UH-1 Iroquois (Huey)

Overview:

The Bell UH-1 Iroquois is a multipurpose military helicopter, famous for its use in the Vietnam War. It is commonly known as (or officially in the U.S. Marine Corps) the "Huey". The UH-1 was developed by Bell Helicopter from 1955 US Army trials with the Bell Model 204. The initial designation of HU-1 (helicopter utility) led to its nickname, Huey. The aircraft was first used by the military in 1959 and went into tri-service production in 1962 as the UH-1. The last were produced in 1976 with more than 16,000 made in total, of which about 7,000 saw use during the Vietnam War. The UH-1 is a general utility helicopter. It has a metal fuselage of semi-monocoque construction with tubular landing skids and two rotor blades on the main rotor. Early UH-1 models featured a single Lycoming T53 turboshaft engine in versions with power ratings from 700 shp (522 kW) to 1,400 shp (1,040 kW). Later UH-1 and related models would feature twin engines and four-blade rotors. All aircraft in the UH-1 family have similar construction. The most-produced version, the UH-1H, is representative of all types, particularly the long-body versions. The main structure consists of two longitudinal main beams that run under the passenger cabin to the nose and back to the tail boom attachment point. The main beams are separated by transverse bulkheads and provide the supporting structure for the cabin, landing gear, under-floor fuel tanks, the transmission, engine and tail boom. The main beams are joined at the lift beam, a short aluminum girder structure that is attached to the transmission via a lift link on the top and the cargo hook on the bottom and is located at the aircraft's centre of gravity. The lift beams were changed to steel later in the UH-1H's life, due to cracking on high-time airframes. Both the fuselage and the tail boom are of a semi-monocoque design. The tail boom attaches to the fuselage with four bolts. The UH-1H's dynamic components include the engine, transmission, rotor mast, main rotor blades, tail rotor driveshaft, 42 degree and 90 degree gearboxes. The transmission is of a planetary type and reduces the T53-L13B engine's output to 324 rpm at the main rotor. The two-bladed, semi-rigid rotor design, with pre-coned and under-slung blades, is a development of early Bell model designs, such as the Bell 47 with which it shares common design features, including a dampened stabilizer bar. The two-bladed system reduces storage space required for the aircraft, but at a cost of higher vibration levels. The two-bladed design also is responsible for the characteristic 'Huey thump' when the aircraft is in flight, which is particularly evident during descent and in turning flight. The tail rotor is driven from the main transmission, via the two directional gearboxes which provide a tail rotor speed approximately six times that of the main rotor to increase tail rotor effectiveness. The UH-1H also features a synchronised elevator on the tail boom, which is linked to the cyclic control and allows a wider centre of gravity range. The standard fuel system consists of five interconnected fuel tanks, three of which are mounted behind the transmission and two of which are under the cabin floor. The landing gear consists of two arched cross tubes joining the skid tubes. The skids have replaceable sacrificial skid shoes to prevent wear of the skid tubes themselves. Skis and inflatable floats may be fitted. Internal seating is made up of two pilot seats and seating for up to 13 passengers or crew in the cabin. The maximum seating arrangement consists of a four man bench seat facing rearwards behind the pilot seats facing a five man bench seat in front of the transmission structure. Beside the transmission structure on either side of the aircraft are two two-man bench seats, facing outwards. All passenger seats are aluminium tube with canvas seat material and are quickly removable and reconfigurable. The UH-1H is rarely capable of lifting 15 people, except at very low density altitudes, fuels loads, and hovering heights and so fewer seats are usually fitted. The cabin may also be configured for up to six stretchers, an internal rescue hoist, auxiliary fuel tanks, spotlights or many other mission kits. Access to the cabin is via two aft-sliding doors and two small forward hinged panels. The doors and hinged panels may be removed for flight or the doors may be pinned open. Pilot access is via individual hinged doors. While the five main fuel tanks are self-sealing, the UH-1H was not equipped with factory armour, although armoured pilot seats were available. The UH-1H's dual controls are conventional for a helicopter and consist of a single hydraulic system boosting the cyclic stick, collective lever and anti-torque pedals. The collective levers have integral throttles, although these are not used to control rotor rpm, which is automatically governed, but are used for starting and shutting down the engine. The cyclic and collective control the main rotor pitch through torque tube linkages to the swash plate, while the anti-torque pedals change the pitch of the tail rotor via a tensioned cable arrangement. Some UH-1Hs have been modified to replace the tail rotor control cables with torque tubes similar to the UH-1N Twin Huey.

Specifications:

Role

• Multipurpose utility helicopter.

First Flight

• 22 October 1956

Introduction

• 1959

Primary Users

• United States Army.
• Japan Ground Self-Defense Force.
• Australian Army.
• Philippine Air Force.

Number Built

• >16,000

Crew

• 1-4

Capacity

• 3,880 lb including 14 troops or 6 stretchers or equivalent cargo.

Length

• 57 ft 1 in with rotors (17.4 m).

Height

• 
  

• 14 ft 5 in (4.4 m).

Empty Weight

• 5,215 lb (2,365 kg).

Loaded Weight

• 9,040 lb (4,100 kg).

Max Takeoff Weight

• 9,500 lb (4,310 kg).

Powerplant

• 1× Lycoming T53-L-11 turboshaft.
• 1,100 shp (820 kW).

Weapons

• Variable, but may include a combination of:
• 2x 7.62 mm M60 machine gun, or 2x 7.62 mm GAU-17/A machine gun.
• 2x 7-round or 19-round 2.75 in (70 mm) rocket pods.
• 2x 7.62 mm Rheinmetall MG3 (German Army and German Luftwaffe).