HSL-1

The Bell HSL‑1 was a light anti‑submarine helicopter developed by Bell Textron in the early 1960s to meet the U.S. Navy’s “Helicopter, Anti‑Submarine Light” (HSL) requirement. Drawing on the proven Bell 47 lineage, Bell created an all‑metal airframe with a four‑blade main rotor and a streamlined, bubble‑cockpit that could be operated from the cramped decks of destroyers and frigates. Power was supplied by a compact Allison T63 turboshaft engine, delivering roughly 350 shp and granting the HSL‑1 a maximum speed near 150 kt and a range of about 300 nm, sufficient for short‑range patrols and rapid response to submarine contacts.

Key features included a retractable landing gear, a foldable rotor system for shipboard stowage, and an integrated suite of ASW sensors: a dipping sonar, magnetic anomaly detector and lightweight torpedoes or depth charges. Although only a limited batch of prototypes entered service, the HSL‑1 demonstrated the feasibility of operating a dedicated, ship‑based ASW platform in the littoral environment. Its design concepts directly informed later naval helicopters such as the Kaman SH‑2 and the modern SH‑60 series, marking the HSL‑1 as an important evolutionary step in maritime aviation and naval warfare.