Engine | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) |
SL Thrust | 140klbf | ? | ? |
Vac Thrust | 155klbf | ?(better than expected) | ?(expect even better) |
SL isp | 280s | ? | ? |
Vac isp | 310s | 309s? | ? |
T/W | 160 | ? | ? |
Chamber Pressure | 1420psi | ? | ? |
Expansion | 16 | 16? | 16?(this shouldn’t vary much from design) |
Throttle range | 70-100% | 70%-100%? | 70%-100%? |
Engine weight | 440kg? | ? | ? |
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).
Engine | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) |
SL Thrust | 140klbf | ? | ? |
Vac Thrust | 155klbf | ?(better than expected) | ?(expect even better) |
SL isp | 280s | ? | ? |
Vac isp | 310s | 309s? | ? |
T/W | 160 | ? | ? |
Chamber Pressure | 1410psi | ? | ? |
Expansion | 16 | 16? | 16?(this shouldn’t vary much from design) |
Throttle range | 70-100% | 70%-100%? | 70%-100%? |
Engine weight | 440kg? | ? | ? |
Engine | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) |
SL Thrust | 140klbf | ? | ? |
Vac Thrust | 155klbf | ?(better than expected) | ?(expect even better) |
SL isp | 280s? | ? | ? |
Vac isp | 310s | 309s? | ? |
T/W | 160 | ? | ? |
Chamber Pressure | 1410psi | ? | ? |
Expansion | 16 | 16? | 16?(this shouldn’t vary much from design) |
Throttle range | 70-100% | 70%-100%? | 70%-100%? |
Engine weight | 440kg? | ? | ? |
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?
My guesstimate is that your way off on the weight of the Merlin. It should be closer to 1700-2000 pounds IMHO.
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.
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.
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.
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.”
This in an avleak article:Hm... that article leans towards the position that the new engine is LH2.
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=defenseQuoteRevealing 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.”
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.
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?
Gwynne said SpaceX will make 100 engines total in 2011.Maybe they're just ramping up for their ambitious Launch Manifest?
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?
Gwynne said SpaceX will make 100 engines total in 2011.Maybe they're just ramping up for their ambitious Launch Manifest?
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?
That seems like the most likely to me.Gwynne said SpaceX will make 100 engines total in 2011.Maybe they're just ramping up for their ambitious Launch Manifest?
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 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.
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.
“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.
“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.
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).
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.
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.
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?
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:QuoteDevelopment 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?
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.
QuoteDevelopment 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?
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 ;)
QuoteDevelopment 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 VAB?
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.
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:QuoteDevelopment 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.
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.
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.
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.
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.
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...
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.
Engine | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) | Merlin 1D VAC |
SL Thrust | 140klbf | ? | ? | - |
Vac Thrust | 155klbf | ?(better than expected) | ?(expect even better) | (155klbf)? |
SL isp | 280s? | ? | ? | - |
Vac isp | 310s | 309s? | ? | 348s( an educated WAG)? |
T/W | 160 | ? | ? | ? |
Chamber Pressure | 1410psi | ? | ? | ? |
Expansion | 16 | 16? | 16?(this shouldn’t vary much from design) | ? |
Throttle range | 70-100% | 70%-100%? | 70%-100%? | 70%-100%? |
Engine weight | 440kg? | ? | ? | >M1D production |
Costs | <M1C? | - | ? | <M1CVAC? |
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?
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.
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)
Thanks great pic!
@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?
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.
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.
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.
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):-QuoteWeighing 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.
"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
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):-QuoteWeighing 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.
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.
Which doesn't solve unless B= negative 6,000 lbs, etc.
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
From this article (http://spacenews.com/profiles/110425-elon-musk.html):I don't think that's what he meant by "sandbagging."QuoteWhat 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.
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.
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.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.
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?
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.
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.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.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.
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%.Interesting.
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.
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.
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
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.
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.
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?
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?
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?
