[Illustration: 81. Three chase planes salute the M2-F3 wingless
lifting body following one of its rocket-powered flights. The
blunt-nosed M2-F3 achieves its aerodynamic lift from the shape of
its body.]
This wingless craft is called a lifting body, because it derives its
lift from the fuselage rather than from wings. Removing the wings
reduces the weight of the craft, but adds significant control problems.
The lifting body concept was developed early in the last decade to
explore the problems of aerodynamic heating and vehicle control during
reentry from earth orbit. These are the problems that will be especially
critical in the space shuttle of the 1980s.
The M2-F3 tested flight behavior of wingless craft over a wide range of
speeds.
The M2-F3’s forerunner, the M2-F2, made 16 flights—all unpowered—between
July 1966 and May 1967. On May 10, it crashed on landing, partly due to
control instability. The craft was rebuilt, and the center fin was
added. This modification effectively solved the control problem, and the
new craft, designated M2-F3, logged 27 more flights by December 1972.
Some of the M2-F3’s flights were powered by a 3630-kilogram (8000-pound)
thrust rocket which boosted the craft to a higher altitude.
The M2-F3 was launched from a B-52 bomber at a height of about 13,300
meters (45,000 feet) and a usual speed of 730 kilometers (450 miles) per
hour. The maximum altitude achieved was 21,800 meters (71,500 feet). The
M2-F3’s record speed was 1718 kilometers (1066 miles) per hour. The
M2-F3 was built by Northrop.
The craft on exhibit is from the National Aeronautics and Space
Administration.
Length 6.8 m. (22 ft., 2 in.)
Span 2.9 m. (9 ft., 7 in.)
Height 2.5 m. (8 ft., 10 in.)
Weight 2720 kg. (6000 lb.) empty; 4540 kg. (10,000 lb.)
fueled
Speed 1718 km. per hr. (1066 m. per hr.) max. achieved
Altitude 21,800 m. (71,500 ft.) max. achieved
Mach number 1.5 max. achieved