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is being maintained and adjust the throttle accordingly. The
throttle setting for this condition should be noted and all
future changes in weight, trim speed, and density altitude
referenced to this known throttle setting.
After level fl ight is mastered in calm air, it can be practiced
in air that is moving, minor turbulence or “active air.” The
throttle settings for similar weight, trim, and density altitude
are the same, but more pilot input is required to maintain a
constant altitude. The throttle is used to maintain a selected
distance above the reference point for local air movement, but
the pitch pressure (nose up or nose down) is used to control
this attitude for shorter duration air disturbances.
Typically, updrafts or thermals raise the nose of the aircraft
and downdrafts at the edge of thermals lower the nose of the
aircraft. For minor updrafts the nose is lowered by pitch control
input by the pilot slightly increasing the speed of the aircraft
to keep the pitch at a constant level. In moderate to severe
updrafts, the throttle can be reduced to assist in maintaining
a reasonably constant pitch angle with the horizon.
Similarly for minor downdrafts that lower the nose, the nose
is raised by pitch control input by the pilot slightly decreasing
the speed of the aircraft to keep the pitch at a constant level.
An additional caution for raising the nose and decreasing the
speed is that raising the nose too high could stall the aircraft.
Therefore, caution must be exercised in moderate downdrafts
not to reduce the speed too much to approach a stall speed/
critical angle of attack. Similar to reducing the throttle in
updrafts to reduce pitch angle, increasing the throttle typically
increases the pitch angle. [Figure 6-8]
WSC aircraft can use the front tube as a reference to align
perpendicular with the horizon and the wings leveled. It
should be noted that any time the wings are banked even
slightly, the aircraft will turn.
The front tube can be used as an indicator to determine turn
rate. If the bar is moving side to side to any established
reference point, the aircraft is banked and should be corrected
to eliminate any turn. The objective of straight-and-level
fl ight is to detect small deviations from level fl ight as soon
as they occur, necessitating only small corrections.
Straight-and-level fl ight requires almost no application of
control pressures if the aircraft is properly trimmed and the
6-6
Reference point on front tube lined
up with reference point on horizon
Figure 6-7. Pilot’s view of a reference point on the front tube chosen for level flight and lined up with the reference point on the horizon
for straight-and-level flight.
Figure 6-6. A reference point on the horizon chosen.
Reference point on the horizon
6-7
Figure 6-8. Thermal updraft and downdraft sequence.
Bar at trim Bar in—fast flight Bar out—slow flight Bar at trim
A Air not rising or falling BB UUppddrraafftt C Downdraft D Air not rising or falling
air is smooth. For that reason, pilots must not form the habit
of constant, unnecessary control movement. Pilots should
learn to recognize when corrections are necessary, and then
make a measured response easily and naturally.
Common errors in the performance of straight-and-level
fl ight are:
• Attempting to use improper reference points on the
aircraft to establish attitude.
• Forgetting the location of selected reference points.
• Too tight a grip on the fl ight controls resulting in
overcontrol and lack of “feel.”
• Improper scanning and/or devoting insuffi cient time
to outside visual reference (head in the fl ight deck).
• Fixation on the nose (pitch attitude) reference point
only.
• Unnecessary or inappropriate control inputs.
• Failure to make timely and measured control inputs
when deviations from straight-and-level fl ight are
detected.
• Inadequate attention to sensory inputs in developing
feel for the aircraft.
Trim Control
The use of trim systems relieves the pilot of the requirement to
exert pressures for the desired fl ight condition. An improperly
trimmed aircraft requires constant control pressures, produces
pilot tension and fatigue, distracts the pilot from scanning,
and contributes to abrupt and erratic aircraft control.
Most WSC aircraft have a ground adjustable pitch/speed
trim system that adjusts the carriage hang point on the wing
keel that is set for the desired speed. Some WSC aircraft
have additional pitch control systems that can adjust the
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Weight-Shift Control Aircraft Flying Handbook(70)
