Author Topic: Stoke Space Technologies: General Company and Development Updates and Discussions  (Read 184977 times)

Online FutureSpaceTourist

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https://twitter.com/stoke_space/status/1732399479276355610

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Stage 1, I see you. 👀🚀

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Offline Gliderflyer

Oh hello
I tried it at home

Offline ThePonjaX

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The put one more picture on Instagram:
https://www.instagram.com/p/C0g5uiarrXA/


Offline kkattula

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That is assuming a traditional capsule design flying on top of the upper stage, no?  Since the upper stage is already capable of entry and landing, you could add an integrated crew cabin with life support, like a sort of "mini starship".  Power is probably already available if the upper stage is designed for long-duration missions (fuel cells?)  Thermal control might require adding some radiators, but this wouldn't be a huge amount of mass. 

I don't know the exact mass breakdown of Dragon, but I would guess that more than half the mass is the propulsion systems, heat shield, parachutes, etc.  So it seems plausible that you could build an integrated stage/crew vehicle roughly on-par with Dragon in capability by adding 3mT of mass.

Incorporating a launch escape system into such a design would add back most of the mass you're saving. Launch escape may be overrated but for now many customers including NASA do care about it so it can't be ignored.

Just give the crew ejection seats. 

A modern ejection seat is about 60 kg.  Call it 100 with extra propulsion to get well away and a deployable shield for extra protection from the slipstream, plus a ballute heat shield if they're high enough to need to re-enter. If it was good enough for Gemini and Shuttle...

Offline TrevorMonty



That is assuming a traditional capsule design flying on top of the upper stage, no?  Since the upper stage is already capable of entry and landing, you could add an integrated crew cabin with life support, like a sort of "mini starship".  Power is probably already available if the upper stage is designed for long-duration missions (fuel cells?)  Thermal control might require adding some radiators, but this wouldn't be a huge amount of mass. 

I don't know the exact mass breakdown of Dragon, but I would guess that more than half the mass is the propulsion systems, heat shield, parachutes, etc.  So it seems plausible that you could build an integrated stage/crew vehicle roughly on-par with Dragon in capability by adding 3mT of mass.

Incorporating a launch escape system into such a design would add back most of the mass you're saving. Launch escape may be overrated but for now many customers including NASA do care about it so it can't be ignored.

Just give the crew ejection seats. 

A modern ejection seat is about 60 kg.  Call it 100 with extra propulsion to get well away and a deployable shield for extra protection from the slipstream, plus a ballute heat shield if they're high enough to need to re-enter. If it was good enough for Gemini and Shuttle...

Safety standards have moved on from Gemini and Shuttle days.

Offline john smith 19

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The put one more picture on Instagram:
It looks a very conventional rings-and-stringer design.

This is interesting as this is part of how the Titan II achieved it's very good mass ratio (although historically it's been expensive) that have suggested it's stages could have achieved SSTO individually.

Personally I always thought there were better ways to do the mfg.

I pictured 2 sheets. Press the stringers into one, form it into a cylinder, then wrap a second sheet around it as the skin, then join together, then cut out the sheet sections between the stringers.
What made rings-and-stringer expensive was the huge amount of parts handling and the individual QC documentation for each individual stringer (and ring)
If they have found a better way to do it ( which IMHO should be possible, given the 8 decades since the first successful Titan 1 launch in 1959) this could be a winner.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¨cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Crispy

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Personally I always thought there were better ways to do the mfg.

I pictured 2 sheets. Press the stringers into one, form it into a cylinder, then wrap a second sheet around it as the skin, then join together, then cut out the sheet sections between the stringers.
What made rings-and-stringer expensive was the huge amount of parts handling and the individual QC documentation for each individual stringer (and ring)
If they have found a better way to do it ( which IMHO should be possible, given the 8 decades since the first successful Titan 1 launch in 1959) this could be a winner.
"Cutting out the section between the stringers" seems like the hard part, as they touch the outer skin. You'd need a very well tuned laser, or a sawblade exactly as long as the inner skin is thick!

How about instead, laser cut the whole internal stiffening sheet first, press/bend the stringers (and rings? or at least small flat ring-segments to keep things stable) into it while flat, then roll it up in the outer skin like a sushi chef with a spot welder running back and forth until it curves round to be joined at the seam.

Offline Action

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It looks a very conventional rings-and-stringer design.

This is interesting as this is part of how the Titan II achieved it's very good mass ratio (although historically it's been expensive) that have suggested it's stages could have achieved SSTO individually.

I'm pretty sure the Titan II used a milled isogrid for a very strong and very lightweight structure, but I understand that technique is expensive.  Conventional stringers are known to be heavy.

Offline TrevorMonty

Being reuseable Stoke can afford to spend a bit more to make it super light weight.

Quote
Let's go!  Stage 1 dev tank on the road to our Moses Lake Test Site for proof testing.

https://x.com/stoke_space/status/1735298587251081259?s=20
« Last Edit: 12/14/2023 03:04 pm by spacenuance »

Offline Emmettvonbrown

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It looks a very conventional rings-and-stringer design.

This is interesting as this is part of how the Titan II achieved it's very good mass ratio (although historically it's been expensive) that have suggested it's stages could have achieved SSTO individually.

