An ultralight, single-seat amateur aircraft in biplane configuration, designed and built from scratch by Jerzy Ostrowski, world champion in model aircraft class F4B (control-line scale models). The designer began work on the aircraft in 1978 in a basement of an apartment block, which necessitated easy assembly as well as disassembly. For this reason, the aircraft has detachable wings, and the final assembly of individual components took place after carrying them outside.
Initially, the designer used an MZ 250 motorcycle engine for propulsion, which after unsuccessful trials was replaced with a 2-cylinder Trabant car engine in inline configuration of 26 hp. Construction of the aircraft took five years and was completed in 1983. The aircraft made its maiden flight on 10 February 1983.
The machine was one of the few privately owned aircraft in the People’s Republic of Poland. In September 1984, during the 3rd Amateur Aviation Rally at the Gliding Centre airfield in Leszno, the aircraft won third place “for the high technical standard and exemplary construction quality and cross-country flight”.
After Ostrowski’s death, the aircraft was fitted with a 2-cylinder liquid-cooled boxer engine from a Citroen 2CV of 27 hp, which was subsequently replaced with a 2-cylinder, two-stroke Rotax 503 aviation engine of 45.6 hp. The aircraft is the last completed work of Jerzy Ostrowski.
| Wingspan | 5.64 m |
| Length | 4.72 m |
| Takeoff weight | 215 kg |
| Maximum speed | 105 km/h |
| Range | 170 km |
| Engine | two-cylinder, two-stroke Rotax 503 engine of 45.6 hp Previously: 2-cylinder Trabant engine in inline configuration of 26 hp |
