The Mitsubishi Army Type Ko 1 Trainer was a licence-built version of the Nieuport 81-E2, one of the standard training aircraft in the early expansion of Japanese Army aviation.
The Nieuport 81-E2 was two-seat sesquiplane, with a smaller lower wing. It was powered by a Le Rhône radial engine, and was fairly typical for its period, built around a wooden framework with a fabric cover and small patches of plywood and metal in key positions. Forty 81-E2s were imported from France from January 1919. As the original aircraft were damaged or destroyed, and the need for training aircraft began to increase, the Japanese Army decided to manufacture the 81-E2 and 83-E2 itself, but this arrange only lasted for a short period. The army then gave Mitsubishi a contract to produce the 81-E2. The first Mitsubishi-produced 81-E2 was completed in May 1922.
During the planning process the Mitsubishi-produced aircraft were known as the 81-E2, but in 1921 the Japanese Army introduced a new designation system for aircraft of foreign origin. Each manufacturer was given a symbol, Ko in the case of Nieuport, and each new aircraft type was given a number. These numbers were linked to the foreign manufacturer and not the Japanese company. The 81-E2 became the Ko 1. The Ko 2 was the 83-E2 trainer, which was produced in Japan by Nakajima. The designation system didn’t take into account the role of aircraft, so the Nakajima Ko 3 was a licence built version of the Nieuport 24.C 1 fighter.
A total of 57 Ko 1s were built. They were used at the Tokorozawa Army Flying School, which was opened in 1922, and in small numbers at other institutions. They remained in use with the Army until 1926, and many of the surviving aircraft were then transferred to civilian flying schools. The Ko 1 was replaced as a trainer by the Mitsubishi Ki 1 Trainer, a licence-built version of the Hanriot HD-14, which remained in use with the army until 1935.
Engine: Le Rhône nine-cylinder air cooled rotary engine
Span: 30ft 2.25in
Length: 23ft 7.5in
Height: 8ft 6.25in
Empty weight: 1,080lb
Loaded weight: 1,675lb
Max speed: 81mph
Service ceiling: 13,123ft