> > I once heard that SR-71s actually leak gas on the tarmac before takeoff due > to the seals being designed for flight temperature (over 550c degrees I > think) and they had to develop new low flashpoint fuel for it. > > Anyone know if that's true or an urban legend?
(You mean "high flashpoint" - "low flashpoint" would burn more easily) Perfectly true. You can throw lighted matches into buckets of the SR-71 fuel and it won't ignite. (In fact you can throw lighted matches into buckets of regular Jet-A, too, but that's a whole different can of worms). But you don't want to do that with the SR-71; there's all sorts of very nasty additives in the fuel that do bad things if you breathe them. The planes are fuelled by ground erks in full-cover hazmat-suits, with cleanup crews standing by. One of the many problems with the SR-71 is getting it started again if it flames out. It carries a small amount of special primer designed to ignite the fuel; enough for about ten start sequences. Use all that up and the only choice is euphemistically referred to by the pilots as "giving the aircraft back to the taxpayer". (This information comes from a retired flight engineer who looked after the SR-71s that NASA used at Edwards AFB, California).