I'm pretty sure the Titan II used a milled isogrid for a very strong and very lightweight structure, but I understand that technique is expensive.  Conventional stringers are known to be heavy.

It still has the propellant mass fraction record (Titan II, stage 1) at 0.962  - 118 mt with propellant tanks filled, only 4.5 mt with empty tanks. As good as a coke can, except one much larger and that rockets into space.
Titan was to be Atlas backup because the later balloon tanks and droppable engines scared SAC generals. In the end, Martin  almost bet Convair's Atlas at its own game - except with a classic rocket. Titan I was already pretty lightweight, yet they managed to weight trim it even more to create Titan II.

Offline Action

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It looks a very conventional rings-and-stringer design.

This is interesting as this is part of how the Titan II achieved it's very good mass ratio (although historically it's been expensive) that have suggested it's stages could have achieved SSTO individually.

I'm pretty sure the Titan II used a milled isogrid for a very strong and very lightweight structure, but I understand that technique is expensive.  Conventional stringers are known to be heavy.

It still has the propellant mass fraction record (Titan II, stage 1) at 0.962  - 118 mt with propellant tanks filled, only 4.5 mt with empty tanks. As good as a coke can, except one much larger and that rockets into space.
Titan was to be Atlas backup because the later balloon tanks and droppable engines scared SAC generals. In the end, Martin  almost bet Convair's Atlas at its own game - except with a classic rocket. Titan I was already pretty lightweight, yet they managed to weight trim it even more to create Titan II.

Oh, for sure.  The Titan II first stage was incredibly lightweight, and it achieved that while carrying a heavy upper stage and moving out very quickly. 

However, it is not the same structural system Stoke is using.  What Stoke is doing is likely to be simpler, cheaper, and heavier.

Stoke appears to be making a number of decisions in their Version 1.0 that are geared towards ease of debug and getting a product to market sooner.  That makes a ton of sense - they can optimize the darn thing later.

Offline c4fusion

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Being reuseable Stoke can afford to spend a bit more to make it super light weight.

Only to a certain degree as they need to add a bit of strength and hardware for recovery.

Offline Robotbeat

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Being reuseable Stoke can afford to spend a bit more to make it super light weight.
Agreed, they can, but they're not doing that, here.

Stringers are a pretty inexpensive construction method, generally cheaper than isogrid. It's also pretty much the only option for Stainless Steel, as SS is slower to machine a bunch of material out of and its greater density makes isogrid less effective for weight savings.

SpaceX has some of the cheapest rockets to manufacture, and they use a lot of stringers on both Falcon 9 and Starship.

Stoke is actually NOT taking an "afford to make it super lightweight because it's reusable" approach. They chose basically the least expensive approach to making medium/large rockets, basically like Starship but smaller (and built in a factory instead of a field in Texas, making quality control a lot easier).

Sure, hypothetically stringers are more work than you'd want, but it's a very appropriate option for Stoke, here.
« Last Edit: 12/15/2023 03:06 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Shaving percents off the mass fraction of the first stage is pretty much always marginal enough to be irrelevant anyway. Doubly so in a reusable vehicle; lower and slower staging means less of the ∆V comes from the 1st stage, which means the 1st stage mass fraction matters even less.
Wait, ∆V? This site will accept the ∆ symbol? How many times have I written out the word "delta" for no reason?

Offline Robotbeat

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Actually, it helps a lot even for the first stage if you're doing RTLS or a substantial reentry/landing burn as you have less dry mass to push around.
« Last Edit: 12/15/2023 03:14 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Actually, it helps a lot even for the first stage if you're doing RTLS or a substantial reentry/landing burn as you have less dry mass to push around.

That does makes sense. I spend too much time reading through historical rocket trade studies, and end up slipping back into an entirely payload-centric mindset for evaluating performance.
« Last Edit: 12/15/2023 03:21 am by JEF_300 »
Wait, ∆V? This site will accept the ∆ symbol? How many times have I written out the word "delta" for no reason?

Offline Robotbeat

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Actually, it helps a lot even for the first stage if you're doing RTLS or a substantial reentry/landing burn as you have less dry mass to push around.

That does makes sense. Will my payload-centric performance mindset ever fully die?
It's a great problem to have! Where most of the (US, at least) launchers under development are reusable, and there's over half a dozen being developed.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline greybeardengineer

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Actually, it helps a lot even for the first stage if you're doing RTLS or a substantial reentry/landing burn as you have less dry mass to push around.

That is far from the only consideration for a reusable booster. Remember that Falcon 9 gained mass and dropped in performance going from block 4 to block 5 booster from features to improve robustness, increase flight lifetime, and reduce maintenance time and effort between flights.

Offline Robotbeat

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Actually, it helps a lot even for the first stage if you're doing RTLS or a substantial reentry/landing burn as you have less dry mass to push around.

That is far from the only consideration for a reusable booster. Remember that Falcon 9 gained mass and dropped in performance going from block 4 to block 5 booster from features to improve robustness, increase flight lifetime, and reduce maintenance time and effort between flights.
It didnít drop in performance overall; performance has improved in fact.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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