The Kettering Aerial Torpedo

Precision guided munitions have become a staple of modern aerial warfare.  Cruise missiles are high-tech vehicles which can fly hundreds of miles and hit their targets with pin-point accuracy.  While the common perception is that these are recent developments, the roots of these weapons go all the way back to the First World War.  One of the first “cruise missiles” was the Kettering Aerial Torpedo, designed by the famous American inventor Charles F. Kettering in 1917.
Kettering’s reputation as an engineer lead to a request from the U.S. Army for a flying bomb with a 40 mile range.  Orville Wright was the aerodynamics consultant, Elmer Sperry designed the controls.  The “Bug”, as the design was to become known, was produced by the Dayton-Wright Company of Dayton, Ohio, which also produced DH-4s and Standard SJ-1 trainers.  Film here:
The Bug was powered by a Ford De Palma four cylinder engine rated at 40 HP.  Flight speed was a modest 50 miles per hour (80 kph).  Kettering exceeded the design requirement with a range of 75 miles (119 km).  Payload was 180 pounds (82 kg) of explosives.  Each Bug cost $400.
The Aerial Torpedo was guided by a bearing and range system.  Bearing was maintained by a simple gyroscope.  Range was determined by calculating the number of engine revolutions required to cover the distance to the target, allowing for wind.  When the set point was reached, the engine was shut off and the wings were released, turning the Bug into a bomb.
The Bug was launched using a wheeled cradle which rolled on a set of rails.  The rails were portable, and could be quickly erected in the field.  The launch dolly fell away from the aircraft upon take off.
Wingspan of the Bug was 15 feet (4.6 m), length was 12 feet 6 inches (3.8 m).  Total weight was 530 pounds (241 kg).
The Bugs were first flight tested in October 1918.  Approximately fifty were produced before the war ended and the remaining units were canceled.  The Army continued to test the Bug into the early 1920s.  Army film of 1919 testing here:
No original Kettering Aerial Torpedos exist today.  However, a reproduction is on display at the National Museum of the United States Air Force in Dayton, Ohio.