Discussion Leviathan launch vehicle

[Wishbone]

http://www.launchcomplexmodels.com/DirectP2/Information/Baseball_Card_-_Leviathan_H2008.pdf

Among the craziest ideas out there... 180 (sic!) first stage LH2/LOX engines, pressure-fed and non-gimballed. While I appreciate the amount of thought that went into eliminating turbopumps (at least somebody learns the lessons of N-1), reliability leaves a lot to be desired.

Would like to elicit your comments on this project and other cheesy super-heavy launcher (upwards of 120 metric tonnes to 407 km circular orbit) proposals. Super-heavy Falcons, Delta IV next gen, even Angaras. Maybe by 2040 we'll have one such vehicle in working order...

 

[Ark]

I kind of like the whacky ideas they had for expanding the Saturn platform.

 

[Urwumpe]

Eliminating turbopumps is not good, while it makes the rocket engines simpler, it means more tank pressure and more tank mass, also the engine performance is pretty poor.

I had calculated the numbers of DIRECT last weekend, they assume a vacuum specific impulse of 4885 m/s of their first stage engine (the figure is not published in their technical data), that is, even with high performance engines, pretty hard to achieve - also NASA research about the effectivity of such plug nozzles does not confirm such a strong boost in exhaust velocity.

 

[Wishbone]

Yup, this brochure skips over the question of specific impulse, and it pretty much looks like a step back from the current generation of engines.

 

[Urwumpe]

Yup, this brochure skips over the question of specific impulse, and it pretty much looks like a step back from the current generation of engines.

It is not a bad design, really - but the numbers won't work out like that. Also I would say a single central turbopump could also do that... the "engines" in such a design are rather combustion chambers, some aircraft also already have a dozen of these. The problem is just getting the pressure from tank head to a good injection pressure - the closer the injection pressure is to the theoretical optimum, the better it is.