Description: The Mielec M-15 was a jet agricultural aircraft, manufactured by PZL Mielec in Poland for the USSR agricultural aviation. It was the only jet biplane and only jet agricultural plane in the world. For its strange looks and noisy engine it was nicknamed Belphegor after the noisy demon.
The aircraft was designed in Poland in response to a Soviet requirement for a new agricultural plane to use on great areas of the Soviet collective farms (kolkhoz and sovkhoz), more modern and efficient than the Antonov An-2SKh and An-2R. Poland had already produced the agricultural Antonow An-2R under licence for export back to the USSR, and agricultural planes became a Polish specialization in the Comecon. The Soviet side insisted on using a jet engine in a new plane, and also participated in the design process.
In order to research new problems connected with using the jet engine on a slow agricultural biplane, first an experimental plane Lala-1 for Latające Laboratorium 1 (Polish: Flying Laboratory 1) was built in Poland and flown on 10 February 1972. It used the whole front part of an An-2, with wings, while the rear part was cut off and replaced with a frame construction, housing the Ivchenko-Progress AI-25 jet engine (known for powering the tri-engined Yakovlev Yak-40 and the Aero L-39 Albatros fighter-trainer). The Lala-1 was equipped with agricultural devices. Its tests helped to design the M-15.
The first variant of the M-15 was flown on 30 May 1973, and the second prototype on 9 January 1974. During the next few years it was intensively tested, along with a pre-production series. The M-15 was shown at the Paris Air Show in 1976, where it was nicknamed the "Belphegor" due to its strange look.
Serial production started in 1976. Soviet agriculture planned to order as many as 3,000 aircraft, but the first experiences of M-15 service were disappointing. The jet agricultural plane was not economical, and production ceased in 1981 after 175 aircraft were built. It was only used in the USSR.