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.
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.
Would M1D performance enable e.g. a Falcon-7 configuration?M1C+: 125 klbf SL * 9 = 1.125 mlbf
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.
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?
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.
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.
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.
10 F9 launches + 10 FH launches = 380 engines.I think I unintentionally started something here. :(
400 = a small surplus that can be sandbagged for future use?
10 F9 launches + 10 FH launches = 380 engines.I think I unintentionally started something here. :(
400 = a small surplus that can be sandbagged for future use?
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.
got to watch a Merlin run...
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.
Looks like a upper stage MVac run... Assuming that is an integrated stage and not a generic tank.
Merlin 1D?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?
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.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.
Merlin 1D?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?
No reason to believe that. I know of at least several M1c's being acceptance-tested there. Perhaps the majority of them all.
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.
So any info on how often 1st stage test firings been occuring in the last 6 months?
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.QuoteSo 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.
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.
Agreed, worst case scenario they have the hold before release capability.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.
Agreed, worst case scenario they have the hold before release capability.
Just as everyone else.
So watch for announcements of M1DVAC testing starting.
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.Agreed, worst case scenario they have the hold before release capability.Just as everyone else.
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.
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.Agreed, worst case scenario they have the hold before release capability.Just as everyone else.
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...
Anything that uses solids doesn't have that. The shuttle obviously didn't have that. A lot of liquids don't have it too.
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.
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?
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?
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
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.
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?
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.
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.
Engine | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) |
SL Thrust | 140klbf | ? | ? |
Vac Thrust | 155klbf | ?(better than expected) | ?(expect even better) |
SL isp | 280s? | ? | ? |
Vac isp | 310s | 309s? | ? |
T/W | 160 | ? | ? |
Chamber Pressure | 1410psi | ? | ? |
Expansion | 16 | 16? | 16?(this shouldn’t vary much from design) |
Throttle range | 70-100% | 70%-100%? | 70%-100%? |
Engine weight | 440kg? | ? | ? |
Costs | <M1C? | - | ? |
Engine | Merlin 1DVAC (Design) | Merlin 1DVAC (Test article) | Merlin 1DVAC (Production) |
Vac Thrust | 174klbf? | ? | ? |
Vac isp | 348s?(an educated WAG) | ? | ? |
T/W | 160? | ? | ? |
Chamber Pressure | 1410psi? | ? | ? |
Expansion | ? | ? | ? |
Throttle range | 70-100%? | ? | ? |
Engine weight | >440kg? | ? | ? |
Costs | <M1CVAC? | - | ? |
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).Great matrix, very helpful.
Summary of what we know so far:
I removed the M1D VAC column and put it into its own table:
Engine Merlin 1D (Design) Merlin 1D (Test article) Merlin 1D (Production) SL Thrust 140klbf ? ? Vac Thrust 155klbf ?(better than expected) ?(expect even better) SL isp 280s? ? ? Vac isp 310s 309s? ? T/W 160 ? ? Chamber Pressure 1410psi ? ? Expansion 16 16? 16?(this shouldn’t vary much from design) Throttle range 70-100% 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.
Engine Merlin 1DVAC (Design) Merlin 1DVAC (Test article) Merlin 1DVAC (Production) Vac Thrust 174klbf? ? ? Vac isp 348s?(an educated WAG) ? ? T/W 160? ? ? Chamber Pressure 1410psi? ? ? Expansion ? ? ? Throttle range 70-100%? ? ? Engine weight >440kg? ? ? Costs <M1CVAC? - ?
To get the higher thrust etc. How much larger will the 5 inch feed lines have to go ya think?
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.
