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Glider Flying Handbook(73)

时间:2010-05-10 17:47来源:蓝天飞行翻译 作者:admin 点击:
  
too great for the angle of bank. Correction of a skidding
turn thus involves a decrease in yaw (rudder), an
increase in bank (aileron), or a combination of the two
changes. [Figure 7-27]
The yaw string identifies slips and skids. In flight, the
rule to remember is simple: step away from the tail of
the yaw string. If the tail of the yaw string is to the left
of center, press the right rudder pedal to coordinate the
glider and center the yaw string. If the tail of the yaw
string is right of center, pressure the left rudder pedal
to coordinate the glider and center the yaw string.
[Figure 7-28]
The ball in the slip/skid indicator also indicates slips
and skids. When using this instrument for coordination,
you should apply rudder pressure on the side that
the ball is offset (step on the ball).
Correction for uncoordinated condition should be
accomplished by using appropriate rudder and aileron
control pressures simultaneously to coordinate the glider.
STEEP TURNS
Soaring flight requires competence in steep turns. In
thermalling flight, small-radius turns are often necessary
to keep the glider in or near the core of the thermal
updraft, where lift is usually strongest and rapid climbs
are possible. At any given airspeed, increasing the angle
of bank will decrease the radius of the turn and increase
the rate of turn. The radius of a turn at any given bank
angle varies directly with the square of the airspeed at
which the turn is made, therefore the slower the airspeed
the smaller the turn radius. To keep the radius of
turn small, it is necessary to bank steeply, while maintaining
an appropriate airspeed, such as minimum sink
or best glide speed. The pilot must be aware that as the
bank angle increases, the stall speed increases.
Before starting the steep turn, the pilot should ensure
that the area is clear of other traffic since the rate of
turn will be quite rapid. After establishing the appropriate
airspeed, the glider should be smoothly rolled
into a coordinated steep turn with at least 45° of
bank. The pilot should use outside visual reference
to establish and maintain the desired bank angle. If
the pilot does not add back pressure to maintain the
desired airspeed after the bank is established, the
glider will have a tendency to enter a spiral. To counteract
the overbanking tendency caused by the steep
turn, the pilot should apply top aileron pressure.
Because the top aileron pressure pulls the nose away
from the direction of the turn, the pilot also has to
apply bottom rudder pressure. A coordinated (no slip
or skid) steep turn requires back pressure on the elevator
for airspeed control, top aileron pressure for
bank control, and bottom rudder pressure to stream
line the fuselage with the flight path.
COMMON ERRORS
• Failure to clear turn.
• Uncoordinated use of controls.
• Loss of orientation.
• Failure to maintain airspeed within tolerance.
• Unintentional stall or spin.
• Excessive deviation from desired heading
during roll-out.
SPIRAL DIVE
Allowing the nose of the glider to get excessively low
during a steep turn may result in a significant increase
Skidding Turn: Excess rudder applied
during banked turn.
Yaw String
Indication
Slipping Turn: Insufficient rudder applied
during banked turn.
Yaw String
Indication
Coordinated Turn
Yaw String
Indication
Figure 7-27. Skidding turn.
Figure 7-26. Slipping turn.
Figure 7-28. Coordinated turn.
7-26
in airspeed and loss in altitude. This is known as a
spiral dive. If the pilot attempts to recover from this
situation by only applying back elevator pressure, the
limiting load factor may be exceeded, causing structural
failure. To properly recover from a spiral dive,
the pilot should first reduce the angle of bank with
coordinated use of the rudder and aileron, then
smoothly increase pitch to the proper attitude.
COMMON ERRORS
• Failure to recognize when a spiral dive is
developing.
• Rough, abrupt, and/or uncoordinated control
application during recovery.
• Improper sequence of control applications.
MANEUVERING AT MINIMUM CONTROL
AIRSPEED, STALLS, AND SPINS
All pilots must be proficient in maneuvering at minimum
controllable airspeed and stall recognition and recovery.
In addition, all flight instructor applicants must be proficient
in spins entries, spins, and spin recovery.
MANEUVERING AT MINIMUM CONTROLLABLE
AIRSPEED
Maneuvering during slow flight demonstrates the
 
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