SpaceX Merlin 1C Engine

[canoe76]

Has anyone heard how Qualification of the engine is going.  In the last company update, Aug. 17, it sounded like they were close to starting Qual.

[jiggawo]

SpaceX decides what qualification is, so it will be ready whenever they want it to be ready.

[braddock]

canoe76 - 19/10/2007  1:02 PM

Has anyone heard how Qualification of the engine is going.  In the last company update, Aug. 17, it sounded like they were close to starting Qual.

The latest information is from our own Q&A with Elon on Sept 24th:
http://www.nasaspaceflight.com/content/?cid=5237

Q: Is the next Falcon 1 Launch still on track for mid-January?

This schedule is dependent on completing qualification of the Merlin 1C engine, so it is impossible to predict with precision what the launch date will be.  All we can do is state that the first countdown will probably be in the Jan/Feb timeframe, unless the Merlin 1C qualification takes longer than expected.

Reports from the local Texas paper Waco Tribune Herald last week stated that SpaceX had done over 1,800 test stand firings over the past several years.  I sure hope that has given them enough opportunities to work the kinks out!

http://www.wacotrib.com/news/content/news/stories/2007/10/14/10142007wacrockets.html

[canoe76]

jiggawo - 21/10/2007  4:16 PM

SpaceX decides what qualification is, so it will be ready whenever they want it to be ready.

Nice contribution.

[TrueGrit]

SpaceX decides qualification until they want a real government contract and Aerospace shows up with a quiver full of arrows

[MKremer]

TrueGrit - 24/10/2007  12:58 AM

SpaceX decides qualification until they want a real government contract and Aerospace shows up with a quiver full of arrows

So you're implying they don't really have any actual income-producing contracts for any of their LVs, yet?

[canoe76]

MKremer - 24/10/2007  1:01 AM

TrueGrit - 24/10/2007  12:58 AM

SpaceX decides qualification until they want a real government contract and Aerospace shows up with a quiver full of arrows

So you're implying they don't really have any actual income-producing contracts for any of their LVs, yet?

wow, I was just asking if anyone knew how Qual Testing was going.

[kkattula]

Apparently they've received 90 odd million of the COTS funding already. And one would think the customers booking future flights have to put some money down.

[TrueGrit]

What I'm saying is that SpaceX isn't the final arbritor if the engine is certified, qualified is a whole other thing, for use in launching a satelitte or a NASA cargo.  In the end the costumer decides on if it meets the particular military/NASA standards.  If SpaceX tries to shortcut the process the Aerospace/NASA review teams will recommend not launching.  They've done it plenty of times in the past...  Both EELVs worked with Aerospace in certifing their systems and yet to this day Aerospace recommendations have resulted in additional special engine testing to keep flying.  And anyone who's launched a payload for the Air Force or NASA knows that you can be easily outnumber 10:1 in a pre-flight petegree review by the government reviewers.  DARPA is a completely different animal...  Little science projects don't have nearly the same risk adverse attitude to a multi billion dollar military payload.

[Danderman]

kkattula - 24/10/2007  6:55 AM  Apparently they've received 90 odd million of the COTS funding already. And one would think the customers booking future flights have to put some money down.

At this point, it appears that SpaceX is using the COTS money to fund Falcon 9, with some small part of the cash flows being used to fund paperwork on their Dragon. I could be wrong, but I don't see any evidence that Dragon is in the kind of workflow that would lead to early flight.

 If I were in charge, I certainly wouldn't spend the big bucks on Dragon until I were pretty sure that Falcon I and 9 were going to fly.

 

[Nate_Trost]

They better be working on Dragon, according to schedule (regardless of how based it is in reality), 13 months from now they need to be able to mount one on top of a Falcon 9.

[Danderman]

Nate_Trost - 29/10/2007  8:03 AM  They better be working on Dragon, according to schedule (regardless of how based it is in reality), 13 months from now they need to be able to mount one on top of a Falcon 9.

I understand the schedule, but I have seen no evidence that, 13 months from now, Dragon will be in orbit. This could be ignorance on my part, however.

 

 

[Frediiiie]

There is an image on the SpaceX web site of the Merlin 1c being fired.
http://www.spacex.com/photo_gallery.php
But personally I think they are being very quiet very deliberately.
The last thing they would want to do is spook ULA into taking SpaceX seriously and actually starting work on a competative system.
When they return to flight in the new year it will be with effectively a 3rd generation engine (1c),
And a craft that flew with only minor problems (read the DARPA report on the Falcon 1's second flight)
At the moment everyone is saying SpaceX can not be taken seriously as they haven't had a successful flight yet.
By this time next year SpaceX is likely to have 2 Falcon 1 launches under it's belt, and a Falcon 9 on the pad ready to go.
Suddenly the rocket business is serilously competative.

[Jim]

Frediiiie - 6/11/2007  7:23 PM

1.The last thing they would want to do is spook ULA into taking SpaceX seriously and actually starting work on a competative system.

........
2.  By this time next year SpaceX is likely to have 2 Falcon 1 launches under it's belt, and
3.  a Falcon 9 on the pad ready to go.
Suddenly the rocket business is serilously competative.

1.  ULA does not develop spacecraft

2.  Or another failure

3.  No chance of this happening in 2008

[Jim]

Nate_Trost - 29/10/2007  11:03 AM

They better be working on Dragon, according to schedule (regardless of how based it is in reality), 13 months from now they need to be able to mount one on top of a Falcon 9.

There won't be a F9 to mount it on yet.  Also the first flight has no Dragon on it

[Nate_Trost]

They are being quiet because everybody is too busy trying to meet extremely aggressive schedules. ULA? Even if SpaceX somehow gets Falcon 9 into service by 2010, they won't be in a position to start trying to steal ULA government business before the middle of next decade at the earliest, COTS notwithstanding. It seems unlikely at this point that we'll ever see an Atlas V Heavy, much less ULA developing a completely new LV. Orbital's proposed Taurus is probably more of a 'threat', but you're not going to see ULA roll their own Delta II replacement.

SpaceX probably has a window of opportunity with COTS and Bigalow. If they miss it, one really has to wonder if they'd be able to win a high enough flight rate on F9 to make it viable.

[Comga]

Jim - 6/11/2007  5:48 PM

Nate_Trost - 29/10/2007  11:03 AM
They better be working on Dragon, according to schedule (regardless of how based it is in reality), 13 months from now they need to be able to mount one on top of a Falcon 9.

There won't be a F9 to mount it on yet.  Also the first flight has no Dragon on it

From the SpaceX website Dragon page;
In fulfillment of the COTS phase I contract, Dragon will perform three cargo demonstration missions:
                                               
Demo  1
Date Q3 2008
Duration 5 hours
Objectives Launch and separate from Falcon 9, orbit Earth, transmit telemetry, receive commands, demonstrate orbital maneuvering and thermal control, re-enter atmosphere, and recover Dragon capsule

It goes on from there to Demos 2 and 3, both of which involve Dragons.
Regardless of how long it will really take, they have announced flights of Dragon commencing in less than 14 months.

[Nate_Trost]

Jim,

I was talking about Q4 08, not this winter. I know the first F9 test flight is sans Dragon. But the first COTS flight with a Dragon is scheduled in the same quarter. Yes, I know they aren't going to be ready in Q4 '08, much less Q1 '09, but that's still the schedule.

My point was countering the assertion that Dragon wasn't really being funded or in development except on paper at this point. Unless the schedule is really beyond a paper fantasy, there's no way they could be ostensibly not be working all-out on Dragon if they are supposed to stack it a little over a year from now.

Comga,

That's out of date, to the best of my knowledge the first Falcon 9 demo flight (originally supposed to be for the "US Government") comes before COTS Flight 1, but both are still publicly scheduled for Q4 '08.

[Jim]

I wasn't talking about this year
There won't be an F9 on the pad, much less launched in 2008

[CFE]

Does anybody have any idea of what the Isp will be for the Merlin IC?  I'd expect an increase of perhaps 10 sec for the vacuum Isp over the ablative Merlin I.  I don't think the Isp will be better than about 315 sec or so.

[Comga]

Nate_Trost - 6/11/2007  6:04 PM
Comga,
That's out of date, to the best of my knowledge the first Falcon 9 demo flight (originally supposed to be for the "US Government") comes before COTS Flight 1, but both are still publicly scheduled for Q4 '08.

You could be right.  I confused "Falcon 9 Demo Flight 1" with the "NASA COTS Demo 1", which are both listed (despite the near physical impossibility of a first and second launch in one calendar quarter.)

Our point remains, though.  SpaceX has a Dragon flight on their manifest for less than 14 months from now.  

After the first Falcon 1 failure, we didn't hear much for over a half year until mid January when they showed the second Falcon 1 on Omelek.  It would be within this past experience to not show the Falcon 1 or Dragon hardware until close to rollout.  Whether it is within their capabilities is another issue.

[Frediiiie]

1. ULA does not develop spacecraft
Sorry, said ULA to cut down a long post rather than spell out a lot of names.
Agree on another failure
But SpaceX have 3 F9's scheduled for 2008. There might be some slipage, but given the high degree of comonality between F1 & F9 this is less likely. Same engines, same flight software (except triple redundant)
They might surprise us//

[Frediiiie]

The point I'm making is that SpaceX is not just launching a rocket or two to show off
They're gearing up to be a major launch supplier
They are getting set to churn out 25 + merlin engines a year.
6 Kestrals a year & a suitable number of rocket bodies F1 & F9s
They think they can easily get their launch numbers up to 1 a month if required.
The question is is there a market for this many launches?
Elon seems to think there is.
They already have 12 bookings. 5 F1s & 7 F9s in the next 3 years.
And this is without a single successful flight
Can they do it?
Elon's got the money.
He's got the people.
Looking at the DARPA report on F1s second flight I think he's pretty well got F1 nailed
That puts them a long way towards getting F9 as well.

[kevin-rf]

There will be able to build to one launch a month if they can fly falcon 9 without failures for less than Ariane/Orbital/ILS/China/India are charging for everything including spacecraft integration.

Notice Is said "IF" ... I wish them luck.

[Analyst]

My launch schedule shows two Saturn V in 2008. Schedules are just paper. They don't even have their launch infrastructure ready. Come on guys, lets be realistic. We can dream when we sleep.

Analyst

[Jim]

Frediiiie - 7/11/2007  3:51 AM

But SpaceX have 3 F9's scheduled for 2008.

Not even one is going to make it to pad in 2008

[8900]

Jim - 7/11/2007  9:01 PM

Frediiiie - 7/11/2007  3:51 AM

But SpaceX have 3 F9's scheduled for 2008.

Not even one is going to make it to pad in 2008

Then SpaceX is going to face the same fate as RpK?
NASA will eventually  terminate their COTS funding like they do to RpK?
as the fate of RpK indicates, NASA will not tolerate missing/slipping milestones

[Analyst]

8900 - 7/11/2007  4:28 PM

as the fate of RpK indicates, NASA will not tolerate missing/slipping milestones

This is the way it should be. I find it strange some new space companies (not only SpaceX) are very critically about the government space program (NASA, government sponsored EELVs etc.) but at the very same time complain about not getting enough money from this very government (via NASA).

Analyst

[Comga]

Analyst - 7/11/2007  9:52 AM

8900 - 7/11/2007  4:28 PM
Then SpaceX is going to face the same fate as RpK?
NASA will eventually terminate their COTS funding like they do to RpK? as the fate of RpK indicates, NASA will not tolerate missing/slipping milestones

This is the way it should be. I find it strange some new space companies (not only SpaceX) are very critically about the government space program (NASA, government sponsored EELVs etc.) but at the very same time complain about not getting enough money from this very government (via NASA).
Analyst

Agreed that NASA should not tolerate significant schedule slips.  They appeared to be more than patient with RpK.

However, SpaceX is quite unlike RpK.  SpaceX has Musk's money and connections to start with.   Musk started without COTS.  He would likely go on without COTS.  RpK and its predecessors have always been scrounging.
SpaceX built its own hardware.  RpK contracted.   SpaceX is trying to get to space, and then see what they can make reuseable.  RpK made things reusable, in theory, and afterwards would try to get to space.  Night and day, with the exception that they are both long shots at best.

