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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.

H-21 Shawnee/Workhorse
Piasecki H-21 (modified).jpg
A US Army Piasecki H-21
Role Cargo helicopter
National origin United States
Manufacturer Piasecki Helicopter
First flight 11 April 1952
Retired 1967
Status Retired
Primary users United States Air Force
United States Army
French Army Aviation
Produced 1952-1959
Developed from HRP Rescuer

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 °F (−54 °C), and could be routinely maintained in severe cold weather environments.

Design and developmentEdit

Piasecki H-21 cockpit

Piasecki Helicopter designed and successfully sold to the United States 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 strike 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-21 Workhorse to the United States Air Force (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 nine-cylinder Curtis-Wright R-1820-103 Cyclone supercharged 1,150 hp (858 kW) air-cooled radial engine.

After the first flight of the YH-21 on 11 April 1952,[1] the USAF 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 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.

Piasecki H-21 interior view of the cabin

In 1952, some H-21As were evaluated by USMC helicopter squadron HMX-1 in the air assault role.[2] In 1957, an H-21B was loaned to the United States Marine Corps (USMC) to evaluate the helicopter as an airborne tug to tow disabled landing ships and amphibious landing vehicles to the beach. During the evaluation, the H-21B towed an LST at 5 knots and a simulated tracked amphibious vehicle from the water to the beach.[3] 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 1959 Vertol Aircraft, the new name for Piasecki Helicopters, came up with a concept for heavy lift over short distances where between two and six H-21Bs would be linked by beams to lift heavy loads. It was considered to be unsafe, because if one helicopter had mechanical problems during the lift it could cause an unbalanced situation and cause all helicopters to crash.[4]

Operational historyEdit

French service in the Algerian WarEdit

A Shawnee over rice paddies in Vietnam.

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 (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) M2 Browning machine gun or the (ex-German) MG 151/20 20 mm aircraft cannon for defensive use when landing assault forces under fire.[5][6][7]

Though the H-21 had been removed from the ground-attack role, official U.S. 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 helicopters in large-scale counterinsurgency operations.[5][6][7]

U.S. Army operationsEdit

The H-21C saw extensive service with the U.S. Army, primarily for use in transporting troops and supplies. On 24 August 1954, with the assistance of inflight 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.[8] 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 Army of the Republic of Vietnam troops. In Army 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 North Vietnamese Army and Vietcong ground forces, which were increasingly well supplied with automatic small arms and heavy (12.7 mm) AA machine guns. The H-21, which was designed for cold weather operations, performed poorly in the hot weather of Vietnam. Despite being capable of carrying 20 passengers, it carried only nine when operating in Vietnam. Pilots reported that engines that were rated for 600 hours of flying time were lasting only 200 hours or less in Vietnam.[9] The shooting down of a CH-21 Shawnee near the Laotian-Vietnamese border with the death of four aviators in July 1962 were some of the U.S. Army's earliest Vietnam casualties.[10] 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 Bell UH-1 Huey. In 1965, the Boeing 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.


USAF designation of the first H-21 prototype.
YH-21 Work Horse
USAF Search And Rescue (SAR) 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 one 1250hp Wright R-1820-102, re-designated CH-21A in 1962, 32 built for USAF, 6 for the Royal Canadian Air Force
H-21B Work Horse (Model 42)
Same as H-21A but with uprated Wright engine (1425hp) and seats for 20 troops, autopilot as standard and limited armour protection and external fuel tanks, became CH-21B in 1962, 163 built for U.S. forces. 10 built for Japanese Self-Defense Forces; 10 H-21B built for the French Navy.
SH-21B Work Horse
Rescue conversion of the H-21B, became HH-21B in 1962.
H-21C Shawnee (Model 43)
US Army version of the H-21B, became CH-21C in 1962, 334 built for U.S. forces. 32 built under license by Weser Flugzeugbau for the West German Army. 98 built for the French Air Force and French Army Aviation (ALAT).
XH-21D Shawnee (Model 71).
Two H-21Cs re-engined with two General Electric T58 turboshaft engines in place of the Wright R-1820. Not placed into production.
H-21A redesignated in 1962.
H-21B redesignated in 1962.
H-21C redesignated in 1962.
SH-21B redesignated in 1962.
Model 42A
Conversion by Vertol Aircraft (Canada) of eight Royal Canadian Air Force H-21s for civilian use. Equipped to carry 19 passengers or 2,820lb (1,279kg) of internal cargo or a 5,000lb (2,268kg) slung load.
Model 44A
Commercial 19-passenger transport version of the H-21B. 11 total (Swedish military designation: Hkp 1), 2 for the Swedish Air Force, 9 for the Swedish Navy. 2 used for test/evaluation purposes by Japan Self-Defense Forces.
Model 44B
Commercial 15-passenger/freighter version of the H-21B.
Model 44C
Commercial eight-passenger executive version of the H-21B.
Vertol Canada Model 44
Piasecki HkP1
Piasecki model 44 for the Swedish Navy


