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UH-1N

The Bell UH-1N Twin Huey is a medium military helicopter that first flew in April, 1969. The UH-1N has a fifteen seat configuration, with one pilot and fourteen passengers. In cargo configuration the UH-1N has an internal capacity of 220 ft³ (6.23 m³). An external load of 5,000 lb (2,268 kg) can be carried by the UH-1N. The CUH-1N (later CH-135) Twin Huey was the original version, first ordered by the Canadian Forces.

 

Development

Based on the stretched fuselage Bell 205, the Bell 212 was originally developed for the Canadian Forces (CF) under the designation CUH-1N Twin Huey. Later the CF adopted a new designation system and the aircraft was re-designated as the CH-135 Twin Huey. The CF approved the development of the aircraft on 1 May 1968 and purchased 50 aircraft, with deliveries commencing in May 1971.

 The US military came very close to not procuring the Twin Huey. The purchase of the aircraft for US military use was opposed by the Chairman of the House Armed Services Committee at the time, L. Mendel Rivers. Rivers took this position because the aircraft powerplant, the Pratt & Whitney Canada PT6T was produced in Canada. The Canadian government had not supported US involvement in Vietnam and had opposed US policies in southeast Asia, as well as accepting US draft dodgers. Rivers was also concerned that procurement of the engines would result in a negative trade deficit situation with Canada. Congress only approved the purchase when it was assured that a US source would be found for the PT6T/T400 engines. As a result the United States military services ordered 294 Bell 212s under the designation UH-1N, with deliveries commencing in 1970.

Unlike in the Canadian Forces, in US service, the UH-1N retained the official name "Iroquois" from the single engined UH-1 variants, although US service personnel refer to the aircraft as a "Huey" or "Twin Huey".

The Bell 412 is a further development of the Bell 212, the major difference being the composite four-blade main rotor. The UH-1N has also been developed into the upgraded, four-blade UH-1Y.

 

Design

 in Pac made up of two Pratt & Whitney Canada PT6 turboshaft power turbines driving a single output shaft. They are capable of producing up to 1,342 kW (1,800 shp). Should one engine fail the remaining engine can deliver 671 kW (900 shp) for 30 minutes or 571 kW (765 shp) enabling the UH-1N to maintain cruise performance at maximum weight.[3]

The United States Marine Corps (USMC) modified a large number of their UH-1Ns with a Stability Control Augmentation System (SCAS) which provides servo inputs to the rotor head to help stabilize the aircraft during flight. This modification removed the gyroscopic "Stabilization Bar" on top of the main rotor head, instead relying on the computer system for stability.

 

Operational history

The United States Air Force employs UH-1Ns to fulfill its ICBM mission, providing a utility helicopter for transport between bases such as Minot AFB, Francis E. Warren AFB and Malmstrom AFB to missile launch sites in North Dakota, Montana, Wyoming, Nebraska, and Colorado. The UH-1N is also used by the 36th Rescue Flight (36 RQF) at Fairchild AFB, WA for conducting Search-and-Rescue (SAR) and medical evacuation missions.

During the 1982 Falklands War, the Argentine Air Force deployed two Bell 212 to Goose Green grass airstrip from where they performed general support duties including the recovery of many downed pilots. By the end of the hostilities both aircraft were still intact and both captured by the British.

USMC UH-1Ns were used by the USMC during its 2003 invasion of Iraq. UH-1Ns provided reconnaissance, and communications support to Marine ground troops. They were also called upon to provide close air support during heavy fighting in Nasiriyah.

 

General characteristics

Crew: 4 (Pilot, copilot, crew chief, gunner)

Capacity: 6-8 combat-equipped troops, or equivalent cargo

Length: 41 ft 8 in (12.69 m)

Rotor diameter: 48 ft 0 in (14.6 m)

Height: 14 ft 5 in (4.4 m)

Disc area: 1,808 ft² (168.0 m²)

Empty weight: 6,000 lb (2,721.5 kg)

Loaded weight: 10,500 lb (4,762.7 kg)

Useful load: 4500 lb (2038.0 kg)

Max. takeoff weight: 10,500 lb (4,762.7 kg)

Powerplant: 2 × Pratt & Whitney Canada T400-CP-400 turboshaft, 900 shp (671 kW), (total 1,250 shp) each

 

Performance

Maximum speed: 120 knots (135 mph, 220 km/h)

Cruise speed: 110 knots (126 mph, 207.3 km/h)

Range: 248 nmi (286 mi, 460 km)

Service ceiling: 17,300 ft (5,273 m)

Rate of climb: 1,755 ft/min (8.9 m/s)

Power/mass: hp/lb (W/kg)

 

Armament

2.75-inch (70 mm) rocket pods,

GAU-16 .50 Cal. Machinegun,

GAU-17 7.62mm minigun or M240 7.62mm lightweight machinegun