As early as 1933, Aleksandr Moskalyev was designing a rocket-powered, tailless aircraft with an ogival or gothic delta wing, wingtip fins and rudders, which would be able to fly faster than sound.

[1] The all-metal Sigma was intended to investigate the manoeuvrability and field of fire of a two seat, tailless, wingtip finned fighter aircraft, using a less radical low aspect ratio, trapezoidal plan wing.

[1] The Sigma was powered by a 820 hp (610 kW) V-12 Mikulin AM-34 engine mounted ahead of the wing leading edge and driving a four blade, wooden propeller.

It was judged dangerous to fly as it was hard to keep straight during take-offs and had a high landing speed of 138 km/h (86 mph; 75 kn).

Its flight characteristics were never fully explored and it never reached its estimated top speed of 500 km/h (310 mph; 270 kn) at altitude.