[mr.columbus]

Comga - 8/11/2007  1:56 AM

Analyst - 7/11/2007  9:52 AM

8900 - 7/11/2007  4:28 PM
Then SpaceX is going to face the same fate as RpK?
NASA will eventually terminate their COTS funding like they do to RpK? as the fate of RpK indicates, NASA will not tolerate missing/slipping milestones

This is the way it should be. I find it strange some new space companies (not only SpaceX) are very critically about the government space program (NASA, government sponsored EELVs etc.) but at the very same time complain about not getting enough money from this very government (via NASA).
Analyst

Agreed that NASA should not tolerate significant schedule slips.  They appeared to be more than patient with RpK.

However, SpaceX is quite unlike RpK.  SpaceX has Musk's money and connections to start with.   Musk started without COTS.  He would likely go on without COTS.  RpK and its predecessors have always been scrounging.
SpaceX built its own hardware.  RpK contracted.   SpaceX is trying to get to space, and then see what they can make reuseable.  RpK made things reusable, in theory, and afterwards would try to get to space.  Night and day, with the exception that they are both long shots at best.

That does not change the fact that if there is a further serious slip to demo flight 1, NASA should terminate the SpaceX Space Act Agreement. The problem is of course, in that case NASA would admit that its initial choice of companies for the 500 million seed money was totally flawed.

[Analyst]

mr.columbus - 8/11/2007  8:08 AM

The problem is of course, in that case NASA would admit that its initial choice of companies for the 500 million seed money was totally flawed.

Maybe because there is no easy, cheap and at the same time reliable way into orbit - unmanned and even more manned? Every NASA choice for seed money would be flawed, some space cadets don't want to accept this. Ares and Orion may be overpriced, but look at Ariane V development or EELVs. 250 million is nothing for the tasks required: You buy one GEO comsat at best (excluding launch) for this, based on a proven platform.

Analyst

[hyper_snyper]

Development is done on Merlin 1C

http://home.businesswire.com/portal/site/google/index.jsp?ndmViewId=news_view&newsId=20071112005019&newsLang=en

[Crispy]

Great hi-res photo of a test in that article.
Actually, spacex has the same shot, but not at this resolution.

Figures from the article:

Thrust (sea level) 95,000 lbs
Thrust (vacuum) 108,000 pounds
SI (vacuum) 304 seconds
350 lbs/second of propellant

A planned turbopump upgrade in 2009 will improve the thrust by over 20% and the thrust to weight ratio by approximately 25%

Planned production rate of 50 engines in 2008!

[G-pit]

Wow, the article says they ran nearly one engine firing per working day in August.

Also they are gearing up to "Produce more rocket engines than the rest of US production combined" in 2008.

Even if they do half that, go SpaceX! Keep up the good work.

[CFE]

Crispy - 12/11/2007  3:16 PM

Great hi-res photo of a test in that article.
Actually, spacex has the same shot, but not at this resolution.

Figures from the article:

Thrust (sea level) 95,000 lbs
Thrust (vacuum) 108,000 pounds
SI (vacuum) 304 seconds
350 lbs/second of propellant

A planned turbopump upgrade in 2009 will improve the thrust by over 20% and the thrust to weight ratio by approximately 25%

Planned production rate of 50 engines in 2008!

Merlin IC Isp is only 304 seconds?  I thought that the regen nozzle would have improved Isp over the 304 sec figure quoted for the original Merlin I.  I suspect that Merlin I never met the 304 sec goal, hence the need to develop Merlin IC.  304 sec sounds reasonable for Merlin IC, based on the numbers for the F-1.

[Comga]

Crispy - 12/11/2007  3:16 PM
A planned turbopump upgrade in 2009 will improve the thrust by over 20% and the thrust to weight ratio by approximately 25%

Merlin-1D?  Musk seems intent on maintaining the software/computer business model of continuous improvement and version release.  Third version of the engine "complete" and a fourth planned.  First version of the single engine rocket almost complete, and the second version announced.  Second (or third?) version, albeit the first release, of the multi-engine rocket announced.  It will be fascinating to see if and how he/they achieve design completion with so much evolution going on.

This is definitely not the way it has been done.

[Damon Hill]

Tweaking of a design early in a program is not uncommon; Saturn V was modified and upgraded during its (brief) lifetime, both to fix problems and improve performance.  Once a program reaches some maturity, significant changes stop unless there's a need and development money for it.  I'm not surprised to see the changes going on at SpaceX because they're still in early development and on
the steep part of the learning curve.

It does look like a Merlin 1D is in planning; what's the Merlin 2 going to be like?

[JIS]

It's a good idea to keep those development people around. It's quite likely that there will be failures in the future and it will be quite easy to move people from development to redesign.
Falcon 1 has been redesigned several times and Falcon 9, Dragon or Falcon 9 heavy will be the same.
They might want to develop LOX/LHX engine for GEO/beyond as well.

[Crispy]

When you're building so many engines, I suppose you still get economies of scale even when you're upgrading the design every 2-3 years.

[pippin]

G-pit - 13/11/2007  2:12 AM

Also they are gearing up to "Produce more rocket engines than the rest of US production combined" in 2008.

Lemme guess: They need about the "rest of US production combined" number of engines to make one F9, right?

EDIT: OKOKOK, maybe two...

[wannamoonbase]

Crispy - 13/11/2007  7:49 AM

When you're building so many engines, I suppose you still get economies of scale even when you're upgrading the design every 2-3 years.

True, but also need to take into account that they are probably into the early part of a learning curve and as time moves on they may get to a more stable Merlin 1 design and they can tweak here and there instead of major changes and full redesigns.  

I hope the high volume, lower cost and performance model works out, it could be a paradigm shift for the US launch industry.

At some point SpaceX needs to start flying far more often and get some flight data and paying customers.  Whether successfully or not it looks like 08 is giong to be a put up or shut up year for SpaceX.  One launch in 2008 isn't going to be enough.

Best of luck SpaceX.

[William Barton]

pippin - 13/11/2007  8:48 AM

G-pit - 13/11/2007  2:12 AM

Also they are gearing up to "Produce more rocket engines than the rest of US production combined" in 2008.

Lemme guess: They need about the "rest of US production combined" number of engines to make one F9, right?

EDIT: OKOKOK, maybe two...

How many engines are produced in the US each year, given that the Atlas V 1st stage engines are imported? The 50 cited in the article would be enough for ten Falcon 9s, 25 Falcon 1s, or, come to think of it, one Falcon 9 Heavy with 22 assorted engines left over...

[pippin]

William Barton - 13/11/2007  2:59 PM

pippin - 13/11/2007  8:48 AM

G-pit - 13/11/2007  2:12 AM

Also they are gearing up to "Produce more rocket engines than the rest of US production combined" in 2008.

Lemme guess: They need about the "rest of US production combined" number of engines to make one F9, right?

EDIT: OKOKOK, maybe two...

How many engines are produced in the US each year, given that the Atlas V 1st stage engines are imported? The 50 cited in the article would be enough for ten Falcon 9s, 25 Falcon 1s, or, come to think of it, one Falcon 9 Heavy with 22 assorted engines left over...

   10 F9??? you mean: 5 F9, one F9 takes 10 engines.

I guessed at about 12 flights of Atlas and Delta IV, with, say, 6 RS68 for the Delta and one RL10 for any of the Deltas and Atlas'. What I don't know is about DII, AFAIK the RS27s have all been produced but what about 2nd stage?
Jim?

EDIT: let's not count solids ;-)

[William Barton]

pippin - 13/11/2007  9:09 AM

William Barton - 13/11/2007  2:59 PM

pippin - 13/11/2007  8:48 AM

G-pit - 13/11/2007  2:12 AM

Also they are gearing up to "Produce more rocket engines than the rest of US production combined" in 2008.

Lemme guess: They need about the "rest of US production combined" number of engines to make one F9, right?

EDIT: OKOKOK, maybe two...

How many engines are produced in the US each year, given that the Atlas V 1st stage engines are imported? The 50 cited in the article would be enough for ten Falcon 9s, 25 Falcon 1s, or, come to think of it, one Falcon 9 Heavy with 22 assorted engines left over...

   10 F9??? you mean: 5 F9, one F9 takes 10 engines.

I guessed at about 12 flights of Atlas and Delta IV, with, say, 6 RS68 for the Delta and one RL10 for any of the Deltas and Atlas'. What I don't know is about DII, AFAIK the RS27s have all been produced but what about 2nd/3rd stage?
Jim?

You're right, I meant five F9s. I don't have enough fingers and toes to do the calculation correctly on the first try.  :laugh:

[pippin]

William Barton - 13/11/2007  3:14 PM

You're right, I meant five F9s. I don't have enough fingers and toes to do the calculation correctly on the first try.  :laugh:

OK, that explains why you had the heavy right at 28 engines. Can put your shoes back on

[pippin]

Em... myself learning to count, too :-o

[Avron]

Release on SpaceX site as well "SPACEX COMPLETES DEVELOPMENT OF MERLIN REGENERATIVELY COOLED ROCKET ENGINE "

[NotGncDude]

From the release: "It is among the highest performing gas generator cycle kerosene engines ever built, [...] on par with the Saturn V F-1 engine. ".  On what grounds?

[pippin]

ISP. F-1 was huge, but actually not the most efficient engine around. They decided to solve one problem at a time and the problem they solved with F-1 was: grow big.

[kkattula]

Actually the Isp for the F-1 slightly exceeded the published figures for the Merlin-1. I haven't yet seen any figures specifically for the Merlin-1C.

I do think it beats the F-1 in T/W (96 to 94) and burn time. (190 to 160).  Still a very pretty engine.

Beats me how upgrading the J-2X can cost 1.2 billion, when Space-X have built this engine, 3 others, several factories, test stands, 2 launch pads, 2 new launch vehicle designs, and a manned/unmanned capsule, for an order of magnitude less.

[stockman]

kkattula - 14/11/2007  10:15 AM

Beats me how upgrading the J-2X can cost 1.2 billion, when Space-X have built this engine, 3 others, several factories, test stands, 2 launch pads, 2 new launch vehicle designs, and a manned/unmanned capsule, for an order of magnitude less.

 


Capatilism/Free enterprise   vs    Government Pork project thinking.

[wannamoonbase]

stockman - 14/11/2007  10:17 AM

kkattula - 14/11/2007  10:15 AM

Beats me how upgrading the J-2X can cost 1.2 billion, when Space-X have built this engine, 3 others, several factories, test stands, 2 launch pads, 2 new launch vehicle designs, and a manned/unmanned capsule, for an order of magnitude less.

 


Capatilism/Free enterprise   vs    Government Pork project thinking.

To a point I agree and the cost does baffle me as well.  For something that is suppose to have heritage and a little off the shelf ability the length of time and shear amount of money is incredible.  I would think that the schedule and budget should be about half of what it is.


Regarding the supposed magic of SpaceX's accomplishment keep in mind they are using RP1 and not LH2 and that its about 40% the size of the J-2X.    And that it is to be man rated.

If SpaceX is successful with all their promises and they get the F1 and F9 flying and delivering payloads to orbit and their claimed costs hold up and their engines are reliable then yes they have accomplished something truly amazing (and I hope they do.)  But to date we have claims, pictures and two test flights that have not placed anything into orbit.  They have a way to go yet.

[William Barton]

It has seemed to me that SpaceX's signal achievement to date is putting together an engine design bureau on a realtively small budget that's capable of putting out a viable product. I don't really know anything about the commercial rocket engine market, especially given the existence of ITAR, but it does seem like if they were just in the engine business people would be looking at them with interest. It seems like they would be able to build that 1Mlbf BFE for a single-engine 1st stage Falcon 9 upgrade, and then (assuming they've long ago solved all their launch vehicle design issues) go for the prophesied BFR. I'd like to think a Falcon 9/Dragon success would make a few of those infamous politicians start to think.

[Crispy]

Is there an existing market for a 45mT Kerosene/LOX engine that Spacex could commercialise the Merlin 1C in?

[William Barton]

Is there an existing market for any US engine other than the launcher designed around it? I think "existing market" may  be a bit of red herring. If SpaceX were to develop an engine in the same performance class as the RD-180, and if P&W proved unable to build its own RD-180s, and if Russia decided not to sell un any more, and if the stockpile of RD-180s were used up, would it be cheaper to re-engine the Atlas V with a SpaceX BFR, or to develop a new LV based on the BFR from scratch. I'm guessing it might be the latter. My sense is, if SpaceX were an engine design bureau producing engines significantly cheaper than anyone else on a class by class basis, then the only reason new launchers wouldn't use their engines would be political pork.

