Author Topic: Raptor Engine - Maiden Flight Options  (Read 14452 times)

Offline tp1024

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Raptor Engine - Maiden Flight Options
« on: 01/09/2015 11:16 pm »
Ok, the idea behind this is as follows:

It would not be clever to build a full up BFR with 10 Raptor engines (or more) without first having tested Raptor engines in a real space environment. If I was in charge of building something like BFR, I'd insist on first building something that is easy, predictable and cheap ... and only has a single Raptor engine to take care of.

My first thoughts revolved around improving what they have or building another rocket. Something that might be useful.

1) A 200t, two stage rocket. First stage powered by a Raptor (150t fuel, 7t empty mass), second stage is a Merlin Vac (40t fuel, 3t empty mass), which results in a performance roughly comparable to a Soyuz rocket. (roughly 8t LEO, 3t GTO)

Disadvantages: Non-reusable, redundant (a Falcon 9 can do this with reusable 1st stage)

2) An improved Falcon Heavy upper stage, using a vacuum Raptor - this should result in roughly 30% higher GTO payloads in fully expendable flights. More in reusable flights. This has a chance of working if it is true that it can be throttled down deeply (supposedly from 100% to 30% if memory serves - which would be in line with similar engines).

This actually seems like it might be a good idea in the long run. But - Disadvantages: Requires an expensive Falcon Heavy just to test Raptor (plus: payloads would be hard to come by or without much profit). Raptor cannot be safely started on the ground.

2*) A combination of 1) and 2) - build the rocket of the first suggestion, test it, use it a few times, put it on top of a Falcon Heavy. Because, secretly, we all know that rockets are LEGOs. ::)

3) Forget about all that. Build a single Falcon9-derived stage with 200t of mass and a single Raptor engine. Empty mass should be no more than 8t (including some residual fuel). This stage could single-handedly deliver a 4t payload into LEO. 8)

Disadvantage: Non-reusable. No further economic usefulness.

Offline Lars-J

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Re: Raptor Engine - Maiden Flight Options
« Reply #1 on: 01/10/2015 02:04 am »
Ok, the idea behind this is as follows:

It would not be clever to build a full up BFR with 10 Raptor engines (or more) without first having tested Raptor engines in a real space environment. If I was in charge of building something like BFR, I'd insist on first building something that is easy, predictable and cheap ... and only has a single Raptor engine to take care of.

My first thoughts revolved around improving what they have or building another rocket. Something that might be useful.

1) A 200t, two stage rocket. First stage powered by a Raptor (150t fuel, 7t empty mass), second stage is a Merlin Vac (40t fuel, 3t empty mass), which results in a performance roughly comparable to a Soyuz rocket. (roughly 8t LEO, 3t GTO)

Disadvantages: Non-reusable, redundant (a Falcon 9 can do this with reusable 1st stage)

2) An improved Falcon Heavy upper stage, using a vacuum Raptor - this should result in roughly 30% higher GTO payloads in fully expendable flights. More in reusable flights. This has a chance of working if it is true that it can be throttled down deeply (supposedly from 100% to 30% if memory serves - which would be in line with similar engines).

This actually seems like it might be a good idea in the long run. But - Disadvantages: Requires an expensive Falcon Heavy just to test Raptor (plus: payloads would be hard to come by or without much profit). Raptor cannot be safely started on the ground.

2*) A combination of 1) and 2) - build the rocket of the first suggestion, test it, use it a few times, put it on top of a Falcon Heavy. Because, secretly, we all know that rockets are LEGOs. ::)

3) Forget about all that. Build a single Falcon9-derived stage with 200t of mass and a single Raptor engine. Empty mass should be no more than 8t (including some residual fuel). This stage could single-handedly deliver a 4t payload into LEO. 8)

Disadvantage: Non-reusable. No further economic usefulness.

There is absolutely no reason for this. Ground testing is sufficient to iron out combustion and do thorough testing. If there was no need to mount the F-1 on a tiny rocket before launching the Saturn V, there it sure isn't needed for Raptor.

Keep in mind that if the vehicle is reusable, it can be tested like Grasshopper as well. Test as you fly. Fly as you test.

Offline macpacheco

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Re: Raptor Engine - Maiden Flight Options
« Reply #2 on: 01/14/2015 05:33 pm »
There is absolutely no reason for this. Ground testing is sufficient to iron out combustion and do thorough testing. If there was no need to mount the F-1 on a tiny rocket before launching the Saturn V, there it sure isn't needed for Raptor.