Aircraft on displayEdit



  • FR94 – H-21C on static display at the Musée de l'Aviation Légere de l'Armée de Terre et de l'Hélicoptère in Dax, Landes.[23]
  • FR106 is on display at the "Ailes Anciennes" Museum at Toulouse-Blagnac Airport.[24]





United StatesEdit

Static Display
Model 44A with the JGSDF at Bihoro Aviation Park, August 2009
CH-21 in RCAF markings at the Canadian Museum of Flight
Stored or under restoration

Specifications (CH-21C)Edit

Data from U.S. Army Aircraft Since 1947 [75]

General characteristics

  • Crew: 3–5 (Pilot, co-pilot, crew chief and one or two gunners in Vietnam)
  • Capacity:
    • 20 troops or
    • 12 stretchers
  • Length: 52 ft 6 in (16.01 m)
  • Rotor diameter: 44 ft 0 in (13.41 m)
  • Height: 15 ft 9 in (4.80 m)
  • Disc area: 3,041 ft2 (282.6 m2)
  • Empty weight: 8,950 lb (4,058 kg)
  • Loaded weight: 15,200 lb (6,893 kg)
  • Max. takeoff weight: 15,200 lb (6,893 kg)
  • Powerplant: 1 × Wright R-1820-103 radial engine, 1,425 hp (1,063 kW) driving 2 rotors



