500,000 lbs/6672 kN per core) are either rounding errors or wishful thinking on SpaceX's part.

Or they somehow managed 9 more seconds of vacuum Isp without affecting SL performance.

OR the mass flow rate is not the same; another explanation could be that they run the engines at lower throttle near SL, and then throttle up in vacuum (after MaxQ). However, I can't see why you would throttle down early during launch - during MaxQ, yes, but the initial flight?

I agree with the rounding; 282/311 Isp & 1323 klbf SL thrust, means Vac thrust is 1459 klbf, which would not be totally unreasonable to round to 1500 klbf for marketing purposes. However, then we would have an inconsistency with the 801 kN Merlin 1DVac thrust (assuming equal mass flow - full throttle).

Doesn't it depend on the stage? AFAIK, the 2nd stage Merlin 1D is optimized for vacuum, with larger nozzle.

If thrust is increased from 147 klbf (Merlin 1D SL) to 180 klbf (Merlin 1DVac), by means of less ambient atmosphere, nozzle extension, etc, while keeping the same fuel and fuel-flow; the Isp ratio will be the same as thrust ratio, in this case 180/147 = 1.224, which means Isp for Merlin 1DVac would be 345.3.

the 2nd stage merlin is optimized for vacuum and its isp = 340 s
source: http://www.spacex.com/falcon9 - you can see the info, when you click the "inside the interstage" blue text

There is inconsistencies in the information, yes. If we assume the 340s number is correct (which some say would be lower than the Merlin 1C, hence unreliable), the 1DVac thrust should be 177 klbf, which in itself is not unreasonable to round to 180 klbf.

(personally, I don't believe in the "wishful thinking" hypothesis)
Title: Re: SpaceX: Merlin 1D thread
Post by: Arthree on 08/22/2013 03:53 pm
Quote
If we assume the 340s number is correct (which some say would be lower than the Merlin 1C, hence unreliable), the 1DVac thrust should be 177 klbf, which in itself is not unreasonable to round to 180 klbf.

Good point -- 177000 lbs is more in line with Elon's "80 tons" statement, and 340s might be reasonable if the vacuum nozzle is actually shortened to fit into a smaller interstage.
Title: Re: SpaceX: Merlin 1D thread
Post by: Chris Bergin on 10/02/2013 03:25 pm
Thread 2:
http://forum.nasaspaceflight.com/index.php?topic=32983.0