Sikorsky H-52

The Sikorsky H‑52, originally designated the S‑52, was the first helicopter produced by Sikorsky Aircraft Corporation after World War II. First flown on 28 July 1947, the prototype demonstrated a novel, fully articulated three‑bladed main rotor and a streamlined fuselage that reduced drag and increased speed. Powered by a 250‑horsepower Lycoming XO‑435‑5 engine, the H‑52 could reach 115 knots and carry up to four passengers or a single stretcher, making it attractive for both civil and military roles. The United States Army adopted a limited number as the H‑52A for light utility and liaison duties, while the United States Navy evaluated the type as the HO3S‑1 for ship‑board operations. Although production numbers remained modest—only 27 airframes were completed—the aircraft introduced several innovations that influenced later Sikorsky designs, such as the use of a semi‑monocoque metal skin and a fully articulated rotor hub that improved handling and vibration characteristics. The H‑52’s combination of speed, simplicity, and reliability helped prove the viability of small, fast helicopters in post‑war aviation, paving the way for subsequent utility helicopters like the S‑58 and the iconic UH‑60 Black Hawk.