PIASECKI H-21

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. It was used for Arctic rescue because it performed so well at low temperatures.

Contents

Design and development

Operational history

Algerian War

Vietnam

Variants

Operators

Military Operators

Civil Operators

Specifications (CH-21C)

References

Related content

Design and development

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 provided the H-21 Workhorse to the USAF, which was an improved, all-metal derivative of the HRP-1.

Operational history

Algerian War

In 1956, seeking a way to use helicopters in a ground attack role in the Algerian War, the French Air Force experimented with arming the Sikorsky S-55, then being superseded in service by the more capable Piasecki H-21 and Sikorsky H-34 helicopters. The H-19 was originally fitted with a 20-mm cannon, two rocket launchers, two 12.7-mm machine guns, and a 7.5-mm light machine gun firing from the cabin windows, but this load proved far too heavy, and even more lightly-armed H-19 gunships proved underpowered. Some Piasecki H-21 helicopters were subsequently armed with fixed, forward-firing rockets and machine guns and a few even had racks for bombs, but the H-21 lacked the maneuverability and performance needed for offensive action. Most CH-21s in service were eventually fitted with a door-mounted 12.7- or 20-mm gun for self-defense only.^[1][2][3]
The Sikorsky CH-34 was also modified into a gunship by the French Navy. While the CH-34 was effective in the ground attack role, official evaluations at the time indicated that the CH-21 was more likely to survive multiple hits by ground fire than was the CH-34; this was assumed to be a consequence of the location and construction of the CH-34's fuel tanks. Nevertheless, by the close of the Algerian War, attack helicopters such as the CH-34 were being used in synchronized operations with troop-carrying CH-21 helicopters in large-scale counterinsurgency operations.^[1][2][3]

Vietnam

The 'CH-21B' assault helicopter could carry 22 fully-equipped troops, or 12 stretchers, plus space for two medical attendants, in the MedEvac role. The CH-21B was first deployed to Vietnam in December 1961 with the Army's 8th and 57th Transportation Companies, in support of ARVN (Army Vietnam) troops. The CH-21B/CH-21C Shawnee could be armed with 7.62 mm (.308 in) or 12.7 mm (.50 in) door guns. The CH-21 was relatively slow. Its cables and fuel lines were so vulnerable to small arms fire- it was even rumored that a CH-21 had been downed by a Viet Cong spear. The Shawnee was the "Workhorse" of Vietnam until it was replaced with the fielding of the UH-1 Huey, and the later fielding of the CH-47 Chinook in the mid-1960s. The Shawnee had two tandem fully-articulated three-bladed counter-rotating rotors. The CH-21 was powered by one Curtis-Wright R1820-103 Cyclone supercharged 1150 hp piston engine. The CH-21B was equipped with an uprated 1425 shaft horsepower (1063 kW) engine.

Variants

;XHRP-1
:Two prototypes powered by 600hp Pratt & Whitney R-1340-AN-1 for the United States Navy
;HRP-1 Rescuer
:Production version for the United States Navy with fabric covered fuselage, 35 built.
;HRP-2 Rescuer
:United States Coast Guard version of the HRP-1 with a re-designed all-metal fuselage, five built.
;YH-21 Work Horse
:USAF version of the HRP-2 for service test, eighteen built
;H-21A Work Horse (Model 42)
:Same as YH-21 with detailed changes and powered by two 1250hp Wright R-1820-102, redesignated CH-21A in 1962, 38 delivered (including six for the Royal Canadian Air Force)
;H-21B Work Horse
:Same as H-21A but with engine re-rated at 1425hp and seats for 20 troops, autopilot as standard and limited armour protection and external fuel tanks, became CH-21B in 1962, 163 built.
;SH-21B Work Horse
:Rescue conversion of the H-21B, became HH-21B in 1962.
;H-21C Shawnee (Model 43)
:USAF version built by Vertol.^[7] US Army version of the H-21B, became CH-21C in 1962, 334 built. An additional 32 were built under licence by Weser Flugzuegbau for the West German Army.
;H-21D Shawnee (Model 71)
:Two H-21Cs re-engined with two T-58-GE engines.
;CH-21A
:H-21A redesignated in 1962.
;CH-21B
:H-21B redesignated in 1962.
;CH-21C
:H-21C redesignated in 1962.
;HH-21B
:SH-21B redesignated in 1962.
;Model 44A
:Commercial 19-passenger transport version of the H-21B.
;Model 44B
:Commercial 15-passenger/freighter version of the H-21B.
;Model 44C
:Commercial eight-passenger executive version of the H-21B.
;HKP-1
:Swedish designation of the Model 44A, nine bought new, two former civil Model 44Bs were modified to HKP-1 standard for the Swedish Air Force

Operators

Military Operators

;Canada

★ Royal Canadian Air Force operated H-21A and Model 44A helicopters.
;

★ French Army operated H-21C helicopters.
;

★ German Air Force operated H-21C helicopters.

★ German Army operated H-21C helicopters.
;

★ Swedish Air Force operated HKP-1 helicopters.

★ Swedish Navy operated HKP-1 helicopters.
;United States

★ United States Army operated H-21C from 1949 to 1967.

★ United States Air Force operated H-21A, H-21B and SH-21B helicopters.

★ United States Coast Guard operated HRP-1 and HRP-2 helicopters.

Civil Operators

;Canada

★ Dominion Helicopters
;United States

★ New York Airways

Specifications (CH-21C)

References

★ Duke, R.A., ''Helicopter Operations in Algeria'' [Trans. French], Dept. of the Army (1959)
1. France, Operations Research Group, ''Report of the Operations Research Mission on H-21 Helicopter'' (1959)
2. Riley, David, ''French Helicopter Operations in Algeria'', Marine Corps Gazette, February 1958, pp. 21-26
3. Shrader, Charles R. ''The First Helicopter War: Logistics and Mobility in Algeria, 1954-1962'' Westport, CT: Praeger Publishers (1999)
4. France, Operations Research Group, ''Report of the Operations Research Mission on H-21 Helicopter'' (1959)
5. Riley, David, ''French Helicopter Operations in Algeria'', Marine Corps Gazette, February 1958, pp. 21-26
6. Shrader, Charles R. ''The First Helicopter War: Logistics and Mobility in Algeria, 1954-1962'' Westport, CT: Praeger Publishers (1999)
7. Wings Over the Rockies Air & Space Museum Vertol H-21C

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