J.Wegg General Dynamics Aircraft and Their Predecessors Since 1912 (Putnam)
A few months after the United State entered the Great War, a scheme was devised to spring a surprise attack on German cities and industrial targets behind the front line using large numbers of unmanned flying bombs. By this action, it was hoped that morale would be broken and the conflict brought to a swift conclusion.
The Aircraft Production Board issued specifications in great secrecy in early October 1917 to three manufacturers, Dayton Wright, Curtiss, and Lawrence Sperry. The requirements were simple, a small self-controlled aircraft capable of flying 200 miles, carrying 200 lb of explosives, with the cost not to exceed $200 each. The trajectory had to be predetermined on the ground and an electrically-driven gyro controlled the direction of flight, an altimeter the height, and a subtracting anemometer the distance. A speed of over 100mph was desired but not specified.
Initial studies were undertaken by Fred Nash and Orville Wright designed a small biplane which came to be known as the Bug. Constructed of scrap aircraft spruce, plywood, and paper, the Bug could be assembled in five minutes by two men with a screwdriver and spanner. Initially, a two-cylinder engine was planned for the Bug, but this idea was abandoned in favour of a 37hp four-cylinder engine designed by Dayton Wright and built by the DePalma Manufacturing Co. This drove a 5ft diameter wooden propeller and the control surfaces through a system of valves and bellows.
Early in 1918, Kettering decided to build a man-carrying biplane to test the new engine and a lightweight single-seater was designed by O W Thomas, formerly of Thomas Brothers, and now with Dayton Wright. The aircraft was built at South Field and flown by Howard Rinehart in early spring. However, the engine was unsuited for manually-controlled flight and the testbed was quickly abandoned.
Test flights with Bugs started in late spring, launching Bugs from a car driven on a track, and in calm air the Bug flew well at 120-125mph. After inspection by the Army, at least twenty Bugs were sent to NAS Pensacola for trials and 'shot' at anchored targets 90 mil s away in the Gulf of Mexico. Evidently, these were successful and a contract for full-scale production awarded but the signing of the Armistice caused the Bug's cancellation.
Span 15ft; length 12ft.
Форум Breguet's Aircraft Challenge
The Kettering Bug was a small biplane of decidedly cheap construction. It used a wooden framework, which was covered with pasteboard on the fuselage and tail surfaces, and with doped paper and muslin on the wings. The wings had 10° of dihedral, which was intended to improve stability on take-off. Flight distance was measured by counting air-impeller revolutions, and when the preset distance was reached, the engine was cut, the wings detached, and the Bug fell to the ground. For testing purposes, a slightly larger manned version of the aircraft was flown a few times, beginning in July 1918. The unmanned Bug had no undercarriage, and was launched on a four-wheel dolly running on a track. The first flight attempt on 2 October failed, but a second try two days later was more successful. The Bug remained in the air for about 45 minutes, but did fly in large circles instead of the intended straight line. The flight was impressive enough to secure an order for 75 additional Bugs.
After the end of the war, the Army continued the experiments with the Kettering Bug, but the overall results were disappointing and the program was terminated in late 1919. Out of a total of 24 attempts at unmanned flights, only 7 could be considered at least partially successful. In the end, these early flying bombs failed because of the limited reliability of key components (engine and automatic pilot) as well as the incomplete knowlegde of aerodynamics at that time. The Army nevertheless continued experimenting with unmanned flight during the 1920s, using manned aircraft fitted with improved gyrostabilizers and radio-control systems.
Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!
Data for Liberty Eagle (Kettering "Bug"):
Length 3.8 m (12 ft 6 in)
Wingspan 4.6 m (15 ft)
Weight 240 kg (530 lb)
Speed 185 km/h (115 mph)
Ceiling 3650 m (12000 ft)
Range > 100 km (60 miles)
Propulsion Wills/DePalma 4-cyl. piston engine; 27 kW (37 hp)
Payload 80 kg (180 lb) high-explosive