Glossary aerodynamics:  the science of air in motion and the motion of  objects in air  air resistance:  aloft:  the length of time a plane stays in the air altitude: the height of something above the earth's surface atmosphere: the air in any given place aviator:  an airplane pilot Bernoulli's Principle:  The law, discovered by Daniel Bernoulli, which states that when air speeds up its pressure is reduced, and when the air slows down its pressure is increased. blimp:  a dirigible that is non rigid buoyancy:  the principle that an object will float if it weighs less than the substance in which it is suspended cambered:  slightly convex; curved dirigible:  a balloon that can be steered; also called an airship drag:  the force which pulls back the airplane and slows it down elevator:  horizontal flap on the tail which is used to move the plane up and down  flight attendant:  a person who works on a commercial aircraft and assists passengers fuselage:  the body of an aircraft glide:  to descend with little or no engine power, using airflow to control lift gravity:  force that tends to draw all bodies in the earth's sphere toward the center of the earth    jet stream:  the stream of exhaust from any reaction engine latitude:  angular distance, measured in degrees, north or south from the equator lift:  the force that exerts an upward pull longitude:  distance east or west on the earth's surface, measured as an arc of the equator (in degrees up to 180o or by the difference in time) between the meridian passing through a particular place and a standard or prime meridian. mass:  the quantity of matter in a body as measured by inertia navigator:  a person who navigates, to steer or direct an aircraft pilot:  a person qualified to operate the controls of an aircraft or spacecraft pressure:  a constraining force propeller:  a device that consists of a central hub with radiating blades that is used to pull or lift a vehicle (as a ship or a plane) resistance:  opposition to rudder:  vertical flap on the tail fin that directs left/right movement stability:  the capacity of an object to return to equilibrium or to its original position after being displaced stabilizer:  any of the fixed vanes that keep an airplane steady in flight thrust:  the forward force produced in reaction to the gases escaping rearward from a jet or rocket engine turbulence:  irregular motion or swirling agitation of water, air, gas, etc.  velocity:  a rate of change of position in relation to time weight:  the force of gravity acting on a body, equal to the mass of the body multiplied by the acceleration of gravity zeppelin:  a dirigible with an internal frame, which makes it rigid