See alsoEdit


  1. ^ Bridgman 1952, p. 30.
  2. ^ "Here Comes the Leathernecks." Popular Mechanics, April 1952, p. 101, bottom of page.
  3. ^ "Flying Salvage Craft Works on Land Or Sea." Popular Mechanics, July 1957, p. 106
  4. ^ "Workhorses of the Air." Popular Mechanics, March 1959, p. 100.
  5. ^ a b France, Operations Research Group, Report of the Operations Research Mission on H-21 Helicopter (1959)
  6. ^ a b Riley, David, French Helicopter Operations in Algeria, Marine Corps Gazette, February 1958, pp. 21-26
  7. ^ a b Shrader, Charles R. The First Helicopter War: Logistics and Mobility in Algeria, 1954-1962 Westport, CT: Praeger Publishers (1999)
  8. ^ The New Propwash, Fox Valley Sport Aviation Assoc., Vol.2, Issue 12, p. 5
  9. ^ Halberstam, David (19 January 1963). "Army Copter Pilots in Vietnam Say H-21's Are Not Adequate". The New York Times. p. 3. Retrieved 3 May 2019.
  10. ^ Harding 1990, pp. 261–262.
  11. ^ "World Air Forces 1955 pg. 621". Retrieved 4 August 2018.
  12. ^ "Trade Registers". Retrieved 3 February 2019.
  13. ^ Arkell Flight 21 June 1957, p. 844.
  14. ^ "World Helicopter Market 1967 pg. 60". Retrieved 4 August 2016.
  15. ^ "aéronautique navale H-21". Retrieved 5 January 2013.
  16. ^ a b "World Helicopter Market 1967 pg. 62". Flightglobal Insight. 2018. Retrieved 4 August 2018.
  17. ^ "World Helicopter Market 1967 pg. 65". Retrieved 4 August 2016.
  18. ^ Swanborough and Bowers 1963, pp. 398–399.
  19. ^ Flight 13 May 1955, p. 668.
  20. ^ "World Helicopter Market 1967 pg. 61". Retrieved 4 August 2016.
  21. ^ "Helicopters in Civil Operations pg. 388". 21 March 1958. Retrieved 10 February 2015.
  22. ^ "Harold A. Skaarup, author of Shelldrake". Retrieved 6 January 2019.
  23. ^ "Airframe Dossier - Piasecki-Vertol H-21C-PH Shawnee, s/n FR94 AdT, c/n FR94". Aerial Visuals. Retrieved 21 October 2016.
  24. ^ "Ailes Anciennes Toulouse". Retrieved 23 November 2016.
  25. ^ "Vertol V-43 (H-21C)". Das Hubschraubermuseum Bückeburg. Retrieved 21 October 2016.
  26. ^ "Airframe Dossier - PiaseckiH-21, s/n 83+07 Heeresfliegertruppe, c/n WG7". Aerial Visuals. Retrieved 21 October 2016.
  27. ^ "Transporthubschauber Vertol (Piasecki) V-43A (H-21C) (Luftfahrzeugkennung der Bundeswehr: 83+08)". Militärhistorische Museum der Bundeswehr Flugplatz Berlin Gatow (in German). 2 January 2016. Retrieved 20 October 2016.
  28. ^ "Flugzeuge". Flugausstellung. Archived from the original on 31 December 2015. Retrieved 21 October 2016.
  29. ^ "Airframe Dossier - PiaseckiH-21, s/n 83+17 Luftwaffe, c/n WG17". Aerial Visuals. Retrieved 21 October 2016.
  30. ^ a b Thompson, Paul. "JGSDF – Where Are They Now?". J-Hangar Space. J-HangarSpace. Retrieved 21 October 2016.
  31. ^ "Experience Exhibits". Tokorozawa Aviation Museum. Tokorozawa Aviation Museum. Archived from the original on 14 March 2016. Retrieved 21 October 2016.
  32. ^ "Airframe Dossier - Piasecki 44A, s/n 50002 JASDF, c/n 44-20". Aerial Visuals. Retrieved 21 October 2016.
  33. ^ "Airframe Dossier - Piasecki-Vertol CH-21B Work Horse, s/n 02-4756 JASDF, c/n B148". Aerial Visuals. Retrieved 21 October 2016.
  34. ^ Thompson, Paul. "JASDF – Where Are They Now?". J-HangarSpace. J-HangarSpace. Retrieved 21 October 2016.
  35. ^ "Airframe Dossier - Piasecki 44C, c/n 44-417, c/r N74056". Aerial Visuals. Retrieved 21 October 2016.
  36. ^ "Hkp 1". flygvapenmuseum (in Swedish). 21 April 2010. Archived from the original on 13 August 2010. Retrieved 21 October 2016.
  37. ^ "Vertol H-21 Shawnee/Work Horse". Classic Rotors. Retrieved 20 October 2016.
  38. ^ "FAA REGISTRY [N64606]". Federal Aviation Administration. U.S. Department of Transportation. Retrieved 20 October 2016.
  39. ^ "Vertol CH-21B Workhorse". National Museum of the US Air Force. 29 May 2015. Retrieved 20 October 2016.
  40. ^ "AIRCRAFT COLLECTION". Battleship Memorial Park. USS ALABAMA. Archived from the original on 28 December 2016. Retrieved 20 October 2016.
  41. ^ "Airframe Dossier - Piasecki-Vertol CH-21B Work Horse, s/n 51-15859 USAF, c/n B.6". Aerial Visuals. Retrieved 20 October 2016.
  42. ^ "Airframe Dossier - Piasecki CH-21C Shawnee, s/n 51-15886 US, c/r N48082". Aerial Visuals. Retrieved 20 October 2016.
  43. ^ Carroll, Sean. "[Untitled]". Retrieved 21 October 2016.
  44. ^ "CH-21B "Work Horse"". Strategic Air Command & Aerospace Museum. Strategic Air Command & Aerospace Museum. Retrieved 20 October 2016.
