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tailwheel-type because the airplane’s surface area
behind the main landing gear is greater than in
nosewheel-type airplanes.
Point of
Wheel Pivoting
C.G.
Figure 13-2. Effect of CG on directional control.
Ch 13.qxd 5/7/04 10:04 AM Page 13-5
13-6
Pilots should be familiar with the crosswind component
of each airplane they fly, and avoid operations in
wind conditions that exceed the capability of the
airplane, as well as their own limitations.
While the airplane is decelerating during the
after-landing roll, more aileron must be applied to keep
the upwind wing from rising. Since the airplane is
slowing down, there is less airflow around the ailerons
and they become less effective. At the same time, the
relative wind is becoming more of a crosswind and
exerting a greater lifting force on the upwind wing.
Consequently, when the airplane is coming to a stop,
the aileron control must be held fully toward the wind.
WHEEL LANDING
Landings from power approaches in turbulence or in
crosswinds should be such that the touchdown is made
with the airplane in approximately level flight attitude.
The touchdown should be made smoothly on the main
wheels, with the tailwheel held clear of the runway.
This is called a “wheel landing” and requires careful
timing and control usage to prevent bouncing. These
wheel landings can be best accomplished by holding
the airplane in level flight attitude until the main
wheels touch, then immediately but smoothly
retarding the throttle, and holding sufficient forward
elevator pressure to hold the main wheels on the
ground. The airplane should never be forced onto the
ground by excessive forward pressure.
If the touchdown is made at too high a rate of descent
as the main wheels strike the landing surface, the tail is
forced down by its own weight. In turn, when the tail is
forced down, the wing’s angle of attack increases
resulting in a sudden increase in lift and the airplane
may become airborne again. Then as the airplane’s
speed continues to decrease, the tail may again lower
onto the runway. If the tail is allowed to settle too
quickly, the airplane may again become airborne. This
process, often called “porpoising,” usually intensifies
even though the pilot tries to stop it. The best
corrective action is to execute a go-around procedure.
SHORT-FIELD LANDING
Upon touchdown, the airplane should be firmly held in
a three-point attitude. This will provide aerodynamic
braking by the wings. Immediately upon touchdown,
and closing the throttle, the brakes should be applied
evenly and firmly to minimize the after-landing roll.
The airplane should be stopped within the shortest
possible distance consistent with safety.
SOFT-FIELD LANDING
The tailwheel should touch down simultaneously with
or just before the main wheels, and should then be held
down by maintaining firm back-elevator pressure
throughout the landing roll. This will minimize any
tendency for the airplane to nose over and will provide
aerodynamic braking. The use of brakes on a soft field
is not needed because the soft or rough surface itself
will provide sufficient reduction in the airplane’s
forward speed. Often it will be found that upon
landing on a very soft field, the pilot will need to
increase power to keep the airplane moving and from
becoming stuck in the soft surface.
GROUND LOOP
A ground loop is an uncontrolled turn during ground
operation that may occur while taxiing or taking off,
but especially during the after-landing roll. It is not
always caused by drift or weathervaning, although
these things may cause the initial swerve. Careless use
of the rudder, an uneven ground surface, or a soft spot
that retards one main wheel of the airplane may also
cause a swerve. In any case, the initial swerve tends to
cause the airplane to ground loop.
Due to the characteristics of an airplane equipped with
a tailwheel, the forces that cause a ground loop
increase as the swerve increases. The initial swerve
develops inertia and this, acting at the CG (which is
located behind the main wheels), swerves the airplane
even more. If allowed to develop, the force produced
may become great enough to tip the airplane until one
wing strikes the ground.
If the airplane touches down while drifting or in a crab,
the pilot should apply aileron toward the high wing
and stop the swerve with the rudder. Brakes should be
used to correct for turns or swerves only when the
rudder is inadequate. The pilot must exercise caution
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AIRPLANE FLYING HANDBOOK 飞机飞行手册下(58)
