Piasecki H-21

https://en.wikipedia.org/wiki/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.

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.

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 its maiden flight in April 1952, 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.

In 1952, some H-21As were evaluated by USMC helicopter squadron HMX-1 in the air
assault role. 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.

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, who had acquired Piasecki, 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.


Role
Cargo helicopter

Manufacturer
Piasecki Helicopter

First flight
1952; 65 years ago

Retired
1967; 50 years ago

Status
Retired

Primary users
United States Air Force
United States Army
French Army Aviation

Produced
1952-1959

Developed from
HRP Rescuer

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.

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. 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. 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.

Specifications (CH-21C)

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

Performance
Maximum speed: 127 mph (110 knot, 204 km/h)
Cruise speed: 98 mph (85 knots, 158 km/h)
Range: 265 mi (230 nmi, 427 km)
Service ceiling: 9,450 ft (2,880 m)
Disc loading: 5 lb/ft² (24 kg/m²)
Power/mass: 0.09 hp/lb (150 W/kg)

Armament

Varying, but usually one or two .50 (12.7 mm) or 7.62 mm M60 machine guns.





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