Główny Instytut Lotnictwa GIL-4 / BŻ-4 Żuk
Work on the BŻ-4 Żuk began at the research institute Główny Instytut Lotnictwa - Main Aviation Institute in Warsaw in 1953, under the leadership of Dipl. Ing. Bronisław Żurakowski, who had earlier designed the experimental BŻ-1 GIL helicopter. Due to the delicate political situation in postwar Poland (Soviet influences and centrally planned economy), progress was slow. The main object was to produce a simple and inexpensive general use light helicopter. Its purpose was also to develop and test the novel rotor and transmission system, which eliminates vibration and improves control. Initially it was designated GIL-4.
The BŻ-4 Żuk was based on a single main three-blade rotor powered by an indigenous one 320 hp Narkiewicz WN-4 piston engine in a fuselage made of a steel frame, behind a cabin section. It had an open frame rear boom structure and a fixed four-wheel undercarriage. Main rotor was atypical, for it had a smaller upper steering rotor and was fitted with an automatic stabilization system, of the Hiller principle. The cabin had four doors with two front seats and a rear bench. There were two fuel tanks, 220 litre in total.
Four main variants were planned: a passenger version accommodating a pilot and three passengers, an ambulance variant carrying pilot, one stretchers and an attendant, an agricultural variant carrying pilot and spraying or dusting equipment and a dual control trainer.
The first prototype of the BŻ-4 Żuk four-seat helicopter was manufactured and displayed publicly in the Polish Aviation Day Exhibition in August 1956. Due to a long program of ground testing and fixing faults, it flew first only on 10 February 1959 and completed 17 flights for a total of 3 hrs, 40 minutes. The Żuk was still in the development stage when further work was cancelled in favor of the licence production of the Mil Mi-1, that had already started in WSK PZL-Świdnik. The prototype was damaged during landing on 31 August 1959, and despite being repaired, it was not used again. Two additional prototypes were not completed.
One damaged and incomplete prototype is preserved in the Polish Aviation Museum in Kraków.
Powerplant: 1× Narkiewicz WN-4 7-cylinder air cooled radial engine, 320 shp (237 kW)
Fuselage length: 10.55 m
Rotor diameter: 12 m (39 ft 4.5 in)
Height: 2.8 m
Empty weight: 1,050 kg (2,313 lb)
Loaded weight: 1,500 kg (3,307 lb)
Useful load: 450 kg
Maximum speed: 156 km/h (97 mph)
Range: 260 km (161 miles)
Service ceiling: 3000 m
Rate of climb: 4.6 m/s, 276 m/min
Crew: one, pilot
Capacity: three passengers