I realized the tech must have been winding up a flywheel, and then the pilot engaged a clutch to dump the flywheel's inertia into the engine.
The engineer in me loves the simplicity and low tech approach - a ground cart isn't needed nor is a battery charger (and batteries don't work in the cold). Perfect for a battlefield airplane.
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I saw an exhibit of an Me-262 jet fighter engine. Looking closely at the nacelle, which was cut away a bit, I noticed it enclosed a tiny piston engine. I inferred that engine was used to start the jet engine turning. It even had a pull-start handle on it! Again, no ground cart needed.
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I was reading about the MiG-15. American fighters used a pump to supply pressurized oxygen to the pilot. The MiG-15 just used a pressurized tank of air. It provided only for a limited time at altitude, but since the MiG-15 drank fuel like a drunkard, that was enough time anyway. Of course, if the ground crew forgot to pressurize it, the pilot was in trouble.
Again, simple and effective.
point of trivia: Messerschmitt, yes, but Bf-109, produced by Bayerische Flugzeugwerke.
you don't want to get your flugzeug works confused
BTW, since we are Birds of a Feather, I bet you'd like the movie "The Blue Max". It's really hard to find on bluray, but worth it! The flying sequences are first rate, and no cgi.
And, despite the news reports, this is not a true blackstart. Some power survived.