U.S.. Army CH-21 Shawnee helicopters on Banchee Field, Fort Rucker, Ala., in 1963. A short time later many were in Vietnam. (U .S. Army)

The HRP-2 was an improved version of the U .S. Navy's HRP-l Rescuer (listed separately), with a streamlined, all-metal fuselage skin increasing its performance. Although the Navy procured only four HRP-2s, preferring instead the smaller but more capable Piasecki HJP/HUP, the U.S. Air Force purchased 214 H-21s with the name Workhorse and the U .S. Army acquired another 334 H-21s which were assigned the name Shawnee. From December 1961 until late 1963 the H-21 was the Army's workhorse of the Vietnam War, being replaced by the HU-l/UH-l Huey. Production of the H-21 was started by the Piasecki Helicopter Corporation, as the firm was known from 1949, but was continued from 1955 by the successor Vertol Aircraft Corporation.* The 40-series designations were assigned by Vertol. Production totaled 557 HRP-2/H-21s for U.S. service plus almost 150 for foreign use. 

A U.S. Army H-21 made the first nonstop transcontinental helicopter flight across the United States on 24 August 1956, traveling 2,610 miles in 37 hours.

The HRP-2/H-21 design was a single-engine, tandem-rotor helicopter with three-bladed rotors mounted at the extremities of the fuselage. There was a Plexiglas cabin in the nose, behind which was the cargo compartment, with the engine mounted in the rear of the fuselage. The HRP-2 was configured for 8 passengers or 6 stretchers, while the H-21A could carry 14 troops or 12 stretchers, and the H-21B/C could lift 20 troops. The Navy aircraft had a 600-hp Pratt & Whitney R-1340-AN-l; the Army/Air Force helicopters had a Wright R-1820 piston radial providing more than twice that power. Two H-21Cs had their single radials replaced by two General Electric T58 turbo shaft engines. These were redesignated H-21D. There was no procurement of this configuration. The H-21s retained the Navy's close-set tricycle landing gear with fixed undercarriage. However, helicopters assigned to SAR functions often had doughnut-shaped floats fitted instead of wheels. Twin vertical fins were usually fitted at the tail. Several experimental weapon suites were fitted to Army H-21s, with one Army H-21C being armed with two .30-caliber and two .50-caliber forward-firing machine guns, a rocket pack with 24 2.75-inch folding-fin rockets, and two .30-caliber flexible machine guns fitted at the side doors.

The Marine Corps flew three of the Navy’s HRP-2s. The Air Force H-21 program began with 18 YH-21s, the first tandem-rotor helicopter flown by that service. Subsequently, 33 H-21A models were ordered for USAF SAR operations, mainly in the Arctic, and another five went to Canada. These were followed by 334 H-21C variants for U.S. Army and foreign use. Of the latter, 26 went to the West German Army, 98 to the French Army, 10 to the French Navy, and 6 to the Japanese Air Self-Defense Force. Vertol also produced 11 Model44A helicopters for use by the Swedish Navy, designated HPK-l by that service.

First flight: 

HRP-2: 10 November 1949 

YH-21 11 April 1952 Service introduction: 1950

Users: Canada, France, West Germany, Japan, Sweden, United States

This H-21 of the u.s. Air Force's 516th Troop Carrier Group is flying cargo to a radar station in the Arctic. These helicopters were used extensively and effectively by the USAAF and Army from the Arctic ice to the jungles of Vietnam before they were discarded in the mid-1960s. (The U.S. Army used them in Vietnam until June 1964.) (U.S. Air Force)

Soldiers secure an Army H-2IC assigned to the 509th Transportation Company. Note the attitude of the H-21 when at rest; in flight the cabin is level, increasing crew comfort. The aircraft resembles only superficially its HRP-1 predecessor. The naval version of the H-21, the HRP-2 Rescuer, was not produced in significant numbers. (U.S. Army)

An Army H-21C blasts away with rockets and machine guns during tests of armed helicopter configurations. Although such helicopters were used extensively by the French Army in Algeria (after some experiments in Indochina), the first true helicopter gunships to be employed in combat were the U.S. Army UH-IB Hueys of the Utility Tactical Transport Helicopter Company, which arrived in South Vietnam in mid-1962. (U.S. Army)

U.S.. Army CH-21 Shawnee helicopters on Banchee Field, Fort Rucker, Ala., in 1963. A short time later many were in Vietnam. (U .S. Army)