Aerospace Terms

Aileron

Small-hinged sections on the outboard portion of a wing that are used to generate a rolling motion for an aircraft.

Airfoil

Any surface, such as a wing, which provides aerodynamic force when it interacts with a moving stream of air.

Angle of Attack

The angle formed by the wing chord line and the relative wind.

Aspect Ratio

The relationship between the length and width of a wing.

Boundary Layer

A thin layer of air next to the surface of an airfoil which shows a reduction in speed due to the air’s viscosity.

Center of Gravity

The common reference point for the three axes of the aircraft.

Cockpit

The space in the fuselage of a small airplane containing seats for the pilot, copilot, and sometimes passengers.

Controllability

The capability of an aircraft to respond to your flight inputs, especially with regard to attitude and flight path.

Dihedral

The mounting of wings so that the wingtips are higher than the wingroot.

Drag

Acts in the opposite direction of flight, opposes the forward-acting force of thrust, and limits the forward speed of the aircraft.

Dynamic Stability

Out of its own accord, an aircraft eventually returns to and remains at its equilibrium position over a period of time.

Elevator

A rear horizontal stabilizer that controls up and down or pitching motion of the aircraft nose.

Empennage

The tail assembly of an aircraft, including the horizontal and vertical stabilizers, elevators and rudder.

Flaps

Control surfaces attached to the trailing edge of the wing extending outward from the fuselage to the midpoint of each wing. Flaps can increase the lifting efficiency of the wing and decrease stall speed.

Fuselage

Houses the cabin, the cockpit and is a common attachment point for the other major components.

Glider

An aircraft that is designed to fly without an engine.

Horizontal Stabilizer

A structure that creates up and down forces at the tail to keep the fuselage aligned in pitch with the relative wind. The structure itself is horizontal while the forces it creates are vertical.

High hypersonic

Aircraft speeds between Mach 10 and 25.

Hypersonic

Aircraft speeds between Mach 5 and 10.

Keel Effect

The flat surfaces located behind the center of gravity tend to weathervane with the wind.

Lapse Rate

The rate at which temperature decreases with an increase in altitude.

Lateral Axis

The horizontal line that passes through the center of gravity of the aircraft, perpendicular to its flight path.

Leading Edge

The part of the airfoil that meets the airflow first.

Lift

The force created by the effect of airflow as it passes over and under the wing.

Longitudinal Axis

A straight line parallel to the length of the fuselage but that runs through the aircraft’s center of gravity.

M

Mach. A decimal number representing the true airspeed relationship to the local speed of sound.

Maneuverability

Characteristic of the aircraft that permits you to maneuver it easily and allows it to withstand the stress resulting from the maneuver.

Pitch

Motion around the lateral axis caused by deflection in the elevator controlled by moving the yoke forward and aft.

Powerplant

Consists of both the engine and propeller in a small airplane.

Reynolds Number

The ratio of inertial forces to viscous forces.

Roll

Rolling motion about the longitudinal axis caused by ailerons deflecting in opposite directions and controlled by twisting the yoke.

Rudder

A rear vertical stabilizer that controls side-to-side or yawing motion of the aircraft nose.

Stability

Aircraft stability is the characteristic of an airplane in flight that causes it to return to a condition of equilibrium, or steady flight, after it is disturbed.

Stall

Caused by the separation of airflow from the wing’s upper surface resulting in a rapid decrease in lift.

Static Stability

Forces and moments on the body caused by a disturbance tend initially to return the body toward its equilibrium position.

Subsonic

Aircraft speeds under Mach 1.

Supersonic

Aircraft speeds between Mach 1 and 5.

Taper

A reduction in the chord of a wing as measured from the root to the tip of the wing.

Thrust

Forward-acting force which opposes drag and propels the aircraft through the air.

Trailing Edge

The last point on an airfoil that interacts with the airflow around the wing.

Vertical Axis

A straight line through the center of gravity of the aircraft and at 90° to lateral and longitudinal axis.

Vertical Stabilizer

A structure that creates left to right forces to keep the fuselage aligned in yaw with the relative wind. The structure itself is vertical while the forces it creates are horizontal.

Wash In/Wash Out

A built in twist in the wing so that the trailing edge at the wingtip is raised (Wash out) or lowered (Wash in). This significantly affects the slow flight and stall characteristics of the wing.

Weight

A force caused by the gravitational attraction of the Earth.

Wing

Generates the lifting force that helps the airplane fly when air flows around it.

Wing Planform

The outline shape of a wing when viewed from above.

Wing Span

The distance from wing tip to wing tip of a wing planform.

Yaw

The movement about the vertical axis produced by the rudder and controlled by pedals.