Engine | Merlin 1C (Flight) | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) |
SL Thrust | 95klbf (ref1) | 140klbf | ? | ? |
Vac Thrust | 108.5klbf (ref1) | 155klbf | ?(better than expected) | ?(expect even better) |
SL isp | 266s (ref1) | 280s? | ? | ? |
Vac isp | 304s (ref1) | 310s | 309s? | ? |
T/W | 92 (ref1) | 160 | ? | ? |
Chamber Pressure | 1000psi? | 1410psi | ? | ? |
Expansion | ? | 16 | 16? | 16?(this shouldn’t vary much from design) |
Throttle range | 100% only | 70-100% | 70%-100%? | 70%-100%? |
Engine weight | 469kg? (calculated) | 440kg? | ? | ? |
Costs | >$1M? | <M1C? | - | ? |
Engine | Merlin 1CVAC (flight) | Merlin 1DVAC (Design) | Merlin 1DVAC (Test article) | Merlin 1DVAC (Production) |
Vac Thrust | 92.5klbf (ref1) | 174klbf? | ? | ? |
Vac isp | 336s (ref1) | 348s?(an educated WAG) | ? | ? |
T/W | <92? | 160? | ? | ? |
Chamber Pressure | 1000psi? | 1410psi? | ? | ? |
Expansion | ? | ? | ? | ? |
Throttle range | 70-100%? | 70-100%? | ? | ? |
Engine weight | >469kg? | >440kg? | ? | ? |
Costs | >$1M? | <M1CVAC? | - | ? |
2.1.1 Grasshopper RLVSource (http://www.faa.gov/about/office_org/headquarters_offices/ast/media/20110922%20SpaceX%20Grasshopper%20Draft%20EA.Final.pdf)
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.
Quote2.1.1 Grasshopper RLVSource (http://www.faa.gov/about/office_org/headquarters_offices/ast/media/20110922%20SpaceX%20Grasshopper%20Draft%20EA.Final.pdf)
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.
What happened? This is less then Merlin-1C+ maximum thrust.
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?
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.
First pic from McGregor test.-Spacex Facebook
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?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.
It looks a lot more like the Merlin 1A than the 1C, anyone know where you can find a nice 1A test stand picture?
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?
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?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.
It looks a lot more like the Merlin 1A than the 1C, anyone know where you can find a nice 1A test stand picture?
BTW, NEW test stand.
That glowing piping is also a dead give away.
The piping isn't glowing - it looks like reflected light from the flames below.
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?
That glowing piping is also a dead give away.
What do you make of it? I don't know a lot about these engines...
First pic from McGregor test.-Spacex Facebook
Heh, looks like a museum of modern art!
The piping isn't glowing - it looks like reflected light from the flames below.
still think its glowing,
Ha, so it does! See you at the Guggenheim.First pic from McGregor test.-Spacex FacebookHeh, looks like a museum of modern art!
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.
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.
They would need a different stand for M1DVAC engines if tested with the extension.
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.
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.
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.
I think they mentioned they were switching from electro deposition to explosive forming.
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(?).
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.
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.
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.
..."
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.
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:
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?
How much of that wiring harness is likely to be test instrumentation, and how much will stay on the production engine?
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
A close-up/gamma-adjusted pic showing the pump & exhaust.
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:
low bandwidth people.lol.
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.
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.
There will be a vacuum version of the 1D for the Falcon Heavy second stage.(My highlight)
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)):-QuoteThere 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)Presumably the core stage will burn out not just higher but a lot faster than would be the case of a Falcon 9.
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.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)
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%.
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.
A bit of image processing for a side-by-side....
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.
Are we certain that his talking of alternative fuels doesn't also include alternative non-cryo oxidizers?
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.
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.
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)
You are kidding, right? About the Excel? If not, I really need to raise the game on my Excel trajectory simulation efforts!What are you using for these simulations?
--N
I wrote it using excel and a lot of math. ;)
I agree. I removed my posts that did not contribute to the M1D conversation.
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
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
I thought that was going to be ~160 ish sea level?They had previously said it was going to be ~140ish sea level.
I thought that was going to be ~160 ish sea level?They had previously said it was going to be ~140ish sea level.
