| H-21 Shawnee/Workhorse | |
|---|---|
| USAF CH-21B at the National Museum of the United States Air Force. | |
| Role | Cargo helicopter |
| Manufacturer | Piasecki Helicopter |
| First flight | 1952 |
| Retired | 1967 |
| Primary users | United States Air Force United States Army French Army Aviation |
| Developed from | HRP Rescuer |
The Piasecki H-21 Workhorse/Shawnee is an American helicopter, the fourth of a line of tandem rotor helicopters designed and built by Piasecki Helicopter (later Boeing Vertol). Commonly called the "flying banana", it was a multi-mission helicopter, utilizing wheels, skis, or floats.
The H-21 was originally developed by Piasecki as an Arctic rescue helicopter. The H-21 had winterization features permitting operation at temperatures as low as -65 degrees F, and could be routinely maintained in severe cold weather environments.
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Piasecki Helicopter designed and successfully sold to the US Navy a series of tandem rotor helicopters, starting with the HRP-1 of 1944. The HRP-1 was nicknamed the "flying banana" because of the upward angle of the aft fuselage that ensured the large rotors did not hit each other in flight. The name would later be applied to other Piasecki helicopters of similar design, including the H-21.
In 1949, Piasecki proposed the YH-21A Workhorse to the USAF, which was an improved, all-metal derivative of the HRP-1. Using two tandem fully articulated three-bladed counter-rotating rotors, the H-21 was powered by one 9-cylinder Curtis-Wright R-1820-103 Cyclone supercharged 1,150 hp (858 kW) air-cooled radial engine. After its maiden flight in April 1952, the Air Force ordered 32 H-21A SAR models and 163 of the more powerful H-21B assault transport variant. The H-21B was equipped with an uprated version of the Wright 103 engine, developing 1425 shaft horsepower (1063 kW), and featured rotor blades extended by 6 inches (152 mm). With its improved capabilities, the H-21B could carry 22 fully equipped infantrymen, or 12 stretchers, plus space for two medical attendants, in the medevac role. With its Arctic winter capabilities, the H-21A and H-21B were put into service by both the U.S. Air Force (USAF) and the Royal Canadian Air Force (RCAF) to maintain and service DEW (Distant Early Warning) radar installations stretching from the Aleutian Islands and Alaska across the Canadian Arctic to Greenland and Iceland.
The uprated 1425 hp Wright engine used in the H-21B was also used in subsequent variants sold to both the U.S. Army (as the H-21C Shawnee) and the military forces of several other nations. In 1962, the H-21 was redesignated the CH-21 in U.S. Army service.
In 1956, seeking a way to use helicopters in a ground attack role in the Algerian War, the French Air Force and French Army Aviation (ALAT, Aviation Légère de l'Armée de Terre) experimented with arming the Sikorsky S-55, then being superseded in service by the more capable Piasecki H-21 and Sikorsky H-34 helicopters. Some French Air Force and Army aviation H-21C helicopters were subsequently armed with fixed, forward-firing rockets and machine guns. A few even had racks for bombs, but tests subsequently determined that the H-21C lacked the maneuverability and performance needed in the ground-attack role. The H-21C was far more successful as a troop transport, and most H-21Cs in service were eventually fitted with flexible door-mounted guns such as the .50 cal. (12.7 mm) Browning machine gun or the (ex-German) MG 151/20 20 mm aircraft cannon for defensive use when landing assault forces under fire.[1][2][3]
Though the H-21 had been removed from the ground attack role, official Army evaluations at the time indicated that the type was actually more likely to survive multiple hits by ground fire than was the Sikorsky CH-34; this was assumed to be a consequence of the location and construction of the CH-34's fuel tanks. By the close of the Algerian War, troop-carrying H-21C helicopters were being used in concert with H-34 ground-attack helos in large-scale counterinsurgency operations.[1][2][3]
The H-21C saw extensive service with the U.S. Army, primarily for use in transporting troops and supplies. On August 24, 1954, with the assistance of in-flight refueling provided by a U.S. Army U-1A Otter, a H-21C known as Amblin' Annie became the first helicopter to cross the United States nonstop.[4] Various experiments were made by the Army in arming the H-21C as a gunship; some Shawnees were armed with flex guns under the nose, while others were fitted with door guns. One experimental version was tested stateside with a Boeing B-29 Superfortress .50 cal. remote turret mounted beneath the nose. The H-21C (later designated CH-21C) was first deployed to Vietnam in December 1961 with the Army's 8th and 57th Transportation Companies, in support of ARVN (Army Republic South Vietnam) troops. In Army aviation service, the CH-21C Shawnee could be armed with 7.62 mm (.308 in) or 12.7 mm (.50 in) flexible door guns. Relatively slow, the CH-21's unprotected control cables and fuel lines proved vulnerable to the enhanced threat posed by NVA and Viet Cong ground forces, which were increasingly well supplied with automatic small arms and heavy (12.7 mm) AA machine guns. The shooting down of a CH-21 Shawnee near the Laotian-Vietnamese border with the death of four Army aviators in July 1962 were the U.S. Army's first Vietnam casualties.[5] Despite these events, the Shawnee continued in service as the U.S. Army's helicopter workhorse in Vietnam until 1964 when it was replaced with the UH-1 Huey. In 1965, the CH-47 Chinook was deployed to Vietnam, and later that year, most CH-21 helicopters were withdrawn from active inventory in the U.S. Army and Air Force.
Data from U.S. Army Aircraft Since 1947 [9]
General characteristics
Performance
Armament
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