HO5S-1

The Sikorsky HO5S‑1, often called the “Sikorsky HO5S,” was the United States Navy’s first purpose‑built, twin‑engine, ship‑borne helicopter, entering service in 1946. Developed from the R‑4 and R‑5 experimental models, the HO5S‑1 featured a tubular steel frame, a removable fiberglass cabin, and a three‑bladed main rotor driven by two 225‑horsepower Lycoming O‑435 engines mounted side‑by‑side in the forward fuselage. Its compact footprint and fold‑able rotor system made it ideal for operation from aircraft carriers and smaller warships, where storage space was at a premium. The aircraft could transport up to six passengers, perform reconnaissance, search‑and‑rescue, and limited cargo lifts, establishing the tactical role of rotary‑wing aviation in naval operations. During the early Cold War, the HO5S‑1 proved valuable in anti‑submarine warfare drills and in disaster relief missions, demonstrating the versatility of helicopters at sea. Although quickly superseded by the more powerful Sikorsky HO3S‑1 and later the H‑19 “Chickasaw,” the HO5S‑1’s successful integration aboard ships paved the way for modern naval rotorcraft, cementing Sikorsky’s reputation as a pioneer in vertical flight and shaping the future of amphibious and carrier‑based aviation.