  45. ^ "CH-21B "Workhorse"". Museum of Aviation. Retrieved 20 October 2016.
  46. ^ "Airframe Dossier - Piasecki-Vertol H-21B Work Horse, s/n 52-8688 USAF, c/r N6795". Aerial Visuals. Retrieved 20 October 2016.
  47. ^ "Airframe Dossier - Piasecki UH-21B Work Horse, s/n 52-8691 USAF". Aerial Visuals. Retrieved 21 October 2016.
  48. ^ "Heritage Park Tour Briefing" (PDF). Matanuska-Susitna Borough School District. May 2007. Retrieved 21 October 2016.
  49. ^ "Airframe Dossier - PiaseckiH-21, s/n 53-4323 USAF, c/n B.73, c/r N6793". Aerial Visuals. Retrieved 21 October 2016.
  50. ^ "Piasecki CH-21B Workhorse". Vintage Flying Museum. Retrieved 20 October 2016.
  51. ^ "Airframe Dossier - Piasecki CH-21B Work Horse, s/n 53-4324 USAF, c/n B74". Aerial Visuals. Retrieved 21 October 2016.
  52. ^ "H-21 Workhorse". March Field Air Museum. March Field Air Museum. Retrieved 20 October 2016.
  53. ^ "Actual Aircraft Aircraft on Display in Pueblo". Pueblo Weisbrod Aircraft Museum. Archived from the original on 25 December 2016. Retrieved 20 October 2016.
  54. ^ "Aircraft 53-4347 Data". Retrieved 20 October 2016.
  55. ^ "Airframe Dossier - PiaseckiH-21, s/n 53-4354 USAF". Aerial Visuals. Retrieved 8 November 2016.
  56. ^ "Airframe Dossier - PiaseckiH-21, s/n 53-4362". Aerial Visuals. Retrieved 20 October 2016.
  57. ^ "Piasecki H-21B (CH-21B) Workhorse". The Museum of Flight. The Museum of Flight. Retrieved 20 October 2016.
  58. ^ "Aircraft of the Mid-Atlantic Air Museum". Mid-Atlantic Air Museum. Retrieved 20 October 2016.
  59. ^ "Airframe Dossier - Piasecki HH-21B Work Horse, s/n 53-4369 US, c/r N109RB". Aerial Visuals. Retrieved 21 October 2016.
  60. ^ "Airframe Dossier - Piasecki-Vertol CH-21B Work Horse, s/n 53-4389 USAF, c/n B.139". Aerial Visuals. Retrieved 20 October 2016.
  61. ^ "Airframe Dossier - Piasecki H-21B Work Horse, s/n 54-4004 USAF". Aerial Visuals. Retrieved 20 October 2016.
  62. ^ "Piasecki H-21 / CH 21B Workhorse". American Helicopter Museum & Education Center. American Helicopter Museum & Education Center. Archived from the original on 21 October 2016. Retrieved 21 October 2016.
  63. ^ "Airframe Dossier - Piasecki CH-21C Shawnee, s/n 55-4140 US, c/n C.94". Aerial Visuals. Retrieved 21 October 2016.
  64. ^ "Helicopters". Evergreen Museum Campus. Evergreen Museum. Retrieved 20 October 2016.
  65. ^ "Airframe Dossier - PiaseckiH-21, s/n 55-4218 US Army". Aerial Visuals. Retrieved 20 October 2016.
  66. ^ "Airframe Dossier - Piasecki CH-21C Shawnee, s/n 56-2040 US, c/n C.202". Aerial Visuals. Retrieved 21 October 2016.
  67. ^ "Airframe Dossier - Piasecki CH-21C Shawnee, s/n 56-2077 US, c/n C.239". Aerial Visuals. Retrieved 21 October 2016.
  68. ^ "CH-21C "Workhorse"". Hill Air Force Base. 27 September 2007. Retrieved 20 October 2016.
  69. ^ "WORKHORSE". Pima Air & Space Museum. Retrieved 20 October 2016.
  70. ^ "Aircraft Inventory". Flight Test Historical Foundation. Flight Test Historical Foundation. Retrieved 21 October 2016.
  71. ^ "Airframe Dossier - Piasecki H-21B Work Horse, s/n 52-8683 USAF, c/n B.45, c/r N57968". Aerial Visuals. Retrieved 21 October 2016.
  72. ^ "Airframe Dossier - PiaseckiH-21, s/n 53-4329 USAF, c/r N6794". Aerial Visuals. Retrieved 21 October 2016.
  73. ^ "Airframe Dossier - Piasecki-Vertol H-21B Work Horse, s/n FR09 AdT, c/n B.155". Aerial Visuals. Retrieved 21 October 2016.
  74. ^ "Airframe Dossier - Piasecki 44B, c/r N74058". Aerial Visuals. Retrieved 17 November 2016.
  75. ^ Harding 1990, p.262.
  • Arkell, Basil. "Helicopters in Contrast: (2) Flying the American Vertol 44". Flight, Vol. 71, No. 2526. pp. 844–846.
  • Bridgman, Leonard. Jane's All the World's Aircraft 1952–53. London: Sampson Low, Marston & Company, Ltd., 1952.
  • Duke, R.A., Helicopter Operations in Algeria [Trans. French], Dept. of the Army (1959).
  • Harding, Stephen. U.S. Army Aircraft Since 1947. Shrewsbury, UK:Airlife Publishing, 1990. ISBN 1-85310-102-8.
  • Swanborough, F. G. and Bowers, Peter M. United States Military Aircraft since 1909. London: Putnam, 1963.
  • "The World's Air Forces". Flight, Vol. 67, No. 2416, 13 May 1955. pp. 615–668.
  • "World Helicopter Market". Flight, Vol. 94, No. 3096, 11 July 1968. pp. 48–60.
  • United States Air Force Museum (1975 edition)

External linksEdit