Moskalyev SAM-9 Strela

The Moskalyev SAM-9 Strela (Arrow) was a one-off, Soviet, 1930s experimental tailless aircraft designed to test the characteristics of a leaf-shaped low-aspect-ratio delta wing.

Design and development
As early as 1933, Aleksandr Moskalyev was designing a rocket-powered, tailless aircraft with a highly-swept short-span curved delta wing with wingtip fins and rudders, able to fly faster than sound. Because no sufficiently powerful engines were available at the time, the Moskalyev SAM-4 Sigma was never built but it led to two interim types, the SAM-7 Sigma and SAM-9 Strela.

The tailless Strela was built to test the behaviour of the SAM-4's radically new wing plan using a highly swept delta with moderately convex leading and trailing edges.

Set at shoulder height, the wing root ran from ahead of the engine to the extreme tail and was fitted with broad-chord elevons equipped with trim tabs. It had the unusually low aspect ratio of 0.925. Like the rest of the Strela, the wing structure was wood. Control surfaces were fabric covered but the rest of the Strela's skin was plywood. Moskalyev had intended to use a 570 kW Hispano-Suiza 12Y engine, but only a 200 kW Renault 6P was available. The Strela's enclosed cockpit was at about mid-chord with a fairing behind it reaching the large, triangular fin with a narrow chord rudder equipped with a trim tab. The Strela had a fixed conventional undercarriage, with cantilever faired legs based on those of the Moskalyev SAM-5 and a sprung tailskid.

It was first flown, at Voronezh, in early 1937 by A.N.Rybo. A.N.Gusarov and A.P.Chernavskii explored its characteristics over the next few months, finding it controllable but demanding. The high landing angle of attack (around 20°) typical of delta wing aircraft was not yet familiar but worrying. In mid-1937 development of the SAM-9 was ended.