In the early 20th Century Many Aircraft Engines Were Started With A?
Answer: Shotgun Shell
There have been more than a few ways to start large engines over the years, but not many of them would raise the eyebrows of a modern reader like the now long defunct Coffman engine starter.
The Coffman engine starter found peak use during the 1930s-1940s and relied on a simple if somewhat dangerous sounding method. In order to generate the compression necessary to turn over the pistons the first time and start the engine, the Coffman starter relied on a shotgun shell (loaded with cordite, a smokeless powder explosive). Coffman’s design stood apart from other shotgun starting mechanisms of the day because the compression generated by the shell was used to push a special piston forward and turn a threaded screw and spiral gears (which rotated and then turned over the engine) as opposed to the less popular designs which discharged directly upon an engine piston and turned the rest of the engine over.
While such a starting mechanism may seem strange to a modern reader, it had clear advantages over other systems of the day. Electric starters required bulky and expensive batteries. Compressed-air starters could be recharged by the engine while the plane was in flight, but required the compressor and tank. Crank starting, which preceded all the previous methods, was impractical and needed an extra set of hands to operate. Barring running out of ignition shells, the Coffman engine starter was practically fool proof.
Those readers with a love of vintage adventure films may recall the most notable use of the Coffman engine starter in popular media, thanks to the 1965 film The Flight of the Phoenix. The starter was featured in the film as a plot device when pilot Frank Towns (played by James Stewart) had a limited number of ignition shells with which to start his makeshift airplane’s engine.
FM-2 Wildcat shotgun starter loading, image courtesy of Conrad.