The Boeing-Sikorsky RAH-66 Comanche was an advanced five-blade armed reconnaissance and attack helicopter designed for the United States Army. The RAH-66 program was canceled in 2004, before mass production began, after nearly US$7 billion was spent on the program.
During the early 1980s, the U.S. Army began formulating a requirement for the replacement of its helicopters then in service, resulting in the Light Helicopter Experimental program. In 1991, the Boeing-Sikorsky team was chosen to produce prototypes. The Comanche would incorporate stealth technologies, featuring a number of designs previously untried. It was to employ advanced sensors in its reconnaissance role, and was intended to designate targets for the AH-64 Apache. The aircraft was also armed with missiles and rockets to destroy armored vehicles. Two RAH-66 prototypes were built and conducted flight testing from 1996 to 2004. Since the cancellation the prototypes have been placed on display.
Design and development
Origins and LHX
In 1982 the U.S. Army started the Light Helicopter Experimental (LHX) program to replace UH-1, AH-1, OH-6, and OH-58 helicopters. It took six years, until 1988, before the request for proposal (RFP) was issued, in which the requirement was changed to a reconnaissance helicopter. In October 1988, the Boeing-Sikorsky and Bell-McDonnell Douglas teams received contracts for their designs. The program's name was changed to Light Helicopter (LH) in 1990. In April 1991, the Boeing-Sikorsky team was selected as the contest winner and received a contract to build four prototypes for a demonstration and evaluation phase. Also that month the helicopter was designated RAH-66 Comanche by the Army.
In November 1993, the first prototype began assembly at Sikorsky's Stratford and Boeing's Philadelphia plants, before the sub-assemblies were transferred to the former location for final assembly. The following year the number of prototypes was cut to two. The first Comanche prototype was rolled out of the Sikorsky Aircraft's helicopter production facility on 25 May 1995, before being transferred to West Palm Beach, Florida, for flight testing. The prototype, piloted by Bob Gradle and Rus Stiles, made its 39-minute maiden flight on 4 January 1996. The flight was originally planned for August 1995, but was delayed by structural and software problems. The second prototype made its first flight on 30 March 1999.
The RAH-66 was intended to be a stealth helicopter; it incorporated multiple techniques to reduce its radar cross-section (RCS) and other areas of visibility. Its outer surfaces were faceted and had radar-absorbent material (RAM) coatings and infrared-suppressant paint applied; with these measures, the Comanche's RCS was 360 times smaller than the AH-64 Apache attack helicopter. The Comanche's noise signature was noticeably quieter than comparative helicopters; this was partly achieved through the all-composite 5-blade main rotor and tail rotor assembly.