Aeronautical Terms beginning with L
Landing gear extended speed
The maximum speed at which an aircraft can be safely flown with the landing gear extended.
Landing gear operating speed
The maximum speed at which the landing gear can be safely extended or retracted.
Landing Weight
The takeoff weight of an aircraft less the fuel burned and/or dumped en route.
Lateral Axis
An imaginary line passing through the center of gravity of an airplane and extending across the airplane from wingtip to wingtip.
Lateral Offset Moment
The moment, in lb-in, of a force that tends to rotate a helicopter about its longitudinal axis. The lateral offset moment is the product of the weight of the object and its distance from butt line zero. Lateral offset moments that tend to rotate the aircraft clockwise are positive, and those that tend to rotate it counterclockwise are negative.
Lateral Stability (Rolling)
The stability about the longitudinal axis of an aircraft. Rolling stability or the ability of an airplane to return to level flight due to a disturbance that causes one of the wings to drop.
Lead-Acid Battery
A commonly used secondary cell having lead as its negative plate and lead peroxide as its positive plate. Sulfuric acid and water serve as the electrolyte.
Leading Edge
The part of an airfoil that meets the airflow first.
Leading Edge Devices
High lift devices which are found on the leading edge of the airfoil. The most common types are fixed slots, movable slats, and leading edge flaps.
Leading Edge Flap
A portion of the leading edge of an airplane wing that folds downward to increase the camber, lift, and drag of the wing. The leading-edge flaps are extended for takeoffs and landings to increase the amount of aerodynamic lift that is produced at any given airspeed.
Lean of Peak
A mixture setting where the mixture was leaned from the full-rich fuel flow position to lean of peak exhaust gas temperature (EGT).
LEMAC
Leading Edge of the Mean Aerodynamic Chord.
Licensed Empty Weight
The empty weight that consists of the airframe, engine(s), unusable fuel, and undrainable oil plus standard and optional equipment as specified in the equipment list. Some manufacturers used this term prior to GAMA standardization.
Lift
One of the four main forces acting on an aircraft. On a fixed-wing aircraft, an upward force created by the effect of airflow as it passes over and under the wing.
Lift Coefficient
A coefficient representing the lift of a given airfoil. Lift coefficient is obtained by dividing the lift by the free-stream dynamic pressure and the representative area under consideration.
Lift/Drag Ratio
The efficiency of an airfoil section. It is the ratio of the coefficient of lift to the coefficient of drag for any given angle of attack.
Limit Load Factor
Amount of stress, or load factor, that an aircraft can withstand before structural damage or failure occurs.
Load Cell
A component in an electronic weighing system that is placed between the jack and the jack pad on the aircraft. The load cell contains strain gauges whose resistance changes with the weight on the cell.
Load Factor
The ratio of the load supported by the airplane’s wings to the actual weight of the aircraft and its contents. Also referred to as G-loading.
Loading Graph
A graph of load weight and load moment indexes. Diagonal lines for each item relate the weight to the moment index without having to use mathematics.
Loading Schedule
A method for calculating and documenting aircraft weight and balance prior to taxiing, to ensure the aircraft will remain within all required weight and balance limitations throughout the flight.
Loadmeter
A type of ammeter installed between the generator output and the main bus in an aircraft electrical system.
Longitudinal Axis
An imaginary line through an aircraft from nose to tail, passing through its center of gravity.
Longitudinal Balance
Balance around the pitch, or lateral, axis.
Longitudinal stability (pitching)
Stability about the lateral axis. A desirable characteristic of an airplane whereby it tends to return to its trimmed angle of attack after displacement.
LOP
Lean of Peak
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