Wednesday, February 4, 2009

Takeoff Roll - Takeoffs And Departure Climbs

After taxiing onto the runway, the airplane should be
carefully aligned with the intended takeoff direction,
and the nosewheel positioned straight, or centered.
After releasing the brakes, the throttle should be
advanced smoothly and continuously to takeoff power.
An abrupt application of power may cause the airplane
to yaw sharply to the left because of the torque effects
of the engine and propeller. This will be most apparent
in high horsepower engines. As the airplane starts to
roll forward, the pilot should assure both feet are on

the rudder pedals so that the toes or balls of the feet are
on the rudder portions, not on the brake portions.
Engine instruments should be monitored during the
takeoff roll for any malfunctions.

In nosewheel-type airplanes, pressures on the elevator
control are not necessary beyond those needed to
steady it. Applying unnecessary pressure will only
aggravate the takeoff and prevent the pilot from recognizing when elevator control pressure is actually
needed to establish the takeoff attitude.

As speed is gained, the elevator control will tend to
assume a neutral position if the airplane is correctly
trimmed. At the same time, directional control should
be maintained with smooth, prompt, positive rudder
corrections throughout the takeoff roll. The effects of
engine torque and P-factor at the initial speeds tend to
pull the nose to the left. The pilot must use whatever
rudder pressure and aileron needed to correct for these
effects or for existing wind conditions to keep the nose
of the airplane headed straight down the runway. The
use of brakes for steering purposes should be avoided,
since this will cause slower acceleration of the airplane's speed, lengthen the takeoff distance, and
possibly result in severe swerving.

While the speed of the takeoff roll increases, more
and more pressure will be felt on the flight controls,
particularly the elevators and rudder. If the tail surfaces are affected by 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.

The feel of resistance to the movement of the controls and the airplane's reaction to such movements
are the only real indicators of the degree of control
attained. This feel of resistance is not a measure of
the airplane's speed, but rather of its controllability.
To determine the degree of controllability, the pilot
must be conscious of the reaction of the airplane to
the control pressures and immediately adjust the
pressures as needed to control the airplane. The pilot
must wait for the reaction of the airplane to the
applied control pressures and attempt to sense the
control resistance to pressure rather than attempt to
control the airplane by movement of the controls.
Balanced control surfaces increase the importance
of this point, because they materially reduce the
intensity of the resistance offered to pressures
exerted by the pilot.

At this stage of training, beginning takeoff practice, a
student pilot will normally not have a full appreciation
of the variations of control pressures with the speed of
the airplane. The student, therefore, may tend to move
the controls through wide ranges seeking the pressures
that are familiar and expected, and as a consequence
over-control the airplane. The situation may be aggravated by the sluggish reaction of the airplane to these
movements. The flight instructor should take measures
to check these tendencies and stress the importance of
the development of feel. The student pilot should be
required to feel lightly for resistance and accomplish
the desired results by applying pressure against it. This
practice will enable the student pilot, as experience is
gained, to achieve a sense of the point when sufficient
speed has been acquired for the takeoff, instead of
merely guessing, fixating on the airspeed indicator, or
trying to force performance from the airplane.

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