PZL-104 Wilga (Golden Oriole) is a Polish short-takeoff-and-landing (STOL) utility aircraft designed and built by PZL "Warszawa-Okęcie"; in one version or another, the Wilga has been in continuous production from 1962 to the present.
Design and development
The PZL-104 was designed mainly for use in sports aviation, especially for glider-towing and parachute training. The prototype of the initial Wilga 1 variant was first flown on April 24 1962. It used a Polish 220 hp flat engine PZL WN-6RB. The Wilga 1 revealed numerous faults, the most serious of which were that it was too heavy and the crew could not see a towed glider. As a result, the airframe was thoroughly redesigned by a team led by Bronisław Żurakowski and Andrzej Frydrychewicz, retaining only the general composition and part of wings in common with the initial design. A completely new slimmer, strengthened fuselage was provided, which offers an excellent view for the crew. Side doors open upwards and it is possible to fly with doors open for a better observation or performing parachute jumps.
The new variant, PZL-104 Wilga 2, flew first on 1 August 1963. A short production run followed (later converted to the Wilga C and Wilga 3 configurations). On December 30, 1963 the Wilga C (or Wilga 2C), an export variant for Indonesia, was flown, powered by an imported 225 hp flat engine Continental O-470. While the Wilga 2 airframe proved a successful design, the WN-6 engine was not fully reliable and did not enter serial production. As a result, it was decided to use a radial engine, the 260 hp Ivchenko AI-14R; this led to the PZL-104 Wilga 3 variant, which first flew on 31 December 1965. The new engine was more powerful, but it spoilt the previously clean and slim fuselage lines, designed for a flat engine; nonetheless, the new variant was successful. Especially high was its rate of climb - maximum 11 m/s (2,165 fpm) with minimal load. One of few flaws was relatively uneconomical engine.
Another variant, the Wilga 32, was an improved small series export variant with Continental flat engine, produced also in Indonesia as Gelatik. After producing 13 Wilga 3s, there were some improvements made, most notably a landing gear base increased from 2.12 m to 2.83 m to improve stability. An improved model, designated PZL-104 Wilga 35, first flew on 29 June 1967, then it entered mass production. Most numerous variant of Wilga 35 was the utility plane Wilga 35A, others were built in small numbers or remained prototypes.
From 1979 the Wilga 80 went into production, an improved model certified for the US market. In the late 1990s the PZL-104M Wilga 2000 family was developed with Lycoming flat engines and with improved aerodynamics.
Over 1000 of all types of the Wilga have been built, including 935 of the Wilga 35 and 80, which made it the most numerous-built plane of Polish design. EADS-PZL has announced on its web page, that it had decided to stop the production of the PZL-104MA Wilga 2000.
Metal construction high-wing cantilever monoplane, conventional in layout. It is covered with thin metal sheets, rifled to increase durability, retaining low mass. Semi-monocoque fuselage. Rectangular single-spar wings, fitted with slotted flaps and slats. Four seat cabin, with two large side doors, opened upwards. Conventional fixed landing gear with tail wheel. Two-blade wooden propeller. Two fuel tanks in wings (195 L/42.9IGal/51.5USGal).
Wilgas are mostly used for touring aviation, glider towing and parachute training. In Poland, most were used by the Polish Aero Club and they are still basic aircraft of regional aero clubs. Polish pilots flying Wilgas have won numerous prizes in the FAI World Rally Flying and Precision Flying Championships, from 1978 to 2006.
For the Royal Canadian Air Cadet Gliding Program, a military-civilian partnership, as glider tow aircraft. One aircraft was purchased for testing with the intention of purchasing more, however with the end of the production of this aircraft, the aircraft used by the Air Cadets is now being sold.
Specifications (Wilga 35A)
Published in July 2009.
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