Diborane / Fluorine / LH2 / Aluminium [s]Engine[/s] Death Machine 9000

[Skye]

Ignore the absolute nightmare that handling this would be - this is a purely theoretical idea. What sort of advantage would this have over other propellants?

Aluminium (reacts with the fluorine so the boron & hydrogen don’t - HF is NASTY) gelled in LH2 (low density, high I_sp), Diborane (supposedly high theoretical I_sp, though you’d need high combustion temperature to prevent glassy deposits in the throat and nozzle, which is why we have fluorine) & Fluorine (only practical oxidiser for any Borane, plus generally good performance)

Diborane and Oxygen would go to B₂O₃ & H₂O, and Fluorine would go with aluminium to AlF₃.

Fluorine goes through a preburner to make it a gas (less awful, plus more performance), and into the chamber

Diborane does the same as the fluorine

LH₂ / Al goes through the nozzle / throat / chamber to cool it, (expander, drives pumps) then into the chamber

[Paul451]

I guess it won't need a flight termination system.

[Skye]

Lmao, not wrong, just open the fluorine valve or smth and let it explode on contact with the air (or the fluorine & LH2 valves if it’s in a vacuum or near-vacuum)