[Analyst]

stockman - 14/11/2007  4:17 PM

kkattula - 14/11/2007  10:15 AM

Beats me how upgrading the J-2X can cost 1.2 billion, when Space-X have built this engine, 3 others, several factories, test stands, 2 launch pads, 2 new launch vehicle designs, and a manned/unmanned capsule, for an order of magnitude less.

 


Capatilism/Free enterprise   vs    Government Pork project thinking.

Great. Now they only have to keep their schedule, which is already impossible, even taking the latest revision; reach LEO; keep their costs in check to keep their prices; be reliable; have a launch infrastructure; customer service ...

Analyst

[jongoff]

Analyst - 14/11/2007  9:03 AM

stockman - 14/11/2007  4:17 PM

kkattula - 14/11/2007  10:15 AM

Beats me how upgrading the J-2X can cost 1.2 billion, when Space-X have built this engine, 3 others, several factories, test stands, 2 launch pads, 2 new launch vehicle designs, and a manned/unmanned capsule, for an order of magnitude less.

 


Capatilism/Free enterprise   vs    Government Pork project thinking.

Great. Now they only have to keep their schedule, which is already impossible, even taking the latest revision; reach LEO; keep their costs in check to keep their prices; be reliable; have a launch infrastructure; customer service ...

Analyst

Of course to be fair, the same can be said about NASA.  How many upper stages has NASA successfully developed, fielded, and operated in oh say my lifetime?

~Jon

[Crispy]

Barton - I see now, that makes sense

[wannamoonbase]

Analyst - 14/11/2007  12:03 PM
Great. Now they only have to keep their schedule, which is already impossible, even taking the latest revision; reach LEO; keep their costs in check to keep their prices; be reliable; have a launch infrastructure; customer service ...

Analyst

My point exactly.  SpaceX may yet prove they can do it.  But they have only proven themselves to about the 10 or 20% level.  They have so far to go yet.

As for a million pound thrust engine, these things don't scale linearly.  The amount of work to develop that engine would be very prohibitive.  And so what if Elon built a monster rocket, how many customers exist that look for those payloads.  Not nearly enough to maintain the low cost because of high volume that they need.   If 90% of the cost of a rocket is in the engine than save your money there and SpaceX seems to want to do that by high volume production.  Big engine doesn't help in this matter.

As crazy as it sounds to use 27 engines it might be what is required to put rocket engines on an assembly line, then who knows where that could go.  Getting 27 liquid engines all running properly for the full flight, that will be something to see.  I fully intent to be present to watch that lift off.

I do wish them the best and I hope they are successful.

[William Barton]

wannamoonbase - 14/11/2007  4:36 PM

Analyst - 14/11/2007  12:03 PM
Great. Now they only have to keep their schedule, which is already impossible, even taking the latest revision; reach LEO; keep their costs in check to keep their prices; be reliable; have a launch infrastructure; customer service ...

Analyst

My point exactly.  SpaceX may yet prove they can do it.  But they have only proven themselves to about the 10 or 20% level.  They have so far to go yet.

As for a million pound thrust engine, these things don't scale linearly.  The amount of work to develop that engine would be very prohibitive.  And so what if Elon built a monster rocket, how many customers exist that look for those payloads.  Not nearly enough to maintain the low cost because of high volume that they need.   If 90% of the cost of a rocket is in the engine than save your money there and SpaceX seems to want to do that by high volume production.  Big engine doesn't help in this matter.

As crazy as it sounds to use 27 engines it might be what is required to put rocket engines on an assembly line, then who knows where that could go.  Getting 27 liquid engines all running properly for the full flight, that will be something to see.  I fully intent to be present to watch that lift off.

I do wish them the best and I hope they are successful.

A suppose a lot will depend on how the market itself works out. Arguably the most likely use for a 1Mlbf engine is as a replacement for the 9 engines on the bottom of a Falcon 9, in some decade-from-now Golden Age where the flight rate justifies the investment. Clearly they're smart enough to know rocket engines don't scale linearly, since Merlin isn't just a linear scale-up of Kestrel, and it looks like they have the talent to do it. The question is, do they have a reason to do it? And do they have the money to do it? Those are both market-based questions, at whose answer I couldn't hazard a guess. Put a SuperMerlin on bottom of a Falcon 9 reenginneered to be some kind of "CBC," cluster 7 of them together, and you've got something that would be roughly equivalent to an S-1C. Short of an Unobtanium-D mine on Mars, I'm not sure what market force would drive that.

I hope to be at some of the Falcon 9 launches too. I have a gut feeling that if Falcon 9/Dragon works out, it will be some kind of historical cusp. And if it doesn't work out. Hell, they'll be in good historical company. Lots if nifty ideas don't work out, and they seem to be giving it a heroic try.

[Giovanni DS]

Would be possible to cluster 4 merlins and create something like the rd170 ? this could cut the costs probably.

[meiza]

RD-170 has one gas generator and pump, just four chambers and nozzles. Interesting proposal nevertheless. If the nozzle and thrust chamber manufacturing infrastructure is complex, with all the grooved copper and the nozzle tubings, it could make sense.

I think it was done for the RD-170 because a single F-1 size thrust chamber was troublesome with thrust oscillations. Merlin 2 is probably still a very long way from that scale, Merlin 1 is 1/17th.

Here's a table of a few lox/kerosene engines. Thrust is sealevel/vacuum.

Merlin - Falcon 1 & 9 - 450/500 kN
RS-27C - Delta II - 900/1000 kN
RD-180 - Atlas V - 3800/4200 kN
F-1 - Saturn V - 6700/7700 kN
RD-171 - Zenit 2/3sl - 7600/7900 kN

A good easy to remember rule of thumb is that F-1 was 7 MN (meganewtons).
RD-171 is roughly similar. So RD-180 is about half of that. You need about nine Merlin 1:s to match the RD-180.

[hop]

A good easy to remember rule of thumb is that F-1 was 7 MN (meganewtons).
RD-171 is roughly similar. So RD-180 is about half of that. You need about nine Merlin 1:s to match the RD-180.

And they won't match the ISP, and so probably aren't a viable drop-in replace anyway.

Adding ISPs (vac/sl) from astronautix.com

Merlin - Falcon 1 & 9 - 450/500 kN - 304/??? (from spacex, probably for the non-C version), 310/261 (from astronautix, probably old ?)
RS-27C - Delta II - 900/1000 kN - 302/255
RD-180 - Atlas V - 3800/4200 kN - 338/311
F-1 - Saturn V - 6700/7700 kN  - 304/265
RD-171 - Zenit 2/3sl - 7600/7900 - 337/309
A couple more possibly relevant entries
RD-117 - Soyuz-FG strap-on - 800/1000 - 310/264 (there seems to be some conflict between sources about the exact specs, and which variant goes with which launcher)
NK-33 - N1/K1/"Taurus II" - 1510/1638 - 331/297

[coach]

"Clearly they're smart enough to know rocket engines don't scale linearly, since Merlin isn't just a linear scale-up of Kestrel, and it looks like they have the talent to do it. The question is, do they have a reason to do it? And do they have the money to do it? Those are both market-based questions, at whose answer I couldn't hazard a guess."

William, I'll hazard a guess.  Robert Bigelow will have thriving R&D/tourism market in LEO soon.  SpaceX is a likely transport.  Soon after (2020?), Bigelow will start putting inflatables on the moon.  SpaceX will be the transport.  Because of the low cost and steady income of private enterprise, SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?).  NASA may even pay for the initial trips.  NASA may get to the moon first but Musk and Bigelow will set up shop.

Just a guess.


Coach

[jimvela]

coach - 14/11/2007  7:51 PM
NASA may get to the moon first but Musk and Bigelow will set up shop. Just a guess.

At the current slow rate of exploration progress, the first NASA astronaut on Mars might take the Virgin Galactic/SpaceX/Northrop mars express, check in at the Bigelow Mars Uzboi Vallis, and drive off in an Eddie Bauer edition Hertz/GM Mars Hummer IX.  They could stop off at the BP/Mars for an homebrew fuelup, and rent a tour of the interesting places from the Six flags mars extreme adventure.  They could get the trip for half price if that rental had the big red Anheuser-Busch "Bud" logo plastered on the hood.

Even that would be great for SpaceX, there'd be a bundle of private rockets in such a mission.

Too bad we can't put our petty differences aside and mount a mission with modules and missions from all the space faring nations.  We could be there in a decade to stay.

[Comga]

meiza - 14/11/2007  6:05 PM
..... You need about nine Merlin 1:s to match the RD-180.

That's why it's a Falcon-9, don't you think?

coach - 14/11/2007  7:51 PM
William, I'll hazard a guess.  .....  Soon after (2020?), Bigelow will start putting inflatables on the moon.  

Not if NASA can help it, and they can.  Check out this:
http://www.spaceref.com/news/viewpr.html?pid=24027
Bigelow talks about putting his modules on the moon and POOF!  NASA has their first inflatable module in years ready for trials in Antarctica. (Anyone know any of the financial details of the Dover contract for inflatable structures? )

With or without the best of intentions, some parts of NASA will undercut the commercial market. The kind view is that these people seriously believe that their labor intensive, document heavy process is the only way to do space missions reliably.  Therefore they feel that they are doing the right thing by running programs that parallel private efforts, which they don't believe have sufficient quality and rigor to succeed.  The unkind view is that they are defending their turf.

Bigelow sees that NASA can duplicate their technology, which started with abandoned NASA technology, and provide "internal" competition for a product Bigelow wants to offer to NASA.  That has to put some damper on their business plans beyond LEO stations.  That puts some damper on the market for SpaceX to pursue moon capable rockets, if such a thing were to exist.

coach - 14/11/2007  7:51 PM

SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?). NASA may even pay for the initial trips. [/QUOTE]

Not if the pattern continues.  NASA *IS* the customer for Moon and Mars flights.  They are signaling, intentionally or not, that they don't want to buy missions or mission hardware.  Their jobs are and have been to make mission hardware and run missions.  Anything industry can develop, the can pay people to replicate, only with "appropriate" processes and quality control.

We can only hope that Musk and Bigelow can generate a sufficient independent market for private space stations, and build the seriously complicated systems to get people to orbit and support them their.  If they can make a go of that, and it is by no means assured, they may be able to branch out on their own.  But first (and second and third)... things first.

[wannamoonbase]

Comga - 14/11/2007  11:45 PM
SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?). NASA may even pay for the initial trips.

I'll take that bet.  

Space exploration is not like computers or the internet it does not evolve into a new generation every 18 months.

I wasted much of my 20's waiting for SSTO and second generation RLVs, then I learned enough to know that the status quo is that way for many good reasons.  Its hard accelerating something to 5 or 7 miles per second and getting it there safely.  

SpaceX is going to learn a great deal as they roll out the F9 and they will start to resemble ULA and other established operators.

Sadly, until flight rates go up significantly to make RLVs worth while or someone can make a Carbon fiber nanotube elevator and keep it operating we are looking for improvements in the single digit percentage points.

[William Barton]

meiza - 14/11/2007  8:05 PM

RD-170 has one gas generator and pump, just four chambers and nozzles. Interesting proposal nevertheless. If the nozzle and thrust chamber manufacturing infrastructure is complex, with all the grooved copper and the nozzle tubings, it could make sense.

I think it was done for the RD-170 because a single F-1 size thrust chamber was troublesome with thrust oscillations. Merlin 2 is probably still a very long way from that scale, Merlin 1 is 1/17th.

Here's a table of a few lox/kerosene engines. Thrust is sealevel/vacuum.

Merlin - Falcon 1 & 9 - 450/500 kN
RS-27C - Delta II - 900/1000 kN
RD-180 - Atlas V - 3800/4200 kN
F-1 - Saturn V - 6700/7700 kN
RD-171 - Zenit 2/3sl - 7600/7900 kN

A good easy to remember rule of thumb is that F-1 was 7 MN (meganewtons).
RD-171 is roughly similar. So RD-180 is about half of that. You need about nine Merlin 1:s to match the RD-180.

