Stoke Space

[Spaceception]

This may be an interesting video for you guys. I like the channel a lot. This isn't focused on Nova, but instead the business side of Stoke. He has a more restrained opinion about them, and is worried about funding and potential markets amid already established providers.

 

 

[Exoscientist]

23 hours ago, tater said:

The patents (US links here):

https://ppubs.uspto.gov/dirsearch-public/print/downloadPdf/20220412709

https://ppubs.uspto.gov/dirsearch-public/print/downloadPdf/20210381469

Have the same wording as the previous links. They mention that the plug/aerospike nozzle was discussed before 1960. The only patent by Bono (submitted by James Webb, NASA) dates to 1967 (there's a second also Webb that I can't find, but it's not the detailed one). A patent filed in 1961 for a plug rocket engine was granted in 1967 as well, not Bono. Nonetheless, it was apparently not a new concept even in 1961. I suppose there could well be scholarly articles regarding plug/aerospikes that are not online, but it seems hard to find references.

Krase, 1959 (w citations from well before)

 
    Yes. The plug  nozzle, variously called the aerospike and aeroplug, was known about since the early days of the space program. Bono’s innovative idea was to use to it deal with the heating during reentry. The plug nozzle then to Bono had two benefits. It would improve engine performance for a SSTO, or a near-SSTO that used drop tanks, whose engines had to fire efficiently from sea level all the way to orbit and would solve the problem of the reentry heating for that stage returning from orbit.

 It was the reentry thermal control purpose for the plug nozzle for which Bono was granted the patent. If you look at the interviews of Andy Lapsa of Stoke Space such as by Everyday Astronaut and NasaSpaceflight it is this purpose for which Stoke Space is praised for their “innovativeness”. My opinion, Phil Bono should have been given credit for this innovation.

 

 Bob Clark 

[sevenperforce]

On 3/14/2024 at 9:43 AM, Exoscientist said:

It was the reentry thermal control purpose for the plug nozzle for which Bono was granted the patent. If you look at the interviews of Andy Lapsa of Stoke Space such as by Everyday Astronaut and NasaSpaceflight it is this purpose for which Stoke Space is praised for their “innovativeness”. My opinion, Phil Bono should have been given credit for this innovation.

No, the innovation for which Stoke Space has received praise and attention is the use of a thermally-powered, actively-cooled heat shield. The fact that this heat shield also happens to function (somewhat) as a plug nozzle is secondary, and not that rare of an idea anyway. The Chrysler SERV and the Phoenix SSTO were designed to use the same approach.

Saying that Stoke Space is getting undue credit for "copying" Phil Bono's idea is like saying that Reaction Engines Limited gets undue credit for "copying" the Space Shuttle, because both designs were spaceplanes that used hydrolox for the main push to orbit, circularized with hypergolics, and landed horizontally. The thing that makes the Skylon concept unique is the super-cold heat exchanger in the SABRE engine, not the brute notion of a spaceplane. Likewise, the thing that makes the Nova rocket concept unique is the use of re-entry heat to operate the pumps for the actively-cooled heat shield using the same system that powers the engines. 

[Exoscientist]

8 minutes ago, sevenperforce said:

No, the innovation for which Stoke Space has received praise and attention is the use of a thermally-powered, actively-cooled heat shield. The fact that this heat shield also happens to function (somewhat) as a plug nozzle is secondary, and not that rare of an idea anyway. The Chrysler SERV and the Phoenix SSTO were designed to use the same approach.

 

 That is what I what I was trying to say. Phil Bono’s proposal predates Chrysler SERV and Phoenix SSTO.

    Bob Clark

[tater]

 

[Spaceception]

Looks like a 1st stage tank (probably dev) in the background.

Also

We could see a first stage engine test from them in the near future.

[sevenperforce]

11 hours ago, tater said:

That's gorgeous to see!

It's very curious to me that neither turbopump is being placed inline with the engine. An inline approach (Raptor, BE-4, RD-191) would seem like the simpler, more lightweight design. Granted, other single-chamber engines with dual-shaft (separate turbines) turbopumps (RS-25, RS-68, YF-100, Vulcain, YF-20, YF-77) have both turbopumps off-axis, but that feels like it has almost always been due to other design constraints. Maybe it's an engine length issue? Something to do with how they are handling gimbal?

I wonder if the gimbal is happening halfway down the nozzle rather than up at the top. The structure of the top of the engine looks pretty gimbal-unfriendly, and these highlighted bits around the nozzle extension look suspiciously like gimbal mounts:

(Notable that those are clearly Lapsa's kids which is just awesome.)

Putting the gimbal halfway down the engine bell is....definitely different. Probably lower control authority, among other things. But I suppose it could really reduce weight in other places.

[tater]

 

 

[AckSed]

21 hours ago, sevenperforce said:

I wonder if the gimbal is happening halfway down the nozzle rather than up at the top. The structure of the top of the engine looks pretty gimbal-unfriendly, and these highlighted bits around the nozzle extension look suspiciously like gimbal mounts

Could they be the same mountings I saw for the second-stage engine in Everyday Astronaut's walkaround? Those looked mobile, but weren't.