Keep in mind that if the vehicle is reusable, it can be tested like Grasshopper as well. Test as you fly. Fly as you test.
So what you're saying is that testing the engine itself only needs the test stand. After stand testing is done, they are testing the rocket instead of the engine ?
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Offline Lars-J

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Re: Raptor Engine - Maiden Flight Options
« Reply #3 on: 01/14/2015 06:07 pm »
There is absolutely no reason for this. Ground testing is sufficient to iron out combustion and do thorough testing. If there was no need to mount the F-1 on a tiny rocket before launching the Saturn V, there it sure isn't needed for Raptor.

Keep in mind that if the vehicle is reusable, it can be tested like Grasshopper as well. Test as you fly. Fly as you test.
So what you're saying is that testing the engine itself only needs the test stand. After stand testing is done, they are testing the rocket instead of the engine ?

Basically, yes. The engine won't be flown on a rocket until it has been qualified through testing.

Offline AncientU

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Re: Raptor Engine - Maiden Flight Options
« Reply #4 on: 01/14/2015 06:17 pm »
There is absolutely no reason for this. Ground testing is sufficient to iron out combustion and do thorough testing. If there was no need to mount the F-1 on a tiny rocket before launching the Saturn V, there it sure isn't needed for Raptor.

Keep in mind that if the vehicle is reusable, it can be tested like Grasshopper as well. Test as you fly. Fly as you test.
So what you're saying is that testing the engine itself only needs the test stand. After stand testing is done, they are testing the rocket instead of the engine ?

Basically, yes. The engine won't be flown on a rocket until it has been qualified through testing.

For M1D, that was flight qualification of the design (exhaustive testing regime) followed by testing each flight engine individually at McGregor and then the set of nine at McGregor for full duration.  Of course, there is also the static fire on the pad before launch which is more about the full launch system readiness...

The testing approach not broken, so why fix it.
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Offline J-V

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Re: Raptor Engine - Maiden Flight Options
« Reply #5 on: 01/15/2015 06:03 am »
What if they start with an equivalent of Grasshopper first? Instead of building a full blown BFR, just start with one engine and make sure you can land with it. Then add more engines, fix problems as they arise, and when everything is working with full number of engines, add the second stage.

Offline macpacheco

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Re: Raptor Engine - Maiden Flight Options
« Reply #6 on: 01/15/2015 02:32 pm »
What if they start with an equivalent of Grasshopper first? Instead of building a full blown BFR, just start with one engine and make sure you can land with it. Then add more engines, fix problems as they arise, and when everything is working with full number of engines, add the second stage.
They need to test the engine alone, then test the rocket stages that will actually fly.
The Grasshopper program main purpose was to learn the reusability algorithms, concepts, get the knowlege. Once they have the methods that result in success for reuse, they just need to scale them for a bigger (operational) rocket.
I initially thought like you, but it seems our idea makes no sense.
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Offline tp1024

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Re: Raptor Engine - Maiden Flight Options
« Reply #7 on: 01/15/2015 03:28 pm »

For M1D, that was flight qualification of the design (exhaustive testing regime) followed by testing each flight engine individually at McGregor and then the set of nine at McGregor for full duration.  Of course, there is also the static fire on the pad before launch which is more about the full launch system readiness...

The testing approach not broken, so why fix it.

Yes, but that was an engine derivative of Merlin-1C, which they had a lot of flight experience with. Raptor is a completely new engine. It's not just higher pressure and a new turbo pump for a well-known engine. This is genuinely new stuff. And I wouldn't want to nurse 5 or 9 completely new engines at the start of a new rocket program, if I was in charge of it. SpaceX is still having the occasional trouble with Merlin 1D and I don't think they'll take it lightly. (Just remember the failure to restart after Cassiope was released.)

Before Falcon 9, they build Falcon1 to test the whole system. And that turned out to be a good idea if you look at flights 1 and 3. It would have been absolutely unreasonable to start with a Falcon 9 or a Falcon 5 (which the plan originally called for). Simply because a higher number of engines makes for a more complex rocket stage.

The same thing is true for the Angara rockets. Testing started (arguably) with South Koreas Naro rockets and despite three successful (1st stage) flights there, they still felt compelled to start testing with Angara 1.2 instead of Angara 5.

