Induction manifold.  The part of the engine that distributes  intake air to the cylinders.  Inertia.  The opposition which a body offers to a change of  motion.  Initial climb.  This stage of the climb begins when the  airplane leaves the ground, and a pitch attitude has been  established to climb away from the takeoff area.  Instrument Flight Rules (IFR).  Rules that govern the  procedure for conducting flight in weather conditions below  VFR weather minimums. The term “IFR” also is used to  define weather conditions and the type of flight plan under  which an aircraft is operating.  Integral fuel tank.  A portion of the aircraft structure, usually  a wing, which is sealed off and used as a fuel tank. When a  wing is used as an integral fuel tank, it is called a “wet wing.”  Intercooler.  A device used to reduce the temperature of the  compressed air before it enters the fuel metering device. The  resulting cooler air has a higher density, which permits the  engine to be operated with a higher power setting.  Internal combustion engines.  An engine that produces  power as a result of expanding hot gases from the combustion  of fuel and air within the engine itself. A steam engine where  coal is burned to heat up water inside the engine is an example  of an external combustion engine.  International Standard Atmosphere (ISA).  Standard  atmospheric conditions consisting of a temperature of 59 °F  (15 °C), and a barometric pressure of 29.92 "Hg. (1013.2  mb)  at sea level. ISA values can be calculated for various altitudes  using a standard lapse rate of approximately 2 °C per 1,000  feet.  Interstage turbine temperature (ITT).  The temperature  of the gases between the high pressure and low pressure  turbines.  Inverter.  An electrical device that changes DC to AC power.  Kinesthesia.  The sensing of movements by feel.  Jet powered airplane.  An aircraft powered by a turbojet or  turbofan engine.  Lift-off.  The act of becoming airborne as a result of the  wings lifting the airplane off the ground, or the pilot rotating  the nose up, increasing the angle of attack to start a climb.  Lift/drag ratio (L/D).  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.  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.  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.  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.  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.  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.  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.  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.  Lateral axis.  An imaginary line passing through the center  of gravity of an airplane and extending across the airplane  from wingtip to wingtip.  L K J