The Coffman starter (or "shotgun starter") is a 1930s-1940s engine starter system that used a blank, gunpowder-filled cartridge to ignite and generate high-pressure gas. This gas pushed a piston that rotated the engine, often used in WW2 aircraft like the Spitfire to avoid heavy batteries
The original system focused the explosive gasses at the piston face, later versions fired the explosion into a geared starter drive, which rotated the engine via the flywheel.
The system worked well on remote Pacific Islands and on the battlefront. It was standard equipment in several World War II aircraft engines, including the Rolls-Royce Merlin engine used in British Spitfires, Pratt and Whitney R-1820 engines used in Grumman FM-2 Wildcats and Napier Sabre engine used in Hawker Typhoons. Several jet engines also used the Coffman starter
One of the drawbacks of using the Coffman starter was the build-up of carbon in the starting cylinder. As you see in Flight of the Phoenix, cartridges often had to be wasted as a means of blowing out the accumulated carbon in the cylinder before the engine would be able to start. Although sometimes referred to as a shotgun shell, the actual shell used was a four-gauge, much larger in height and diameter than 12- or 20-gauge shotgun shells. Variations on the Coffman starter were employed depending on application. Some geared starter drives held one, two or three cartridges while others held six or more.
One of the drawbacks of using the Coffman starter was the build-up of carbon in the starting cylinder. As you see in Flight of the Phoenix, cartridges often had to be wasted as a means of blowing out the accumulated carbon in the cylinder before the engine would be able to start. Although sometimes referred to as a shotgun shell, the actual shell used was a four-gauge, much larger in height and diameter than 12- or 20-gauge shotgun shells. Variations on the Coffman starter were employed depending on application. Some geared starter drives held one, two or three cartridges while others held six or more.