[darthgently]

29 minutes ago, AckSed said:

Could they be the same mountings I saw for the second-stage engine in Everyday Astronaut's walkaround? Those looked mobile, but weren't.

That is what I was thinking, just engine mounts.  Maybe the plan is a mix of gimballed and fixed engines like many boosters?

[Spaceception]

I'm looking forward to seeing their next funding round later this year. Having an engine test fire should do wonders in giving investors confidence that it's worth putting funding into, on top of whatever other progress they achieve. On the outside, I think there's a good chance they'll have all the major components of Nova (engines, tanks, avionics, heatshield, payload integration) ready to begin putting together for an inaugural launch by the end of the year.

I wonder what the payload will be, probably a dummy one, but Stoke seems like the type to have fun with it.

[Spaceception]

Okay, that looks amazing

 

[sevenperforce]

On 4/5/2024 at 8:58 AM, Spaceception said:

Okay, that looks amazing

 

Looks like a behemoth! Reminds me of the early Raptor 1s with all the extra tubing and such.

[StrandedonEarth]

What a plumbing nightmare. Dev version, I hope...

[tater]

 

[Spaceception]

Stoke has hot-fired their first stage engine! About a 2 second burn, but looking to mature the engine, conduct longer tests, abd build flight stages throughout the year.

https://x.com/stoke_space/status/1800498602361622906?t=kYqk_E6baBGvdZrehOpuUA&s=19

https://www.stokespace.com/stoke-space-completes-first-successful-hotfire-test-of-full-flow-staged-combustion-engine/

https://arstechnica.com/space/2024/06/stoke-space-ignites-its-ambitious-main-engine-for-the-first-time/

[Spaceception]

Pictures, now that I can post from my laptop

 

 

 

[Exoscientist]

On 6/11/2024 at 11:36 AM, Spaceception said:

Stoke has hot-fired their first stage engine! About a 2 second burn, but looking to mature the engine, …

 Following the SpaceX lead, this now counts as a “full duration” burn. 
 

  Bob Clark

[sevenperforce]

10 hours ago, Exoscientist said:

 Following the SpaceX lead, this now counts as a “full duration” burn. 

For the nth time -- if the duration of the test was intended to be two seconds, then this engine completed the full duration of the test fire.

If I attempt to complete a certain amount of work and I complete 100% of the work I attempted to complete, then I have completed that work even if another part of the underlying task remains outstanding for the next day.

[darthgently]

1 hour ago, sevenperforce said:

For the nth time -- if the duration of the test was intended to be two seconds, then this engine completed the full duration of the test fire.

If I attempt to complete a certain amount of work and I complete 100% of the work I attempted to complete, then I have completed that work even if another part of the underlying task remains outstanding for the next day.

Yep. Has there ever been a rocket engine test officially tagged a "partial duration test" for example?  But even if one means that an engine should be fired for the same duration as it would be during launch, well those are done quite often.  But most publicity video shorts are short videos of full tests of shorter duration. 

And a "launch duration test" ™️ still doesn't test fuel icing and slosh, ambient pressure changes with altitude, and bird strikes.  For full safety we really need to be doing full bird strike tests of all rocket engines.  Until then every one of them is a ticking timebomb

Edited June 18 by darthgently

[Exoscientist]

3 hours ago, sevenperforce said:

For the nth time -- if the duration of the test was intended to be two seconds, then this engine completed the full duration of the test fire.

If I attempt to complete a certain amount of work and I complete 100% of the work I attempted to complete, then I have completed that work even if another part of the underlying task remains outstanding for the next day.

 If Blue Origin continually referred to their little suborbital hops by New Shepard  as “flights to orbit”, it would then be accepted in the rest of the industry they are flights to orbit. You just have to keep repeating it.

  Bob Clark

[darthgently]

20 minutes ago, Exoscientist said:

You just have to keep repeating it.

But you keep repeating things and it isn't working.  Strange

[magnemoe]

2 hours ago, darthgently said:

Yep. Has there ever been a rocket engine test officially tagged a "partial duration test" for example?  But even if one means that an engine should be fired for the same duration as it would be during launch, well those are done quite often.  But most publicity video shorts are short videos of full tests of shorter duration. 

And a "launch duration test" ™️ still doesn't test fuel icing and slosh, ambient pressure changes with altitude, and bird strikes.  For full safety we really need to be doing full bird strike tests of all rocket engines.  Until then every one of them is a ticking timebomb

Agree, now an rocket engine burning for minutes would get kind of dull to watch. Also starting the engine is harder than running it. 
Still why call it full duration burns if its not?  I'ts also an static fire but here I think of the full stage firing not an single engine on a stand.

[JoeSchmuckatelli]

3 hours ago, magnemoe said:

full duration burns

I've always assumed that phrase meant 'duration the rocket would be lit during a launch' - so, like, a little over 2 minutes for a Falcon. 

Doesn't that allow them to make sure the engine won't eat itself before stage separation? 

[tater]

Full duration for a test is the duration required to get the data they need. I would imagine for a new engine, the biggest concerns would be startup transients. They want to see it move to steady state—they they're done.

Longer burns will certainly be done at some point I would assume.