The amateur-built motor glider Stratus was constructed by Józef Borzęcki between 1952 and 1961. It was initially powered by an engine taken from a Czech chainsaw, and its wings came from a Żuraw glider. Rebuilt at the turn of the 1960s and 1970s, it was fitted with lighter wings from the Komar glider and a new two-stroke engine combining two Riedel starter motors derived from the German Junkers Jumo 004 turbojet engine of World War II. The modified motor glider was renamed Altostratus and made its first flight in 1972. It remained in service until 1982.