The RAH-66 Comanche cost the U.S. Army $6.9 billion for two prototypes, then went straight to museums

The RAH-66 Comanche was conceived as a revolutionary reconnaissance and attack helicopter, but after $6.9 billion in development spending, only two prototypes remained. Both ultimately went to aviation museums instead of combat.

Developed by Boeing and Sikorsky, the aircraft was designed during the Cold War to replace older reconnaissance and attack helicopters. Its first flight took place on January 4, 1996. The concept was ambitious: a helicopter that could enter enemy territory without being detected, identify targets and send information to other combat systems, especially AH-64 Apache helicopters.

The Comanche used composite materials and carefully shaped surfaces to reduce radar detection. Its landing gear retracted, its 20-millimeter cannon stayed concealed when not in use, and its weapons could be carried in internal compartments. Engineers also worked to reduce its infrared and acoustic signatures. The engines mixed hot exhaust with air to lower the apparent temperature, while the five-blade main rotor and enclosed tail rotor aimed to reduce noise.

The aircraft was 14 meters long and 3.4 meters high. It carried a two-person crew, used two LHTEC T800 engines and had a maximum speed of 324 kilometers per hour. Its armament included the retractable cannon and space for missiles and rockets.

The Army initially planned to buy 1,213 aircraft, then cut the target to 650 in 2002. The Government Accountability Office estimated that completing development and acquisition would require nearly $27 billion. As wars in Afghanistan and Iraq created other priorities, the Army questioned whether it needed a stealth helicopter rather than upgrades to existing aircraft, new helicopters and unmanned systems. The program was canceled on February 23, 2004, freeing billions for those alternatives. Each of the two remaining aircraft had cost $3.45 billion.