On 11th April 1952, prototype of YH-21 rotorcraft, successfully performed its first flight.
The helicopter was designed by Frank N. Piasecki, the American aviation engineer and rotorcraft pioneer, and was developed in response to the United States Air Force request for a high-altitude, Arctic rescue helicopter.
Piasecki won the competition with his advanced rotorcraft design, able to carry up to fourteen troops or twelve stretchers, and capable to operate in cold weather environment with temperatures as low as -54°C.
Shortly after its maiden flight, the helicopter was ordered by the USAF and officially designated H-21 Work Horse (also spelled as Workhorse). Initially, the rotorcraft was produced in two different configurations – a search-and-rescue variant and an assault helicopter.
More information about the H-21, including history of its development and operational service, can be found in our article from Photo of the Week series – Vertol V-43 / Piasecki H-21C.
Cover photo: Vertol V-43 / Piasecki H-21C, Hubschraubermuseum Bückeburg (Bückeburg Helicopter Museum), 2023
