YR-13 Sioux

The Bell Textron YR‑13 Sioux is a light, single‑engine helicopter that entered service in the mid‑1950s as the Army’s first dedicated trainer and liaison rotorcraft. Developed from the successful Bell 47 series, the YR‑13 prototype first flew on 17 June 1955 and received its Navy/Army designation the following year. Powered by a 100‑horse‑power Lycoming VO‑435‑A1B piston engine, the Sioux featured a distinctive bubble canopy, tandem seating, and a fully articulated two‑bladed main rotor with wooden spars later replaced by metal. Its simple mechanical linkages, low operating cost, and forgiving flight characteristics made it an ideal platform for novice pilots, forward‑air‑observation crews, and medical evacuation missions during the Korean and early Vietnam conflicts. Over 7,000 units were produced, many of them exported to allied nations, cementing the model’s reputation as a reliable workhorse. The YR‑13’s straightforward design set the standard for future training helicopters and helped establish rotary‑wing aviation as a versatile branch of the armed forces, influencing both military doctrine and civilian helicopter development for decades. Today, a handful of restored YR‑13 Siouxs are displayed in aviation museums and continue to demonstrate the timeless simplicity that made the aircraft a cornerstone of early helicopter training worldwide.

Bell Textron

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