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Document related concepts
Heavier than air aerodynes, including autogyros, helicopters and
variants, and conventional fixed-wing aircraft: aeroplanes in
Commonwealth English (excluding Canada), airplanes in North
American English. Fixed-wing aircraft generally use an internalcombustion engine in the form of a piston engine (with a propeller) or a
turbine engine (jet or turboprop), to provide thrust that moves the craft
forward through the air. The movement of air over the airfoil produces
lift that causes the aircraft to fly. Exceptions are gliders which have no
engines and gain their thrust, initially, from winches or tugs and then
from gravity and thermal currents. For a glider to maintain its forward
speed it must descend in relation to the air (but not necessarily in relation
to the ground). Helicopters and autogyros use a spinning rotor (a rotary
wing) to provide both lift and thrust. The abbreviation VTOL is applied
to aircraft other than helicopters that can take off or land vertically.
STOL stands for Short Take Off and Landing.
Forces on an Airplane in Flight
The four aerodynamic forces that act upon an
airplane in flight are lift (the upward acting force),
weight (or gravity, the downward acting force), thrust
(the forward acting force), and drag (the air
resistance or backward acting force). These four
forces are continuously battling each other while an
airplane is in flight.
The ailerons on an airplane's wings control roll
around the longitudinal axis. They work together,
simultaneously, tied to the control wheel, or stick, in
the cockpit. When the control wheel is turned left, the
aileron on the left wing goes up and the one on the
right wing goes down. The opposite occurs when the
wheel is turned right. But how does this make the
airplane roll?
The ailerons alter the lifting ability of the wings
slightly. When an aileron is lowered, the lift on the
outer portion of that wing increases, causing that
wing to rise a little. When an aileron is raised, the lift
on the outer portion of that wing is decreased slightly,
causing that wing to drop a little. Since the ailerons
on an airplane work together, their action causes the
airplane to roll.
The elevators on the horizontal portion of the tail of
an airplane control the pitch of the plane, or its
motion around the lateral axis. They are also tied to
the control wheel in the cockpit. When the wheel is
pulled back, the elevators move upward, causing the
tail of the plane to move downward and the nose to
pitch upward. When the wheel is pushed forward, the
elevators move downward, causing the tail of the
plane to rise and the nose to pitch downward.
The elevators work like the ailerons on the wings, in
that they cause changes in the lift generated by the
tail of the plane. Also, the elevators work together,
simultaneously, like the ailerons, but they do not
work in opposition to one another. Both go up when
the control wheel is pulled back and both go down
when the control wheel is pushed forward.
The rudder on the rear edge of the vertical fin on the airplane's tail
controls yaw around the vertical axis. It is connected to the pedals
at the pilot's feet. Pushing the right pedal causes the rudder to
deflect to the right. This makes the tail of the airplane move toward
the left, causing the nose to move to the right. Pushing the left
pedal makes the rudder deflect to the left, the tail moves to the
right, and the nose points to the left.