The Reduced-Gravity Program provides the unique weightless or zero-g environment of space flight for testing and training of human and hardware reactions. The reduced-gravity environment is obtained with a specially modified KC-135A turbojet transport which flies parabolic arcs to produce weightless periods of 20 to 25 seconds. KC-135A cargo bay test area is approximately 60 feet long, 10 feet wide, and 7 feet high. The image shows KC-135A in flight.

The Boeing KC-135 Stratotanker, besides being used extensively in its primary role as an inflight aircraft refueler, has assisted in several projects at the NASA Dryden Flight Research Center, Edwards, California. In 1957 and 1958, Dryden was asked by what was then the Civil Aeronautics Administration (later absorbed into the Federal Aviation Administration (FAA) in 1958) to help establish new approach procedure guidelines on cloud-ceiling and visibility minimums for Boeing's first jet airliner, the B-707. Dryden used a KC-135 (the military variant of the 707), seen here on the runway at Edwards Air Force Base, to aid the CAA in these tests. In 1979 and 1980, Dryden was again involved with general aviation research with the KC-135. This time, a special wingtip "winglet", developed by Richard Whitcomb of Langley Research Center, was tested on the jet aircraft. Winglets are small, nearly vertical fins installed on an airplane's wing tips to help produce a forward thrust in the vortices that typically swirl off the end of the wing, thereby reducing drag. This winglet idea was tested at the Dryden Flight Research Center on a KC-135A tanker loaned to NASA by the Air Force. The research showed that the winglets could increase an aircraft's range by as much as 7 percent at cruise speeds. The first application of NASA's winglet technology in industry was in general aviation business jets, but winglets are now being incorporated into most new commercial and military transport jets, including the Gulfstream III and IV business jets, the Boeing 747-400 and MD-11 airliners, and the C-17 military transport. In the 1980's, a KC-135 was used in support of the Space Shuttle program. Since the Shuttle was to be launched from Florida, researchers wanted to test the effect of rain on the sensitive thermal tiles. Tiles were mounted on special fixtures on an F-104 aircraft and a P-3 Orion. The F-104 was flown in actual rain conditions, and also behind the KC-135 spray tanker as it rel

Dr. von Braun inside the KC-135 in flight. The KC-135 provide NASA's Reduced-Gravity Program the unique weightlessness or zero-g environment of space flight for testing and training of human and hardware reactions. The recent version, KC-135A, is a specially modified turbojet transport which flies parabolic arcs to produce weightlessness periods of 20 to 25 seconds and its cargo bay test area is approximately 60 feet long, 10 feet wide, and 7 feet high.