'Sigma' projects (SAM-4) by A.S.Moskalev

Using the experimental base of the Voronezh Aircraft Factory OKB and avia-mechanics division of the Voronezh University, A.S.Moskalev in 1933- 1934 performed series of experiments with various wing shapes. Parallel studies were carried out of the cannon fired projectiles and impact of the shape on the drag forces at high speed. Result of those studies was a brilliant prediction of the optimal wing shape for high speed aircraft - flying 'ogival' wing of low aspect ratio.

The final goal was a jet-powered aircraft with supersonic speed. More realistic project was a piston-engined SAM-4. It was designed around two 760hp Hispano-Suiza engines with evaporative coolers. Both engines were completely 'hidden' in the wing. Coaxial counter-rotating propellers had scimitar-shaped blades (like the most modern propellers).

The wing carried endplates on the tips, improving low speed handling and increasing wing lift (like airdynamic fences do). Tricycle retractable landing gear was designed specially for this plane. Pilot's cockpit was flush with the upper wing surface, and pilot had to operate the plane in prone position.

This project was presented to GUAP in 1934. It was too unusual and had too much novelties for bureaucrats to swallow, and received quite a cold reception. A.S.Moskalev was working at the time on the SAM-7 tailless fighter (also part of his 'Sigma' program) and other projects, and SAM-4 was put aside.

Two years later, in 1936, TsAGI scientists received reports from USA about similar studies of aircraft with low aspect ratio wing and prone pilot position. Officials 'woke up' and ordered A.S.Moskalev to build a light experimental analog for low speed behaviour evaluations. This prototype became known under designation 'Strela' ('Arrow').

Created October 27, 1999 with help of

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