Engine | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) |
SL Thrust | 140klbf | ? | 147klbf |
Vac Thrust | 155klbf | ?(better than expected) | 161klbf |
SL isp | 280s? | ? | 282s |
Vac isp | 310s | 309s? | 311s |
T/W | 160 | ? | ? |
Chamber Pressure | 1410psi | ? | ? |
Expansion | 16 | 16? | 16?(this shouldn’t vary much from design) |
Throttle range | 70-100% | 70%-100%? | 70%-100%? |
Engine weight | 440kg? | ? | ? |
Costs | <M1C? | - | ? |
Engine | Merlin 1DVAC (Design) | Merlin 1DVAC (Test article) | Merlin 1DVAC (Production) |
Vac Thrust | 174klbf? | ? | ? |
Vac isp | 348s?(an educated WAG) | ? | ? |
T/W | 160? | ? | ? |
Chamber Pressure | 1410psi? | ? | ? |
Expansion | ? | ? | 117 |
Throttle range | 70-100%? | ? | ? |
Engine weight | >440kg? | ? | ? |
Costs | <M1CVAC? | - | ? |
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.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.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
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.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.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
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)
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.
Just wondering if the new turbo-pump for the M-1D would be the same for the M-1D Vac?
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):-QuoteThe 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
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.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
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)
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.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
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"
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.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.
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?
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 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.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.
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?
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.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.
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.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.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.
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.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.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.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.
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.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.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.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.
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?
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.
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.
http://forum.nasaspaceflight.com/index.php?topic=27748.msg914446#msg914446That'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.
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
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.http://forum.nasaspaceflight.com/index.php?topic=27748.msg914446#msg914446That'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.
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
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.
OK, so where would the control force come from to maintain that pitch, and how would it avoid being broken up?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.
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?
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.
That image is different from the SpaceX FB page, so it is new.
Yes its from the opposite side.
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.
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.
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.
Did we get close to a weight for the 1D?
Why turbine exhaust tube is so long? It's a dead weight...
Why turbine exhaust tube is so long? It's a dead weight...
See first two Atlas launches
Why turbine exhaust tube is so long? It's a dead weight...
See first two Atlas launches
Thank you for the explanation :)See first two Atlas launches
To expand on that, for those who are curious,...
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)
That is *certainly* a Merlin 1C.
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
Not to throw of the discussion, but to me, the Merlin "fineness" ratio seems higher than lets say an H-1...
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
SpaceX Testing: Merlin 1D Engine Firing
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.
I'm trying to imagine 27 of these starting up and firing together.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):
- Ed Kyle
I'm trying to imagine 27 of these starting up and firing together.
- Ed Kyle
This was part of a press releaseOkay, so absolutely no chance of 4 launches this year (which was already essentially known). We might see hardware at VAFB, though...
Vacuum T/W ratio of over 150, flight #6 in 2013 so VAFB will see no launches this year (as expected).
Seeing that single engine firing makes me miss Falcon 1.
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"
Seeing that single engine firing makes me miss Falcon 1.
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.
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.
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.
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.
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
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.
That first link is protected.
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.
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.
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.
This was part of a press release
Vacuum T/W ratio of over 150...
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
Why is the bell smooth? It's still regen cooled, but I don't see the circumferential rings...what are they doing there?
I thought I read corrugated somewhere, but I may just be imagining things.
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.
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.
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.
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.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.
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.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.
This of course will directly contradict any claim for reusability.
Less tests is cheaper, but what I was saying is that shorter tests - not so much.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.
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.
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.
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.
:P So what you are saying is... next steps: staged combustion, multichamber and 12x more thrust?
: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?
If you think so... ::)
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.
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.
The real question is why do you want a staged combustion engine?
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.: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?
