I don't think they were thinking about reusable rocket engines at that point in time. The primary (?) advantage of methane over kerosene is that it doesn't deposit soot on engine parts, which is highly important for SpaceX today, but not really anyone else in history.
Here's one reference to methane-LOX in the book ("nobody could see any point"):
- "The VfR was completely unaware of all of this when they started work. Oberth had originally wanted to use methane as fuel, but as it was hard to come by in Berlin, their first work was with gasoline and oxygen. Johannes Winkler, however, picked up the idea, and working independently of the VfR, was able to fire a liquid oxygen-liquid methane motor before the end of 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." (pages 7-8)
There's more references to methane + [exotic oxidizers], because (going off my memory) they were to trying to min-max Isp performance, for interplanetary probes, constrained to a certain cryogenic temperature range. (This predates radioisotope heaters, I believe. Not *electric* generators -- these little heater things [0]). Liquid CH₄ looked like a good match for the deep-space thermal environment.
- "Deep space probes, working at low temperatures, will probably use methane, ethane, and diborane for fuels, although propane is a possibility. The oxidizers will be OF₂, and possibly ONF₃ and NO₂F, while perchloryl fluoride, ClO₃F, would be useful as far out as Jupiter." (page 191)
(If anyone at Google is reading this, could you consider adding search support for numerals in the superscripts and subscripts block [1]; they don't seem to be normalized in a sensible way. ClO₃F and ClO3F are entirely different searches).
"It's only bad habit is that it decomposes exothermically -- and since
the rate of decomposition is accelerated with temperature, this reaction
can run away from you. But that hardly deserves the bad press it's gotten.
LOX will also bite you, quite readily, if you're careless. "Wings" simply
got it wrong. (Even _Ignition!_, while pretty sour on hydrogen peroxide due
to the decomposition hazard, has the facts right, and only the emphasis is
arguable -- I don't understand how someone can cozy up to ClF5 while
considering peroxide dangerous; but that was Clark's position! )"
SpaceX isn't the only one looking at methalox engines for reusability, though they're definitely the farthest along. Blue Origin's BE-4 engines use methalox; New Glenn's planned to be at least partially reusable, and ULA might try to reuse them on Vulcan with SMART engine recovery.
Technically you could synthesize more complex hydrocarbons such as kerosene as well, it's just that it's way more complexity, energy, and infrastructure required.
Here's one reference to methane-LOX in the book ("nobody could see any point"):
- "The VfR was completely unaware of all of this when they started work. Oberth had originally wanted to use methane as fuel, but as it was hard to come by in Berlin, their first work was with gasoline and oxygen. Johannes Winkler, however, picked up the idea, and working independently of the VfR, was able to fire a liquid oxygen-liquid methane motor before the end of 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." (pages 7-8)
There's more references to methane + [exotic oxidizers], because (going off my memory) they were to trying to min-max Isp performance, for interplanetary probes, constrained to a certain cryogenic temperature range. (This predates radioisotope heaters, I believe. Not *electric* generators -- these little heater things [0]). Liquid CH₄ looked like a good match for the deep-space thermal environment.
[0] https://en.wikipedia.org/wiki/Radioisotope_heater_unit
- "Deep space probes, working at low temperatures, will probably use methane, ethane, and diborane for fuels, although propane is a possibility. The oxidizers will be OF₂, and possibly ONF₃ and NO₂F, while perchloryl fluoride, ClO₃F, would be useful as far out as Jupiter." (page 191)
(If anyone at Google is reading this, could you consider adding search support for numerals in the superscripts and subscripts block [1]; they don't seem to be normalized in a sensible way. ClO₃F and ClO3F are entirely different searches).
[1] https://en.wikipedia.org/wiki/Superscripts_and_Subscripts_(U...