Poll

When will full-scale hot-fire testing of Raptor begin?

Component tests - 2017
3 (0.6%)
Component tests - 2018
21 (4.2%)
Integrated tests -  2017
19 (3.8%)
Integrated tests -  2018
237 (47%)
Integrated tests -  2019
181 (35.9%)
Raptor is not physically scaled up
33 (6.5%)
Never
10 (2%)

Total Members Voted: 504


Author Topic: SpaceX Raptor engine (Super Heavy/Starship Propulsion) - General Thread 1  (Read 869946 times)

Online Robotbeat

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #580 on: 10/22/2017 11:46 pm »
They're going to develop and test BFS before the booster.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline vaporcobra

To me it just sounds like actual rocket engineers being cheesed off that they've been told what's what by armchair rocket engineers.

I fully agree that I am a complete non-expert in comparison to actual propulsion engineers, but that doesn't excuse the highly irrational and arrogant attitude towards Raptor. Even if scaling thrust by ~70% is far more difficult than SpaceX's RPS engineers believe it to be, almost completely discounting 1200 seconds of hot-fires, half a decade of Merlin 1D mass production, and orbital and vacuum rocketry experience fly directly counter to the ideals a functional and rational engineer/scientist ought to hold.

and FWIW, I did not start the discourse. The trash talking was begun unsolicited by a BO propulsion engineer.

I don't know if you really understand what he's saying:

What he's saying is that the Blue Origin engine is full size ... Combustion Chamber, injectors, preburner injectors, pumps, everything is full size, that requires no drawing changes (in theory) when they go to flight, full thrust SHOULD be as easy as opening up the fuel valve to the preburner to let the turbopump spin faster... i don't know if this is what they're using to alter pump speed (inevitably engine power level) or not... whether this happens or not is yet to be seen

SpaceX's Raptor is: what, help me out here ... 80% geometrically the size of the flight engine size, this means new part numbers for the combustion chamber, injector, preburner(s) injectors, pumps, if i'm understanding what Elon has said correctly, everything has to be geometrically scaled up to reach flight engine size, that is not a small task, also, dynamic similitude in fluid mechanics doesn't mean you multiply or divide everything by 0.80 ...

^ my $0.02

C

Thanks, your thoughts are appreciated.

I completely agree, and that's largely how I understood the situation. Scaling up both physical dimensions and chamber pressure by 15-25% is not said and done by any means, and the complexity of RPS and plumbing necessitate that it will be more difficult than "enlarging the CAD model by 15%", as one of the BO employees condescendingly suggested.

Howeverrrrr, I also have little doubt that SpaceX has been iterating and exploring full scale Raptor hardware during the 12+ months they've been testing its scaled prerequisites, thus learning many lessons about running an integrated 1MN methalox FFSC engine. Dozens of times and at considerable duration, as well. (Also some L2 info that strengthens this feeling, but can't say more)

Given how little Raptor will have to grow to reach its current operational performance specs, as well as SpaceX's vast (compared to BO) experience producing rocket propulsion systems, it seems implausible to say that BE-4 is closer to flight readiness because they successfully fired a full sized engine for 3 seconds, after suffering at least one major hardware failure.

Another main difference I perceive simply lies in SpaceX's decision to begin with subscale testing. They've developed some level of expertise with Raptor, even if it may not all remain applicable after scaling thrust by an additional 70%. BO has a sum total of 3 seconds of experience testing an integrated engine, even if it's full scale. Their test program could proceed utterly flawlessly, but that seems improbable. I'm sure SpaceX has had to deal with many issues with scale Raptors over 40+ tests, and I would bet money that a lot of the lessons learned with scale Raptor will transfer to full scale testing.

Again, I am self-admittedly not a technical expert. I don't currently have time to do so, due to school, but my hope is to build a decent foundation of the basics of rocketry and RPS when I have the free time. What minimal reading I've done has informed the above opinions, and I welcome any and all criticisms and corrections, as well as complete refutation. Just trying to better understand things and tweak my intuition along the way.

Offline vaporcobra

Between SX and BO, the former has launched multi-engine, multi-stage rockets to LEO. And while SX has developed almost all the key elements for BFR/BFS into LEO [excluding the refuel maneuver for other uses] in some form or other, BO has done little. Maybe BO can compete with SLS ME2, maybe they will all be close when the combusted fuel hit the launch pad, maybe they will spread over many years, maybe some will fail. But Berger is out on a fishing expediting for bad analysis.
I think Blue will be able to compete eventually. I just think SpaceX is ahead with BFR.

I have to agree. Blue Origin has been around for literally two decades, have manufactured a handful of suborbital rockets, flown those a handful of times, and have failed to travel beyond Mach 4. SpaceX has had plenty of missteps with Falcon 1 and Falcon 9, but orbital rocketry is f***** hard, and at this point they are already normalizing routine recovery and reuse.