Given that F9 cores are already being mass produced, bulding a test article from one of those should be straight-forward. It wouldn't add much work to the test program. There would be no need to wait for facilities to build the much larger BFR stage, instead you could fly the engine independent of that development. You want to find problems as early as possible in the development process, not at the very end of a critical path.

Add to that the possibility to use Raptor in a high ISP 2nd stage for FH, there isn't much reason not to do it.
« Last Edit: 01/15/2015 03:31 pm by tp1024 »

Offline Lars-J

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Re: Raptor Engine - Maiden Flight Options
« Reply #8 on: 01/15/2015 08:19 pm »
What if they start with an equivalent of Grasshopper first? Instead of building a full blown BFR, just start with one engine and make sure you can land with it. Then add more engines, fix problems as they arise, and when everything is working with full number of engines, add the second stage.

That's certainly possible. If it is designed to be fully reusable, starting with short hops on fewer engines might make sense. But that would still be a full-scale vehicle - NOT a small test vehicle as the original thread starter was arguing.

Offline Lars-J

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Re: Raptor Engine - Maiden Flight Options
« Reply #9 on: 01/15/2015 08:21 pm »

There is absolutely no reason for this. Ground testing is sufficient to iron out combustion and do thorough testing. If there was no need to mount the F-1 on a tiny rocket before launching the Saturn V, there it sure isn't needed for Raptor.

Keep in mind that if the vehicle is reusable, it can be tested like Grasshopper as well. Test as you fly. Fly as you test.
Lars, you may have just posted one the most jaw dropping things I've ever read. 

The purpose of "testing" is to show that a design can deliver to the requirements (or... "the operational objectives").  Testing may also be performed to show that a risk is not as significant as may have been subjectively thought prior to its first usage.  But one should not simply define tests for testing sake (which is quite common).

Yes, everyone already knows the system will function like a rocket... but there is a lot more to rocket science that really drives the need for testing.  Aim a Raptor vertically at a floating autonomous barge and impinge the surface with LOX/methane combustion products (or other) similar to the CONOPS. 

Or just do things the hard way.  The world is full of money.

 I think you somehow managed to completely misunderstand what I wrote. Can you highlight the sentence where I  wrote what you think I wrote?

Offline Joel

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Re: Raptor Engine - Maiden Flight Options
« Reply #10 on: 01/15/2015 09:14 pm »
I like the idea of starting with 2nd stage on top of a fully reusable FH first stage. With earlier staging and all three cores return-to-LS. Would be nice to see the math.

Offline newpylong

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Re: Raptor Engine - Maiden Flight Options
« Reply #11 on: 01/16/2015 12:42 am »
There will be no need to test the BFR like grasshopper. That was/is to evaluate and push the envelope on the concepts. They can be adapted to a larger vehicle which can then be dropped into the ocean enough times until it can be recovered, just like F9.

You'll see a single engine tested, then the core tested and then a  full up launch - just like S-V and SLS.

Offline ChrisWilson68

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Re: Raptor Engine - Maiden Flight Options
« Reply #12 on: 01/16/2015 01:48 am »
Given that F9 cores are already being mass produced, bulding a test article from one of those should be straight-forward. It wouldn't add much work to the test program.

I don't agree.  It's a methane engine versus a stage built to store kerosene.  I think you'd need a very different stage for a Raptor engine.

Offline ChrisWilson68

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Re: Raptor Engine - Maiden Flight Options
« Reply #13 on: 01/16/2015 01:50 am »
Given that F9 cores are already being mass produced, bulding a test article from one of those should be straight-forward. It wouldn't add much work to the test program.

I don't agree.  It's a methane engine versus a stage built to store kerosene.  I think you'd need a very different stage for a Raptor engine.

Also, the thrust structure is totally different, because it's not 9 engines.

And the control software needs to be different because it's a different engine with different characteristics.

And you'd need different pad infrastructure to support a kerosene stage versus a methane stage.

It sounds like lots of expense to me.

Offline Patchouli

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Re: Raptor Engine - Maiden Flight Options
« Reply #14 on: 01/16/2015 01:59 am »
Given that F9 cores are already being mass produced, bulding a test article from one of those should be straight-forward. It wouldn't add much work to the test program.

I don't agree.  It's a methane engine versus a stage built to store kerosene.  I think you'd need a very different stage for a Raptor engine.


