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maneuver.
If the turn were made with a constant angle of bank
and a wind blowing directly across the road, it would
result in a constant radius turn through the air. However,
the wind effects would cause the ground track
to be distorted from a constant radius turn or semicircular
path. The greater the wind velocity, the greater
would be the difference between the desired ground
track and the flightpath. To counteract this drift, the
Figure 9-2. Effect of wind during a turn.
9-4
flightpath can be controlled by the pilot in such a manner
as to neutralize the effect of the wind, and cause
the ground track to be a constant radius semicircle.
The effects of wind during turns can be demonstrated
after selecting a road, railroad, or other ground reference
that forms a straight line parallel to the wind. Fly
into the wind directly over and along the line and then
make a turn with a constant medium angle of bank
for 360° of turn. [Figure 9-3] The powered parachute
will return to a point directly over the line but slightly
downwind from the starting point, the amount depending
on the wind velocity and the time required to
complete the turn. The path over the ground will be an
elongated circle, although in reference to the air, it is
a perfect circle. Straight flight during the upwind segment
after completion of the turn is necessary to bring
the powered parachute back to the starting position.
A similar 360° turn may be started at a specific point
over the reference line, with the powered parachute
headed directly downwind. In this demonstration, the
effect of wind during the constant banked turn will
drift the powered parachute to a point where the line
is re-intercepted, but the 360° turn will be completed
at a point downwind from the starting point.
Another reference line which lies directly crosswind
may be selected and the same procedure repeated,
showing that if wind drift is not corrected the powered
parachute will, at the completion of the 360°
turn, be headed in the original direction but will have
drifted away from the line a distance dependent on the
amount of wind.
From these demonstrations, you will see where and
why it is necessary to increase or decrease the angle
of bank and the rate of turn to achieve a desired track
over the ground. The principles and techniques involved
can be practiced and evaluated by the performance
of the ground track maneuvers discussed in
this chapter.
Rectangular Course
Normally, the rectangular course is the first ground
reference maneuver the pilot is introduced to. [Figure 9-4]
The rectangular course is a training maneuver in
which the ground track of the powered parachute is
equidistant from all sides of a selected rectangular
area on the ground. The maneuver simulates the conditions
encountered in an airport traffic pattern. While
performing the maneuver, the altitude should be held
constant.
The maneuver assists the student pilot in perfecting:
• Practical application of the turn.
• The division of attention between the flightpath,
ground objects, and the handling of the powered
parachute.
• The timing of the start of a turn so that the turn
will be fully established at a definite point over
the ground.
• The timing of the recovery from a turn so that a
definite ground track will be maintained.
• The establishing of a ground track and the
determination of the appropriate “crab” angle.
Like those of other ground track maneuvers, one of
the objectives is to develop division of attention between
the flightpath and ground references, while
controlling the powered parachute and watching for
other aircraft in the vicinity. Another objective is to
develop recognition of drift toward or away from a
line parallel to the intended ground track. This will be
helpful in recognizing drift toward or from an airport
runway (landing area) during the various legs of the
airport traffic pattern.
For this maneuver, a square or rectangular field, or an
area bounded on four sides by section lines or roads,
should be selected well away from other air traffic.
The powered parachute should be flown parallel to
and at a uniform distance from the field boundaries,
not necessarily directly above the boundaries. For best
results, the flightpath should be positioned outside the
field boundaries just far enough that they may be easily
observed from either pilot seat by looking out the
side of the powered parachute. If an attempt is made
to fly directly above the edges of the field, the pilot
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Powered Parachute Flying Handbook动力伞飞行手册(72)
