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thinks the aircraft is descending faster than it should, there
is a tendency to increase the pitch attitude and AOA too
rapidly. This not only stops the descent, but actually starts
the aircraft climbing. This climbing during the roundout is
known as ballooning. Ballooning can be dangerous because
the height above the ground is increasing and the aircraft may
be rapidly approaching a stall. The altitude gained in each
instance depends on the airspeed or the speed with which the
pitch attitude is increased.
When ballooning is slight, the nose should be lowered to
increase speed and return to a gradual descent. Recovery
procedures are similar to those for rounding out too high:
lowering the nose slightly and increasing the throttle to
remain level. Then, the pilot gradually reduces throttle and
speed for a controlled descent rate with the throttle at idle
during touchdown.
When ballooning is excessive, it is best to execute a goaround
immediately; do not attempt to salvage the landing.
Full power must be applied and the nose lowered before the
aircraft enters a stalled condition.
The pilot must be extremely cautious of ballooning when
there is a crosswind present because the crosswind correction
may be inadvertently released or it may become inadequate.
Because of the lower airspeed after ballooning, the crosswind
affects the aircraft more. Consequently, crabbing has to
be increased to compensate for the increased drift. It is
imperative that the pilot makes certain that directional control
is maintained. If there is any doubt, or the aircraft starts to
drift, execute a go-around.
Bouncing During Touchdown
When the aircraft contacts the ground with a sharp impact
as the result of an improper attitude or an excessive rate
of sink, it can bounce back into the air. The severity of the
bounce depends on the airspeed at the moment of contact
and the rebound attitude the WSC aircraft. It can increase the
AOA and, in addition to bouncing, be lifted. It can rebound
in a yawed condition and/or nose up or down. Design and
situational factors create their own unique scenarios.
The corrective action for a bounce is the same as for
ballooning and similarly depends on its severity. When the
bounce is very slight and there is not an extreme change in the
aircraft’s pitch attitude, a follow-up landing may be executed
by applying suffi cient power to cushion the subsequent
touchdown and smoothly adjusting the pitch to the proper
touchdown attitude.
Extreme caution and attention must be exercised any time a
bounce occurs, but particularly when there is a crosswind.
During the bounce, the wind causes the aircraft to roll with
the wind, thus exposing even more surface to the crosswind
and drifting the aircraft more rapidly.
When a bounce is severe, the safest procedure is to execute
a go-around immediately. No attempt to salvage the landing
should be made. Full power should be applied while
simultaneously maintaining directional control and lowering
the nose to a safe climb attitude. The go-around procedure
should be continued even though the aircraft may descend and
another bounce may be encountered. It would be extremely
foolish to attempt a landing from a bad bounce since airspeed
diminishes very rapidly in the nose-high attitude, and a stall
may occur before a subsequent touchdown could be made.
Porpoising
In a bounced landing that is improperly recovered, the
aircraft comes in nose fi rst, setting off a series of motions that
imitate the jumps and dives of a porpoise—hence the name.
The problem is improper aircraft attitude at touchdown,
sometimes caused by inattention, not knowing where the
ground is, or forcing the aircraft onto the runway at an
exceedingly high descent rate.
Porpoising can also be caused by improper airspeed control.
Usually, if an approach is too fast, the aircraft fl oats and the
pilot tries to force it on the runway when the aircraft still tends
to fl y. A gust of wind, a bump in the runway, or even a slight
push on the control bar sends the aircraft aloft again.
The corrective action for a porpoise is the same as for a
bounce, and similarly depends on its severity. When it is very
slight with no extreme change in the aircraft’s pitch attitude,
a follow-up landing may be executed by applying suffi cient
power to cushion the subsequent touchdown, and smoothly
adjusting the pitch to the proper touchdown attitude.
When a porpoise is severe, the safest procedure is to execute
an immediate go-around. In a severe porpoise, the aircraft’s
pitch oscillations can become progressively worse until the
　
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本文鏈接地址：Weight-Shift Control Aircraft Flying Handbook(132)