The old cartridge starting system, popular through the late 1930's. The U.S. Navy even required it on the original designs of the F4U Corsair and I have read that it worked ok most of the time, but in cold weather the cartridge was not always sufficient to turn the big R-2800 fast enough for the engine to start on the first attempt. Vought switched to a direct engagement electric starter motor with the F4U-1D/C and subsequent versions. The Same goes for the Goodyear FG-1D.