First Flight:
April 18, 1963
Mission: Full sized test bed for testing
"Laminar Flow Control" (also referred to as boundary layer control)
theory
Major Accomplishments: Proved that while Laminar flow control was
possible, it was not feasible with existing technology.
Power
Source: General Electric J79-GE-13, 9,400 lb thrust max.
Wing Span: 93'
6"
Length: 75' 3'
Weight (Loaded): 83,000
lbs
Maximum Achieved Speed: 560 mph
Maximum Achieved Altitude: 42,500 ft
Additional Information: Only two X-21's were built, and were
actually highly modified Douglas WB-66D's. The X-21 was
flown to test the "Laminar
Flow Control" theory. The basic concept is that the exterior surface of
the aircraft can be designed to create a slight suction during flight. Slots are
incorporated in the aircraft's surface to produce the suction. Though the
concept works, environmental considerations including rain, dirt, dust and other
particulates required excessive maintenance on the aircraft.
The last known location of both X-21's was Edwards AFB, where they had been
gutted of most instrumentation and left out of doors to deteriorate.