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:
Engine Merlin 1D (Design) Merlin 1D (Test article) Merlin 1D (Production) SL Thrust 140klbf ? ? Vac Thrust 155klbf ?(better than expected) ?(expect even better) SL isp 280s ? ? Vac isp 310s 309s? ? T/W 160 ? ? Chamber Pressure 1420psi ? ? Expansion 16 16? 16?(this shouldn’t vary much from design) Throttle range 70-100% 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
How about you simply wait until F9 V 1.1 begins acceptance testing?
How about you simply wait until F9 V 1.1 begins acceptance testing?
we sure the 9 engines havn't been tested as yet?
Ultimately, though, the whole issue is if you can make a business case.
Engine | Merlin 1D (Design) | Merlin 1D (Test article) | Merlin 1D (Production) |
SL Thrust | 140klbf | ? | 147klbf |
Vac Thrust | 155klbf | ?(better than expected) | 161klbf |
SL isp | 280s? | ? | 282s |
Vac isp | 310s | 309s? | 311s |
T/W | 160 | ? | 150+ |
Chamber Pressure | 1410psi | ? | 1410psi? |
Expansion | 16 | 16? | 16?(this shouldn’t vary much from design) |
Throttle range | 70-100% | 70%-100%? | 70%-100% |
Engine weight | 440kg? | ? | 485kg? |
Costs | <M1C? | - | <M1C |
Engine | Merlin 1DVAC (Design) | Merlin 1DVAC (Test article) | Merlin 1DVAC (Production) |
Vac Thrust | 174klbf? | ? | ? |
Vac isp | 348s?(an educated WAG) | ? | ? |
T/W | 160? | ? | ? |
Chamber Pressure | 1410psi? | ? | ? |
Expansion | ? | ? | >117?(this was the MVAC value) |
Throttle range | 70-100%? | ? | ? |
Engine weight | >440kg? | ? | ? |
Costs | <M1CVAC? | - | ? |
That's for the new numbers Atlas.
Where did you get the extra 45kg weight for M1D production from?
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/
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.
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?
Merlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams
https://twitter.com/elonmusk/status/217973460348047360Quote from: Elon MuskMerlin fired at full thrust! Engine weighs half a ton, but has power equal to several Hoover Dams
https://twitter.com/elonmusk/status/217973460348047360Quote from: Elon MuskMerlin 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.
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.
https://twitter.com/elonmusk/status/217973460348047360Quote from: Elon MuskMerlin 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
https://twitter.com/elonmusk/status/217973460348047360Quote from: Elon MuskMerlin 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.
Things to keep in mind: Would a staged combustion engine weigh more or less than a gas generator engine?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.
Merlin 1D (GG) now has the highest (vacuum) T/W ratio of any engine, even higher than the NK-33.
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.
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.
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
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?
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.
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.
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.
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.
(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.
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,....
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.
Not an update on the engine, but starting my next CAD project.Great!
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.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.
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.
OK, that helps. Now, do we know what the RP-1/LOX ratio is?
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.
Not sure if anyone noticed but this can be viewed in 3dI keep a pair of 3D glasses on my desk just for pix like that. Thanks for the heads up.
I just noticed something interesting near the bottom of the second page in this article on smallsats: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).
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.
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.
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.
First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon Musk @elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ
Copied from the "general" thread:-From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust: 161,000 lbfFirst picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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
Copied from the "general" thread:-From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust: 161,000 lbfFirst picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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
Engine | Merlin 1DVAC (Design) | Merlin 1DVAC (Test article) | Merlin 1DVAC (Production) |
Vac Thrust | 174klbf? | 176klbf? | ? |
Vac isp | 348s?(an educated WAG) | ? | ? |
T/W | 160? | ? | ? |
Chamber Pressure | 1410psi? | ? | ? |
Expansion | ? | ? | >117?(this was the MVAC value) |
Throttle range | 70-100%? | ? | ? |
Engine weight | >440kg? | ? | ? |
Costs | <M1CVAC? | - | ? |
Old Atlas, know I shouldn't be thinking this but....I am not OldAtlas_Eguy, but here is my estimated data.
