Aerodynamic Forces, Aircraft Performance, and Flight Principles

Comprehensive vocabulary flashcards covering aerodynamic forces, turn dynamics, stall and spin aerodynamics, aircraft load factors, structural categories, stability axes, and propeller turning tendencies.

Horizontal Component of Lift

The horizontal vector of lift created when an airplane banks, functioning as the centripetal force that makes the airplane turn.

Centrifugal Force

An apparent outward force acting opposite to the horizontal component of lift during a turn that pushes the aircraft and occupants to the outside of the turn.

Load Factor

The resultant vector between centrifugal force and gravity (weight), measured in $G$s (acceleration of gravity), which acts directly opposite to total lift.

Standard Rate Turn

A coordinated turn conducted at a rate of $3^\circ$ per second, indicated when the turn coordinator needle or mark aligns with the alignment index.

Coordinated Turn

A turn in which the horizontal component of lift and centrifugal force are balanced, keeping the inclinometer ball centered in the turn coordinator or glass cockpit brick.

Slipping Turn

An uncoordinated turn where the centrifugal force is less than the horizontal component of lift, causing the airplane to slip inside the turn and the inclinometer ball to deflect toward the inside.

Skidding Turn

An uncoordinated turn where the centrifugal force is greater than the horizontal component of lift, causing the airplane to slide outward from the turn and the inclinometer ball to deflect toward the outside.

Rate of Turn (ROT)

The number of degrees of heading change an aircraft completes per second.

Radius of Turn

The horizontal distance from the center of a circular turn to the flight path of the aircraft, which increases with airspeed and decreases with an increased bank angle.

Stall

A rapid decrease in lift resulting from the separation of airflow from the upper surface of the wing when the critical angle of attack is exceeded.

Critical Angle of Attack

The specific angle between the wing's chord line and the relative wind where airflow separates from the wing, causing maximum coefficient of lift ($C_{L\text{max}}$) to be reached and a stall to occur regardless of airspeed or pitch attitude.

Stall Strip

A strip of plastic or metal fastened to the leading edge of the wing root to disrupt airflow at high angles of attack, ensuring the root stalls prior to the wingtips so aileron effectiveness is retained.

Power-On Stall

A practice stall simulating an excessive pitch attitude during a high-power condition, such as during a takeoff climb or a balked landing go-around.

Power-Off Stall

A practice stall simulating an aircraft inadvertently decelerating to a stall while stretching a glide during landing approach with idle or low power.

Spin

An aggravated stall occurring when an airplane is yawed, causing a downward corkscrew spiral descent where both wings are stalled but one wing is stalled more than the other.

Incipient Spin Phase

The initial transition phase of a spin lasting approximately 4 to 6 seconds from the point of stall and rotation until the spin is fully developed.

Normal Category (Load Limits)

A structural category for general aviation aircraft designed to withstand maximum limit load factors of $+3.8\,G$s and $-1.52\,G$s.

Utility Category (Load Limits)

An aircraft structural certification category designed to support limit load factors of $+4.4\,G$s and $-1.76\,G$s, approved for limited aerobatics and spins.

Acrobatic Category (Load Limits)

An aircraft certification category designed to sustain high structural loads of $+6.0\,G$s and $-3.0\,G$s.

Maneuvering Speed

The maximum airspeed at which an abrupt, full control input can be applied without exceeding the aircraft's structural design limit load factor, as the aircraft will enter an accelerated stall before incurring structural damage.

VG Diagram

A flight envelope graph plotting airspeed ($V$) against load factor ($G$), defining the boundaries for normal operation, accelerated stalls, structural damage, and structural failure.

Aircraft Stability

The inherent aerodynamic quality of an aircraft to return to its original equilibrium state after being disturbed.

Static Stability

The initial tendency of an aircraft to return toward, diverge from, or remain displaced from its original position when disturbed from equilibrium.

Dynamic Stability

The time history and response of an aircraft's oscillations as it attempts to return to equilibrium following an initial displacement.

Longitudinal Stability

Stability about the lateral axis governing pitch movement, controlled by the elevator and determined by the location of the center of gravity relative to the center of lift.

Lateral Stability

Stability about the longitudinal axis governing roll or banking movement, controlled by the ailerons.

Directional Stability

Stability about the vertical axis governing yaw movement, controlled by the rudder.

Geometric Pitch

The theoretical distance a propeller would advance forward in one full revolution in the absence of slip, friction, or aerodynamic losses.

Effective Pitch

The actual distance an aircraft propeller moves forward during one revolution in real-world atmospheric conditions.

Propeller Slippage

The mathematical difference between the propeller's geometric pitch and its effective pitch, representing an efficiency loss of roughly 20%.

Torque Reaction

A left-turning tendency caused by Newton's third law of action and reaction, where the clockwise rotation of the propeller exerts an equal opposite counterclockwise rolling tendency on the airframe.

Corkscrew Effect

A turning tendency (also known as spiraling slipstream) caused by the propeller slipstream wrapping around the fuselage and striking the left side of the vertical tail, pushing the tail right and yawing the nose left.

Gyroscopic Precession

A turning action resulting from a spinning propeller acting as a gyroscope, where an applied pitching force manifests as a resultant force $90^\circ$ later in the direction of rotation.

P-Factor

Asymmetric propeller loading occurring at high angles of attack, where the downward-moving propeller blade on the right produces greater thrust than the upward-moving blade on the left, inducing a yaw to the left.