Vomit Comet
Ralph Jones
Vomit Comet is a nickname for any airplane that briefly provides a
nearly weightless environment in which to train astronauts, conduct
research, and film motion pictures. Versions of such airplanes have in
the past been operated by NASA's Reduced Gravity Research Program
since 1973, where the unofficial nickname originated. NASA then
adopted the official nickname Weightless Wonder, for publication.
The airplane produces weightlessness by following a parabolic vertical
flight path. A parabolic flight path is the same path that would be
taken by an object in free fall, such as a cannonball fired into the
air. As a result, the aircraft does not exert any g-force on its
contents, so the contents have zero apparent weight relative to the
aircraft.
The aircraft heads upward at an angle of 45 degrees. As soon as the
pilot begins the rotation into the parabolic trajectory,
weightlessness is achieved. This lasts all the way "up-and-over the
hump", until the craft reaches a declined angle of 30 degrees. At this
point, the craft has lost a significant amount of altitude, and must
begin to pull into a hard upward turn. The forces are then roughly
twice that of gravity on the way down, at the bottom, and up again.
This lasts all the way until the aircraft is again halfway up its
upward trajectory, and the pilot again initiates the zero-g parabola.
In general, this aircraft is used to train astronauts in zero-g
maneuvers, giving them about 25 seconds of weightlessness out of 65
seconds of flight. This often produces nausea due to airsickness,
especially in novices, giving the plane its nickname.
Don Stockbauer
One out of an infinity of useful write-ups to know and tell.