© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Aerodynamics Chapter 2 Stability and Control

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-1. Positive static stability: tends to return to center.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-2. Neutral static stability: no tendency to return.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-3. Negative static stability: tends to diverge.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-4. Damped oscillation—dynamically stable.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-5. Undamped oscillation—dynamically neutral.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-6. Divergent oscillation—dynamically unstable.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-7. Lift counteracts weight, thrust counteracts drag in straight-and-level flight (moments neutralized by stabilizers and trim). Total weight includes download on the tail.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-8. Thrust and drag form a pitching couple.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 2-9. The lift–weight couple and the thrust–drag couple may be balanced.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Following a loss of thrust the lift–weight couple pitches the airplane nose-down.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The horizontal stabilizer provides the final balancing moment.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Propeller slipstream affects the force generated by the horizontal stabilizer.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Angular movement can occur about three axes.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Rolling about the longitudinal axis.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Pitching about the lateral axis.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Yawing about the vertical axis.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Longitudinal stability following an uninvited nose-up pitch.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Longitudinal stability following an uninvited nose-down pitch.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Longitudinal stability is provided by the tail feathers of a dart.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure A forward CG—greater longitudinal stability.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Directional stability following an uninvited yaw.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Wing dihedral.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Dihedral corrects an uninvited roll.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Sweepback corrects uninvited roll.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure High keel surfaces and a low CG correct uninvited roll.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure A high wing tends to level the wings.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Roll causes yaw.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The CG must remain within the area bounded by the wheels.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure A destabilizing crosswind.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Yaw causes roll.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The primary flight controls: elevator, ailerons, and rudder.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The elevator is the primary pitching control.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure A butterfly tail (early Beech Bonanza model).

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Separate horizontal stabilizer and elevator.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Stabilator.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The ailerons–one up, one down–provide a rolling moment.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The rising wing has increased aileron drag, causing adverse yaw effect.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Differential ailerons reduce adverse yaw.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Frise-type ailerons equalize aileron drag and reduce adverse yaw.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Aileron/rudder interconnect can reduce adverse yaw.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Left rudder pressure—the nose yaws left.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Yaw is followed by roll.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The controls are more powerful with increased airflow.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The slipstream only affects the elevator and rudder.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Hinge moment at the control surface.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Inset hinge balance (at left) and horn balance (at right).

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The balance tab.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure Anti-balance tab on stabilator.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure The anti-balance tab opposes further control deflection and provides feel.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure An elevator trim tab.

© 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure A mass balance moves the control’s CG forward to prevent flutter.