Główny Instytut Lotnictwa BŻ-1
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