by Richard Sheffield
Proposals for a New Helicopter
Congress was finally convinced of the need for this new helicopter and in August of 1972 the AAH (Advanced Attack Helicopter) program was officially announced. In October of 1972, RPVs, or requests for proposals, were issued to the aircraft contractors. The Army wanted to build a helicopter which would meet the following official requirements:
Cruising speed of 145 knots
Ability to carry eight TOW antitank missiles
Operational time of 1.9 hours
Ability to withstand load factors of +3.5 to −1.5 gs at gross weight
Ability to withstand hits from .5-inch heavy machine guns and 23mm cannons
Ability to land on a hard surface at a vertical speed of 42 feet per second with a forward speed of 15 knots
Production proposals were received from Lockheed, Hughes, Boeing-Vertol, Sikorski, and Bell. The design engineers soon found that since none of their existing air frames could be modified to meet the stringent requirements set down by the Army, a totally new aircraft would have to be drawn up.
The Army continued to examine the concept while evaluating the proposals and became concerned about the TOW missile's range. Getting close enough to fire this missile would put the aircraft within range of many enemy air defense systems. The Rockwell Hellfire missile was in the early stages of development but offered a range of six kilometers. Though still unproven, the Army made a wise decision and changed the specifications to include the Hellfire in place of the TOW.
In June 1973, it was announced that the proposals submitted by Bell and Hughes had been accepted and funds would be provided to each firm to develop their designs to a point where a competitive fly-off between the two aircraft could be performed. This competition was to take place in July of 1976.
Since the AH-1 was the previous standard for attack helicopters, it was not surprising that the helicopters designed by both companies took on a similar shape (but on a much larger scale). At 13,000 pounds, the Hughes design weighed twice as much as the AH-1. Both helicopters were of twin-engine design built around the GE YT700 engine.
The major differences between the prototypes devised by Bell and Hughes were that the Bell design used a two-blade rotor as opposed to the four-blade system chosen by Hughes, and Bell chose to put the pilot in the front seat whereas Hughes put the copilot/gunner in the front. There were also differences in the main transmission and tail rotor assemblies. The Bell design was assigned the designation YAH-63; the Hughes model was assigned YAH-64.
The two companies worked furiously and on Sept. 30, 1975, the Hughes YAH-64 flew for the first time. The Bell design flew for the first time the following day. The two aircraft were handed over to the Army for competitive testing in mid-1976, and, by December, the Army had reached a decision. The winner was the Hughes YAH-64.