F9 does carry LOX which is colder then liquid methane.

A test rocket built with F9 tooling could pretty much use construction similar to the lox tank for the methane tank.
« Last Edit: 01/16/2015 02:02 am by Patchouli »

Offline CJ

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Re: Raptor Engine - Maiden Flight Options
« Reply #15 on: 01/16/2015 02:56 am »
IMHO, the second stage raptor (Raptor Vac) is the one that might need some creative testing methods (conventional ground testing should suffice for the first stage engines). The issue I'm concerned about for the Raptor Vac is ignition. 

Some second stage engines have required vacuum changers of immense proportions to test their ignition in a vacuum; the 350 million A3 test stand at Stennis comes to mind. It was intended for the JX2.

If (and that's the reason for my post, I don't know) the Raptor Vac would need such a stand, perhaps a flight test would be cheaper? Would it, perhaps, be more cost effective to use a F9 first stage as a launch vehicle for a Raptor Vac 2nd test stage modeled on a F9 2nd stage? You wouldn't need to get it to orbit, just to staging height - velocity is irrelevant for this. Could doing a couple of launches like that with existing F9 first stages be cheaper than a Raptor Vac test stand?

One huge problem comes to mind regarding this idea; a raptor attached to a stage with the same mass as a F9 2nd stage would pull one hell of a lot of G, resulting in failure. However, if all they are looking to test is ignition, it might not matter. Or, if they need to both ignite and do a burn, a wild idea I had (and perhaps too much so) would be mount the raptor powered 2n'd stage upside down, and don't sep the stages.

I have no idea how hard it would be to create a small F9 2nd stage raptor version. My guess is it'd take a lot of engineering to convert the RP1 tank to methane, and the thrust structures would need to be totally re-engineered (and that's a lot more involved than even converting the tank).  But, *if* they'd otherwise need to build an enormous vacuum chamber test stand (a big brother to A3) might it be the least bad option?


     

Offline Lars-J

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Re: Raptor Engine - Maiden Flight Options
« Reply #16 on: 01/16/2015 03:20 am »
IMHO, the second stage raptor (Raptor Vac) is the one that might need some creative testing methods (conventional ground testing should suffice for the first stage engines). The issue I'm concerned about for the Raptor Vac is ignition.

Why? Not a single SpaceX upper stage engine has failed to start.

Re-start? Yes, there has been one (or two?) occurrence. But starting an upper stage engine is NOT cutting edge science.

Offline CJ

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Re: Raptor Engine - Maiden Flight Options
« Reply #17 on: 01/16/2015 04:51 am »
IMHO, the second stage raptor (Raptor Vac) is the one that might need some creative testing methods (conventional ground testing should suffice for the first stage engines). The issue I'm concerned about for the Raptor Vac is ignition.

Why? Not a single SpaceX upper stage engine has failed to start.

Re-start? Yes, there has been one (or two?) occurrence. But starting an upper stage engine is NOT cutting edge science.

I do see your point, but what's confusing me is this; the J2X was based on the already-proven J2 engine, which was also vac start. The J2 apparently didn't need an enormous vacuum-chamber test stand, but for some reason, the J2x would, and badly enough that they spent $350 million on a vacuum test stand.

So, seeing as how no one has ever vac started a staged combustion methlox engine, can we be sure that whatever required a vacuum chamber test stand for the J2X doesn't apply to the Raptor vac? I certainly hope it doesn't, for things would be far simpler without any need for vac testing, but do we actually know?


Offline J-V

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Re: Raptor Engine - Maiden Flight Options
« Reply #18 on: 01/16/2015 05:58 am »
There will be no need to test the BFR like grasshopper. That was/is to evaluate and push the envelope on the concepts. They can be adapted to a larger vehicle which can then be dropped into the ocean enough times until it can be recovered, just like F9.

You'll see a single engine tested, then the core tested and then a  full up launch - just like S-V and SLS.

I used the grasshopper above, even though I should have used BFR-dev1. In my opinion the reason to start development with small hops isn't technological difficulties (not that there wouldn't be enough of those), but economical. AFAIK there aren't any payloads that need the capability of BFR and a rocket of that size won't be cheap. That means that dropping first stages to the drink until all the details are ironed out is going to be expensive. Very expensive.

