The first successful helicopter designed in Poland. During World War II, a new type of flying machine made its debut. It was the helicopter — an aircraft in which the lift and thrust needed for flight were generated by a main rotor, which, combined with a tail rotor, could be integrated into the control system. Thanks to the properties of its lift-propulsion system, the helicopter was capable of vertical takeoff and landing, hovering, and backward flight. These characteristics made it particularly attractive as a means of transport, evacuation and reconnaissance. At that time, no aeroplane could boast of similar capabilities.
The pioneers in the use of helicopters in military operations were the Germans and Americans. After the war, several more countries joined them, conducting pioneering research on such designs. Poland was among them.
After the end of hostilities, in war-ravaged Warsaw, the pre-war Institute of Aviation Technology was reactivated in 1946. Its name was changed to the Main Institute of Aviation, under which it operated until 1956 when it was renamed the Institute of Aviation. This research unit was intended to support the rebuilding Polish aviation industry, which had developed so splendidly in pre-war Poland. The idea of designing and building a helicopter appeared as early as 1946, conceived by Dr. Eng. Zbigniew Brzoska.
On the path to realising this bold undertaking stood the lack of scientific publications on the subject; the only source of knowledge was the aviation press, which followed aeronautical novelties. Work therefore began on gathering whatever information was available on the topic. In 1947, a three-person team was established to design such a flying machine. The team comprised: Dr. Eng. Zbigniew Brzoska, responsible for the powerplant; Eng. Bronislaw Zurakowski, working on the main rotor; and Eng. Tadeusz Chylinski, designing the fuselage, tail boom, tail rotor and undercarriage. In 1949, the design work was completed and construction of an experimental prototype began, with assembly taking place in the summer of that year. It was given the civil registration SP-GIL, but was not assigned an official designation.
The helicopter was designed in a “classic” configuration (single-rotor with a tail rotor). The main rotor, based on the system of the American Hiller company, had two wooden lift blades and two small control blades. This solution provided inherent stability and reduced forces on the control stick, greatly facilitating piloting. The fuselage, covered with fabric and removable duralumin panels (on the engine compartment), was constructed as a welded steel tube truss framework, transitioning into a wooden tail boom. The cabin was designed for two people, though in practice only one flew. The tricycle undercarriage with a nose wheel had oil-pneumatic shock absorption. The powerplant was the excellent German Hirth HM 504 aircraft engine, with parts from a German Zundapp motorcycle used in the power transmission system.
In April 1950, flight testing of the helicopter began, with one of the designers, Eng. Boleslaw Zurakowski, serving as the test pilot. It is noteworthy that these were his first-ever helicopter flights, and immediately as pilot-in-command. Testing was hampered by numerous failures of various mechanical drive components. Vibration was also a serious problem, being the cause of many helicopter design failures worldwide. In 1951, during subsequent repairs, vibration was significantly reduced thanks to the application of a special resonance vibration damper on the rotor; the originator of this system was Dr. Eng. Zbigniew Brzoska, and it was implemented by Eng. Bronislaw Zurakowski.
After a breakdown in November 1953, trials were suspended. The helicopter was repaired but not cleared for flight. It was returned to flying status in autumn 1956. For this purpose, several modifications and structural reinforcements were made. In February 1957, following another failure, flights were discontinued and the helicopter was scrapped.
In retrospect, its design may appear very primitive, but it should be remembered that it was merely an experimental aircraft. Its purpose was to gather experience in a field little known after World War II — helicopters. It was built at low cost, in a war-devastated country where funding for such experiments was hard to find. And yet, for such an innovative concept, it performed splendidly. One can only regret that it did not open the door for Poland to develop its own helicopter designs at that time.
Poland did begin helicopter production, but under Soviet licence. It is a pity, because the beginning was promising. Poland entered this field practically at the same time as the most famous designers and manufacturers in the world, where similar experiments were also being conducted, interrupted by constant failures and accidents. The helicopter never received an official name, possessing only the registration SP-GIL. In some publications, the designation BZ-1 “GIL” is used, but this is merely a literary convenience for type identification.
| Rotor diameter | 8.5 m |
| Fuselage length | 8.6 m |
| Takeoff weight | 610 kg |
| Maximum speed | 140 km/h |
| Ceiling | 2000 m |
| Range | 50 minutes of flight |
| Armament | – |
| Engine | piston, inline, 4-cylinder Hirth HM 504, 100 hp (74 kW) |
