Tarczyński and Stępniewki TS-1/34 Promyk

The Tarczyński and Stępniewki TS-1/34 Promyk was a Polish short span, high performance sailplane from the mid-1930s and was the first Polish sailplane equipped with flaps. Its construction was delayed by a financial crisis and its development terminated by World War II.

Design and development

In the mid-1930s there was international interest in short span but high performance sailplanes, because their ability to turn tightly would enable them to remain within narrow thermals. The German Darmstadt D-28 Windspiel, built in 1933, was an early example. The structure of the later, experimental Promyk (Small Radius) was almost twice as heavy as that of the delicate Windspiel, though the span was slightly less. Otherwise known as the TS-1/34, its design was started in 1934 but construction in the ZASPL workshops in Lwów was delayed by a financial crisis in Poland between 1935 and 1936 which led to a government clampdown on prototype building. The delay gave Stępniewki the opportunity to make the Promyk the first Polish sailplane with flaps. It finally flew in the spring of 1937.

The single-seat Promyk was an all-wood aircraft with a cantilever, one piece wing which was trapezoidal in plan out to rounded tips. Sources differ somewhat on its construction: Cynk describes it as a two spar structure, samolotypolskie as having a single spar, assisted by an angled auxiliary strut. It was covered by a mixture of plywood and fabric.