Aero Chapter 02, High-Speed Flight
T-45 Aerodynamics Student Workbook
LATERAL CONTROL
Lateral control remains crisp to 0.9
Mach. During loaded rolls at Mach
numbers greater than 0.8 Mach, roll
Smooth
response can be unpredictable. Roll
Lift
rates greater than 260 per second
Distribution
may occur due to reduced roll
Transonic
Lift
damping at AOA near stall.
Lift
Coefficient
Distribution
At approximately 0.92 Mach, either
wing may become heavy due to a
normal shock wave in the wing tip
area, reducing wing tip effectiveness
(Figure 44). The aircraft will begin a
slow roll. Up to lateral stick
Root
Span Location
Tip
deflection may be required to
maintain wings level flight. Between
0.92 and 0.95 Mach, roll rate
Figure 44: LATERAL CONTROL
degrades rapidly with roll rates as
low as 27 per second observed at
0.95 Mach with full stick deflection. As speed increases through 0.95 Mach, wing heaviness disappears
and aileron authority returns. Above Mach 1.0, full stick aileron rolls can generate a roll rate of
approximately 120 per second.
TRANSONIC PITCHUP
Shortly into recovery from the dive, at Mach 0.99, a sharp pitchup occurs that must be countered by
quickly relaxing back stick to avoid overstress of the aircraft. This pitchup occurs due to the sudden shift
in center of pressure as the aircraft slows. No more than 4.0 g's should be maintained following the first
pitchup because it is followed shortly by a second pitchup during deceleration between Mach 0.95 and
0.85 as AOA reaches 10 - 11 units. Following the second pitchup, longitudinal characteristics become
predictable.
(7-99) Original
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