Quote:
Originally Posted by pmulcahy11b
Fixed-wing propeller-driven aircraft sometimes have batteries and sometimes not. Have you ever seen footage of ground crews for World War 2 bombers turning the propellers by hand? They're sort of "winding up" the engines -- developing a charge in a part of the engines (I think it's a capacitor, but don't quote me on that).
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Actually I won't. Those engines getting props rotated were on radial engines. When the engine was idle (not running) lube oil settled in the lower cylinders. The purpose of rotating the props was to (1) get rid of some of the built up oil in the lower cylinder, and (2) lube the upper cylinders. IIRC they had electric starters, so I would imagine they had some sort of battery, thought it might have been provided by a ground unit (apu).
During this period they did not have the 'sophisticated' batteries of today. I don't know that they were sealed at all, so aerobatics would be a problem with an acid filled battery. The Optima gel cell that was menitoned elsewhere only came into being in the late 90's IIRC, at least on the open market.