Probably why there's 9 Merlins on the bottom of a Falcon 9 and one RD-180 on the bottom of an Atlast V?  :laugh:

[William Barton]

coach - 14/11/2007  9:51 PM

"Clearly they're smart enough to know rocket engines don't scale linearly, since Merlin isn't just a linear scale-up of Kestrel, and it looks like they have the talent to do it. The question is, do they have a reason to do it? And do they have the money to do it? Those are both market-based questions, at whose answer I couldn't hazard a guess."

William, I'll hazard a guess.  Robert Bigelow will have thriving R&D/tourism market in LEO soon.  SpaceX is a likely transport.  Soon after (2020?), Bigelow will start putting inflatables on the moon.  SpaceX will be the transport.  Because of the low cost and steady income of private enterprise, SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?).  NASA may even pay for the initial trips.  NASA may get to the moon first but Musk and Bigelow will set up shop.

Just a guess.


Coach

When I hazard guesses they're called science fiction stories. In my most recent publication, I had my astronauts make it to a NEO with a hodge-podge of Bigelow, SpaceHab, SpaceDev, and SpaceX hardware, bought with a $600M grant from the Gates Foundation. Fun to write and see in print, but, sadly, the real world seldom conforms to my wishful thinking.

[A_M_Swallow]

hop - 15/11/2007  2:00 AM

Adding ISPs (vac/sl) from astronautix.com

Merlin - Falcon 1 & 9 - 450/500 kN - 304/??? (from spacex, probably for the non-C version), 310/261 (from astronautix, probably old ?)

If the Merlin's ISP is smaller than estimated will the Falcons have to reduce their payloads?

[meiza]

Smaller than estimated by whom and when? Your question does not make any sense.

[A_M_Swallow]

meiza - 15/11/2007  7:17 PM

Smaller than estimated by whom and when? Your question does not make any sense.

I quoted 3 estimates of the ISP, your answer could choose which ever one is appropriate.  The payload sizes are stated on SpaceX's website.  All the values to complete the question are therefore available even if the answer is likely to be embarrassing.


Quoting from the SpaceX website on 15 November 2007

Page 19 of the Falcon 1 User Guide says
"Falcon 1 Launch Vehicles are capable of delivering approximately a 723 kg (1590 lbs) payload
into a due east (9.1 degree) low Earth orbit with 200 km circular altitude, when launched from
Omelek Island in the Kwajalein Atoll."

From the Falcon 9 webpage:
"Falcon 9 Performance
Launch Site:                                             Kwajalein         Cape Canaveral AFS
Inclination:                                                 9 degree      28.5 degree
LEO Mass to Orbit (185 km circular):     10,400 kg        9,900 kg
GTO Mass to Orbit (185 x 35,788 km):    5,070 kg      4,900 kg
"

[meiza]

There were two, one by astronautix (old) and one by spacex.
You can read Elon's old updates, I think there he mentions how close they were to reach efficiency, thrust and ISP figures when the original Merlin 1 was developed. I think they were pretty close but somewhat below. I don't remember what Falcon I figures were released when. Falcon 9 wasn't even planned back then.

It's been an ongoing development, both the engine and the rockets. It's not a simple question. Payload, margins and designs have probably fluctuated a lot.

[hop]

Given the astronautix number is so far off spacex own, I'd take it with a grain of salt. It could be from a very early estimate something like that. I only included it because I couldn't find any sea level value anywhere else, and thats where I got the other numbers.

[coach]

"With or without the best of intentions, some parts of NASA will undercut the commercial market."

Who will be able to live in these NASA inflatables?  Only NASA astronauts.  Who will do scientific research in them?  Only NASA employees.  Bigelow will build his inflatables "across the street" from NASA's and will use professional astronauts along with scientists from all backgrounds and tourists from anywhere in the world.  

A reduction in cost to the lunar surface by a factor of ten through innovation over the next two decades is not unreasonable.  This cost reduction may be low enough for corportations and universities, as well as rich private citizens, to do research and business on the moon.  NASA can't undercut this endeavor no more than they can undercut DirectTV from putting a satellite in orbit.


Coach

[Chris-A]

On a hunch, I was looking up a old flight global article and Merlin 1c 92k lb thrust is the block I design with the plump upgrade will increase the thrust to 102k lb, block II.

[coach]

"At the current slow rate of exploration progress, the first NASA astronaut on Mars might take the Virgin Galactic/SpaceX/Northrop mars express, check in at the Bigelow Mars Uzboi Vallis, and drive off in an Eddie Bauer edition Hertz/GM Mars Hummer IX."

Jimvela, too funny.  I'm not that negative of NASA and I may certainly be wrong on any number of points but I am an optimist.  I believe that free markets, following government sponsored exploration is THE best model to open up the solar system.  SpaceX and Bigelow have the best opportunity for than at any time in history.  I may be wrong but I think we all hope I'm not.


Coach

[coach]

"Merlin 1c 92k lb thrust is the block I design with the plump upgrade will increase the thrust to 102k lb, block II."

Are they planning on using the upgraded turbo pump on the F9 Heavy?  SpaceX just updated their F9 Heavy specs page and I was curious if this new pump was a part of it.

Coach

[Comga]

coach - 15/11/2007  7:57 PM

"With or without the best of intentions, some parts of NASA will undercut the commercial market."

Who will be able to live in these NASA inflatables?  Only NASA astronauts.  Who will do scientific research in them?  Only NASA employees.  Bigelow will build his inflatables "across the street" from NASA's and will use professional astronauts along with scientists from all backgrounds and tourists from anywhere in the world. ....

This does not refute my contention.  There is an institutional bias, for good and bad reasons, against what you think is the "best way".   If it is a good idea, and cost reductions are small contributors to "good" at NASA, they will bring it "in house" to a vendor under their direct control.

[meiza]

I'm curious how the F9 has comparable performance to Atlas V 401 even though their first stage has same thrust but less performance and the upper stage is much heavier too... They must have a better mass fraction.

[Danderman]

meiza - 15/11/2007  8:34 PM  I'm curious how the F9 has comparable performance to Atlas V 401 even though their first stage has same thrust but less performance and the upper stage is much heavier too... They must have a better mass fraction.

I don't know how they get a better mass fraction than a Centaur. I will say that LEO performance of Atlas V suffers due to the single engine Centaur.

 

[jongoff]

Danderman - 15/11/2007  10:10 PM

meiza - 15/11/2007  8:34 PM  I'm curious how the F9 has comparable performance to Atlas V 401 even though their first stage has same thrust but less performance and the upper stage is much heavier too... They must have a better mass fraction.

I don't know how they get a better mass fraction than a Centaur. I will say that LEO performance of Atlas V suffers due to the single engine Centaur.

Well, by using a denser propellant it actually isn't too hard to beat the Centaur.  Centaur has awesome mass fraction for LOX/LH2, but the low bulk density of the propellants really hurts it.  Also having a high thrust upper stage engine like a Merlin (with vacuum optimized nozzle) probably helps somewhat too.

Another interesting thought is that Musk mentioned that they're looking at a turbopump upgrade next year that would increase thrust and T/W by something like 20-25%.  It could possibly be that the F9 numbers they're quoting are assuming that better, upgraded version of the Merlin-1C, not the current version that just finished development.  I don't have any special insight on this, but that would be my guess.

~Jon

[Frediiiie]

The turbo pump upgrade is evidently in the Merlin 1e engine not due till 2009.
I've no idea what upgrades are in Merlin 1d

[JIS]

meiza - 15/11/2007  9:17 PM

There were two, one by astronautix (old) and one by spacex.
You can read Elon's old updates, I think there he mentions how close they were to reach efficiency, thrust and ISP figures when the original Merlin 1 was developed. I think they were pretty close but somewhat below. I don't remember what Falcon I figures were released when. Falcon 9 wasn't even planned back then.

It's been an ongoing development, both the engine and the rockets. It's not a simple question. Payload, margins and designs have probably fluctuated a lot.

They had problems with ablative nozzle. With regenerative nozzle the ISP and thrust issue go away. They can try to squeeze maximum from the current Merlin design and production line.

[meiza]

Yeah but high mass fraction doesn't help that much since the second stage even with infinite tankage ratio would lose to a lox/lh2 stage in mass (payload needs a certain amount of propellants to accelerate to a certain delta vee even if tankage and engine mass is zero). And thus a bigger first stage is needed.

That's why hydrogen helps with second stages, the overall mass matters there more than in the first stage.

[wannamoonbase]

meiza - 16/11/2007  11:00 AM

Yeah but high mass fraction doesn't help that much since the second stage even with infinite tankage ratio would lose to a lox/lh2 stage in mass (payload needs a certain amount of propellants to accelerate to a certain delta vee even if tankage and engine mass is zero). And thus a bigger first stage is needed.

That's why hydrogen helps with second stages, the overall mass matters there more than in the first stage.

Yep, hard to beat the weight and ISP advantages of LH2.  That's why the best vehicles, Atlas V, Delta 4 and Ariane 5 use cryogenic upper stages.

RP1 maybe more affordable and easier to develop but it is not a superior upper stage fuel.

[kkattula]

I've seen mention of SpaceX plans to build a cryogenic upper stage later on. I guess using the same propellants for bother stages, (and same engine for F9),  makes the initial development process a lot easier. IIRC the Falcon tanks are quite light too, and the engines have high t/w. So the Falcon first stage makes up a bit for the less efficient RP-1 second stage.

Still Falcon 9 compared to an Atlas V 402, LEO 28.5 payload is only 9,900 kg vs 12,500 kg, 79%
But launch mass is 325 mt compared to 546 mt, 59%.

So Falcon 9 seems to be more efficient at payload / gross mass? (3% vs 2.2%)  I didn't expect that.

I believe it's because the RL-10 engine has quite low thrust. Less than 3% of the RD-180 first stage. Whereas the F9 upper stage Merlin is about 11% of the first stage thrust. This makes the F9 a bit better balanced in stage budgets. Atlas V and Delta IV suffer from bad second stage gravity losses.

I guess it depends on your definition of superior fuel.  

[CFE]

It's debatable whether the next step for SpaceX should be an LH2 upper stage, or a "BFR."  I think BFR should be sized to replace the nine-Merlin cluster, rather than trying to compete with the F-1.  There's also the possibility that SpaceX and OSC could work together on an LH2 upper stage, which could see use on both Falcon 9 and Taurus-II/Cygnus.

Of course, it's important for SpaceX to actually get Falcon I working properly before even contemplating its next steps.  I suppose the next Falcon I flight will continue to use the standard Merlin, but I can imagine Merlin IC flying on the fourth Falcon I flight.

[JIS]

CFE - 17/11/2007  7:59 AM

It's debatable whether the next step for SpaceX should be an LH2 upper stage, or a "BFR."  I think BFR should be sized to replace the nine-Merlin cluster, rather than trying to compete with the F-1.  

What would be commercial benefit in replacing 9 Merlins with one new engine? They should size their engine to get around 20t to LEO or 10t to GEO in two stages one engine each.

[wannamoonbase]

CFE - 17/11/2007  2:59 AM

It's debatable whether the next step for SpaceX should be an LH2 upper stage, or a "BFR."  I think BFR should be sized to replace the nine-Merlin cluster, rather than trying to compete with the F-1.  There's also the possibility that SpaceX and OSC could work together on an LH2 upper stage, which could see use on both Falcon 9 and Taurus-II/Cygnus.

If they are going to be a viable commercial entity then they should see what the market supports.

I possible that the F9 with a high enough flight rate could do all of that and they could just make minor improvements for years to come and lower the individual costs of each launch.  Being in a continous design cycle will become extremely expensive to operations.

However, like you said they need to get the F1 flying and commercially available first, then the F9.  Then worry about BFRs and cryogenic engines and stages.

[Analyst]

Someone less lazy than I am should calculate the Falcon 9 payload capability using the ISPs, stage masses (empty and fueled) and the rocket equation. Maybe some performance funnies disappear sooner than later.

Analyst

[CFE]

JIS - 17/11/2007  2:02 AM

CFE - 17/11/2007  7:59 AM

It's debatable whether the next step for SpaceX should be an LH2 upper stage, or a "BFR."  I think BFR should be sized to replace the nine-Merlin cluster, rather than trying to compete with the F-1.  

What would be commercial benefit in replacing 9 Merlins with one new engine? They should size their engine to get around 20t to LEO or 10t to GEO in two stages one engine each.

The commercial benefit is that a 28-engine monster like Falcon 9 Heavy could become a manageable, four-engine rocket if you dropped a BFR in place of each nine-Merlin cluster.  Perhaps Falcon 9 Heavy can be made to work reliably with 27 engines on the first stage, but that remains to be seen.  Using three BFR's in parallel might solve any reliability problems.

