The Lockheed AH-56 Cheyenne | The Rise of the Attack Helicopter
The Lockheed AH-56 Cheyenne: A Bold Vision Grounded by Reality
The Lockheed AH-56 Cheyenne promised to revolutionize military aviation as the U.S. Army’s first dedicated attack helicopter, blending high-speed innovation with formidable firepower. Born from the Advanced Aerial Fire Support System (AAFSS) program, it aimed to provide armed escort for transport helicopters like the Bell UH-1 Iroquois. Yet, despite its ambitious design and impressive test flights, the Cheyenne’s complexity and rising costs would ultimately lead to its downfall.
Background
The Cheyenne’s story begins in the early 1960s, amid a shift in military aviation. In 1962, the Howze Board recommended an airmobile division supported by 90 armed helicopters, spurring early experiments like arming 15 UH-1A Iroquois for Vietnam. Until then, armed helicopters were adaptations of utility designs, not purpose-built for combat. Bell Helicopter took a bold step forward with the D-255 Iroquois Warrior, a dedicated attack platform based on the UH-1B, featuring a nose-mounted turret and stub wings for rockets or missiles. This marked the dawn of the attack helicopter era, setting the stage for the AAFSS program that would produce the Cheyenne.
In 1964, the Army sought innovative designs through the AAFSS, soliciting proposals from 148 contractors. By February 19, 1965, Lockheed and Sikorsky emerged as finalists. On November 3, 1965, Lockheed won, its design deemed less expensive, faster to deliver, and lower-risk than Sikorsky’s Rotorprop. Meanwhile, the Army deployed the interim Bell AH-1 Cobra in Vietnam, which would later dominate its attack fleet.
Construction began after the Army awarded Lockheed a contract for 10 AH-56 prototypes on March 23, 1966. Built in Van Nuys, California, the first Cheyenne rolled out on May 3, 1967, and took flight on September 21, 1967. Pre-production funding for 375 aircraft followed on January 8, 1968, with initial operating capability targeted for 1972—optimistically, late 1970. All 10 prototypes were completed by 1969, but the Vietnam War’s financial strain loomed large.
Funding Challenges
The war in Vietnam underscored the need for attack helicopters while draining funds for projects like the Cheyenne. The Army initially hoped to order 600 units but settled for 375, driving up the unit cost. Prototype testing intensified, with the first major milestone planned for September 1968—a key flight test, not operational deployment. Delivery of operational aircraft was slated for a year later, though delays soon mounted.
Design Innovations
The Cheyenne’s compound design fused helicopter and fixed-wing elements for superior speed. Its rigid main rotor, low-mounted wings, and rear pusher propeller—powered by a General Electric T64 turboshaft engine—enabled speeds exceeding 200 knots (230 mph). At high velocity, the wings and propeller provided most lift and thrust, reducing rotor strain to just 20% of total lift, adjustable via pitch controls.
The two-seat cockpit featured a pilot in the rear and a gunner in front. The gunner’s station was a standout: the entire seat, sighting system, and controls rotated to align with the turret, linked to a periscopic sight for direct targeting. The pilot used a helmet-mounted system to aim weapons. Six external hardpoints—two under each wing and two on the fuselage—carried firepower: inner wing pods held three BGM-71 TOW missiles, outer wings mounted 7- or 19-rocket launchers, and fuselage points bore fuel tanks, with wings optionally plumbed for extra fuel.
Triumph and Tragedy
Flight tests in 1968 showcased the Cheyenne’s edge over the AH-1 Cobra, excelling in close and direct support with significant firepower and standoff range. But disaster struck on March 12, 1969, when test pilot David Beil was killed at 2,500 feet. The rotor oscillated violently, slicing into the cockpit and tail boom, killing him instantly. The fleet was grounded, and investigations by the Army, FAA, and Stanford Research Institute faulted Lockheed for design flaws. Lockheed contested the findings, implementing fixes like stiffer blades and improved gyros, but the damage was done.
On May 19, 1969, the Army cancelled production, citing instability and cost overruns. A wind tunnel accident on September 17, 1969, destroyed another Cheyenne, though no one was injured. While unrelated to real-world flight, it further tarnished the program’s reputation. By August 9, 1972, after spending over $400 million—with unit costs exceeding $4 million—the Secretary of the Army terminated the Cheyenne entirely. Its large size, inadequate night and all-weather capabilities, and analogue systems—outpaced by emerging digital technology—sealed its fate, especially as the A-10 Thunderbolt II vied for a similar role.
Legacy and Succession
The Cheyenne’s end launched the Advanced Attack Helicopter (AAH) program in 1972. Lockheed pitched a twin-engine variant without the pusher propeller, but Hughes’ AH-64 Apache won the contest, blending Cheyenne-inspired advances with a simpler, more practical design. Though the Cheyenne never saw combat, its bold vision shaped the evolution of attack helicopters.
The Cheyenne remains a testament to ambition and innovation undone by practicality. Its cancellation reflected not just technical setbacks but the shifting priorities of a military stretched thin by war and budget constraints. The AH-64 Apache would carry forward its legacy, proving the attack helicopter’s worth in conflicts worldwide.