PZL M-15 Belphegor

M-15 Belphegor
M-15 at Monino museum
Role	Agricultural (jet) aircraft
National origin	Poland
Manufacturer	WSK PZL-Mielec
First flight	20 May 1973
Number built	175

The Mielec M-15 was a jet agricultural aircraft, manufactured by PZL Mielec in Poland for Soviet agricultural aviation. For its strange looks and noisy engine it was nicknamed Belphegor, after the noisy demon.

Development

The aircraft was designed in Poland in response to a Soviet requirement for a new agricultural plane, for use above the very large areas of Soviet farms, the kolkhoz collectives, and state-owned sovkhoz. A requirement was that the new aircraft was to be more modern and efficient than the Antonov An-2SKh and An-2R. Poland had already produced the agricultural Antonov An-2R under licence for export back to the USSR, and agricultural planes became a Polish specialization within the Comecon. The Soviets insisted on the use of a jet engine in the new aircraft, and also participated in the design process. The chiefs of the design team were Kazimierz Gocyła and Riamir Izmailov.

In order to research new problems connected with using a jet engine in a slow agricultural biplane, an experimental plane Lala-1, for Latające Laboratorium 1 ("Flying Laboratory 1"), was first built in Poland and flown on 10 February 1972. It used the whole forward part of an An-2, together with its wings, while the rear part was cut off and replaced with a frame construction, housing a Ivchenko-Progress AI-25 jet engine (as used on the tri-engined Yakovlev Yak-40 and the single-engined Aero L-39 Albatros fighter-trainer). The Lala-1 was equipped with agricultural devices, and its testing helped inform the design of 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 first experience of the M-15 in actual service was disappointing. The jet aircraft was not economical, and production ceased in 1981 after 175 aircraft were built; it was only used in the USSR. The PZL M-15 is believed to be the world's only jet agricultural plane (e.g., the world's only jet cropduster), the world's only jet biplane and the world's slowest jet, at least as far as aircraft that have been put in mass production.

Description

M-15 at Polish Aviation Museum

The aircraft was a metal twin-boom sesquiplane, with a jet engine over the crew cabin. Part of lower wings and chemicals tanks were made of a laminate to avoid corrosion. The upper and lower wings were connected with two thick columns which housed the chemical tanks, 1450 L (377 US gal) each. The tricycle landing gear was fixed. The crew was a single pilot; two technicians could be carried if necessary. The M-15 was fitted with spraying and dusting gear, powered with compressed air.

Specifications (M-15)

Data from

General characteristics

• Crew: 1
• Capacity:
  
  • Seats for two groundcrew for ferry flights
  • 2,900 L (638 imp gallons) liquid chemicals or
  • 2,200 kg (4,850 lb) dry chemicals
• Length: 12.72 m (41 ft ​8 ³⁄₄ in)
• Wingspan: 22.33 m (73 ft ​3 ³⁄₄ in)
• Height: 5.34 m (17 ft ​6 ¹⁄₂ in)
• Wing area: 67.50 m² (726.6 sq ft)
• Empty weight: 3,090 kg (6,812 lb)
• Max. takeoff weight: 5,650 kg (12,456 lb)
• Powerplant: 1 × Ivchenko-Progress AI-25 turbofan, 14.7 kN (3,306 lbf)

Performance

• Maximum speed: 200 km/h (108 knots, 124 mph)
• Cruise speed: 140–165 km/h (76–89 knots, 87–103 mph) (normal operating speed)
• Stall speed: 108 km/h (58.5 knots, 67.5 mph)
• Range: 400 km (216 nmi, 248 mi)
• Rate of climb: 4.8 m/s (950 ft/min)