New Armstrong Speculation and Discussion

[Aeneas]

Would Blue Origin copy SpaceX's use of stainless steel?

Sounds very plausible that BO could build NA out of stainless steel.

I doubt it. I'd bet aluminum or possibly composite.

Do you think they can reduce production costs similar to the stainless steel designs?

[TrevorMonty]

For  RLV build cost is less important than operational cost. I think they will use the same construction system as NG for booster. US I don't know.

[spacenut]

For reusable upper stages, stainless steel seems to be a good choice since it can take higher temperatures, and is cheaper to use.  A composite would be great, but would require more heat shielding, which could be a trade off, but be more expensive.  Aluminum has a low melting point and also would require more heat shielding.  Don't know what New Armstrong would use. 

[TrevorMonty]

Can use Al with heatshield (ceramic composite) and water or LH cooling on high temp spots, this was Skylon design.

[envy887]

For  RLV build cost is less important than operational cost. I think they will use the same construction system as NG for booster. US I don't know.

Stainless should reduce operational cost, in addition to build cost, for an RLV. It's less affected by reentry heating, and needs less TPS. TPS tends to be fragile, complex, and expensive to build and maintain, and anything that simpiflies it will trade well for an RLV.

[TrevorMonty]

For  RLV build cost is less important than operational cost. I think they will use the same construction system as NG for booster. US I don't know.

Stainless should reduce operational cost, in addition to build cost, for an RLV. It's less affected by reentry heating, and needs less TPS. TPS tends to be fragile, complex, and expensive to build and maintain, and anything that simpiflies it will trade well for an RLV.

Need to perfect that SS construction technology, something opposition is struggling with. Current Al methods are working for most of industry, lot expertise out there which they can or already have employed.

[Pipcard]

If New Armstrong will use a hydrogen upper stage, how will they deal with hydrogen embrittlement and boil-off?

[DJPledger]

If New Armstrong will use a hydrogen upper stage, how will they deal with hydrogen embrittlement and boil-off?

I am sure BO will work that out with NG dev. They will have plenty of H2 experience by the time they start serious dev. on NA.

[Aeneas]

If New Armstrong will use a hydrogen upper stage, how will they deal with hydrogen embrittlement and boil-off?

Why do you consider this still a problem? Boil-off can be dealt with with a small cooling device and embrittlement is a problem but with solutions...

[TrevorMonty]

For reuseable 2nd stage that only goes to LEO methane maybe better option.

[JEF_300]

For reuseable 2nd stage that only goes to LEO methane maybe better option.

If they do have a reusable, LEO only second stage for NA, which makes a ton of sense to me, then they'd probably keep the NG second stage around to use as a kicker/departure stage.

Maybe one of the fabled BE-5/6 is a Methalox upper stage engine? Personally, I think it's more likely that Blue will just stick with hydrogen, but it would make sense.

Any reasonable chance you could make a reusable upper stage a biconic? That's the only sort of orbital reentry shape Blue has any experience at all with, to my knowledge.

[envy887]

For reuseable 2nd stage that only goes to LEO methane maybe better option.

If they do have a reusable, LEO only second stage for NA, which makes a ton of sense to me, then they'd probably keep the NG second stage around to use as a kicker/departure stage.

Maybe one of the fabled BE-5/6 is a Methalox upper stage engine? Personally, I think it's more likely that Blue will just stick with hydrogen, but it would make sense.

Any reasonable chance you could make a reusable upper stage a biconic? That's the only sort of orbital reentry shape Blue has any experience at all with, to my knowledge.

Blue has a design for a large methalox upper stage engine: the BE-4U, formerly planned to be uses on the New Glenn 2nd stage. It's no longer in active development AFAIK, and was dropped because it needed the 3rd stage to compete for NSSL.

[JEF_300]

For reuseable 2nd stage that only goes to LEO methane maybe better option.

If they do have a reusable, LEO only second stage for NA, which makes a ton of sense to me, then they'd probably keep the NG second stage around to use as a kicker/departure stage.

Maybe one of the fabled BE-5/6 is a Methalox upper stage engine? Personally, I think it's more likely that Blue will just stick with hydrogen, but it would make sense.

Any reasonable chance you could make a reusable upper stage a biconic? That's the only sort of orbital reentry shape Blue has any experience at all with, to my knowledge.

Blue has a design for a large methalox upper stage engine: the BE-4U, formerly planned to be uses on the New Glenn 2nd stage. It's no longer in active development AFAIK, and was dropped because it needed the 3rd stage to compete for NSSL.

I thought about that, but I figured that if they want to propulsively land the second stage, then the BE-4U may actually be too big. A BE-4U is just way more thrust than would be needed to land even a large second stage; remember that Blue's rockets hover over the pad before they actually land, so the thrust needs to be pretty well balanced.

[Aeneas]

For reuseable 2nd stage that only goes to LEO methane maybe better option.

Why? A larger stage offers a better surface-to-mass ratio to reenter with a heat shield. And you have more Isp to carry a heat shield.

[TrevorMonty]

For reuseable 2nd stage that only goes to LEO methane maybe better option.

Why? A larger stage offers a better surface-to-mass ratio to reenter with a heat shield. And you have more Isp to carry a heat shield.

Which requires larger heatshield, 1m3 of heatshield that can handle twice heat load of 2m3 heatshield would be lighter.

[Aeneas]

Which requires larger heatshield, 1m3 of heatshield that can handle twice heat load of 2m3 heatshield would be lighter.
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Bitte the surface-to-mass ratio would be better, so less load on a mē of heat shield, wouldn't it?

[Seamurda]

Would Blue Origin copy SpaceX's use of stainless steel?

Sounds very plausible that BO could build NA out of stainless steel.

I doubt it. I'd bet aluminum or possibly composite.

Do you think they can reduce production costs similar to the stainless steel designs?

I suspect that it won't matter that much for fast followers. Stainless has advantages in terms of the iterative design process.

By the time you get to fully fitted out human rated vehicles the cost of the tank wall material will be relatively irrelevant. A crew Dragon is ten of millions of dollars for comparison.

BO will be in a position to copy what worked on Starship and potentially improve on it.

One improvement would be to leap past steel plus tiles and go directly to a fully hot nickel based alloy structure.

[Aeneas]

One improvement would be to leap past steel plus tiles and go directly to a fully hot nickel based alloy structure.

Such alloys exist? What are the stats?

[jstrotha0975]

One improvement would be to leap past steel plus tiles and go directly to a fully hot nickel based alloy structure.

Such alloys exist? What are the stats?

Nickel alloys are used in making jet engines.

[Seamurda]

One improvement would be to leap past steel plus tiles and go directly to a fully hot nickel based alloy structure.

Such alloys exist? What are the stats?

Nickel alloys are used in making jet engines.

Yep quite a lot of experience there, maximum metal temperatures in a high pressure turbine are in the region of 1470K though gas's temps go up to 2000K.

Basically as your surface area to mass ratio goes up your peak heating temperature goes down. Eventually you get to a point where structural alloys retain most of their strength at that temperature and the heat shield can be dropped as a separate structure.

The best expression of this was some near SSTO that Boeing worked on for NASA in the late 1970's as a successor to the shuttle. These would have used a Rene 41 nickel superalloy honeycomb structure on the windward side and a titanium honeycomb structure on the back. The leading edge would have been carbon carbon and niobium alloys.

Surface temperatures on the bottom would have been in the 900-1100k range.

The X33 was going to use an Inconnel tile for its heat shield.