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control may lead to an aggravated, uncontrolled, tight
turn on the ground, or a ground loop. The combination
of inertia acting on the CG and ground friction of the
main wheels resisting it during the ground loop may
cause the airplane to tip or lean enough for the outside
Main Gear and Tailwheel
Touch Down Simultaneously
Hold Elevator
Full Up
Normal
Glide
Start Roundout
to Landing Attitude
Figure 13-1.Tailwheel touchdown.
Ch 13.qxd 5/7/04 10:04 AM Page 13-4
13-5
wingtip to contact the ground, and may even impose a
sideward force that could collapse the landing gear.
The airplane can ground loop late in the after-landing
roll because rudder effectiveness decreases with the
decreasing flow of air along the rudder surface as the
airplane slows. As the airplane speed decreases and the
tailwheel has been lowered to the ground, the steerable
tailwheel provides more positive directional control.
To use the brakes, the pilot should slide the toes or feet
up from the rudder pedals to the brake pedals (or apply
heel pressure in airplanes equipped with heel brakes).
If rudder pressure is being held at the time braking
action is needed, that pressure should not be released
as the feet or toes are being slid up to the brake pedals,
because control may be lost before brakes can be
applied. During the ground roll, the airplane’s
direction of movement may be changed by carefully
applying pressure on one brake or uneven pressures on
each brake in the desired direction. Caution must be
exercised, when applying brakes to avoid
overcontrolling.
If a wing starts to rise, aileron control should be
applied toward that wing to lower it. The amount
required will depend on speed because as the forward
speed of the airplane decreases, the ailerons will
become less effective.
The elevator control should be held back as far as
possible and as firmly as possible, until the airplane
stops. This provides more positive control with
tailwheel steering, tends to shorten the after-landing
roll, and prevents bouncing and skipping.
If available runway permits, the speed of the airplane
should be allowed to dissipate in a normal manner by
the friction and drag of the wheels on the ground.
Brakes may be used if needed to help slow the airplane.
After the airplane has been slowed sufficiently and has
been turned onto a taxiway or clear of the landing area,
it should be brought to a complete stop. Only after this
is done should the pilot retract the flaps and perform
other checklist items.
CROSSWIND LANDING
If the crab method of drift correction has been used
throughout the final approach and roundout, the crab
must be removed before touchdown by applying
rudder to align the airplane’s longitudinal axis with its
direction of movement. This requires timely and
accurate action. Failure to accomplish this results in
severe side loads being imposed on the landing gear
and imparts ground looping tendencies.
If the wing-low method is used, the crosswind
correction (aileron into the wind and opposite rudder)
should be maintained throughout the roundout, and the
touchdown made on the upwind main wheel.
During gusty or high-wind conditions, prompt
adjustments must be made in the crosswind correction
to assure that the airplane does not drift as it touches
down.
As the forward speed decreases after initial contact,
the weight of the airplane will cause the downwind
main wheel to gradually settle onto the runway.
An adequate amount of power should be used to
maintain the proper airspeed throughout the approach,
and the throttle should be retarded to idling position
after the main wheels contact the landing surface. Care
must be exercised in closing the throttle before the
pilot is ready for touchdown, because the sudden or
premature closing of the throttle may cause a sudden
increase in the descent rate that could result in a hard
landing.
CROSSWIND AFTER-LANDING ROLL
Particularly during the after-landing roll, special
attention must be given to maintaining directional
control by the use of rudder and tailwheel steering,
while keeping the upwind wing from rising by the use
of aileron. Characteristically, an airplane has a greater
profile, or side area, behind the main landing gear than
forward of it. [Figure 13-3] With the main wheels
acting as a pivot point and the greater surface area
exposed to the crosswind behind that pivot point, the
airplane will tend to turn or weathervane into the wind.
This weathervaning tendency is more prevalent in the
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AIRPLANE FLYING HANDBOOK 飞机飞行手册下(57)
