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the fi eld should be the same regardless of whether the course
is fl own to the left or right. Turns should be started when
the aircraft is abeam the corner of the fi eld boundaries, and
the bank normally should not exceed 45°. These should be
the determining factors in establishing the distance from the
boundaries for performing the maneuver.
Although the rectangular course may be entered from any
direction, this discussion assumes entry on a downwind.
On the downwind leg, the wind is a tailwind and results in
increased groundspeed. Consequently, the turn onto the next
leg is entered with a fairly fast rate of roll-in with relatively
steep bank. As the turn progresses, the bank angle is reduced
gradually because the tailwind component is diminishing,
resulting in a decreasing groundspeed.
During and after the turn onto this leg (the equivalent of the
base leg in a traffi c pattern), the wind tends to drift the aircraft
away from the fi eld boundary. To compensate for the drift,
the amount of turn is more than 90°.
The rollout from this turn must be such that as the wings
become level, the aircraft is turned slightly toward the fi eld
and into the wind to correct for drift. The aircraft should
again be the same distance from the fi eld boundary and at
the same altitude as on other legs. The base leg should be
continued until the upwind leg boundary is being approached.
Once more, the pilot should anticipate drift and turning
radius. Since drift correction was held on the base leg, it is
necessary to turn less than 90° to align the aircraft parallel
to the upwind leg boundary. This turn should be started with
a medium bank angle with a gradual reduction to a shallow
bank as the turn progresses. The rollout should be timed
to assure paralleling the boundary of the fi eld as the wings
become level. [Figure 9-5]
While the aircraft is on the upwind leg, the next fi eld boundary
should be observed as it is being approached to plan the turn
onto the crosswind leg. Since the wind is a headwind on this
leg, it reduces the aircraft’s groundspeed and tries to drift the
aircraft toward the fi eld during the turn onto the crosswind
leg. For this reason, the roll-in to the turn must be slow and
the bank relatively shallow to counteract this effect. As the
turn progresses, the headwind component decreases, allowing
the groundspeed to increase. Consequently, the bank angle
and rate of turn are increased gradually to assure that upon
completion of the turn, the crosswind ground track continues
the same distance from the edge of the fi eld. Completion of
the turn with the wings level should be accomplished at a
point aligned with the upwind corner of the fi eld.
As the wings are rolled level, the proper drift correction
is established with the aircraft turned into the wind with a
change in heading of less than 90°. If the turn has been made
properly, the fi eld boundary will again be the same distance
as it was in the previous legs. While on the crosswind leg,
the wind correction angle should be adjusted as necessary to
maintain a uniform distance from the fi eld boundary.
As the next fi eld boundary is being approached, the pilot
should plan the turn onto the downwind leg. Since a wind
correction angle is being held into the wind and away from the
fi eld while on the crosswind leg, this next turn requires a turn
of more than 90°. Since the crosswind becomes a tailwind,
causing the groundspeed to increase during this turn, the bank
initially should be medium and progressively increased as
the turn proceeds. To complete the turn, the rollout must be
timed so that the wings become level at a point aligned with
the crosswind corner of the fi eld just as the longitudinal axis
of the aircraft again becomes parallel to the fi eld boundary.
The distance from the fi eld boundary should be the same as
from the other sides of the fi eld.
Usually, drift should not be encountered on the upwind or the
downwind leg, but it may be diffi cult to fi nd a situation where
the wind is blowing exactly parallel to the fi eld boundaries.
This would make it necessary to use a slight wind correction
9-7
Figure 9-5. Pilot’s view coming out of a left turn to straighten out for the rectangular leg on the lower left. The next left turn of the
rectangular course is shown by the red line for reference.
angle on all the legs. It is important to anticipate the turns
to correct for groundspeed, drift, and turning radius. When
the wind is behind the aircraft, the turn must be faster and
steeper; when it is ahead of the aircraft, the turn must be
　
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本文鏈接地址：Weight-Shift Control Aircraft Flying Handbook(105)