Space Exploration Stack Exchange is a question and answer site for spacecraft operators, scientists, engineers, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
When it was the first time the liquid methane was used in a rocket engine? I mean for space launches, but it would be interesting to also know about first uses in experimental [rocket] engines, in military, sounding and maybe aircraft.
And why it wasn't used before that?
Liquid methane (Methalox) has never been used in an orbital, or even very high flying rocket. It's a long story, but the short is methalox requires a bit better metal alloys then were available until recently, and that is why the sudden heavy interest in it. Methane in and of itself isn't optimal for atmospheric or above-atmosphere range, but has a good mix of the two properties. I haven't found a really great reason why it hasn't been used until recently, but it seems like other fuels were simply easier to make in to rocket engines.
So far as I can tell, the first reasonably large methane rocket test was in 2007 by XCOR. The altitude record appears to be 4 km. The size record of course is the Starship prototype recently launched, although Starhopper might have actually been more massive due to a thicker wall used for it.
According to Clarke's Ignition! (1972), German rocket experimenter Johannes Winkler fired a methane-LOX rocket motor in 1930:
This work led nowhere in particular, since, as methane has a performance only slightly superior to that of gasoline, and is much harder to handle, nobody could see any point to following it up.
By 1970, NASA had experimented with using methane and FLOX (liquid fluorine/liquid oxygen mixture) in a modified RL10 rocket engine. Performance was good, but FLOX is not an oxidizer I'd recommend.
Ignition! has a lot of discussion of nitromethane and tetranitromethane as oxidizers, and suitably horrified anecdotes of engineers suggesting a methane-LOX mix as a monopropellant in the 1950s and 1960s, but Winkler's 1930 experiment is the only mention of firing a methane/LOX bipropellant.
Methane has been considered as a jet fuel, with NASA studies circa 1970 suggesting that its cooling capability would make it a winner for a mach 3 SST, but as far as I know hasn't been used in any production aircraft. Methane's low density relative to kerosene poses a bigger challenge for aircraft than for spacecraft.
