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PZL Warszawa-Okecie PZL-104 Wilga

Designed as a successor to the Polish-built Yak-12 and the P.Z.L. 101 developed from it, the original P.Z.L. 104 Wilga 1 (Thrush) prototype, powered by a 134kW Narkiewicz WN-6 flat-six engine, was flown for the first time on 24 April 1962.

A cantilever high-wing monoplane with fixed tailwheel landing gear and an enclosed cabin, it was followed by prototypes of the Wilga 2P and Wilga CP, powered by the 138kW Narkiewicz WN-6RB2 and 168kW Continental O-470-13A or O-470-L flat-six engines respectively. Intended as a general-purpose aircraft, the P.Z.L. 104 was offered initially in versions equipped for use as a four-seat passenger-carrying or liaison aircraft; for club flying, glider towing or parachuting; for agricultural use with a 500-litre hopper for dust or liquid application; and as an air ambulance carrying pilot, doctor, two stretcher patients and medical equipment.

Following construction of a number of prototypes, the type entered production initially as the Wilga 3A club aircraft and the Wilga 3S air ambulance. In 1967 the design was revised to give better cabin accommodation and with improved landing gear, production beginning in 1968 of the Wilga 35 which, powered by a 194kW Ivchenko AI-14R engine, had flown for the first time on 28 July 1967, and of the Wilga 32 with a 172kW Continental O-470-K flown on 12 September 1967. This last version was built under licence in Indonesia as the Lipnur Gelatik 32 (rice bird) with a Continental O-470-R engine of similar output. The Wilga 35 first flew on 28 July 1967.

The later versions have automatic wing leading-edge slats, an all moving tailplane and a detachable under-fuselage cargo container.

 

 

The Wilga's design incorporates an air-powered starting system for one. It looks complex, but it has one advantage in that batteries are almost worthless in extreme cold. The landing gear incorporates a short trailing beam at the end of each main gear strut so that its wheels recoil up and rearward, enhancing its ability to handle rough, off-airport landings. Engine cooling is designed to cope with wide air-temperature extremes, long climbs and rapid descents. The cowl shutters, manually operated by a knob in the cockpit open fully to cool the 620-cubic-inch radial on a climb, then close tightly so the airplane can perform its patented 4,000fpm descents without warping the cylinder heads. The airplane is not only adapted very nicely to hauling sailplanes aloft but also to winter operations without fancy cold-weather kits. The engine will run on anything from 70-octane fuel up. A gear-driven supercharger provides a constant boost of about three inches, and it has a two-blade constant-speed prop.

The wing is strut-less, fully cantilevered; the ailerons droop with full flaps for landing, and there's a fixed, full-span leading-edge slot. The tail-cone carries its structural members outside the skin, giving the impression of widely spaced corrugations; Four low bucket seats occupy the cabin, with an aft cargo compartment under glass. It has dual flight controls except for trim, and both rudder pedals carry toe brakes. The throttle and prop controls are designed to be operated with one hand; their rates are nicely matched so that for a go-around, you grab both handles and push.

The Wilga demonstrates excellent STOL performance, accelerating crisply and lifting off at a radical climb angle. At sea level, the airplane is said to produce a climb of 1,240 feet per minute at its gross weight of 2,711 pounds, which is lighter than a Cessna 180 but with more horsepower to heft it. This airplane's empty weight is 1,874 pounds, and it carries 252 pounds of fuel; its payload, after allowing for oil and incidentals, is probably around 550 pounds. The Wilga is slow, producing only 104 knots at maximum cruise on about 15 gallons per hour.

 

 

Developments of the Wilga 35 have included the Wilga 35A intended for aeroclub use; the Wilga 35H floatplane fitted with Airtech (Canada) LAP-3000 floats; the multi-purpose Wilga 35M fitted with a 260kW M-14P radial engine, flown in prototype form in 1990; the Wilga 35P tourer or air-taxi version; and the Wilga 35R agricultural variant. A version generally similar to the Wilga 35, but meeting US FAR Part 23 requirements, is designated the Wilga 80. The first of these flew on 30 May 1979, and is available in three versions, the 80A, for aeroclub use, the 80H floatplane, and as the 80R for agricultural use. A more radical redesign, originally identified as the Wilga 88, has become the P.Z.L. 105 Flamingo. The Wilga 35 and 80 remain in production in 1993, by which time P.Z.L. had sold around 900 variants to countries around the world.

Certification of the PZL-104 Wilga 35A is under European Aviation Safety Agency EASA A.061.

Some 800 PZL 104 have been manufactured, but was no longer in production in 1991.

PZL 104 Wilga