曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
has a load factor of one. Load factor increases rapidly
as the angle of bank increases. [Figure 3-21]
In a turn at constant speed, increasing the angle of
attack must occur in order to increase lift. As the bank
angle increases, angle of attack must also increase to
provide the required lift. The result of increasing the
angle of attack will be a stall when the critical angle of
attack is exceeded in a turn. [Figure 3-22]
Figure 3-20. During a sideslip, the glider is helped to
stay in alignment with the relative wind due to the
added surface area behind the CG.
Figure 3-21. The loads placed on a glider increase as
the angle of bank increases.
3-12
Induced drag also increases as a result of increased lift
required to maintain airspeed in the turn. This increased
induced drag results in a greater rate of sink during a
turn compared to level flight.
RATE OF TURN
Rate of turn refers to the amount of time it takes for a
glider to turn a specified number of degrees. If flown at
the same airspeed and angle of bank, every glider will
turn at the same rate. If airspeed increases and the angle
of bank remains the same, the rate of turn will decrease.
Conversely, a constant airspeed coupled with an angle
of bank increase will result in a faster rate of turn.
RADIUS OF TURN
The amount of horizontal distance an aircraft uses to
complete a turn is referred to as the radius of turn.
The radius of turn at any given bank angle varies
directly with the square of the airspeed. Therefore, if
the airspeed of the glider were doubled, the radius of
the turn would be four times greater. Although the
radius of turn is also dependent of a glider’s airspeed
and angle of bank, the relationship is the opposite of
rate of turn. As the glider’s airspeed is increased with
the angle of bank held constant, the radius of turn
increases. On the other hand if the angle of bank
increases and the airspeed remains the same, the radius
of turn is decreased. [Figure 3-23]
TURN COORDINATION
It is important that rudder and aileron inputs are coordinated
during a turn so maximum glider performance
can be maintained. If too little rudder is applied or
if rudder is applied too late, the result will be a slip.
Too much rudder or rudder applied before aileron
results in a skid. Both skids and slips swing the fuselage
of the glider into the relative wind, creating additional
parasite drag, which reduces lift and airspeed.
Although this increased drag caused by a slip can be
useful during approach to landing to steepen the
approach path and counteract a crosswind, it
decreases glider performance during other phases
of flight.
When you roll into a turn, the aileron on the inside of
the turn is raised and the aileron on the outside of the
turn is lowered. The lowered aileron on the outside
increases the angle of attack and produces more lift for
that wing. Since induced drag is a by-product of lift, the
outside wing also produces more drag than the inside
wing. This causes a yawing tendency toward the outside
of the turn called adverse yaw. Coordinated use of
rudder and aileron corrects for adverse yaw and aileron
drag.
SLIPS
A slip is a descent with one wing lowered and the
glider’s longitudinal axis at an angle to the flight path.
It may be used for either two purposes, or both of them
combined. A slip may be used to steepen the approach
path without increasing the airspeed, as would be the
case if a dive were used. It can also be used to make
the glider move sideways through the air to counteract
the drift, which results from a crosswind.
Figure 3-23. The radius of a turn is directly related to airspeed and bank angle.
3-13
Formerly, slips were used as a normal means of controlling
landing descents to short or obstructed fields,
but they are now primarily used in the performance of
crosswind and short-field landings. With the installation
of wing flaps and effective spoilers on modern
gliders, the use of slips to steepen or control the angle
of descent is no longer a common procedure. However,
the pilot still needs skill in performance of forward
slips to correct for possible errors in judgment of the
landing approach.
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 short-field
landings, this erratic practice invariably will lead to trouble
since enough excess speed may result to prevent
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：
Glider Flying Handbook(29)
