Alternative Methods Of Heating Hydrogen For High Efficiency Rockets

[Skye]

Ok, hear me out - dried, (edit: dried of water) dead gerbils! 

(Still soaked in LH2, of course! )

[Vultur]

That would basically become a tripropellant - dried gerbil/LOX/LH2.

[Skye]

lol - wonder how well it would work?

Get DARPA on this now! 

[Vultur]

Tripropellants with H2 where you have a really high energy chemical reaction to heat the H2, which is the low molar weight propellant, were actually tried, in the 60s I think -- though not involving gerbils.

"Ignition" talks about this, a lithium/fluorine/H2 system was actually measured at 542 seconds Isp! (But talk about a handling and environmental nightmare...)

[Skye]

Yup, Ignition! is a great book 

Why not just the FLiH system but replace H with B5H9 & replace Li with Cs?

Oh and add (CH3)2Hg to reduce performance!

I mean, if you want the most immoral rocket engine ever, just make one that burns dried humans - or puppies

[redneck]

On paper, one could burn aluminum and oxygen for the energy and use hydrogen for the reaction mass. Retain the AL2O3 on board and use the long coast periods to refine it back to aluminum and oxygen. Per mass, aluminum and oxygen create a lot of energy when burned, though the mechanism for using that to heat the hydrogen AND keeping it on board could get entertaining.

[Skye]

You could combust them in a chamber above the main chamber, then have a filter that filters out the Al2O3 (& other heavy particles) and vacuums(?) them back & filters them out after combustion, while allowing the H2 to pass through? Would be quite interesting to see!

[Vultur]

On paper, one could burn aluminum and oxygen for the energy and use hydrogen for the reaction mass. Retain the AL2O3 on board and use the long coast periods to refine it back to aluminum and oxygen. Per mass, aluminum and oxygen create a lot of energy when burned, though the mechanism for using that to heat the hydrogen AND keeping it on board could get entertaining.

Beryllium/oxygen/hydrogen was actually tested but had really disappointing performance compared to theoretical calculations, according to "Ignition!".

[redneck]

On paper, one could burn aluminum and oxygen for the energy and use hydrogen for the reaction mass. Retain the AL2O3 on board and use the long coast periods to refine it back to aluminum and oxygen. Per mass, aluminum and oxygen create a lot of energy when burned, though the mechanism for using that to heat the hydrogen AND keeping it on board could get entertaining.

Beryllium/oxygen/hydrogen was actually tested but had really disappointing performance compared to theoretical calculations, according to "Ignition!".

The concept with the aluminox>hydrogen was that the aluminox would create the temperatures that would heat the hydrogen to >SSME temperatures. Then the hydrogen at 1/9 the molecular mass would have 3 times the Isp going by the square root of temperature over molecular mass. Even duping the AL2O3 overboard would net a 50% net gain.  Many people argued against the concept quoting various programs that disn't seem to address the actual idea. It took me going to a chemistry book to figure out that the problem was in the heat capacity of hydrogen. The net temperatures would have been so low that the Isp would be down in the 300s.

[Vultur]

There is a non-hydrogen aluminum/oxygen rocket idea around. Isp isn't great, but the idea is that both propellants can be processed from the lunar regolith and you don't need great Isp for a lunar takeoff.

[Skye]

On paper, one could burn aluminum and oxygen for the energy and use hydrogen for the reaction mass. Retain the AL2O3 on board and use the long coast periods to refine it back to aluminum and oxygen. Per mass, aluminum and oxygen create a lot of energy when burned, though the mechanism for using that to heat the hydrogen AND keeping it on board could get entertaining.

Beryllium/oxygen/hydrogen was actually tested but had really disappointing performance compared to theoretical calculations, according to "Ignition!".

Indeed it was, but, well, Beryllium…

[Apollo22]

There is a non-hydrogen aluminum/oxygen rocket idea around. Isp isn't great, but the idea is that both propellants can be processed from the lunar regolith and you don't need great Isp for a lunar takeoff.

Specific impulse is 285 seconds BUT lunar orbit & escape velocities are merely 2400 m/s, which really helps. I have this idea stuck in my head for a long time, of Al-Lox lunar SSTOs ; eventually manufactured on the Moon.

[Skye]

Could absolutely work, though you’d need to be able to manufacture a hybrid rocket on the moon, and ideally make it reusable 

[redneck]

Could absolutely work, though you’d need to be able to manufacture a hybrid rocket on the moon, and ideally make it reusable 

You may not care about reusable depending on the goals to be achieved. If delivering aluminum to orbit for process into structure, you may consider a thick walled aluminum hybrid that delivers the remaining wall thickness to the orbital facility. LOX cooling of the aluminum throat and nozzle. Detachable brain and control systems for reuse.

There are a lot of possible ideas out there. I wish I had more time to discuss them. 750 seconds?
 https://selenianboondocks.com/2008/10/tetherocket/     

[Skye]

I suppose, though Reusability would be nice for certain situations

759 seconds sounds nice? 

[Apollo22]

Could absolutely work, though you’d need to be able to manufacture a hybrid rocket on the moon, and ideally make it reusable 

You may not care about reusable depending on the goals to be achieved. If delivering aluminum to orbit for process into structure, you may consider a thick walled aluminum hybrid that delivers the remaining wall thickness to the orbital facility. LOX cooling of the aluminum throat and nozzle. Detachable brain and control systems for reuse.

There are a lot of possible ideas out there. I wish I had more time to discuss them. 750 seconds?
 https://selenianboondocks.com/2008/10/tetherocket/   

Spot on. You know, I'm just a pragmatic who started from lunar regolith composition (as detailed here - https://en.wikipedia.org/wiki/Lunar_resources#Resources ) and wondered what could be done  with oxygen aluminum and silicium - the three most abundant resources.

The answer ? solar arrays, SBSP for a lunar base, and lunar SSTOs running on aluminum and LOX.  Bringing lunar LOX to EML-1 or EML-2 to fuel Mars-bound spaceships.

Mining regolith further, two interesting byproducts might be a) the ill-named rare earths (REE) and of course, b) PGM from asteroid impacts (see Dennis Wingo 20 years old book Moonrush)