I would also imagine that BFR could be developed fairly inexpensively by scaling the Merlin up.  However, F-1 still went through a lengthy development in spite of Rocketdyne's history with engines like S-3D and H-1.

[josh_simonson]

A big part of SpaceX's plans are to use economies of scale with the Merlin engine, chugging them out at relatively low cost and high reliability.  Sort of the Otrag approach but only with the expensive parts, not the tanks.  Their engine out plans go out the window if they use BFR on the F9, particularly the F9H.  As per their page they believe that the two most reliable designs are single engine/stage or multi-engine with engine out.  The F9H with single engine cores would have three parallel engines that must all work for a successful mission.  

Following their philosophy, I'd expect their first BFR to be a BF5 or BF9 - perhaps with redundant Merlins on the second stage.  Mainly because of the emphasis they've placed on engine-out, and because it would be in a class above F9H rather than competing with it.

It may make more sense in the near term to develop a cryogenic stage, but I think their rumer-mongering of the BFR is to kickstart NASA into contemplating the existence of such a thing in the medium term (~2020).  A cryogenic stage makes particular sense if they're making fuel deliveries for lunar/mars missions because the fuel to be delivered will almost certainly be hydrogen.  If they're going to develop tankage and pad infrastructure to deal with LH2 on payloads, they might as well use it in an upper stage too.

[aero313]

josh_simonson - 19/11/2007  2:02 PM

A big part of SpaceX's plans are to use economies of scale with the Merlin engine, chugging them out at relatively low cost and high reliability.

I still maintain that this "production line" approach is a fallacy.  Automakers don't string together a bunch of single cylinder engines for each car, they build the one engine that is required.  This "mass production" concept doesn't account for the significantly increased amount of touch labor required to integrate the nest of engines.  Every single one of the multitude of fluid connections on each engine (the dreaded "B-nuts") needs to be mated, leak checked, and validated by a second set of eyes (per SpaceX's own flight assurance procedure).  Every one of those connections is a potential source of a mission failure.  The more you have, the lower your reliability - Futron "study" notwithstanding.  Add to this the increased complexity of the thrust structure required to mount all these engines, the added number of actuators, the added number of valves, the added number of control electronics boxes, ...well, you get the idea.  I also maintain that if this vehicle REALLY has engine out capability under all flight regimes (including the first five seconds of flight) then it is not the lowest possible cost.

The lowest cost and most reliable launch vehicle will consistently be the one with the fewest parts.

aero313 - 19/11/2007  1:46 PM  

josh_simonson - 19/11/2007  2:02 PM  A big part of SpaceX's plans are to use economies of scale with the Merlin engine, chugging them out at relatively low cost and high reliability.

 I still maintain that this "production line" approach is a fallacy.  ... The lowest cost and most reliable launch vehicle will consistently be the one with the fewest parts.

Soyuz R-7 family used this strategy. It is the most successful, most launched vehicle of all time.

Still, the evolutionary path for Soyuz is to reduce parts. So both are true.

Perhaps the best way to look at it is through the eyes of a new launch vehicle source. You know you're sources of error and economics are tied to minimizing the number of new things. So it's far more risky the number of different engines and systems than multiple systems. And as a business, you sell what you have.

After you've proven the systems/engines, then the argument is over proven systems verses unproven systems. But at some point, the economics of loss/risk begin to favor enhanced redesign/replacement, so then (like Soyuz U/2/3 or Atlas II/V) you factor in incrementally changes.

Space-X is doing the correct strategy here. Don't get dogmatic - they will doubtlessly reduce engine number with bigger/fewer engines when appropriate. For now, its make a reliable Falcon 1 with Merlin 1c's , then increase lift capacity with a Falcon 9 using Merlin 1c's, then make a heavy out of 3 CBC's ala Delta IV. Pull that off, and you have still a potentially excellent LV business irrespective of number of engines.

Or, fiddle fart with vehicles, optimizing engines for each, and have little history for each of your engines/systems, so you don't know how much exposure you have with each, and you die the death of 1,000 cuts, and everyone laughs at you. Great. They are hard enough on Space-X as it is with F1 and F9. Rather do it with multiple Merlin 1c's.

[William Barton]

It sometimes seems to me that princple "The lowest cost and most reliable launch vehicle will consistently be the one with the fewest parts" can only be stretched so far. As for the automotive analogy, while it's true manufacturers don't build cars with a large number of small one-cyclinder engines, they also don't build cars with large one-cylinder engines with "the fewest parts." Automotive engines are lineally descended from late 19th century reciprocating engine technology and are designed the way they are for historical reasons more than anything else (remember the Wankel-engine Mazda?). By the same token, you don't see too many single-engine commercial airliners out there, either.

[Jim]

But on the converse, there aren't aircraft with more 4 engines.  27 engines is not good

[William Barton]

Jim - 19/11/2007  4:16 PM

But on the converse, there aren't aircraft with more 4 engines.  27 engines is not good

So it seems as if we are approaching a principle that there's is a point of diminishing return in each direction. B-52 was designed with 8 engines 60 years ago, and my guess is because that's how many of the size engines they could make back then that it took for that size aircraft. I hazily remember there was a proposal decades back to re-engine the B-52 with 4 big turbofans. So what's the optimum number of engines to get realistic engine out capability on an LV (assuming engine out a T-0 means not launching)? Five?

[sitharus]

It's a matter of diminishing returns. Using many units of a small cheap engine lowers manufacturing costs, but it will generally raise integration and running costs. Developing a large efficient engine takes a lot of capital, but running it will be cheaper, as there are fewer duplicate components adding to the dead weight.

However, duplication can prove useful, so long as you make sure you're not causing excessive vibration...

[edkyle99]

William Barton - 19/11/2007  3:32 PM

Jim - 19/11/2007  4:16 PM

But on the converse, there aren't aircraft with more 4 engines.  27 engines is not good

So it seems as if we are approaching a principle that there's is a point of diminishing return in each direction. B-52 was designed with 8 engines 60 years ago, and my guess is because that's how many of the size engines they could make back then that it took for that size aircraft. I hazily remember there was a proposal decades back to re-engine the B-52 with 4 big turbofans. So what's the optimum number of engines to get realistic engine out capability on an LV (assuming engine out a T-0 means not launching)? Five?

When was the last time an engine on a space launch vehicle went "out" in a recoverable way anyway?  

Sea Launch Zenit early this year suffered an engine failure at T-0 essentially - the kind of engine-out failure that I doubt any launch vehicle could recover from.  The same could probably be said for last year's GSLV Vikas booster engine failure right off the pad and the Soyuz Foton failure a few years ago.  Before that there were two Proton second stage engine failures in 1999 due to "foreign particles".  Falcon 9 wouldn't have survived those failures since it only has one second stage engine.  

Before the Proton failures I think you have to go back to the AC-74 Atlas booster engine failure back in 1993, but that was about 75-ish Atlases ago.  That rocket suffered a failure that caused reduced thrust beginning about 25 seconds after liftoff.  Perhaps that would have been a recoverable failure for a Falcon 9, but that was one instance in 14 years.  There have probably been roughly 1,000 space launches worldwide, give or take a few dozen, since then.

 - Ed Kyle

[kraisee]

Yes, Ed.   I'm trying to remember the last time anyone had a cryogenic engine suffer a catestrophic failure (i.e. the engine blows up) on a launcher?

I don't think there has been a case in quite a while of an engine going bad in such a way that it did or might have taken a neighbouring adjascent engine out too.

STS-93 came close perhaps when all those controllers shut down, but even that flew successfully in the end.

As long as the Merlin has been able to lean on the vast library of lessons learned previously in other engine development programs, Space-X should be in a pretty solid position.


I'm still curious about that rumour a while back about Space-X considering an F-1 class engine in the future.

Ross.

[William Barton]

edkyle99 - 19/11/2007  4:50 PM

William Barton - 19/11/2007  3:32 PM

Jim - 19/11/2007  4:16 PM

But on the converse, there aren't aircraft with more 4 engines.  27 engines is not good

So it seems as if we are approaching a principle that there's is a point of diminishing return in each direction. B-52 was designed with 8 engines 60 years ago, and my guess is because that's how many of the size engines they could make back then that it took for that size aircraft. I hazily remember there was a proposal decades back to re-engine the B-52 with 4 big turbofans. So what's the optimum number of engines to get realistic engine out capability on an LV (assuming engine out a T-0 means not launching)? Five?

When was the last time an engine on a space launch vehicle went "out" in a recoverable way anyway?  

Sea Launch Zenit early this year suffered an engine failure at T-0 essentially - the kind of engine-out failure that I doubt any launch vehicle could recover from.  The same could probably be said for last year's GSLV Vikas booster engine failure right off the pad and the Soyuz Foton failure a few years ago.  Before that there were two Proton second stage engine failures in 1999 due to "foreign particles".  Falcon 9 wouldn't have survived those failures since it only has one second stage engine.  

Before the Proton failures I think you have to go back to the AC-74 Atlas booster engine failure back in 1993, but that was about 75 Atlases ago.  That rocket suffered a failure that caused reduced thrust beginning about 25 seconds after liftoff.  Perhaps that would have been a recoverable failure for a Falcon 9, but that was one instance in 14 years.  There have probably been nearly 1,000 space launches worldwide since then.

 - Ed Kyle

How many launch vehicles are flying which could survive any sort of first-stage engine out event, no matter how benign? Other than the Shuttle, which has survived a few, I don't know. I don't know anything about Proton plumbing, and it's one of the few multi-engine launchers that could be cross-fed (if it is, I don't know). If the Zenit 3SL had been a 9-engine LV instead of a 1-engine LV, would it have fallen back through the hole? How reliable are commercial jet engines? Should we be building single-engine airliners?

[edkyle99]

William Barton - 19/11/2007  4:15 PM

How many launch vehicles are flying which could survive any sort of first-stage engine out event, no matter how benign? Other than the Shuttle, which has survived a few, I don't know. I don't know anything about Proton plumbing, and it's one of the few multi-engine launchers that could be cross-fed (if it is, I don't know). If the Zenit 3SL had been a 9-engine LV instead of a 1-engine LV, would it have fallen back through the hole?

Upon further review, I suppose that it would not have fallen back, since Zenit 3SL has a liftoff thrust to weight ratio greater than 1.55.  If it lost 1/9th of its liftoff thrust, if would still have had a very positive thrust to weight ratio of something like 1.39.  Whether it would make up for gravity losses and still make the planned orbit is another question.

Falcon 9 is shown as having a high liftoff T/W ratio like Zenit, so perhaps T-0 engine-out is the plan.  If so, SpaceX is giving up a lot of payload for the rare "save" result.

How reliable are commercial jet engines? Should we be building single-engine airliners?

Reliability is such that they went from three or four-engines to two-engines on trans-Atlantic routes a decade or two ago.  Jetliners are not often falling into the sea to the best of my knowledge, although the occasional engine-out does occur.

 - Ed Kyle

[Jim]

William Barton - 19/11/2007  5:15 PM

1.  How many launch vehicles are flying which could survive any sort of first-stage engine out event, no matter how benign? Other than the Shuttle, which has survived a few, I don't know.

2.   I don't know anything about Proton plumbing, and it's one of the few multi-engine launchers that could be cross-fed (if it is, I don't know).

3 If the Zenit 3SL had been a 9-engine LV instead of a 1-engine LV, would it have fallen back through the hole?

4.   How reliable are commercial jet engines? Should we be building single-engine airliners?

1.  none

2.  not crossfed

3.  More than likely, especially if there is collateral damage.  Spacex Kevlar "shields" have not been tested

4.  Very, hence the ability of long range airliners to go from 4/3 to 2 engine  under ETOPS.  Also aircraft can glide.

[hop]

sitharus - 19/11/2007  1:42 PM

It's a matter of diminishing returns. Using many units of a small cheap engine lowers manufacturing costs, but it will generally raise integration and running costs.

The earlier suggestion of a 1 pump/multi-chamber (like the RD-170 and RD-107 families) development of the merlin seems like an interesting compromise.

Much of your production line can be common between different engines sizes (astronautix describes the RD-170 and 180 as being 70% common parts, and the development of the RD-180 was definitely cheap and quick compared to clean sheet designs), and you have less moving parts per engine. OTOH, you don't get the same engine out capabilities.

