In name only

Air Classics, Jan 2003

THE AU-1 WAS BUILT WITH JUST ONE OBJECTIVE IN MIND -- GROUND ATTACK

Sometimes the United States government and military work in mysterious ways. Take for example the AU-1 Corsair. AU-1? Yes, that is a correct designation for the aircraft that was a Corsair in name only. The island war in the Pacific proved that the Corsair could be an extremely effective ground attack aircraft but could its capabilities be improved if the design was optimized for that role only? The answer was yes and the new variant would be known as the NU-6.

The war had been over for a while and aircraft orders had drastically been chopped - however, the Corsair was still in production even in the face of the new generation of jet warplanes. The F4U-5 was being built in limited numbers and Vought designers took the basic Corsair design and added the necessary modifications for the low-level role. The Pratt & Whitney R-2800-83W was chosen as the powerplant.

The R-2800-83W had a single stage blower and was the only Corsair variant to mount such an engine. With a maximum speed of just 283 mph at 9500 feet, the aircraft was a bit of a dog but it could deliver the goods. The use of this powerplant resulted in a much simpler induction system and the wing leading edge scoops supplied ram air directly to the downdraft carburetor via simple circular section trunks- Dual circular oil coolers were located in front of the firewall. The lack of an auxiliary stage blower and its associated trunking, ductwork, and intercooler simplified the situation but this was, of course, at the expense of altitude performance. Cooling was now considerably simpler without the additional burden of intercoolers. The dual oil coolers were situated at 90 degrees to the longitudinal axis of the aircraft. Cooling air that came through the cooler was discharged into the space between the rear of the powerplant and the firewall. Small fixed cooling flaps allowed the cooling air to be vented overboard.

Unfortunately, the government did not want to order more F4Us. An ingenious solution was to change the designation of the aircraft to AU-1! Also, the start of the Korean War spurred the need for ground attack aircraft and 111 AU-1s were ordered, the first flying on 29 December 1951.

The aircraft had additional armor for fuel tank, engine accessory compartment, and cockpit to counter the increased ground fire the plane would receive in its low level mission. Fitted with four 20mm cannon, the AU-1 had ten underwing pylons which could tote 4000 pounds of weapons. The majority of the production run went to the Marines and they had received their aircraft by 10 October 1952. In Korea, the craft's load carrying ability was certainly put to good use in support of the Marines on the ground.

Some AU-1s were transferred to France for use in French Indochina. Survivors were returned to the United States but in 1955 some of these aircraft were overhauled and sold to France to bolster that country's F4U-7 fleet. Although having a different designation, the AU-1 proved to be just as effective of a fighting machine as its high altitude brothers.