Piasecki H-21

Infobox Aircraft
name= H-21 Shawnee/Workhorse


caption=USAF CH-21B at the National Museum of the United States Air Force.
type=Cargo helicopter
manufacturer= Piasecki Helicopter
designer=
first flight=
introduced=1949
retired=1967
status=
primary user=United States Air Force
more users=United States Army
produced=
number built=
unit cost=
developed from=HRP Rescuer
variants with their own articles=

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.

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a ground attack role in the Algerian War, the French Air Force experimented with arming the Sikorsky S-55, then being superseded in service by the more capable Piasecki H-21 and Sikorsky H-34 helicopters.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. [France, Operations Research Group, "Report of the Operations Research Mission on H-21 Helicopter" (1959)] [Riley, David, "French Helicopter Operations in Algeria", Marine Corps Gazette, February 1958, pp. 21-26] [Shrader, Charles R. "The First Helicopter War: Logistics and Mobility in Algeria, 1954-1962" Westport, CT: Praeger Publishers (1999)] 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. [France, Operations Research Group, "Report of the Operations Research Mission on H-21 Helicopter" (1959)] [Riley, David, "French Helicopter Operations in Algeria", Marine Corps Gazette, February 1958, pp. 21-26] [Shrader, Charles R. "The First Helicopter War: Logistics and Mobility in Algeria, 1954-1962" Westport, CT: Praeger Publishers (1999)]

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 spearFact|date=March 2007. 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

[
Shawnees in formation over South Vietnam in 1962] ;XH-21:US Air Force designation of the first H-21 prototype.;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 one 1250hp Wright R-1820-102, re-designated CH-21A in 1962, 38 delivered (including six for the Royal Canadian Air Force);H-21B Work Horse (Model 42):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. [Wings Over the Rockies Air & Space Museum Vertol H-21C] 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 General Electric T58 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 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.;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

;flag|Canada|1921
*Royal Canadian Air Force operated H-21A and Model 44A helicopters.;FRA
*French Army operated H-21C helicopters.;GER
*German Air Force operated H-21C helicopters.
*German Army operated H-21C helicopters.;SWE
*Swedish Air Force operated HKP-1 helicopters.
*Swedish Navy operated HKP-1 helicopters.;flag|United States|1912
*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, HRP-1G and HRP-2 helicopters.

Civil Operators

;flag|Canada|1921
*Dominion Helicopters;flag|United States|1912
*New York Airways

urvivors

;CH-21B 51-5857:National Museum of the United States Air Force, Wright Patterson AFB, OH;CH-21B 51-5859:At the USS Alabama Museum in Mobile, AL;CH-21C 51-5886:Aerospace Museum of California;CH-21B 51-5892:Quonset Point, RI;CH-21B 52-8623:In store at Edwards AFB, CA;CH-21B 52-8676:Strategic Air and Space Museum, Ashland, NE;CH-21B 52-8685:Museum of Aviation, Warner Robins AFB, GA;CH-21B 52-8688:Travis Air Museum, Travis AFB, CA;CH-21B 52-8691:Kirtland AFB, NM, marked as '34343';CH-21B 53-4324:Pate Museum of Transportation, Cresson, TX;CH-21B 53-4326:March Field Air Museum, Riverside, CA;CH-21B 53-4329:Museum of Flight Restoration Center, Paine Field, Everett, WA;CH-21B 53-4347:Pueblo Weisbrod Aircraft Museum, Pueblo, CO;SH-21B 53-4362:Alaska Museum of Transportation and Industry, Wasilla, AK;CH-21B 53-4366:Museum of Flight, Seattle, WA (previously at the Canadian Museum of Flight);CH-21B 53-4367:Mid-Atlantic Air Museum, Reading, PA;CH-21B 53-4369:U.S. Army Aviation Museum, Fort Rucker, AL;CH-21B 53-4389:Pima Air & Space Museum, Tucson, AZ;CH-21B 54-4001:Classic Rotors Museum, Ramona, CA (the only airworthy example remaining, registered as N64606);CH-21B 54-4003:Florence Air & Missile Museum, Florence, SC;CH-21B 54-4404:Alaska Aviation Heritage Museum, Anchorage, AK;CH-21C 55-4140:Intrepid Sea-Air-Space Museum, New York, NY;CH-21C 55-4218:Wings Over the Rockies Air and Space Museum, Denver, CO, marked as 53-4379;CH-21C 56-2040:U.S. Army Aviation Museum, Fort Rucker, AL;CH-21C 56-2077:U.S. Army Transportation Museum, Ft. Eustis, VA;CH-21C-VL 56-2142:Hill Aerospace Museum, Hill AFB, UT, marked as 54-4002;CH-21C 56-2159:Pima Air & Space Museum, Tucson, AZ;CH-21 ?:Springdale Airport, AR;CH-21 ?:Springdale Airport, AR

pecifications (CH-21C)

aircraft specifications

plane or copter?=copter
jet or prop?=prop

crew=2
capacity=
** 22 troops "or"
** 12 stretchers
length main=52 ft 6 in
length alt=16.0 m
span main=44 ft 0 in
span alt=13.4 m
height main=15 ft 9 in
height alt=4.80 m
area main=3,041 ft²
area alt=282.7 m²
empty weight main=8,950 lb
empty weight alt=4,058 kg
loaded weight main=15,200 lb
loaded weight alt=6,893 kg
max takeoff weight main=
max takeoff weight alt=
engine (prop)=Wright R-1820-103
type of prop=radial engine
number of props=1
power main=1,425 hp
power alt=1,063 kW
power more=driving 2 rotors
max speed main=127 mph
max speed alt=110 kn, 204 km/h
range main=265 mi
range alt=230 nmi, 426 km
ceiling main=9,450 ft
ceiling alt=2,880 m
climb rate main=
climb rate alt=
loading main=5 lb/ft²
loading alt=24 kg/m²
power/mass main=0.09 hp/lb
power/mass alt=150 W/kg
armament=
* Varying, but usually twin or quad .50 (12.7 mm) machine guns.

ee also

aircontent
related=
* HRP Rescuer
* Piasecki H-25/HUP
* CH-46 Sea Knight
* CH-47 Chinook
similar aircraft=
* Bristol Belvedere
* Yakovlev Yak-24
sequence=
lists=
* List of military aircraft of the United States
see also=

References

*Duke, R.A., "Helicopter Operations in Algeria" [Trans. French] , Dept. of the Army (1959)

External links

* [http://www.redstone.army.mil/history/aviation/factsheets/ch21.html H-21 US Army Aviation history fact sheet]