ULA and Arianespace may wave their launch records around with the humility of pop musicians, but the reality is that they've been flying orbital rockets that suffered plenty of failures for the better part of half a century, and Atlas 5, Delta IV, and Ariane 5 are the results. SpaceX has been in the business for 8-9 years total and have only experienced two complete failures. BO has a longggg road ahead of themselves, and excessive arrogance and a lack of humility will only serve to make it even rockier.

As Robert Heinlein definitely 100% said, "The Karman line didn't exist in 1950 but once you're there, you're maybe 20% of the way to orbit."
« Last Edit: 10/23/2017 12:20 am by vaporcobra »

Offline QuantumG

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #583 on: 10/23/2017 12:48 am »
I tell ya, if ULA start flying a vehicle with a Raptor engine I'm going to have to go buy some new ice skates.

Human spaceflight is basically just LARPing now.

Offline groundbound

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #584 on: 10/23/2017 02:32 am »
I tell ya, if ULA start flying a vehicle with a Raptor engine I'm going to have to go buy some new ice skates.

Slightly OT but I would guess it is (slightly) more probably that SpaceX sells Merlins to someone else if they find themselves in dire need of another revenue stream. This assumes they could find a customer that would put it to a use that was not in direct competition.

The wildcard in all of this is the US government. They can potentially offer enough $$ to convince SpaceX to do things they would not otherwise.


Offline Kansan52

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #585 on: 10/23/2017 02:49 am »
Does the new money the Air Force possibly invest in Raptor mean SX can progress faster?

Offline jpo234

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #586 on: 10/23/2017 05:06 am »
Does the new money the Air Force possibly invest in Raptor mean SX can progress faster?
Only if they were ressource constrained before. Otherwise I would go with the old adage: Throwing manpower at a late project makes it later.
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline TomH

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #587 on: 10/23/2017 05:08 am »
I bet BFS will get to space before New Glenn or Vulcan or Ariane 6 or SLS.

Unmanned SLS will get there first. Then you'll see manned BFS on Luna and SLS will never fly again.

Most likely none of those others will ever fly again. Why sail galleons when container ships suddenly show up?

Offline vaporcobra

Does the new money the Air Force possibly invest in Raptor mean SX can progress faster?
Only if they were ressource constrained before. Otherwise I would go with the old adage: Throwing manpower at a late project makes it later.

Yeah, I wouldn't point to the additional $10m of AF money as anything remarkable. SpaceX is contractually required to invest twice as much as the AF, so it's up to around $300m total if the AF contract is taken at face value. I'm sure the money is helpful, but I doubt SpaceX is dependent upon it.

FWIW, I expect we'll see full scale testing begin before the end of 2017.

Offline Rabidpanda

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #589 on: 10/23/2017 06:07 am »

FWIW, I expect we'll see full scale testing begin before the end of 2017.

If they had a full-scale engine almost ready for testing I expect Musk would have shown off some pictures of full-scale hardware at IAC. The fact that he didn't might suggest that they are still a ways off.

FWIW, I wouldn't be surprised if we didn't see a full scale Raptor test fire until late 2018 or even 2019. These things take time.

Offline vaporcobra


FWIW, I expect we'll see full scale testing begin before the end of 2017.

If they had a full-scale engine almost ready for testing I expect Musk would have shown off some pictures of full-scale hardware at IAC. The fact that he didn't might suggest that they are still a ways off.

FWIW, I wouldn't be surprised if we didn't see a full scale Raptor test fire until late 2018 or even 2019. These things take time.

Given the fact that it would barely be appreciably larger, I doubt it. Musk's comment during the AMA also suggests that full scale testing is imminent, like months away.

I'd bet money that full scale hardware ready for testing already exists and full scale preburner testing has already begun.

But just pure speculation at this point. That's it from me!
« Last Edit: 10/23/2017 07:45 am by vaporcobra »

Offline woods170

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #591 on: 10/23/2017 07:28 am »
I bet BFS will get to space before New Glenn or Vulcan or Ariane 6 or SLS.

Unmanned SLS will get there first. Then you'll see manned BFS on Luna and SLS will never fly again.

Most likely none of those others will ever fly again. Why sail galleons when container ships suddenly show up?
Although Raptor will help revolutionize access to space it will not cause the death of all other (new) launch systems.
For example: Ariane 6 will fly, and after it a next generation Ariane vehicle will as well. The reason is simple: Europe wants it's own independently assured access to space.
When the original Ariane vehicle was being developed there was a lot of pressure from the United States to stop that development. The thinking was that Europe could get all the launch services they ever needed by buying them from the United States.
Europe developed Ariane regardless, despite that seeming to be the more expensive option.
The same applies to China.
So, once BFR/BFS is flying, there will still be vehicles such as Ariane 6 and Long March (insert a number here).

