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| How Can Thrust Be Used to Overcome Weight? |
A helicopter's spinning blades create thrust like a large
propeller, but the thrust is directed vertically. This allows
the vehicle to take off and land vertically and to hover. To
move forward, the helicopter tilts slightly to direct some of its
thrust forward.
The large propellers on an XV-15 tiltrotor airplane can be
swiveled up and down. The airplane can take off and land like a
helicopter by directing its thrust vertically, and fly forward
like a regular airplane by directing its thrust horizontally.
The powerful exhaust streams from the jet engine of the
Harrier fighter can be directed downward as well as backward, and
their direction can be changed in mid-flight. This allows the
Harrier to take off vertically, fly forward, stop in mid-air,
back up, and land vertically. It can also take off and land like
a normal airplane.
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(Rev. 09/17/96)