Thrust, which produced velocity, wa

Thrust, which produced velocity, was controlled by a foot pedal that engaged a magneto. The magneto was two-cylinder attached to a flywheel that produced the spark to ignite the fuel inside the engine. It was, practically speaking, a large spark plug. The engine ran full power at all times while the foot pedal was not depressed. Depressing the foot pedal lengthened the spark, slowing down combustion. Airspeed was controlled by alternately pushing the pedal in and letting it spring back out. The magneto control acted something like a gas pedal in an automobile, but instead of providing more fuel, it provided less spark that reduced engine speed. This on-off operation resulted in a characteristic pulsating-engine sound while the machine was flying. In 1912 the procedure was reversed to operate more like a true gas pedal. There was also an emergency engine-shutoff string that hung over the pilot’s head, and pulling the string killed the clanky, putt-putting motor by opening the engine valves. The motor could be restarted by resetting the valves.15