Putilov Stal-11

The Stal-11 (Stal – steel) was a high speed transport aircraft / reconnaissance aircraft designed and built in the USSR from 1933.

Development
The Stal-11 was intended to carry four passengers with mail and baggage as well as fulfil a military reconnaissance role. The Stal-11 was constructed using an Enerzh-6 stainless steel built-up truss covered with Delta-wood for the fuselage, and an all-wood wing with built-up ribs. Two spars and very smooth skinning completed the structure. The prototype was completed in the autumn of 1936, flight trials commencing shortly after, with wheels and skis. Results of the approximately 300 flight tests were promising but the aircraft was expensive to build, with high running costs so no production was authorised.