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

The BŻ-1 was designed at the research institute Główny Instytut Lotnictwa – Main Aviation Institute in Warsaw, from an initiative of Zbigniew Brzoska. The Polish aviation industry was destroyed after World War II, and in addition, the principal of the Institute was the only person who had seen a helicopter (Sikorsky R-4 in England).
Despite severe material shortages, work on the experimental design started in 1948, and the main designer became Bronisław Żurakowski (brother of test pilot Janusz Żurakowski), who designed the helicopter rotor and the control system. It used simpler Hiller rotor type, with two auxiliary blades. The structure of the fuselage, tail boom, auxiliary rotor and tricycle undercarriage were designed by Tadeusz Chyliński. The power unit and final drive were designed by Zbigniew Brzoska. The design utilized some components left by the Germans, like a piston engine Hirth HM 504 (configured for vertical use) and wheels from a glider’s landing gear.
Initially, the helicopter had no name. It only received the registration SP-GIL, from the Institute abbreviation, and soon it became known as GIL (gil also means bullfinch in Polish). Later it was also given the designation BŻ-1, from Żurakowski’s initials.
The helicopter was completed by the end of 1949. During the first flight trial on 15 January 1950, it was overturned by a wind gust and had to be repaired. The test pilot was Bronisław Żurakowski, who taught himself fly a helicopter. The helicopter first flew on 4 April 1950, restrained on tethers by two men for a measure of safety.
During 1950-1953, it underwent a test program and was often modified. At first it had elastic rotor blades. In 1950, it was fitted with rigid blades and an efficient simple custom designed resonant vibration eliminator. During tests, for different reasons, it crashed or was damaged without casualties, at least seven times and was repaired each time.

On 20 July 1952, the BŻ-1 GIL was first displayed to the public, during an air show at Okęcie airfield (it was one of first public helicopter presentations in the Eastern Bloc). On 16 November 1953 the helicopter was damaged when the main rotor was bent by the wind and cut off the rear pylon, thus ending the test program. By then, the prototype had completed 169 flights, 20 hours 21 minutes in total.

In 1956, the helicopter was repaired and used for training flights by helicopter pilots. On 28 June 1957, a tail rotor gear (originally from a World war II Zündapp motorcycle) broke and it could not be replaced, consequently, the helicopter never flew again, being written off in 1960. During 1956–1957 it had completed 185 flights, for a total of 12.5 hours.
Currently, the sole BŻ-1 GIL prototype is preserved in the Polish Aviation Museum in Kraków.

Powerplant: 1× Hirth HM 504, 105 hp
Length: 8.5 m
Rotor diameter: 8.8 m / 28 ft. 11 in
Rotors: 2-blade main; 2-blade tail
Height: 2.29 m
Disc area: 60.8 sq.m
Empty weight: 380 kg
Loaded weight: 610 kg / 1,276 lb
Maximum speed: 140 km/h / 87 m.p.h
Cruise speed: 120 kph
Service ceiling: 2000 m
Absolute ceiling: 3000m / 9,840 ft
Range: 275km / 112 miles at 73 m.p.h.
Rate of climb: 4.5 m/s
Seats: 2