10/31/2007. Sikorsky built two RSRA’s (Rotor Systems Research Aircraft)
to a NASA/US Army contract awarded in January 1974. The first of these
high-speed multi-purpose helicopters (NASA 740) made its first flight at
Stratford, Connecticut, on October 12, 1976. After 14 hours of testing
in 21 flights the initial test phase was completed in February 1977.
On July 21, 1977, it was airlifted to NASA’s Langley Research Center,
Hampton, Virginia, in 1979 the program was transferred to NASA's
Ames-Dryden Flight Research Facility (later redesignated Dryden Flight
Research Center), Edwards, California.
The pictured second prototype was built as a compound helicopter
fitted with a 45 ft 1 in (13.74 m) span wing, and two 9,275 lb (4,207
kg) st General Electric TF34-GE-400A turbofan engines additional to
the two 1,400 shp General Electric T58-GE-5 turboshaft engines driving
the standard S-61 rotor system. It made its first flight from
Stratford on April 10, 1978, was also tested at Langley before being
transferred to Ames-Dryden, recoded NASA 741.
In 1987 the second prototype was prepared to demonstrate the advanced
rigid X-wing/rotor system concept, whereby the rotor is stopped in
cruise flight with the blades then acting as wings to provide lift,
whilst engine power is diverted from the rotor system to give pure jet
thrust.
On November 4, high-speed taxi test were performed (without the X-wing
rotor), and the aircraft flew for 16 seconds at an height of 25 ft
(7.6 m), the real first flight (still without the X-wing rotor) took
place on December 2, 1987. However, for financial reasons the program
was ended in January 1988 and the X-wing was never flown.