Offline Peter.Colin

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #592 on: 10/23/2017 07:36 am »
The real question here, is which engine will create the best rocket?
A few heavy 2400 kN BE4’s or many light 1700 KN Raptors?
We miss some data to answer that question, for instance the mass of both engines.

Thats probably question number one, the airforce wanted to know...

« Last Edit: 10/23/2017 07:48 am by Peter.Colin »

Offline KelvinZero

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #593 on: 10/23/2017 07:53 am »
Although Raptor will help revolutionize access to space it will not cause the death of all other (new) launch systems.
For example: Ariane 6 will fly, and after it a next generation Ariane vehicle will as well. The reason is simple: Europe wants it's own independently assured access to space.
Off topic, but I think very true, other nations will not cede space to SpaceX, they will invest what is needed to catch up. That is the really exciting time. Landing on mars is not as fundamental a milestone to me as the moment we see China test their first grasshopper, and the age of reusable rockets is here no matter how badly SpaceX may stuff up in any future endeavour.

Offline guckyfan

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #594 on: 10/23/2017 07:57 am »
I bet BFS will get to space before New Glenn or Vulcan or Ariane 6 or SLS.

Unmanned SLS will get there first. Then you'll see manned BFS on Luna and SLS will never fly again.

Robotbeat said BFS going to space. Which would be an early test flight of the SSTO kind. I fully expect that to happen in 2019 or early 2020. It may very well be BFS first. Though for the full stack I agree. It will likely be SLS.

Offline TomH

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #595 on: 10/23/2017 09:14 am »
Robotbeat said BFS going to space. Which would be an early test flight of the SSTO kind. I fully expect that to happen in 2019 or early 2020. It may very well be BFS first. Though for the full stack I agree. It will likely be SLS.

I think that's optimistic. I am confident BFR/RFS are going to succeed, but let's remember, SX hasn't even put a manned Dragon into orbit yet.

Offline TomH

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #596 on: 10/23/2017 09:22 am »
Although Raptor will help revolutionize access to space it will not cause the death of all other (new) launch systems.
For example: Ariane 6 will fly, and after it a next generation Ariane vehicle will as well. The reason is simple: Europe wants it's own independently assured access to space.
When the original Ariane vehicle was being developed there was a lot of pressure from the United States to stop that development. The thinking was that Europe could get all the launch services they ever needed by buying them from the United States.
Europe developed Ariane regardless, despite that seeming to be the more expensive option.
The same applies to China.
So, once BFR/BFS is flying, there will still be vehicles such as Ariane 6 and Long March (insert a number here).

...I think very true, other nations will not cede space to SpaceX, they will invest what is needed to catch up. That is the really exciting time. Landing on mars is not as fundamental a milestone to me as the moment we see China test their first grasshopper, and the age of reusable rockets is here no matter how badly SpaceX may stuff up in any future endeavour.

Agreed. I should have said other U.S. LVs. It will be hard to compete. Old space is too calcified and most make more money on aircraft. BO could eventually compete, but now Bezos has to think about reusable upper stages in order to do so. I expect to see serious espionage and hacking attempts by the Russians and Chinese to gain SpaceX's technology. Once it becomes obvious that BFR/BFS/Raptor are going to be successful, I expect to see Congress and the Pentagon lay restrictions and protections against that technology making its way to other nations.
« Last Edit: 10/23/2017 09:25 am by TomH »

Robotbeat said BFS going to space. Which would be an early test flight of the SSTO kind. I fully expect that to happen in 2019 or early 2020. It may very well be BFS first. Though for the full stack I agree. It will likely be SLS.

I think that's optimistic. I am confident BFR/RFS are going to succeed, but let's remember, SX hasn't even put a manned Dragon into orbit yet.
You say it like it's indicative of incompetence... no private company has ever put a manned spacecraft into orbit ever, and in the case of BFS/BFR SpaceX can set their own requirements and distribute their milestones in developing a manned ship as they like.
Failure is not only an option, it's the only way to learn.
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Offline RotoSequence

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #598 on: 10/23/2017 10:08 am »
Robotbeat said BFS going to space. Which would be an early test flight of the SSTO kind. I fully expect that to happen in 2019 or early 2020. It may very well be BFS first. Though for the full stack I agree. It will likely be SLS.

I suspect Elon means sub-orbital flight testing, with the first orbital flights not happening until they've ironed out the kinks.

Offline guckyfan

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Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #599 on: 10/23/2017 10:27 am »
Robotbeat said BFS going to space. Which would be an early test flight of the SSTO kind. I fully expect that to happen in 2019 or early 2020. It may very well be BFS first. Though for the full stack I agree. It will likely be SLS.

I suspect Elon means sub-orbital flight testing, with the first orbital flights not happening until they've ironed out the kinks.

He said "orbital speed"

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