Kettering Bug Aerial Torpedo
During World War I, the United States Army aircraft board asked Charles Kettering of Dayton, Ohio to design an unmanned "flying bomb" which could hit a target at a range of 64 kilometres (40 mi). Kettering's design, formally called the Kettering Aerial Torpedo but later known as the Kettering Bug, was built by the Dayton-Wright Airplane Company. Orville Wright acted as an aeronautical consultant on the project, while Elmer Ambrose Sperry designed the control and guidance system. A piloted development aircraft was built as the Dayton-Wright Bug.
The aircraft was powered by one 4-cylinder, 40-horsepower De Palma engine. The engine was mass-produced by the Ford Motor Company for about $40 each. The fuselage was constructed of wood laminates and papier-mâché, while the wings were made of cardboard. The "Bug" could fly at a speed of 80 kilometres per hour (50 mph). The total cost of each Bug was $400.
The Bug was launched using a dolly-and-track system, similar to the method used by the Wright Brothers when they made their first powered flights in 1903. Once launched, a small onboard gyroscope guided the aircraft to its destination. The control system used a pneumatic/vacuum system, an electric system and an aneroid barometer/altimeter.
To ensure the Bug hit its target, a mechanical system was devised that would track the aircraft's distance flown. Before takeoff, technicians determined the distance to be traveled relative to the air, taking into account wind speed and direction along the flight path. This was used to calculate the total number of engine revolutions needed for the Bug to reach its destination. When a total revolution counter reached this value a cam dropped down which shut off the engine and retracted the bolts attaching the wings, which fell off. The Bug began a ballistic trajectory into the target; the impact detonated the payload of 82 kilograms (180 lb) of explosives.