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less and the rate of departure from the road decreases.
9-9
Reference Line
Reference Line
Figure 9-8. Pilot’s view in starting semicircle turning left from
downwind to crosswind.
Figure 9-9. Student completing semicircle, preparing to level out
to cross perpendicular to the road.
[Figure 9-6, position 2 to 3, and Figure 9-8] The wind
correction angle is at the maximum when the aircraft is
headed directly crosswind. [Figure 9-6, position 3]
After turning 90°, the aircraft’s heading becomes more
and more an upwind heading, the groundspeed decreases,
and the rate of closure with the road becomes slower.
If a constant steep bank were maintained, the aircraft
would turn too quickly for the slower rate of closure and
would prematurely be headed perpendicular to the road.
Because of the decreasing groundspeed and rate of closure
while approaching the upwind heading, it is necessary to
gradually shallow the bank during the remaining 90° of the
semicircle, so that the wind correction angle is removed
completely [Figure 9-9] and the wings become level as the
180° turn is completed at the moment the road is reached.
[Figure 9-6, position 4]
At the instant the road is being crossed at 90° to it, a turn in
the opposite direction should be started. Since the aircraft is
still fl ying into the headwind, the groundspeed is relatively
low. Therefore, the turn must be started with a shallow bank
to avoid an excessive rate of turn that would establish the
maximum wind correction angle too soon. The degree of bank
should be that which is necessary to attain the proper wind
correction angle so the ground track describes an arc the same
size as the one established on the downwind side.
Since the aircraft is turning from an upwind to a downwind
heading, the groundspeed increases and after turning
90° the rate of closure with the road increases rapidly.
[Figure 9-6, position 5] Consequently, the angle of bank
and rate of turn must be progressively increased so that
the aircraft has turned 180° at the time it reaches the road.
Again, the rollout must be timed so the aircraft is in straightand-
level fl ight directly over and perpendicular to the road.
[Figure 9-6, position 6]
Throughout the maneuver a constant altitude and airspeed
should be maintained, and the bank should be changing
constantly to effect a true semicircular ground track.
Common errors in the performance of S-turns across a road
are:
• Failure to adequately clear the area.
• Creating too small of a radius/too high of a banked
turn during the start of the maneuver.
• Creating banked turns too high to complete the
maneuver.
• Poor coordination creating variations in airspeeds.
• Gaining or losing altitude.
• Inability to visualize the half circle ground track.
• Poor timing in beginning and recovering from turns.
• Faulty correction for drift.
• Inadequate visual lookout for other aircraft.
• Inability to judge closure rates to the road and adjust
the bank angle so the semi-circle is completed at 90°
to the reference road.
Turns Around a Point
Turns around a point, as a training maneuver, is a logical
extension of the principles involved in the performance of
S-turns across a road. The objectives are to:
• Further perfect turning technique.
• Perfect the ability to control the aircraft subconsciously
while dividing attention between the fl ightpath and
ground references.
9-10
Downwind Half of Circle
Upwind Half of Circle
Wind
Shallowest Bank Steepest Bank
Entry
Figure 9-10. Turns around a point.
• Teach the student that the radius of a turn is a distance
that is affected by the degree of bank used when
turning with relation to a defi nite object.
• Develop a keen perception of altitude.
• Perfect the ability to correct for wind drift while in
turns.
In turns around a point, the aircraft is fl own in two or
more complete circles of uniform radii or distance from a
prominent ground reference point using a maximum bank of
approximately 45° while maintaining a constant altitude.
The factors and principles of drift correction that are involved
in S-turns are also applicable in this maneuver. As in other
ground track maneuvers, a constant radius around a point
requires a constantly changing angle of bank and angles of
wind correction if any wind exists. The closer the aircraft is to
a direct downwind heading where the groundspeed is greatest,
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Weight-Shift Control Aircraft Flying Handbook(107)