The other question is how far you take this. I'm not aware of any multi-chamber engine that uses more than 4 chambers.

The issue here is bootstrapping a LV business. You build one engine and get history on in. You use the crap out of it, taking it as far as you can to grow your business. If that means running 27 engines reliably - so be it.

Lets say you obsessively manage development(not so worried) and operations/dynamics(very worried - given past two launch attempts) to do this.

Lets also say you get a few working flights of Falcon 1 and Falcon 9. You then have very good motivation to move to a new engine with a proven vehicle to work from. And an equally good reason to have highly effective manufacturing, test, qualification, and launch operations to buy time allowing you to operate the Falcon 9 until you have the new engine/vehicle.

Space-X isn't Boeing or LockMart - they have to do 27 engines first stage heavy lift. The way people here are talking, sounds like predicting a failure like Korolev's N1 - not the same. Not easy, but not the same.

If the Falcon 1 does well third/fourth launch, they will have proven enough for Falcon 9. If they can launch a Falcon 9, they can get a heavy.

[Crispy]

to be fair, the N-1 didn't fail because it had so many engines. 30 engines made it harder, sure, but what really killed it was poorly designed and poorly tested hardware. Combine that with a ridiculously rushed program and it was always going to fail. What, specifically, are the issues that running 9 (let's start at the beginning) engines will throw up?

[meiza]

Aero313 already summarized those problems.
There's more hardware and that increases time spent before launch, and there are more things to go wrong both before and during flight.

[William Barton]

Jim - 19/11/2007  5:31 PM

William Barton - 19/11/2007  5:15 PM

1.  How many launch vehicles are flying which could survive any sort of first-stage engine out event, no matter how benign? Other than the Shuttle, which has survived a few, I don't know.

2.   I don't know anything about Proton plumbing, and it's one of the few multi-engine launchers that could be cross-fed (if it is, I don't know).

3 If the Zenit 3SL had been a 9-engine LV instead of a 1-engine LV, would it have fallen back through the hole?

4.   How reliable are commercial jet engines? Should we be building single-engine airliners?

1.  none

2.  not crossfed

3.  More than likely, especially if there is collateral damage.  Spacex Kevlar "shields" have not been tested

4.  Very, hence the ability of long range airliners to go from 4/3 to 2 engine  under ETOPS.  Also aircraft can glide.

Thanks for the info on one & two. That's what I suspected. As for three, I'm guessing SpaceX is hoping the shields are never tested during "rapid unscheduled disassembly." An for item four, I would hate to go through the experience of a dead stick landing in a modern commercial airliner with its fly-by-wire systems inoperative. Even with lots of nice ocean below.

Here's a question: was the 4 to 3 to 2 decrease in airliner engines driven by safety or cost concerns? I'd bet cost.

[wannamoonbase]

Given SpaceX's resources and experience base doing it with 9 or 27 small engines is their only option.  How the economics play-out will be interesting as it could effect the industry world wide.  Can you assemble rocket engines on an assembly line to reduce costs and still get the reliability required.

We may not know until we see if the F9 fly successfully, and more than once.  The F9 HLV would really be something to see lift off no matter how you feel about it.  That would set how many different kinds of records.

I think the examples of the N-1 are flawed because the Soviets never had a good enough grasp on systems integration to pull it off and workmanship and controls were never going to be good enough to control the beast.  

SpaceX's engine out argument is also flawed because they are throwing on so many engines they need an engine out option.

I am getting impatient and want to see some tests and rockets on the pad at this point.

[Lampyridae]

The R-7 used to boost with what, 20 engines and 12 verniers? I don't know how much plumbing was shared on those. The main problem seemed to be valve issues but once those got sorted out it seemed to be highly reliable. I have no idea whether any of them survived an engine-out to orbit though.

That being said, Armadillo's lander hopped all over the place, banging and spewing bits of itself everywhere for 3 flights in a row (with different engines of course). So maybe the idea would hold for F9?

[Lampyridae]

...my point being that rocket motors can be built to be rugged. Armadillo and F9 are in totally different leagues.

[Jim]

Lampyridae - 20/11/2007  8:33 PM

The R-7 used to boost with what, 20 engines and 12 verniers? ?[/QUOTE}

only 5 engines.  Each engine has 4 nozzles.  No need to further expand this part of the thread.  This has been shown over and over

[sitharus]

Lampyridae - 21/11/2007  1:33 PM

The R-7 used to boost with what, 20 engines and 12 verniers? I don't know how much plumbing was shared on those. The main problem seemed to be valve issues but once those got sorted out it seemed to be highly reliable. I have no idea whether any of them survived an engine-out to orbit though.

That depends on how you look at it. R7/Soyuz first stage uses 5 sets of turbopumps driving 20 main chambers/nozzles and 12 verniers. Since the four chambers are powered by one set of pumps it can be considered to be a single engine. Also, each set of pumps has its own dedicated tanks, so the plumbing for each engine is independent. Falcon 9 will have one set of tanks driving 9 turbopumps powering 9 chambers.

[Frediiiie]

Falcon 1 flights 3 & 4 are evidently to be merlin 1c engines to give some flight time to that engine before Falcon 9 flies.

[Chris-A]

M-1C Flight qualification for Falcon 1
http://www.spacex.com/press.php?page=37

Falcon 1 configuration:
- 78,000 lbs at sea level, and 90,000 in vacuum
- Isp 301 seconds in vacuum.

“In the coming weeks we’ll begin qualifying Merlin for the higher thrust and performance levels required by our Falcon 9 rocket, keeping us on track for delivering the first Falcon 9 vehicle to Cape Canaveral by year end.” - Elon

Cool pic :cool:

[Frediiiie]

They also said in this post that they are gearing up to build 1 engine a week.
This is up from the "1 every two weeks" they had said earlier.

[Patchouli]

There was one vehicle that could handle an engine out at any moment in flight that was both Saturn vehicles they both had first stage engine out capability.

The Saturn V did reach orbit a few times after loosing as many as two engines off the second stage.
Falcon 9 should be best compared with the Saturn IB which had 8 H-1 engines .

The N1 first stage wasn't properly tested and the Soviets didn't have kevlar jackets for their engines or computer health monitoring on the level we have today.

The kevlar shields on F9 will be ground tested extensively before it flies.
Spacex has the benefit of a test stand something the N1 designers never had.

If the engines have anti explosion shielding and control computer are up to the task Falcon 9 would likely be able to handle a Zeint type failure of one engine and still complete the mission or atleast perform a safe abort.

Lastly remember the shuttle was saved numerous times by it's health monitoring systems they're partly why the SSME is so reliable despite being a combined cycle engine which historically were very ill behaved and fickle machines.

The Russians blew up a lot of RD170s before they got it right and I think even it uses a lot of health monitoring though I could be wrong.

The Merlin 1C is not a combined cycle engine like the NK-15 used on the N-1.

It's closest relatives are actually the LEM descent engine and the H1 off the Saturn I-B
It's a turbopump cycle pintle injector engine a very simple and reliable design.

Comparing Merlin to the NK-15 would be unfair even silly as one engine operates well within the limits of it's materials and the other operates right on the edge of what it's construction  materials can handle.

It would be like saying all piston engines are very prone to exploding because top fuelers often explode.

To make the difference stresses easy to understand you could compare the Merlin 1C to an F1 racing engine and the NK-15 to a topfuel dragster engine.

As for the existence of two engine airliners it has little to do with safety and everything to do with costs plus cleaner aerodynamics.

1. We just simply have large engines today which didn't exist a few decades ago.

2. We now know how to keep an aircraft under control despite the tenancy of the asymmetric thrust from having one engine operating to make the aircraft yaw which was from what I read a very difficult issue to resolve.

3. The reliability of jet engines have increased greatly over the years so you're a lot less likely to end up having to deal with 2 but it still happens.

[Jim]

Patchouli - 17/3/2008  3:45 PM

There was one vehicle that could handle an engine out at any moment in flight that was both Saturn vehicles they both had first stage engine out capability.

Incorrect.  It could not handle losing one at T+0

[Patchouli]

I thought the Saturn performed a post ignition hold down before letting the vehicle go during launch making such a failure at T+0 just a mission abort where you just simply cut the thrust?

[Crispy]

Strictly speaking, isn't T+0 the moment of release, not the moment of ignition?

[Crispy]

-

double post

[Jim]

Patchouli - 17/3/2008  3:53 PM

I thought the Saturn performed a post ignition hold down before letting the vehicle go during launch making such a failure at T+0 just a mission abort where you just simply cut the thrust?

T+0 is once the vehicle is released, T-0 is before release

[wingod]

Jim - 17/3/2008  3:32 PM

Patchouli - 17/3/2008  3:53 PM

I thought the Saturn performed a post ignition hold down before letting the vehicle go during launch making such a failure at T+0 just a mission abort where you just simply cut the thrust?

T+0 is once the vehicle is released, T-0 is before release

And there is a gulf of time between the two.

[wingod]

Jim - 17/3/2008  2:48 PM

Patchouli - 17/3/2008  3:45 PM

There was one vehicle that could handle an engine out at any moment in flight that was both Saturn vehicles they both had first stage engine out capability.

Incorrect.  It could not handle losing one at T+0

Agreed.  It is my memory that it could handle one F1 out at +100 ft altitude and then reach orbit which is pretty darn good!

[Jim]

wingod - 17/3/2008  9:57 PM

Jim - 17/3/2008  2:48 PM

Patchouli - 17/3/2008  3:45 PM

There was one vehicle that could handle an engine out at any moment in flight that was both Saturn vehicles they both had first stage engine out capability.

Incorrect.  It could not handle losing one at T+0

Agreed.  It is my memory that it could handle one F1 out at +100 ft altitude and then reach orbit which is pretty darn good!

before that, they thought it would hit the LUT

[Analyst]

Jim - 18/3/2008  12:47 PM

before that, they thought it would hit the LUT

If I remember correctly, it depended on which engine failed or gimbaled into the worst case direction.

Analyst

[Big Al]

I’ve been thinking about the Falcon 9 and the closest thing to it was the Saturn 1. I dug out my Spacecraft Films DVD on the Saturn 1 and reviewed it in relation to the Falcon 9.

The first thing you realize is the tanks and manifold system on the Saturn was more complex than the 9 will be. The Saturn 1 had 5 oxygen and 4 fuel tanks plumed to 8 engines. It would be interesting to see how this system was designed. An interview with one of the chief engineers he said “we had some difficulty with the fuel feed”

They also said that they shut down one of the H-1’s on one of the flights to test its engine out capability. Also on another flight one of the engines shut down do to turbo pump failure. They were able to complete the mission without any problems.


This brings up the issue of what type of failure Spacex is planning for. An uncontained pump failure might require a nomex blanket around the turbo pump. An exploding combustion chamber would be difficult to plan for and require some heavy shielding.

One of the things you notice between the Saturn1 and 1B is the turbo pump exhaust. The early H-1’s must have run a very rich mixture in the combustor for the turbo pump. You can see lots of burning fuel from the turbo pump exhaust. The 1B did mot have this. They said in the film that after flight 4 or 5 they started using an upgraded H-1 that had more thrust.

By the way they said the Saturn 1 was held down for 3.2 seconds before launch to stabilize engine thrust.

A question on the Falcon 9, how many fist stage engines will be gimbaled for steering? On the Saturn 1, I would guess that the outer 4 engines were gimbaled. On the 9 how do the plan to do this? Will they use turbo pump exhaust for roll control?

[Jim]

Big Al - 18/3/2008  4:48 PM

1.  One of the things you notice between the Saturn1 and 1B is the turbo pump exhaust. The early H-1’s must have run a very rich mixture in the combustor for the turbo pump. You can see lots of burning fuel from the turbo pump exhaust. The 1B did mot have this. They said in the film that after flight 4 or 5 they started using an upgraded H-1 that had more thrust.

2.  Will they use turbo pump exhaust for roll control?

1.  they were the same.  The 1B didn't duct it outward and overboard

2.  That only works for single engine vehicles.  Multiple engined vehicles roll control by opposing engines gimbaling in the opposite direction

[Big Al]

One more observation about the Saturn 1 program. I was a very conservative flight program. The first three flights were sub-orbital. In terms of the Falcon 9 wouldn’t it be a good idea to do an early first stage only flight to demonstrate their ability to fly a multi engine rocket. They could even do an engine out demo; I think this would really help their standing in the industry and with potential customers. The question of Spacex’s ability to routinely fly a multi-engine rocket is on everybody’s mind and the sooner they prove themselves, the better off they will be.

