Author Topic: BFR/ITS risk due to composites  (Read 15625 times)

Offline john smith 19

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Re: BFR/ITS risk due to composites
« Reply #80 on: 02/20/2018 06:34 PM »
I believe the shuttle lox tank used about 100 deg c GOX for tank pressurization.

A useful data point.  GO2 wan generated by a short heat exchanger pipe wrapped around the SSME.

But the ET was made of Aluminum Lithium .  AlLi retains its strength to about 180c. The tricky part is making sure the CFRP structure can handle both deep cooled LO2 and 100c, and cyclically.

I wonder how the Electron pressurized its LOX tank?  The classic solution is GHe but it should be pretty easy to put some LOX piping around an engine(s) or battery pack(s) to vaporize enough O2 to keep the tank pressure up.
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Offline envy887

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Re: BFR/ITS risk due to composites
« Reply #81 on: Today at 03:21 AM »
nickel-iron-lead isn't light weight.  How thick a layer do they need?  Does it flake off?  Or wear away?  How much mass is that for large tanks?
Once again: An Invar liner is the last resort. Elon said that they look for a coating that can be sprayed on.

I wonder if the coating would be spray foam insulation, BFS needs insulation for deep space and Mars surface (to avoid freezing out dry ice). But urethane foam seems like it would be just as bad as carbon epoxy in the face of hot GOX. A silica fiber based insulation sounds like a better bet but I don't know if they could spray it.

There are high temperature phenolic CRFP resins that can take up to 500 C for short times. Not just stronger at elevated temperatures, but also more resistant to oxidation.

Online Patchouli

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Re: BFR/ITS risk due to composites
« Reply #82 on: Today at 04:49 AM »
Another solution could the inner most layers of the tanks be made from something like Nonburnite which can handle -260C to +280C.
This should exceed anything they'll see in service by a good margin.
« Last Edit: Today at 04:50 AM by Patchouli »