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pressure must be used promptly and smoothly to
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counteract yawing forces so that the airplane continues
straight down the runway.
While the speed of the takeoff roll increases, more and
more pressure will be felt on the flight controls,
particularly the elevators and rudder. Since the tail
surfaces receive the full effect of the propeller
slipstream, they become effective first. As the speed
continues to increase, all of the flight controls will
gradually become effective enough to maneuver the
airplane about its three axes. It is at this point, in the
taxi to flight transition, that the airplane is being flown
more than taxied. As this occurs, progressively smaller
rudder deflections are needed to maintain direction.
TAKEOFF
Since a good takeoff depends on the proper takeoff
attitude, it is important to know how this attitude
appears and how it is attained. The ideal takeoff
attitude requires only minimum pitch adjustments
shortly after the airplane lifts off to attain the speed for
the best rate of climb.
The tail should first be allowed to rise off the ground
slightly to permit the airplane to accelerate more
rapidly. At this point, the position of the nose in
relation to the horizon should be noted, then elevator
pressure applied as necessary to hold this attitude. The
wings are kept level by applying aileron pressure as
necessary.
The airplane may be allowed to fly off the ground
while in normal takeoff attitude. Forcing it into the air
by applying excessive back-elevator pressure would
result in an excessively high pitch attitude and may
delay the takeoff. As discussed earlier, excessive and
rapid changes in pitch attitude result in proportionate
changes in the effects of torque, making the airplane
more difficult to control.
Although the airplane can be forced into the air, this is
considered an unsafe practice and should be avoided
under normal circumstances. If the airplane is forced
to leave the ground by using too much back-elevator
pressure before adequate flying speed is attained, the
wing’s angle of attack may be excessive, causing the
airplane to settle back to the runway or even to stall.
On the other hand, if sufficient back-elevator pressure
is not held to maintain the correct takeoff attitude after
becoming airborne, or the nose is allowed to lower
excessively, the airplane may also settle back to the
runway. This occurs because the angle of attack is
decreased and lift is diminished to the degree where it
will not support the airplane. It is important to hold the
attitude constant after rotation or lift-off.
As the airplane leaves the ground, the pilot must
continue to maintain straight flight, as well as holding
the proper pitch attitude. During takeoffs in strong,
gusty wind, it is advisable that an extra margin of speed
be obtained before the airplane is allowed to leave the
ground. A takeoff at the normal takeoff speed may
result in a lack of positive control, or a stall, when the
airplane encounters a sudden lull in strong, gusty wind,
or other turbulent air currents. In this case, the pilot
should hold the airplane on the ground longer to attain
more speed, then make a smooth, positive rotation to
leave the ground.
CROSSWIND TAKEOFF
It is important to establish and maintain the proper
amount of crosswind correction prior to lift-off; that is,
apply aileron pressure toward the wind to keep the
upwind wing from rising and apply rudder pressure as
needed to prevent weathervaning.
As the tailwheel is raised off the runway, the holding
of aileron control into the wind may result in the
downwind wing rising and the downwind main wheel
lifting off the runway first, with the remainder of the
takeoff roll being made on one main wheel. This is
acceptable and is preferable to side-skipping.
If a significant crosswind exists, the main wheels
should be held on the ground slightly longer than in a
normal takeoff so that a smooth but definite lift-off can
be made. This procedure will allow the airplane to
leave the ground under more positive control so that it
will definitely remain airborne while the proper
amount of drift correction is being established. More
importantly, it will avoid imposing excessive side
loads on the landing gear and prevent possible damage
that would result from the airplane settling back to the
runway while drifting.
As both main wheels leave the runway, and ground
friction no longer resists drifting, the airplane will be
slowly carried sideways with the wind until adequate
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AIRPLANE FLYING HANDBOOK 飞机飞行手册下(55)
