A. B. C. Motors Gnat

The All British Engine Company, Ltd. of London, United Kingdom was founded in 1912. Later, the name was changed to A.B.C. Motors, Ltd. They built a variety of A.B.C. engine types until the end of WWI, including the unsuccessful Dragonfly radial. During WWI, the firm began development of horizontally-opposed auxiliary power units (APU) for aircraft and ground power units (GPU). The firm concentrated on GPU and APU production through and after WWII.

At the end of 1916 two different small fighter aircraft were designed to combat the German Zeppelin airships. Both were diminutive, lightweight planes, each powered by 35-hp A.B.C. Gnats and armed with a single Lewis machine gun. Both were flown in October 1917, and both were rejected. Zeppelins were no longer a serious threat by then, and heavier-than-air bombers were taking their place in the skies over Britain.

The Royal Aircraft Factory at Farnborough built a monoplane in 1917 with a wingspan of 22 feet (6.7 meters) with the Gnat engine as a pilot-less remotely controlled airplane packed with explosives—the original cruise missile. This engine was designed as a ‘throw away’ and had a design life of only two hours. Geoffrey de Havilland also built a little monoplane that flew in March 1917 with the lightweight ABC expendable engine.

The Gnat was a single-ignition engine and was developed in direct-drive and geared versions. Only 17 engines of this 1916 design were built. The Museum is fortunate to have one of these very rare engines in its collection.

Technical Details: (Gnat I)

Engine Type: 2-cylinder air-cooled horizontally opposed
Power:  35 hp (26 kW) at 1800 RPM
Weight:  115 lb (52 kg)
Cylinders: bore 4.3 in (110 mm), stroke 4.7 in (120 mm)
Displacement: 139 cu in (2.3 litres)