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At the end of World War Two the United States Army Air Force USAAF became an independent service called the United States Air Force USAF. This happened in 1948. Under the new arrangements the USAF was to still be responsible for providing Close Air Support to the Army. The USAF was criticised during the Korean and Vietnam wars for lack of commitment to this role and poor coordination with the ground units. The Army responded by trying to run its own fleet of aircraft that would purely be concerned in supporting land operations. The Army then turned their attention to beefing up their attack helicopter. The Pentagon had no problem with the Army running its own fleet of Helicopters. This lead to the design of the successful Apache helicopter gunship that was able to provide close fire support.
Many within the USAF were happy to still use aircraft for which close air support was a secondary consideration like the training aircraft North American T-28 Trojan, Cessna T-37, the fighter F-100 Super Saber, A-1 Skyraider and the bomber B-57 Martin.
The USAF chiefs were not happy with the Army trying to take over the responsibility for CAS. In response to this perceived attack General John P McConnell, USAF Chief of Staff announced a new project called the A-X programme that was designed to produce a new purpose built close air support jet aircraft. The invites to tender were sent out to 21 companies in March 1967. One of the major requirements for this new aircraft was for it to be able to mount a new anti-tank heavy calibre high velocity long range gun. They not only wanted it to use the aircraft in the hostile jungle environments like those found in Vietnam but also against Soviet Warsaw Pact armoured units in cold war Eastern Europe. The companies were told that the aims for the aircraft design were simplicity, responsiveness, combat effectiveness and very importantly, survivability.
The two aircraft companies Fairchild and Northrop got through the paper sift and were instructed to build two prototypes each, that could then be used in a competitive fly-off against each other. The Fairchild YA-10A prototype first flew on 10th May 1972. It was declared the winner in the fly-off against Northrop’s YA-9A because it took less time to service and its survivability and protection was far superior. General Electric GE was awarded the contract to produce the new aircraft’s main weapon, the GAU-8 Avenger multi barrelled gun. They also were given the contract to provide the TF34 turbofan engine that was already in service fitted on the Lockheed S-3 Viking aircraft.
It was now time for the politicians to get involved and check that the public were going to get value for money, the need for a dedicated ground air support plane and that the right aircraft was going to be produced. They ordered a second fly-off take place, this time against the US Navy’s A-7 Corsair, before they would authorise the release of the money to pay for the new air craft. This delayed production. The A-10 easily won. In December 1974 authority was given for 52 A-10 Warthogs to be produced. The first production aircraft flew in October 1975. Throughout its service life there were still attempt to divert production money away from the programme to fund other projects. Some senior Airforce Chiefs still didn’t consider the A-10 to be a ‘proper’ US Air Force aircraft.
The Fairchild Republic’s A-10 Thunderbolt II tank buster Warthog aircraft has to house a long 20ft General Electric GAU-8 Avenger multi barrelled anti-tank gun. Although the A-10 is a large aircraft it is able to take off from short rough airstrips whilst heavily laden. The aircraft is heavily armoured to enable it to survive in a hostile war zone. It can withstand the loss of one engine, part of the wing or tail plane and still fly back to base. The armour is said to be able to withstand hits from 23mm up to 57mm rounds. The airframe is covered in 3,000lbs of armour. It has self-sealing fuel tanks. The designers introduced triple redundancy flight control systems so if the components or wires belonging to one system were damaged they could switch to one of the two back up systems. The airframe is made from removable panels so in battle, damaged sections can easily be replaced.
Large ailerons are nearly half the length of the wing. They are split and act as air breaks to give extra manoeuvrability at slow speeds. The bubble canopy gives the pilot 360o observation. The pilots feel very secure knowing that they are sitting in a 1 ½ inch thick titanium armoured ‘tub’. This means when they are flying at extreme low levels they are not vulnerable to hits from small arms fire.
So why are the Fairchild Republic’s A-10 Thunderbolt Warthog’s twin engines on the back of the aircraft’s fuselage? This is a very strange location. Part of the design requirement for the Warthog was that it had to be able to operate as a short take off aircraft from grass or dirt airstrips. Placing the engines as high up as possible reduced the chance of FOD foreign object damage. It minimised the chance of engine damage from stones and vegetation being sucked into the fans. Another reason for the engines to be placed on the back of the aircraft was to enable more space under the wings to fix rockets, guns, bombs and auxiliary fuel tanks.
The General Electric GAU-8/A Avenger is the A10’s main weapon. It is a hydraulically driven 30mm seven barrelled rotary cannon. The whole assembly gun is very heavy weighing over 4,000lbs when fully loaded. The gun on its own only weights 620lbs. This forms about 16% of the total aircraft weight. When loaded for battle it can take 1,150 rounds. The spent cases are not ejected but recycled back into the drum. The rate of fire is fixed at 3,900 rounds a minute which means the pilot only has enough ammo for a total of a 17 second burst. Tests have shown that when fired at a distance of 4,000ft the gun is an extremely accurate weapon with around 80% of the rounds capable of falling within 40ft around the target. One of the problems the pilot has to compensate for is the 10,000lbs of recoil force exerted onto the airframe. Not only can this effect accuracy but also flight control and has to be compensated for during training.
There are eight hard points under the Warthog’s wings and three under the fuselage. This gives the aircraft the capacity to carry 16,000lbs of bombs or a combination of rocket pods, maverick air to surface missiles, self-defence sidewinder missiles, Electronic Counter Measure ordnance ECM, litening flare chaff pods or extra capacity fuel drop tanks.
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