With dev vehicle there is still a chance of blowing it up, but the risk is much smaller. Also remember that BFR is supposed to be reusable, so why not start with that in the test program. From operations point of view it's more like developing a plane than a traditional rocket, isn't it?

Offline guckyfan

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Re: Raptor Engine - Maiden Flight Options
« Reply #19 on: 01/16/2015 06:18 am »
Actually I have been thinking of placing a Raptor engine on a Falcon 9 first stage tank. But not for flight. I imagine that could be the simplest and most livelike Raptor test stand they could build. Just put that combination on the McGregor  FH testand.

I can't rule out though that the idea is completely nuts for reasons I don't understand.

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Re: Raptor Engine - Maiden Flight Options
« Reply #20 on: 01/16/2015 08:41 am »
I think we'll all be able to see into the depths of our flight test crystal balls more clearly once a raptor engine of any sort has been fired on a test stand.
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Offline Ben the Space Brit

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Re: Raptor Engine - Maiden Flight Options
« Reply #21 on: 01/16/2015 10:43 am »
It depends on the diameter of the engine mechanism (pumps, support frame and articulator) however, one flight test option is to mount one on the bottom of a re-tanked F9 core. It doesn't have to be pretty. It is only intended to make sure the engine flies without suffering a spontaneous in-flight explosive self-disassembly and then plunk into the mid-Atlantic. You don't want to use too many engines, so reusing F9 tooling to build the flight test tanks/fuselage (and reuse F9 core electronics as the IU for the test flight) would make sense.
« Last Edit: 01/16/2015 10:44 am by Ben the Space Brit »
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Offline hrissan

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Re: Raptor Engine - Maiden Flight Options
« Reply #22 on: 01/16/2015 12:18 pm »
There will be no need to test the BFR like grasshopper. That was/is to evaluate and push the envelope on the concepts. They can be adapted to a larger vehicle which can then be dropped into the ocean enough times until it can be recovered, just like F9.

You'll see a single engine tested, then the core tested and then a  full up launch - just like S-V and SLS.

I used the grasshopper above, even though I should have used BFR-dev1. In my opinion the reason to start development with small hops isn't technological difficulties (not that there wouldn't be enough of those), but economical. AFAIK there aren't any payloads that need the capability of BFR and a rocket of that size won't be cheap. That means that dropping first stages to the drink until all the details are ironed out is going to be expensive. Very expensive.

With dev vehicle there is still a chance of blowing it up, but the risk is much smaller. Also remember that BFR is supposed to be reusable, so why not start with that in the test program. From operations point of view it's more like developing a plane than a traditional rocket, isn't it?
I remember Elon said "scaling up" sometimes in reference to BFR, so after good deal of experience with Falcon (it may easily make 100+ core landing attempts (0-1 per F9, 2-3 per F9H) before BFR first flight) they may be confident enough that the very first BFR flight will result in good landing.

But you may also be right, I can easily believe SpaceX turning the structural-test article of BFR stage into giant grasshopper and playing with it, might be rather cheap - free tank and just 1-3 raptors.

And quite naturally if this thing flies up 50+ kilometers, might be a cheap test stand for reignition tests in free-fall/near vacuum, just mount a vacuum raptor with sea-level nozzle.

Offline newpylong

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Re: Raptor Engine - Maiden Flight Options
« Reply #23 on: 01/16/2015 06:04 pm »
IMHO, the second stage raptor (Raptor Vac) is the one that might need some creative testing methods (conventional ground testing should suffice for the first stage engines). The issue I'm concerned about for the Raptor Vac is ignition.

Why? Not a single SpaceX upper stage engine has failed to start.

Re-start? Yes, there has been one (or two?) occurrence. But starting an upper stage engine is NOT cutting edge science.

I do see your point, but what's confusing me is this; the J2X was based on the already-proven J2 engine, which was also vac start. The J2 apparently didn't need an enormous vacuum-chamber test stand, but for some reason, the J2x would, and badly enough that they spent $350 million on a vacuum test stand.

So, seeing as how no one has ever vac started a staged combustion methlox engine, can we be sure that whatever required a vacuum chamber test stand for the J2X doesn't apply to the Raptor vac? I certainly hope it doesn't, for things would be far simpler without any need for vac testing, but do we actually know?

