Aerodynamics, Flight Controls, and Aircraft Systems Summary

Longitudinal Stability: Acts around the lateral axis to control pitch.
Lateral Stability: Acts around the longitudinal axis to control roll.
Vertical/Directional Stability: Acts around the vertical axis to control yaw.
Alternative Control Method: If aileron cable runs snap, an aircraft can still be landed using rudder and trim, as trim uses a dedicated cabling system.

Torque: Engine and propeller rotation in one direction causes the aircraft to roll/turn in the opposite direction; always present while the engine is running.
Spiraling Slipstream: Propeller airflow spirals around the fuselage and strikes the left side of the vertical tail, pushing the tail right and the nose left; always present when the propeller turns.
P-Factor (Asymmetric Propeller Load): In a climb, the descending blade (right side) takes a larger bite of air and produces more thrust than the ascending blade, creating a left-turning force vector. Applies only during climbs.
Gyroscopic Precession:
- Propellers act as gyroscopes governed by rigidity in space and precession (forces manifest $90^\circ$ ahead in the direction of rotation).
- Pitching nose-down produces a left-turning force; pitching nose-up produces a right-turning force.
- Primarily affects taildragger aircraft when pushing forward to raise the tail on takeoff. Tricycle gear aircraft like the Cessna 172 experience a right-turning force when pitching up at rotation.

Ailerons: Control roll around the longitudinal axis.
- Frise-type Ailerons: The bottom edge of the up-deflected aileron protrudes into the relative wind to generate drag and reduce adverse yaw.
- Differential Ailerons: The up-going aileron deflects higher than the down-going aileron to reduce adverse yaw.
- Cessna 172: Incorporates a combination of Frise-type and differential ailerons.
Elevator: Controls pitch around the lateral axis.
- Horizontal stabilizers generate downward tail force to maintain balance around the center of gravity ( $CG$ ).
- Forward $CG$ positions require more tail downforce, generating more induced drag. Rearward $CG$ positions require less tail downforce, resulting in lower drag and increased efficiency.
- Tail configurations include traditional, T-tail, V-tail (combines elevator and vertical stabilizer), and stabilators (all-movable surface with an anti-servo tab).
Rudder: Controls yaw around the vertical axis via pedals.
- Standard configurations integrate toe brakes at the tippy-top of the rudder pedals.

Flaps: Increase lift and drag to allow slower approach speeds and steeper descent angles.
Trim Devices: Relieve pilot control pressure. Anti-servo tabs on stabilators move in the same direction as the surface to prevent over-controlling.
Leading Edge Devices: Slats and wing cuffs allow aircraft to fly extremely slow; common on Short Takeoff and Landing (STOL) aircraft.
Spoilers: Disrupt airflow over the wing to dump lift upon landing.
Noise Diffusers: Exhaust structures on turbofan engines designed to cancel specific harmonic noise frequencies.

Reciprocating (Piston) Engines: Available in horizontally opposed, V-shape, inline, or radial designs; Cessna 172 aircraft use a horizontally opposed engine.
Turbine Engines: Utilize the same four-stroke operating cycles (intake, compression, power/ignition, exhaust) as piston engines.

Flying Without Aileron Cable Runs:
- Question: Can an airplane be landed if the main aileron cables snap?
- Answer: Yes, an airplane can be controlled and landed using rudder to roll and dedicated trim cables to pitch.
Checkride Requirements for Left Turning Tendencies:
- Question: Will applicants be asked to fully explain gyroscopic precession on a checkride?
- Answer: Applicants must name all four left-turning tendencies, but detailed explanations of gyroscopic precession are typically not required.