[Comga]

The stated arguments for flying a full up rocket on the first flight are that the upper stage is not very expensive, there is no better way to test an upper stage than without mechanical constraints in the vacuum of high altitude, and that the avionics are in the upper stage so flying without one requires them to be repackaged.

Did they ever fly a Saturn 1 or 1B with a dummy upper stage?

[Analyst]

Big Al - 19/3/2008  12:31 AM

1) One more observation about the Saturn 1 program. I was a very conservative flight program. 2) The first three flights were sub-orbital.

1) It was the dawn of the space age. Experience was low. Compare this to the earlier Jupiter, Thor, Atlas or Titan development and flight testing. Has been even more conservative.

2) The first four (SA1 - SA4) were suborbitaL, they lacked a live upper stage. Some later flights were suborbital too (by design), despite having an upper stage.

Comga - 19/3/2008  7:23 AM

Did they ever fly a Saturn 1 or 1B with a dummy upper stage?

Yes, four flights: SA1 - SA4.

Analyst

[josh_simonson]

In the Saturn 1 development, the first stage was test launched almost a year before the second stage was even test fired.  If the second stage had been available they probably would have done fewer test flights without the second stage.

SpaceX would have to consider things like range costs, insurance, ect, involved with flying a partial stack against the cost of just putting on the second stage and hoping for the best.  It's only 11% more Merlin engines, and they'll have a decent chance at getting to the second stage.

[Big Al]

My thinking was that it looks like Spacex is much further along with development of the F9 first stage than the second stage. A suborbital first stage flight would be a real confidence builder

Also, now I can't find the source, but I read that Spacex is announcing an 18 month delay for the first flight of the Falcon 9.

[Jim]

Big Al - 19/3/2008  1:56 PM

My thinking was that it looks like Spacex is much further along with development of the F9 first stage than the second stage. A suborbital first stage flight would be a real confidence builder

It would be more work.  The one off vehicle configuration means more drawings and more work, more dead end hardware.  Avionics would have to be relocated and different software used.

Since the Saturn I, rocket science has progressed past the use of incremental testing and "all up" launches in the norm.

[Big Al]

Found my source for the F9 delay, Orlando Sentinel.com, dated 2/28/08

[iamlucky13]

Big Al - 18/3/2008  1:48 PM

1.) This brings up the issue of what type of failure Spacex is planning for. An uncontained pump failure might require a nomex blanket around the turbo pump. An exploding combustion chamber would be difficult to plan for and require some heavy shielding.

2.) A question on the Falcon 9, how many fist stage engines will be gimbaled for steering? On the Saturn 1, I would guess that the outer 4 engines were gimbaled. On the 9 how do the plan to do this? Will they use turbo pump exhaust for roll control?

1.) From http://spacex.com/updates_archive.php?page=0605-1205
"Then there is the question of dealing with the comparatively rare case of a chamber rupture. To protect against this, Falcon 9 will have a blast shield protecting the entire base of the vehicle just above the gimbal joints of the engines. In addition, there will be fireproofed Kevlar fragment containment around each engine, similar to those present in jet engine nacelles. The explosive power of a liquid rocket chamber is actually not exceptionally high – it can be thought of as simply a small pressure vessel containing (in our case) 800 psi hot gas. During the development of Merlin, we saw several of what we refer to as RUD (rapid unscheduled disassembly) events and no fragments have ever penetrated more than 2mm of aluminum. Also, the direction of fragments is in a shallow downward cone away from the vehicle.

As additional measures of protection, all propellant and pneumatic lines have either pre-valves or check valves nested up high in the thrust structure. If anything happens to the engine, the flight computer is able to cut off all propellant and pressurant flow immediately."

I love the term "Rapid unscheduled disassembly" :laugh: but I wonder if the Sea Launch failure last year made SpaceX take a little closer look at the danger.

2.) I think Musk in an interview discussed differences between the gimballing and fixed engines, but I don't remember where. I want to say it's the corner engines, but I can't back that up at the moment.

[meiza]

Ha! So their chamber pressure is actually 800 psi = 55 bars. Haven't seen that officially mentioned in the spec sheets.

[Comga]

Analyst - 19/3/2008  1:32 AM

Comga - 19/3/2008  7:23 AM
Did they ever fly a Saturn 1 or 1B with a dummy upper stage?

Yes, four flights: SA1 - SA4.
Analyst

Another 60's skill kept current at NASA: building dummy/boilerplate upper stages and payloads.
Another NASA SOP being bypassed by SpaceX for better or worse.

[Comga]

Jim - 19/3/2008  12:07 PM
Since the Saturn I, rocket science has progressed past the use of incremental testing and "all up" launches in the norm.

Except for Ares-1, it would appear.  But that is a different discussion.

[Comga]

Big Al - 19/3/2008  12:22 PM
Found my source for the F9 delay, Orlando Sentinel.com, dated 2/28/08

Please post a link or quote.
That's a lot more of a delay than has been reported elsewhere.

[Big Al]

Sorry, I can't come up with the link. I saw the orginal story over at Space Fellowship.com, but I can't even find that now. I also can't get the Orlando Sentinel archives to work for me. I'll keep at it.

[Nate_Trost]

I suspect that refers to an 18-month slip from when SpaceX originally thought they'd fly the F9 (late 2007) when it was announced in 9/2005.

[iamlucky13]

meiza - 19/3/2008  12:10 PM

Ha! So their chamber pressure is actually 800 psi = 55 bars. Haven't seen that officially mentioned in the spec sheets.

As it's from a 2+ year old update, I wouldn't take that as an official spec. That's pre-Merlin 1C and no precision given.

But I am innocently curious why the number excites you?

[Big Al]

Bingo!        http://blogs.orlandosentinel.com/news_space_thewritestuff/2008/02/bad-news-florid.html

[Big Al]

A second reading of the Orlando Sentinal article says a delay of the F9 flight from this summer until the 1st quarter of next year. Spacex was saying the first launch was to be the 4th quarter of this year, so I guess my 18 month delay was wrong. The Sentinal article was info from a Musk interview in Flight International.

[meiza]

iamlucky13 - 20/3/2008  12:56 AM

meiza - 19/3/2008  12:10 PM

Ha! So their chamber pressure is actually 800 psi = 55 bars. Haven't seen that officially mentioned in the spec sheets.

As it's from a 2+ year old update, I wouldn't take that as an official spec. That's pre-Merlin 1C and no precision given.

But I am innocently curious why the number excites you?

Well afaik it's the last missing piece of spec, there has been some speculation about the performance of Merlin and the Falcons. Now it would be easier to figure for example what the ISP is for the big nozzle on Falcon 9's second stage.
I don't know *that* much about rocket engine design, but I hunch that usually chamber pressure is hard to increase much if you want to keep your expensive-to-develop turbines and pumps the same. The spin rate could be increased I guess.

Basically, chamber pressure determines ISP. With nozzle expansion rate and back pressure of course, but these tend to be pretty trivial: first stage nozzle is pretty close to small sea level optimized (exit pressure = back pressure = 1 bar), slightly bigger. And the vacuum big nozzle closes asymptotically in on infinite nozzle ideal ISP.

And flow rate with ISP determines thrust.

(This is just a simplified view of things...)

[iamlucky13]

Ah...I see.

Well, 800 psi is a hint then, but we can only assume one digit of precision meaning +/- 50 psi, further assuming that the number isn't significantly different for the Merlin 1C. So I'm guessing that only puts you within +/- about 20 seconds of the actual ISP.

[josh_simonson]

I'd think the F9 second stage would be very similar to that of the first stage of the F1, which is already developed.

[Crispy]

As far as I understand, the F9 2nd stage is designed to be very similar to the F9 1st stage, just with one engine and fewer tank sections. The aim is to maintain maximum comonality. The only common factor with Falcon 1 is probably the avionics.

[rsnellenberger]

Big Al - 19/3/2008  8:17 PM

A second reading of the Orlando Sentinal article says a delay of the F9 flight from this summer until the 1st quarter of next year. Spacex was saying the first launch was to be the 4th quarter of this year, so I guess my 18 month delay was wrong. The Sentinal article was info from a Musk interview in Flight International.

I haven't seen it mentioned here yet, but I just today noticed the following text at the bottom of SpaceX's manifest page:

           *Target dates are for hardware arrival at the launch site.

Unless they've retconned the manifest by adding this recently, they only have to ship the F9 to the Cape by the end of the year to meet their target...  

[dmc6960]

Its been the way for a few weeks now, since they've publicly stated that they will not launch F9 in 2008, but remain confident they can deliver the first F9 to Florida this year yet.

[edkyle99]

dmc6960 - 20/3/2008  3:29 PM

Its been the way for a few weeks now, since they've publicly stated that they will not launch F9 in 2008, but remain confident they can deliver the first F9 to Florida this year yet.

The sliding scale manifest!  

 - Ed Kyle

[meiza]

Hehe, who believed their schedule originally anyway? Maybe they should be like the games business nowadays: Release date: "when it's done".

[Chris-A]

It would be nice to known what is the progress with the not-existent, or imaginary upper stage is going

[rsnellenberger]

Chris-A - 20/3/2008  8:51 PM

It would be nice to known what is the progress with the not-existent, or imaginary upper stage is going

"It's like totally identical to the first stage, but we only use the center engine!"  :cool:

[Comga]

Crispy - 20/3/2008  1:01 PM
 The only common factor (of the F9 second stage) with Falcon 1 is probably the avionics.

And using the turbopump exhaust for roll control
I have not seen confirmation that each F9 engine has two axis control.  
It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

[aero313]

Comga - 20/3/2008  11:47 PM

Crispy - 20/3/2008  1:01 PM
 The only common factor (of the F9 second stage) with Falcon 1 is probably the avionics.

And using the turbopump exhaust for roll control
I have not seen confirmation that each F9 engine has two axis control.  
It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

You only need single axis steering.  So long as the hinge axis is on a radial line from the center of the stage, four single-axis gimbals provide both attitude and roll control.  This is how the Minuteman first stage works.  The problem is that without two-axis gimbals on all the engines, I don't thing you have true engine-out capability for all failure modes.

[daver]

Elon Musk and Richard Branson to save the world....or get rich trying.
http://www.iht.com/articles/2008/03/20/business/deal.php

[AntiKev]

To be honest, Musk does not look happy to be there in that photo.  I don't know if it was just the pose they put him in or his actual reaction.

[Jim]

aero313 - 21/3/2008  11:39 AM

Comga - 20/3/2008  11:47 PM

Crispy - 20/3/2008  1:01 PM
 The only common factor (of the F9 second stage) with Falcon 1 is probably the avionics.

And using the turbopump exhaust for roll control
I have not seen confirmation that each F9 engine has two axis control.  
It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

You only need single axis steering.  So long as the hinge axis is on a radial line from the center of the stage, four single-axis gimbals provide both attitude and roll control.  This is how the Minuteman first stage works.  The problem is that without two-axis gimbals on all the engines, I don't thing you have true engine-out capability for all failure modes.

there was talk of shutting down corner engines to limit g loads, this would play to the gimbaling scheme

[Jim]

Comga - 20/3/2008  11:47 PM

It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

inner four were fixed and the outer four had 2 axis steering

[meiza]

Musk's still gotta work on showing that big smile when a camera shows up, like the old PR pros.

[William Barton]

daver - 21/3/2008  12:06 PM

Elon Musk and Richard Branson to save the world....or get rich trying.
http://www.iht.com/articles/2008/03/20/business/deal.php

Musk appears to be contemplating the placement of Blair's feet, as in, "Do I tell him what he's just stepped in, or not?"

[William Barton]

Jim - 21/3/2008  12:25 PM

Comga - 20/3/2008  11:47 PM

It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

inner four were fixed and the outer four had 2 axis steering

I'm sure you're right, but when you look at the business end of a Saturn I, it looks like the four outer engines have single axis steering oriented in two directions (opposite corners parallel). I don't actually know what I'm seeing, so it's just an impression from the shape of the openings through which the outer four protrude. Would an arrangement like that be considered 2-axis? (Your comments may be terse, but I always seem to learn something.)

