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Dangerous_Dac t1_iy9588s wrote

Reply to comment by Fearlessleader85 in Rolls-Royce successfully tests hydrogen-powered jet engine by je97

Significant is an understatement. More like "need to develop whole new levels of material science to even begin to consider this viable" levels of engineering challenges.

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Fearlessleader85 t1_iy965pz wrote

We have materials that can hold hydrogen well, and it's trivially easy to make an effectively impermeable coating on something like a compressed gas cylinder. But doing the same for a full plane is less simple.

And we have some promising materials for that, like some graphene based stuff. It's not as far out as you suggest. It's just a long way from cheap.

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CrosshairLunchbox t1_iy97a8w wrote

Slap a bit of gold plating on and you're good up to 1000-2000 PSI Hydrogen last I recall from materials engineering.

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Fearlessleader85 t1_iy9869t wrote

Gold might not be a bad material for it, especially on tubes and engine parts, but I don't know enough about gold playing to know if it's adherence is good enough in a thin film application to coat something like a turbine.

Another problem is hydrogen's flame temp is absolutely insanely hot. Gold has a fairly high melting temp for such a soft metal, but it will need excellent cooling. It's conductivity could help a bunch with that though.

Damn, i wish i was in engine r&d sometimes. All my fiddling with engines is on 4-bangers in my shop. And i don't even have a cnc.

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brcguy t1_iy9zed5 wrote

It’s more about the storage than the turbine tho. The tanks and fuel lines are the problem way before the combustion chambers. Those need to handle more heat, but shouldn’t be in major danger of hydrogen embrittlement as it’s on fire and mixing with air by then. (I could be wrong it’s been a while since I’ve messed with turbines).

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Fearlessleader85 t1_iy9zzsb wrote

I mean, you could be right, but with the lifetimes we're demanding of aircraft, i think it would behoove us to keep everything from hydrogen embrittlement. Injectors might be the main trouble spot, though.

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brcguy t1_iya0urx wrote

Yeah plus I think storing a suitable volume might be a problem too. Just need to make a super efficient electric turbine and then build the whole airframe out of batteries lol.

Who are we kidding - the climate crisis will only be solved by the climate crisis killing half of us. Now I’m sad.

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EmperorArthur t1_iyecwwv wrote

> then build the whole airframe out of batteries

Nuclear!

Actually skip the electric engine, just use the fuel to heat the air.

90% sure the US dreamed up a plane like that in the 60s.

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Statertater t1_iya0ynb wrote

What about ceramic?

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Fearlessleader85 t1_iya1ctf wrote

I'm no expert on hydrogen containers, but i do believe some of our better options emply ceramic coatings, but they can't generally be pure ceramic, because they can't handle the hoop stress. Also, i think most ceramics still leak a significant amount of hydrogen.

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mces97 t1_iyad5r6 wrote

I'm more concerned about what happens if they need to make an emergency landing, if landing gear don't work? Cause if that tank isn't 100% tested against the type of damage that could make it explode, I would be very concerned getting on a plane.

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moofunk t1_iya75dw wrote

Considering how long it takes the FAA to certify unleaded fuel, which is supposed to be done by 2030, I can't imagine how long it would take to certify a hydrogen powered plane.

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Fearlessleader85 t1_iya7b89 wrote

I certainly wouldn't plan on buying tickets on such a plane any time soon.

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Dt2_0 t1_iyb7oi7 wrote

Yea it's looking more like the airline industry will transfer to biofuels and work to be carbon neutral than go for non carbon fuels.

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