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.
Copied from the "general" thread:-From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust: 161,000 lbfFirst picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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
Think that's for the regular version of the Merlin 1-D.
Copied from the "general" thread:-From SpaceX website Merlin Engine(presumably M-1D) Vacuum Thrust: 161,000 lbfFirst picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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
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?
Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon Musk @elonmusk
Now test firing our most advanced engine, the Merlin 1D-Vac, at 80 tons of thrust. pic.twitter.com/HGK1joVQ
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.Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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.
Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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.
Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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.
I could be wrong, been know to happen from time to time.Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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
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.
...the lower regen part of the nozzle was tube-wall design...
I could be wrong, been know to happen from time to time.
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.
It seems that both Merlin C and D Vac are solely channel wall.
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.
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...
Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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?
+1Except 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.
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=2Don'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.
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.
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.
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.
@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.
Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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.
Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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.
Copied from the "general" thread:-First picture of the Merlin 1D-Vac:
https://twitter.com/elonmusk/status/252528724602400768QuoteElon 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
Modemeagle saw it correctly, the flex is under the GG-turbo pump assembly, in the right place for the exaust.
Difficult crunch numbers, without hard design numbers for the engine.
Is there any way to guess the Isp & thrust benefits on the kerolox M1D?
cheers, Martin
(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
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.(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.
Has anyone heard the number of starts that can be done by the Vacuum version of the Merlin 1D?
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.
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.
Merlin 1C can supposedly last for about 10 flight durations.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
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.
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.
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.
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.
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?
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:
Thermal conditioning, too!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.
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.
Tank pressurants ... stage battery life
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.
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.
Thermal conditioning, too!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.
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.
We had heard a number of two or three for the M1C-Vac.Thanks. So there is a number of charges on the engine and each restart consumes one.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.
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.
New image posted on SpaceX' FB an hour ago:
What would methane look like?Likely. Notice all those ice particles flying off near the top of the engine...
Still the greenness (TEB?) of the frame makes me think it's a startup pic...
Still the greenness (TEB?) of the frame makes me think it's a startup pic...
Thanks for the new picture.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.
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? :)
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)
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.
Perhaps they'll just use thrusters.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?
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 certainly looks less complicated (on the outside at least) than the M1C.
It certainly looks less complicated (on the outside at least) than the M1C.
Well, of course, they're still building it.
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.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.
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.
Does the turbopump exhaust really go into the engine bell? That left picture looks like it.
M1DVac does? Ho do they do roll control then?
M1DVac does? Ho do they do roll control then?Not yet known, but may be with cold gas thrusters.
@R7 Do we _know_ that?
Sorry if I'm missing something, but where is the evidence that MDvac turbopump exhaust isn't used for roll control?One page back:
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
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.
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 Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.
that is a long wait?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?
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?
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.
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.
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.
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.)Grasshopper uses cold gas, but it seems unlikely in the extreme the first stage will, at least on the way up.
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.
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.
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)
https://twitter.com/SpaceX/status/314410250574897152QuoteSpaceX @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)
When you grab twitter images instead of having :large on the suffix, change to :orig to get the original resolution, often larger.
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.
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.
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.
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.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.
This might be a stupid question, but I'd like to know why the two engines in the picture look different from eachother?https://twitter.com/SpaceX/status/314410250574897152QuoteSpaceX @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.
28 testsIt 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!
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
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.
Bigger version of the image: https://pbs.twimg.com/media/BF0CdQPCIAAL0_y.jpg:origOn 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?
Video:
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....
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?
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.
I don't understand, how is 75 seconds "full duration"?
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.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?
Video:
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.
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.)
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.
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.
Did anyone else notice the engine gimbal at ~17 seconds.
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.
The post says "to avoid gravity losses..."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.
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.
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.
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...
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.
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?
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?
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.
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.
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.
Better performance margin if you fly to depletion for the first stage... Otherwise, you're leaving some margin behind when you stage.
