Sikorsky S-51 Dragonfly

The Sikorsky S‑51 Dragonfly, produced by Sikorsky Aircraft Corporation from 1946 to 1954, was the first successful post‑war commercial helicopter and a direct evolution of Igor Sikorsky’s earlier R‑4 design. Powered by a 600‑hp Pratt & Whitney R‑985 radial engine, the single‑rotor machine featured a fully articulated three‑blade main rotor and a sturdy tubular steel fuselage that could accommodate up to five passengers or a modest cargo load. Its innovative hydraulic rotor‑pitch control and shock‑absorbing landing gear gave pilots unprecedented handling stability, while the optional floats allowed amphibious operations over water. The S‑51 quickly proved its versatility in civilian roles—air ambulance, news gathering, and aerial surveying—as well as in military service with the U.S. Navy and Coast Guard, where it performed search‑and‑rescue and anti‑submarine patrols. Over 400 units were built, and the type set performance benchmarks that informed later Sikorsky models such as the S‑55 and H‑19. By demonstrating reliable, multi‑mission capability, the S‑51 helped legitimize helicopters as practical tools in both commercial and defense aviation, shaping the future of vertical‑flight operations. Many surviving examples are displayed in aviation museums worldwide, where they continue to educate new generations about the pioneering era of rotorcraft development.

Sikorsky Aircraft Corporation

Sikorsky S-51 Dragonfly

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Design & Classification