[Jim]

William Barton - 21/3/2008  1:03 PM

(Your comments may be terse, but I always seem to learn something.)

just efficient comments, minimal keystrokes.

[Big Al]

I just found a nice 280 page PDF file from the NASA server about the structure and systems for Saturn 1 and 5. The fuel and lox manifolding for the Saturn 1 was indeed complex, no so much for the 5 with a single lox and fuel tank on the first stage. It will be interesting to see how Spacex designs their fuel and Lox feed for the Falcon 9

I also noticed in the section on the H1 that it used a solid fuel start cartrige to get the turbo pump to spin up, what does the Merlin use?

[pippin]

Jim - 21/3/2008  6:25 PM

Comga - 20/3/2008  11:47 PM

It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

inner four were fixed and the outer four had 2 axis steering

Are you sure? I thought they had singe axis tangential steering on the outer 4?

[Big Al]

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710065502_1971065502.pdf
This file is called "Apollo Systems Descriptions" , has everything you ever wanted to know about Saturn. In there they say that the Saturn 1 first stage outer engines can move in an 8 degree square in both pitch and yaw ( suprised me, I thought like pippin that they would have single axis steering only)

[pippin]

Maybe the control authority would have been to difficult for the electronics back then when you lose one of the outer engines. Theoretically you should have enough roll control through the two paired engines to compensate for the roll you induce when pitching/yawing with only one engine but that would be a completely different animal from the "normal" steering.

Thanks for the link :-)

[Big Al]

Which only adds to the mystery of how many of the first stage engines on the Falcon 9 will be gimbaled and will they gimbal in pitch and yaw both?

[Chris-A]

In sort: what was provided then, may be out of date now.

On the space show, Gwynne said all nine engines gimbaled, but was unsure. For the feed lines the pictures show some detail, if you look hard.

[Big Al]

That makes sense, with the close spacing of the engines and the thrust struts look like their the same as a Falcon 1.

[CFE]

On the Falcon IX upper stage, does SpaceX plan on using the Merlin 1C or the standard Merlin 1?  Additionally, how difficult will it be to mod the Merlin for air-start?  Is this a capability that's already been built-in?  If not, it may be quite difficult to pull off (in light of the obstacles to making the SSME into an upper-stage engine.)

[hyper_snyper]

Well it's not like SpaceX has a sprawling amount of ground support equipment as part of their launch concept.  If the Merlin can rely on its own devices for starting at sea level, igniting one mid-flight shouldn't be as crazy as getting the SSME to air-start.

The thing about Merlin that puzzles me is how they're planning on protecting it and anything else vulnerable to sea water when (or if) they start recovering and reusing these stages.

[Jim]

CFE - 30/3/2008  7:50 PM

On the Falcon IX upper stage, does SpaceX plan on using the Merlin 1C or the standard Merlin 1?  Additionally, how difficult will it be to mod the Merlin for air-start?  Is this a capability that's already been built-in?  If not, it may be quite difficult to pull off (in light of the obstacles to making the SSME into an upper-stage engine.)

Air starting an engine is not difficult, only air starting the SSME.  It doesn't use spin start cartridges. hypergol igniters, or boost pumps.  It just uses head pressure

[wannamoonbase]

hyper_snyper - 30/3/2008  8:07 PM
...The thing about Merlin that puzzles me is how they're planning on protecting it and anything else vulnerable to sea water when (or if) they start recovering and reusing these stages.

Great question.  I have been wondering about the effects of being submerged in salt water as well.

That's one big reason I liked the K1's approach to launching over land and using airbags.  To bad some internet billionaire didn't try that approach.  With proper funding maybe it would have worked.

[Lee Jay]

Need a real rocket engineer here.

I've somewhat surmised that the expensive bits of a modern large liquid engine are the controllers, turbo-machinery, valves and plumbing above the combustion chamber.  I'm not sure about the injectors and combustion chamber.  The nozzle seems to be somewhat inexpensive unless its regenerative in which case it's more but not unreasonable.

First of all, that might all be false (hence the first sentence in this post).  But if it's true, wouldn't it be possible to seal all the expensive stuff inside something and just let the salt water flood the nozzle and combustion chamber, thereby saving the really expensive stuff, and at least in the case of an ablative nozzle throwing away mostly what's all used up anyway?

[Patchouli]

wannamoonbase - 30/3/2008  8:55 PM

hyper_snyper - 30/3/2008  8:07 PM
...The thing about Merlin that puzzles me is how they're planning on protecting it and anything else vulnerable to sea water when (or if) they start recovering and reusing these stages.

Great question.  I have been wondering about the effects of being submerged in salt water as well.

That's one big reason I liked the K1's approach to launching over land and using airbags.  To bad some internet billionaire didn't try that approach.  With proper funding maybe it would have worked.

That part also always bugged me but I guess they feel they can just decontaminate it as well as simply avoiding use alloys that are prone to corrosion.

They also could have the stage impact the ocean nose first which would protect the engines from the shock of hitting the ocean at least.

Personally I'd prefer the first stage have a scissor wing or similar but spacex does have some first rate engineers who likely know what they are doing and feel they can solve this problem.

The K1 needed a very large first stage so it could perform that RTL maneuver it also didn't travel far from the launch site.

It also needed very a high performance second stage as well.

The NK-33s are higher ISP engines then the turbine cycle merlin 1C engines Falcon uses which give better mass margins in exchange for higher costs.

As for dragon it's self they seem to be just making sure it's completely seaworthy on the safety issues with splash downs.


Who knows maybe BIll Gates will fund the K1 since it seems every billionaire has a space project and he wouldn't want to be left out.

[madscientist197]

Jim - 30/3/2008  3:01 PM

CFE - 30/3/2008  7:50 PM

On the Falcon IX upper stage, does SpaceX plan on using the Merlin 1C or the standard Merlin 1?  Additionally, how difficult will it be to mod the Merlin for air-start?  Is this a capability that's already been built-in?  If not, it may be quite difficult to pull off (in light of the obstacles to making the SSME into an upper-stage engine.)

Air starting an engine is not difficult, only air starting the SSME.  It doesn't use spin start cartridges. hypergol igniters, or boost pumps.  It just uses head pressure

This is a bit OT, but a rather interesting article on the start/shutdown cycle of the SSME - it's pretty complex, but interesting:
http://www.enginehistory.org/SSME/SSME3.pdf

[Comga]

Jim - 21/3/2008  10:25 AM

Comga - 20/3/2008  11:47 PM
It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

inner four were fixed and the outer four had 2 axis steering

Thanks, Jim
I was basing my assumption on the image shown in an old SpaceX update, and what I remember seeing in the "Rocket Garden" at KSC two years ago.  

If only the outer four engines gimbal, and do so in two axes, it is not clear what those horse-collar shapes are where each of the eight engines projects through the rear surface.

[Antares]

Water + rocket engines.  There's this
http://www.boeing.com/news/releases/1996/news.release.960827a.html

An injector is pretty expensive as well since there's a lot of machining and intricate manufacturing and welding that goes on.  If you allowed water intrusion into the nozzle and chamber, it would back flow up to the valves unless you could capture a bubble and do so repeatedly.

[Jim]

Comga - 1/4/2008  12:49 AM

If only the outer four engines gimbal, and do so in two axes, it is not clear what those horse-collar shapes are where each of the eight engines projects through the rear surface.

Access to remove and replace engines

[marsavian]

A video is worth a thousand pictures

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

[Comga]

The "burp" at shut-down is quite evident here, as it was in the nine engine test video.  I don't remember it in the videos of the Merlin 1A tests.  Is this really benign?

[zeke01]

The "burp" at shut-down is quite evident here, as it was in the nine engine test video.  I don't remember it in the videos of the Merlin 1A tests.  Is this really benign?

As explained elsewhere, the thrust decay is slower in the 1C due to fuel in the regen nozzle being burned off.  If Merlin 1A uses the ablative nozzle, thrust termination is faster because there's much less residual fuel in the plumbing downstream of the valves to burn off.

Old clips of the F-1 firings on the test stand show numerous 'burps' (or should be belches given their size! during shutdown, so it's certainly a known phenomenon.  The Saturns used SRMs to authoritatively separate the stages to overcome any residual thrust.

Benign?  Probably not if puny weak humans were standing next to them.  The burps/belches looked like explosions in the F-1 clips, but the hardware looked tuff enough to withstand them.

[A_M_Swallow]

I read that OSC would consider using the Merlin engine in the Taurus II.
See page 6 of
http://forum.nasaspaceflight.com/index.php?topic=11604.0

Rival firms negotiating over an engine could be fun to watch.

[Nate_Trost]

Even after they upgrade the turbopumps, Merlin doesn't have the thrust to replace the Aerojet engines.

[Jim]

I read that OSC would consider using the Merlin engine in the Taurus II.
See page 6 of
http://forum.nasaspaceflight.com/index.php?topic=11604.0

Rival firms negotiating over an engine could be fun to watch.

Wrong deduction and that is rumor mongering. 

1.  The merlin is not offered.  That is one of the reasons the NK-33 got chosen in the first place. 
2,  All that was basically said it that OSC would perform due diligence if the current supply of NK-33 were run out and Aerojet would have to start manufacturing them.  OSC would look at all the options. 
3.  there would be nothing to watch.  It would happen behind closed doors

[braddock]

I read that OSC would consider using the Merlin engine in the Taurus II.
See page 6 of
http://forum.nasaspaceflight.com/index.php?topic=11604.0

This is distorted quite out of context.

Let's take great care to keep the comments of our more notable members in context.  We are very fortunate that they are here.  We have lost at least one notable personality in the past because someone ran off and blogged his post out of context.

[pippin]

I read that OSC would consider using the Merlin engine in the Taurus II.
See page 6 of
http://forum.nasaspaceflight.com/index.php?topic=11604.0

Rival firms negotiating over an engine could be fun to watch.

Read it again.
antonioe was replying to a comment by me, stating that WHEN NK33s RUN OUT (that's years from now) AND SpaceX is probably not really no longer a fierce competition the world might look different.
My comment was made in the light of an earlier comment I made in another thread stating that if SpaceX adds a few more failed launches to their track record they could end up as an engine manufacturer, since this is where they have developed the biggest asset.
antonioe was stating that if it was on the market and qualified they would seriously consider it BUT that both is not the case today.

BTW, OSC is buying their SRMs from a "Rival" firm today, aren't they?

[kevin-rf]

Well antonioe has made an official reply on the Taurus II and availability of the NK33 thread, page six by my count :

http://forum.nasaspaceflight.com/index.php?topic=11604.75

To quote him ...

Let me assure you that if

 1) the technical and QA characteristics and
 2) the price of the Merlin engines

are suitable for Taurus II, and

 3) SpaceX is interested in offering them to us,

we would consider it very seriously.  As of today, though, I don't know enough about that engine to even answer question 1.
[\QUOTE]

[FutureSpaceTourist]

Cross-post, Elon talks through Merlin 1C engine:

Today we're getting a history and engineering lesson with Elon Musk about SpaceX's Raptor engine. We talk about some of the early design decisions and how the engine has evolved.

Recommended videos to help with some context [Playlist] - https://youtube.com/playlist?list=PLWzKfs3icbT55w6f9wGqXkhk_SlanIhnr

Huge thanks to Ryan Chylinksi from Cosmic Perspective for helping shoot this video! - https://www.youtube.com/c/CosmicPerspective & http://patreon.com/cosmicperspective

00:00 - Intro
00:55 - Overview of Merlin
02:30 - Ablative Merlin
04:45 - Merlin 1C regen and spiral nozzle
09:35 - First Falcon 9 Flight Rotation
11:30 - Pintle Injector
17:00 - Outro

[wannamoonbase]

I watched the video over the weekend.  My take away was the importance of trying different approaches, learning and trying again.

Traditional rocket engine design and development is slow, takes years and billions and is hardware poor.  SpaceX tried a lot of things, broke things and moved fast. 

Knowing what not to do or try matters.

It was interesting to see that Elon, 12 years later, could so easily discuss details and why they tried things.  The dude is many things, including very intelligent.

[FutureSpaceTourist]

In the above interview Tom Mueller mentions that the Merlin 1C, developed for F9, was too powerful on F1 flight 3 for the F1 structures and so had to remain throttled for the flight. He said it stayed at sea level thrust so they had to throttle as it went to vacuum.