INTRO
Throughout the history of aviation, certain designs have emerged which have become icons within popular culture. One such design is the Bell UH-1 ‘Huey’, an aircraft which played a pivotal role in the Vietnam War, and arguably one of the most memorable helicopters of the 20th Century.
CONCEPT VARIANTS
In 1955, Bell Helicopter won a competition held by the US Army to design a helicopter, capable of fulfilling both medevac and general utility roles. Military interest in such a helicopter had steadily increased since the start of the Korean War, when it was shown that helicopters were a true lifesaver, able to safely and quickly evacuate the wounded from the front lines back to mobile hospitals.
Within just a year, Bell had produced what would be broadly referred to as the Model 204, a medium sized helicopter which could accommodate two pilots in the front, and several personnel in the cabin. While earlier helicopters were often powered with standard piston engines, the Bell 204 would use a prototype turbine engine known as the Lycoming YT53-L-1. This initial design impressed the US Army so much so, that six aircraft were ordered before the test flight even took place.
First flying on October 22 1956, the US Army would refer to this initial aircraft as the XH-40 concept, and another two to be delivered the following year. After successful evaluation, the Model 204 would move into its pre-production phase. During this period in 1958, the six aircraft ordered before the test flight were put into produced under the Army designation YH-40, and these too would prove to supersede expectations.
PRODUCTION VARIANTS
HU-1A
The Iroquois as we know it would first emerge in its initial production variant in 1960. Its initial designation – HU-1A – would earn it the nickname Huey. This designation was soon changed to UH-1A, but the nickname would stick.
The first few HU-1A aircraft to be delivered in 1960 were intended for test and evaluation use. However, the Army quickly approved these aircraft, and gave Bell the green light to produce 100 such helicopters to be rushed into operational service. This process of adoption was so rapid, and the feedback so broad, that within 1960 alone, two new and improved variants were already in the works – the UH-1B model, and the UH-1C. This would all take place before the final delivery of the initial 100 A models.
The rapid adoption of these aircraft would soon make sense. In March 1962, 20 of the first of A-model Hueys would arrive in Vietnam with the 57th Medical Detachment. Almost immediately, crews in Vietnam began modifying these early models of the Huey, adding guns, rocket pods, and grenade launchers. Already in 1962, pilots and crews were beginning to see just how versatile the Huey was as a platform.
UH-1B
The B model would enter production shortly after this. It was designed in response to shortcomings noted in the initial Alpha models delivered to the Army. As such, the B model would feature a variety of smaller improvements, including a revised rotor and rotor mast, but would also feature an extended cabin, rated at being able to carry seven people. As rapid troop transport was becoming increasingly necessary in the still small scale Vietnam conflict, the larger cabins would help save massive amounts of time.
But the primary improvement would be the engine. The greatest shortcoming of the A model was its engine, which produced just over 800 horsepower. This was considered insufficient for troop transport and was noted when attempting to equip heavier armament to the aircraft. Thus, the A models Lycoming T53-L-1 power plant was replaced by the improved T53-L-5, which could produce almost 1000 horsepower.
The B models would be mass produced, and would first be sent over to Vietnam in late 1963. Just like the Alpha models, the UH-1B would be modified by personnel in Vietnam. One of the most common modifications was to turn the aircraft into a gunship. But just as with the A model, the UH-1Bs engines would begin to struggle when the aircraft was loaded up with weaponry.
UH-1C
In response to this came the Charlie model Iroquois. It was initially designed alongside the B model in late 1960, following early testing of the A model. As the utility of armed helicopters became more obvious in Vietnam, the development of the C model would continue, aimed with the specific intent of being used as a gunship. Many improvements were incorporated, including a dual hydraulic control system, larger fuel capacity, redesigned tail boom and elevators, a new rotor system, better engine inlet filters to protect against dust – and most importantly – an improved engine – the Lycoming T53-L-9, producing 1100 horsepower. It would finally be sent over to Vietnam for use by the Army in June 1966.
The C model was not intended for long term use by the Army. Instead, Bell intended the Charlie model gunships to be used as placeholders for a newer design based off of the Huey – an attack helicopter known as the AH-1 Cobra.
UH-1D
Leading up to this, the Army had also been requesting a larger variant of the Huey. Despite the initial A and B models proving successful, they were still considered too small for serious troop movements. Proposals were made by the Army, specifically requesting a Huey capable of carrying two pilots, two door gunners, and up to ten ground troops.
The response from Bell was the UH-1D model, a model which had been in its testing stage since August 1960. With the cabin stretched an extra 1 meter, and outwards facing seats added on either side of the engines transmission, the Delta model was capable of carrying both the crew and up to 15 troops. This superseded the Army request, and would allow the Huey to become a truly effective troop transport vehicle. Alongside this improvement came many other modifications, including a new 1100 horsepower engine (the Lycoming T53-L-11), larger rotor blades, a larger tailboom, and a redesigned door system. In the past, the Huey had used sliding doors with a single window; the redesigned variant featured double-windowed sliding doors with hinged extensions, which allowed for full access to the cabin from outside. One of the biggest benefits of this redesign was the ability to carry six stretchers at a time – earlier variants could only carry four. Thus, not only was the Delta model a better troop transport, but it was also twice as effective as a MEDEVAC vehicle.
