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Glider Flying Handbook(84)

时间:2010-05-10 17:47来源:蓝天飞行翻译 作者:admin 点击:
  
However, the pilot still needs skill in
performance of forward slips to correct for possible
errors in judgment of the landing approach.
The primary purpose of forward slips is to dissipate
altitude without increasing the glider’s airspeed, particularly
in gliders not equipped with flaps or those
7-36
be on long final approach to the landing area in use.
The turn to base leg should be timely in order to keep
the point of intended touchdown area within easy gliding
range. The pilot should adjust the turn to correct for
wind drift encountered on the base leg. On base leg, the
pilot should adjust the spoilers/dive brakes, as necessary,
to position the glider at the desired glide angle.
The turn onto the final approach is made so as to line
up with the centerline of the touchdown area. The pilot
should adjust the spoilers/dive brakes as necessary to
fly the desired approach angle to the aim point. The
selected aim point should be prior to the touchdown
point to accommodate the landing flair. The pilot flairs
the glider at or about three to five feet AGL and the
glider floats some distance until it touches down.
When within three to five feet of the ground, begin the
flare with slight back elevator. As the airspeed
decreases, the pilot holds the glider in a level or tail low
attitude so as to touchdown at the slowest possible
speed while the glider still is under aerodynamic control.
After touchdown the pilot should concentrate on
rolling out straight down the centerline of the touchdown
area.
Tracking down the centerline of the touchdown area is
an important consideration in gliders. The long, low
wingtips of the glider are susceptible to damage from
runway border markers, runway light stanchions, or
taxiway markers. Turning off the runway should be
done only if and when the pilot has the glider under
control.
Landing in high, gusty winds or turbulent conditions
may require higher approach airspeeds to improve controllability
and provide a safer margin above stall airspeed.
Arule of thumb is to add 1/2 the gust factor to the
normal approach airspeed. This increased approach airspeed
affords better penetration into the headwind on
final approach. The adjusted final approach airspeed
should not be greater than the maneuvering speed (VA)
or maximum turbulence penetration speed (VB),
whichever is lower.
CROSSWIND LANDINGS
Crosswind landings require a crabbing or slipping
method to correct for the effects of the wind on the final
approach. Additionally, the pilot must land the glider
without placing any unnecessary side load on the landing
gear.
The crab method requires the pilot to point the nose of
the glider into the wind and fly a straight track along
the desired ground path. The stronger the wind, the
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with inoperative spoilers/dive brakes. There are many
circumstances requiring the use of forward slips, such
as in a landing approach over obstacles and in making
off-field landings. It is always wise to allow an
extra margin of altitude for safety in the original estimate
of the approach. In the latter case, if the inaccuracy
of the approach is confirmed by excess altitude
when nearing the boundary of the selected field, slipping
may dissipate the excess altitude.
The use of slips has definite limitations. Some pilots
may try to lose altitude by violent slipping rather
than by smoothly maneuvering and exercising good
judgment and using only a slight or moderate slip. In
off-field landings, this erratic practice invariably will
lead to trouble since enough excess speed may result
in preventing touching down anywhere near the
touchdown point, and very often will result in overshooting
the entire field.
The forward slip is a slip in which the glider’s direction
of motion continues the same as before the slip
was begun. [Figure 7-33] If there is any crosswind, the
slip will be much more effective if made into the wind.
Assuming the glider is originally in straight flight, the
wing on the side that the slip is to be made should be
lowered by using the ailerons. Simultaneously, the
glider’s nose must be yawed in the opposite direction
by applying opposite rudder so the glider’s longitudinal
axis is at an angle to its original flight path. The
degree to which the nose is yawed in the opposite
direction from the bank should be such that the original
ground track is maintained. The nose should also
be raised as necessary to prevent the airspeed from
increasing.
If a slip is used during the last portion of a final
 
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