The Soviet Sigma 4 SAM Interceptor, The First Delta Wing, First Tail Less Configuration.

by Daniel Russ on February 20, 2012

Soviet Sigma 4 SAM

Sigma 4 SAM


1934 to 1936. One of the first, if not the first airplane designed without a rear vertical stabilizer was the Sigma 4 SAM. “M” stands for the designer, Aleksandr Moskalyev who was unconstrained by the trends of his day and used an incredibly agile imagination to come up with better aircraft designs. He sketched the Sigma 4 design while working at another factory. Air pressure builds up in front of wing surfaces as the plane travel faster. His idea was to see if creating a plane without a tail would make it easier to traverse the speed of sound. It was probably the first attempt to do this. It was the first record of  delta wing fighters, that would fill the skies of the world 40 years later.



The problem he imagined was also imagined by Stalin: after watching German bombers decimate partisans in Spain,  he envisioned enemy bombers entering Russian airspace would need to be intercepted. It never actually lifted into the air, but the fact that the Soviets were this far ahead shocked historians.



Of course this was a time when rocket engines were being developed. Unfortunately his airframe design came about ten years before a rocket engine was created that could withstand the forces that a modern airframe would need to withstand. The Sigma 4 was not only the first delta wing design, it featured Schiebe surfaces, or wingtip rudders. Moskalyev decided to place piston engines inside the wings for the prototype, and propellers in front.


Just to be sure that stupidity isn’t found in one place, bureaucrats at the Voronezh Aircraft Factory dismissed the design as too far out. When Stalin learned that western designers were working on tail-less and delta configurations, Moskalyev was asked to build a prototype. It never flew and was scrapped. Only sketches and stories remain.



The Sigma 4 SAM experimental aircraft

Sigma 4 SAM





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