In 1952, Douglas Aircraft turned its mind to the replacement of the USN’s Skyraiders – one of the largest propeller driven fighter-bombers ever built.
The US Navy’s specifications, following the concept of ‘bigger is better’, called for a jet aircraft capable of operating from carriers, costing no more than one million dollars each. It could weigh as much as 30,000 lbs, in order to carry all the ordnance they wanted.
The Douglas Aircraft Corporation (later to become McDonnell-Douglas) gave the task to their best designer, Ed Heinemann, who had been responsible for a long and distinguished list of successful designs including the SBD Dauntless, the B-26 Invader and the AD Skyraider. Heinemann did not share the view the philosophy that successive generations of aircraft needed to be bigger, heavier or more complex. He carefully studied the type of fighting the Navy had been engaged in in Korea and, with his analysis of state of the art jet engine development, resolved to break the ‘creeping size’ mould.
His design philosophy was disciplined: he made a list of the features required of a new aircraft and then ruthlessly deleted everything that wasn’t absolutely necessary to achieve its mission. The resulting design astonished those who were involved, as it could meet the specified payload, range and performance requirements at no more than half of the allowable maximum weight. This was achieved by innovative thinking and design excellence.
Built around one of the new Wright turbojet engines, it carried only enough internal fuel to return from a target: fuel for getting there was carried externally on jettison able tanks. There was no internal bomb-bay: all ordnance was attached to hard points under the wings, made easier by the rigid delta wing design. Similarly, the undercarriage did not penetrate the main wing spar, being mounted so that when retracted only the wheel itself was inside the wing when retracted, whilst the undercarriage struts were housed in a fairing below the lower wing surface. This meant that the wing structure itself could be lighter for the same overall strength, and combined with the lack of a (heavy) wing fold mechanism even more weight was saved.
Radar sets in 1952 were large, heavy and mostly unreliable, so Heinemann made do with a simple optical gun sight. The delta wing design was efficient at the cruise speed of the aircraft, and automatic slats to improve handling at lower landing speeds were simple and effective.
The little Skyhawk soon earned the nicknames “Scooter”, “Bantam Bomber”, “Tink” and, because of its nimble performance, “Heinemann’s Hot-Rod”, but for all its size the Skyhawk packed a mean punch: it had a 20mm cannon in each wing root and could carry an astonishing range of bombs, rockets and missiles.
The A-4 also pioneered the concept of “buddy” air-to-air refuelling, whereby the aircraft could be used as a tanker for others of the same type, removing the need for entirely different tanker aircraft. One A4 was designated a tanker aircraft, with a centre-mounted external fuel tank with a hose reel in the aft section and an extensible drogue type refueling bucket. It was a simple system that allowed aircraft to extend their range without the need for very expensive dedicated tankers.
The Navy issued a contract for the type on June 12 1952, and the first prototype first flew on June 22, 1954. Deliveries to Navy and U.S. Marine Corps squadrons commenced in late 1956. The Skyhawk remained in production until 1975, with a total of 2,960 aircraft built, including 555 two-seat trainers, giving it the longest production run of any tactical aircraft in the history of aviation.
Below: Beautifully designed and engineered, the Skyhawk employed a modular construction, as can be seen from the sequence of four photographs showing the build of an A4 Skyhawk, below. (courtesy of Phil Thompson).
A fascinating video about Project Kahu – how the Kiwis converted their Skyhawks from the 4G to the 4K model, and why they did it and how.