This model would be widely used in the conflict, and would also be exported to other forces. The Royal Australian Air Force would utilise the Delta model extensively, before it would receive the Hotel model some time later. It would enter service in Vietnam over the latter half of 1963.
UH-1H
Feedback from the Delta model was used as the basis for a new variant, the Hotel model. Retaining the same large cabin and improved rotors, the Hotel would integrate an even more powerful engine – the T53-L-13 – capable of producing 1300 horsepower. As such, the creation of Hotel models usually entailed simply upgrading the engines of existing Delta models.
The Hotel model is widely regarded as the most successful – and most iconic – variant of the Huey produced during the Vietnam war. Most allied forces in Vietnam operated the Hotel model at some point following its introduction in late 1967, including the RAAF, who adopted it as a replacement for the Delta models. It remains the most produced variant of the Iroquois.
UH-1E and UH-1F
Several other variants were produced in the interim. These included the Echo model designed for the Marines, which featured the 1100 horsepower T53-L-11 engine, and the Foxtrot model designed for the US Air Force. Unlike many other Hueys, the Air Force requested that the Foxtrot be powered by the General Electric T58, since the Air Force already had a surplus of these engines available. To accomodate this engine, Bell built the Foxtrot on the smaller Bravo model. Both the Echo and Foxtrot would enter service in 1964.
OTHER VARIANTS
From this point onwards, various other models would be produced which were more limited in use. These were primarily based off of Bravo, Charlie, or Delta model aircraft. These included the UH-1J, designed for the Japanese Self Defence Force, the UH-1L, designed for the Marines as an upgrade for the Echo model in 1969, and the UH-1K, designed for the Navy in very small numbers as a search and rescue aircraft in 1970, which would see limited use in Vietnam.
The UH-1M would also see use in the Vietnam War. Designed as a replacement for the Charlie model, the Mike model gunship featured the 1400 horsepower T53-L-13 engine. Like the Hotel model, the Mike model was often the designation given to existing Hueys following engine swaps. In this case, Charlie models refitted with L-13 engines. These would slowly be integrated from roughly 1967 through till 1970. The Mike model was also tested by the US Army Concept team as a night assaut aircraft, equipped with night vision, image intensifier systems, Xenon searchlights bound to a Night Observation Device – or NOD – and an escort of AH-1 Cobras. This program was known as Nighthawk, and proved somewhat effective. Finding targets with infrared light, the white light could then be turned on, allowing door gunners and the Cobra pilots to open fire on the target position.
Following this, several other variants were produced. The UH-1P would serve in limited numbers as a gunship in Vietnam, and the UH-1V would be developed as a MEDEVAC helicopter for US Army Electronics Command.
UH-1N
The UH-1N model would bring about one of the biggest changes to the the Huey airframe. Powered by a Pratt and Whitney Canada PT6T engine, the N model Huey was designed in 1968 following a request from the Canadian Armed Forces for a medium helicopter with a double-engine. Bell would see the project through. Despite several crucial components being produced in Canada – including the engine – the US Air Force decided to acquire N model Hueys, and by the end of 1970, these twin engined variants were being sent to the front lines in Vietnam. These aircraft were specifically given to the 20th Special Operations Squadron, who then outfitted them with rocket pods, miniguns, and 40mm grenade launchers. They were then painted in camouflage, with no US markings, and was used for reconnaissance and support of Special Forces based out of Cam Ranh Bay.
By 1971, the US Navy and Marine Corp were outfitted with UH-1Ns as well, where they would be used to fill various roles. This version of the Huey would prove both strong and difficult to fault, and by the time of the 2003 invasion of Iraq, the aircraft was still in frontline service with the Marine Corp. During the Iraq war, it would be used in a variety of roles – including surveillance – but would soon be called upon to provide close air support to ground troops during several battles.
The N model Iroquois would eventually be retired by both the Marine Corp and US Navy. However, over 60 of the aircraft are still in service with the US Air Force, which operate them in a variety of roles.
UH-1Y
However, the Huey would live on, and improvements would continue to be integrated. In 1996, the Marines had asked Bell helicopter to redesign two of its tried and tested aircraft – the Huey and the Cobra. At this point in time, the Marines were still using the N model Huey, and the AH-1W Super Cobra, however both were showing their age. In response to this, Bell produced concepts for a new type of Huey retaining the N models twin engine design, and a redesigned Cobra known as the AH-1Z Viper. Initially, the plan had been to upgrade the existing N model Huey airframes. Test flights with modified N models were undertaken from 2001 onwards, but by 2005, approval had been granted for Bell to simply produce a completely new helicopter. This would culminate in the Yankee variant.
The UH-1Y Venom, or Super Huey, is the latest and most technologically advanced version of the Iroquois. Entering service in 2008, it features many new electronics systems, including a Forward Looking Infrared system and a flat panel digital cockpit, while also featuring a four-bladed rotor and an extended fuselage. Overall, the Y model outperforms the N model in almost every capacity, with a massively increased operational range, a higher payload capacity, and better speed. Just like the first of the Hueys to enter service in the early 1960s, the Y model is designed as a utility helicopter, capable of filling a variety of roles, and due to its great all-round capabilities, it doesn’t look like it will be retired any time soon.