In the end, J-2X had little to no heritage in J-2. A3 was built because the engine was supposed to have an expandable nozzle bigger than any existing chamber could accommodate. Of course it's just one of many examples of Constellation putting the cart before the house (like the Mobile Launcher and Upper Stage tooling for Ares-I when the vehicle basically failed PDR).

/end history lesson and back to thread topic

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Re: Raptor Engine - Maiden Flight Options
« Reply #24 on: 01/16/2015 06:30 pm »
Given that F9 cores are already being mass produced, bulding a test article from one of those should be straight-forward. It wouldn't add much work to the test program.

I don't agree.  It's a methane engine versus a stage built to store kerosene.  I think you'd need a very different stage for a Raptor engine.


F9 does carry LOX which is colder then liquid methane.

A test rocket built with F9 tooling could pretty much use construction similar to the lox tank for the methane tank.

Tanks would need slight adjustments in length for correct fuel/oxidizer ratio. The other variables would seem to be more problematic.

Offline hkultala

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Re: Raptor Engine - Maiden Flight Options
« Reply #25 on: 01/18/2015 04:27 am »
IMHO, the second stage raptor (Raptor Vac) is the one that might need some creative testing methods (conventional ground testing should suffice for the first stage engines). The issue I'm concerned about for the Raptor Vac is ignition.

Why? Not a single SpaceX upper stage engine has failed to start.

Re-start? Yes, there has been one (or two?) occurrence. But starting an upper stage engine is NOT cutting edge science.

I do see your point, but what's confusing me is this; the J2X was based on the already-proven J2 engine, which was also vac start. The J2 apparently didn't need an enormous vacuum-chamber test stand, but for some reason, the J2x would, and badly enough that they spent $350 million on a vacuum test stand.

AFAIK they had built a gigantic test stand for J-2 in the sixties. And they could have used the same old test chamber with very slight/cheap modifications/reparations also to test J-2X, but pork senators won and instead of repairing/modifying the old chamber, they built a totally new one to get jobs to some senator's district.

Quote
So, seeing as how no one has ever vac started a staged combustion methlox engine, can we be sure that whatever required a vacuum chamber test stand for the J2X doesn't apply to the Raptor vac? I certainly hope it doesn't, for things would be far simpler without any need for vac testing, but do we actually know?

Spacex can launch _many_ first stages for the price of 350 million. NASA cannot. Or it's against their philosophy.

For SpaceX, it's cheaper to "test" the upper stages in real flights than construct a very expensive test stand for the testing.

Offline newpylong

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Re: Raptor Engine - Maiden Flight Options
« Reply #26 on: 01/19/2015 01:07 am »
IMHO, the second stage raptor (Raptor Vac) is the one that might need some creative testing methods (conventional ground testing should suffice for the first stage engines). The issue I'm concerned about for the Raptor Vac is ignition.

Why? Not a single SpaceX upper stage engine has failed to start.

Re-start? Yes, there has been one (or two?) occurrence. But starting an upper stage engine is NOT cutting edge science.

I do see your point, but what's confusing me is this; the J2X was based on the already-proven J2 engine, which was also vac start. The J2 apparently didn't need an enormous vacuum-chamber test stand, but for some reason, the J2x would, and badly enough that they spent $350 million on a vacuum test stand.

AFAIK they had built a gigantic test stand for J-2 in the sixties. And they could have used the same old test chamber with very slight/cheap modifications/reparations also to test J-2X, but pork senators won and instead of repairing/modifying the old chamber, they built a totally new one to get jobs to some senator's district.

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So, seeing as how no one has ever vac started a staged combustion methlox engine, can we be sure that whatever required a vacuum chamber test stand for the J2X doesn't apply to the Raptor vac? I certainly hope it doesn't, for things would be far simpler without any need for vac testing, but do we actually know?

Spacex can launch _many_ first stages for the price of 350 million. NASA cannot. Or it's against their philosophy.

For SpaceX, it's cheaper to "test" the upper stages in real flights than construct a very expensive test stand for the testing.

The vaccum chamber that was used for J-2 and RL-10 testing was a Rocketdyne facility, not NASA. More importantly, it could not accommodate the extendable nozzle of the planned J-2S and subsequent J-2X, and neither could Plum Brook.

That is why A-3 was built.

We have no idea what the testing requirements are going to be for a SpaceX EDS engine - so it is premature to say trial by fire without testing will be the preferred path.
« Last Edit: 01/19/2015 01:22 am by newpylong »

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