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?
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?"
At the very least we know they have a computer per stage in F9 v1.1.
At the very least we know they have a computer per stage in F9 v1.1.
We know this from where?
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.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.
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.
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.
So we had a trade-off: SpaceX wants to experiment with reentry, customers want a stable configuration.
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.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.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.
Has a Merlin 1D ever failed (exploded) in testing?"If engines are not exploding, you are not testing hard enough" ?
If one did would SpaceX disclose 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 existF1 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.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.
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.
"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.
Regarding a hypothetical Merlin 1E, maybe someone remembers - were there any rumors about it before it was revealed? If yes, how long before?
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.
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.
It was Gwynne Shotwell. She was directly asked about it, and the answer was that there will be no 1E.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.)
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.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.
(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.
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.(My highlight)
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.”
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:-
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:-
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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.
btw - is it even a given that when you throttle down, the ISP remains constant?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.
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.
Yes but is Isp equal to fuel consumption?btw - is it even a given that when you throttle down, the ISP remains constant?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.
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.
Yes but is Isp equal to fuel consumption?
Maybe the Isp drops but the engines use less fuel due to lower thrust.
Technically, you used more propellent mass units per unit of thrust. You obviously use less propellant overall since you are throttling.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.
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.
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.That sounds reasonable to me.
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.
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?
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.
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?
How reusable was the FASTRAC pump?
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
The turbopump had no ablative material inside.
The turbopump was deemed highly reusable hardware.
By the way, far heavier than merlin TP.
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=defenseClipped 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:-
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But M1D has an underexpanded nozzle at altitude; isn't possible that throttling makes the nozzle less underexpanded (gaining some ISP).
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.
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.
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.
It was probably relatively easy to convert Merlin 1D into Merlin 1D VAC though, right?
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?
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.
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.Ok thanks for that. More to think about.
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.
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.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.
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?
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
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.
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.
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.
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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?
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?
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.
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.
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?
There are settling thrusters for that
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.
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?
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.
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.
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.
I saw this on the SpaceX website.
http://www.spacex.com/press.php?page=20130320QuoteSpaceX'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.
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)
The claim is that "industry standard" is not to use an engine beyond half of
there's no real penalty for 'over-certifying' a piece of engineering. :)
Exept your stockholders whom financed the extra work and cost for an over engineered rocket.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.
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. :)
Exept your stockholders whom financed the extra work and cost for an over engineered rocket.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.
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. ...
...
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?
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. SoPWRAerojet Rocketdyne could brag demonstrating 15:1 ratio.
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. SoPWRAerojet 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
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. SoPWRAerojet 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?
I count 1 out of 50 for five F9 missions. Unless you count the F1s, and the first failed one wasn't an M1C.
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
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. SoPWRAerojet 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.
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%.I count 1 out of 50 for five F9 missions. Unless you count the F1s, and the first failed one wasn't an M1C.
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
Oh yes, I forgot, Space-X doesn't have failures, they have "anomalies". ;-)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 :)
Zoe
...probably the german space site of Bernd Leitenberger will have some information as well.
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.
Oh yes, I forgot, Space-X doesn't have failures, they have "anomalies". ;-)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 :)
Zoe
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.
Oh yes, I forgot, Space-X doesn't have failures, they have "anomalies". ;-)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 :)
Zoe
Does LOM also account for second(ary) payloads? :)
Zoe
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
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
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".
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".
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.
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR
...
I'm surprised that this picture has not been posted here; http://imgur.com/XvAI5rR
...
IIRC IT has been posted or linked.
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.
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..
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.
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.
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
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)
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.
(801 kN/716 kN)*311 s = 348 s
(801 kN/654 kN)*282 s = 345 s
(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.
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.
Doesn't it depend on the stage? AFAIK, the 2nd stage Merlin 1D is optimized for vacuum, with larger nozzle.
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
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.