Designed during the early stages of the Vietnam War, the Bell AH-1G Cobra provided fire support to ground forces, escorted transport helicopters, and conducted armed reconnaissance. The Boeing AH-64 Apache replaced the Cobra in the U.S. Army, but the Cobra remained the attack helicopter of the Marine Corps. This model carried a 7.62mm minigun and 40mm grenade launcher in its chin turret and four rocket pods holding 52 70mm rockets. Its listed capabilities included a nose gun turret, 70mm rockets, a 7.62 minigun pod or 20mm cannon, a maximum speed of 172 mph, a cruising speed of 130 mph, and a range of 357 miles. The Lockheed AH-56A Cheyenne, with a unique rear pushing propeller, was a prototype built for speed and the Army's first attempt at a dedicated attack helicopter. Designed to attack by diving at its target, it was dropped in favor of the Cobra because conditions in Vietnam, the threat of shoulder-fired missiles, delays, and cost overruns worked against it. Only ten were ever built. Its listed capabilities included nose and belly gun turrets, 70mm FFA rockets, 8GM-71 TOW missiles, a maximum speed of 253 mph, a cruising speed of 225 mph, and a range of 875 miles.