UP, UP, AND AWAY: The Science of Flight - Glossary

aileron

A panel on the main wing of an aircraft that can be raised or lowered to help change the plane's direction.

airfoil

A shape designed to provide lift whenever air moves around it.

Bernouilli's principle

The principle that when the speed of a gas or a liquid increases the pressure it exerts sideways drops.

ceramic

A nonmetallic substance that is light and can withstand high temperatures. New ceramics are being developed for use in aircraft that travel at very high speeds.

Coanda effect

The effect by which gases and liquids tend to follow the outlines of curved objects they flow around.

compressor

The part of a jet engine in which the incoming air is squeezed to a high pressure.

drag

The force that acts to slow down an object as it moves through a gas or a liquid.

elevators

Panels on the tail plane of an aircraft that can be moved up or down to make the nose of the plane fall or rise.

glider

An aircraft that flies without an engine. Its pilot tries to find updrafts of air to gain height and extend the flight.

helium

The second lightest gas. It is safe to use in balloons since it will not catch fire.

hydrogen

The lightest gas of all but dangerous to use since even a small spark can cause it to burn fiercely in air.

jet engine

An engine in which air is sucked in, compressed, and then used to burn a fuel. The hot exhaust gases rushing out of the back of the engine propel a jet aircraft forward.

lift

The upward force produced when air rushes over and around an airfoil.

molecule

The smallest part of a substance that can exist and still have the properties of that substance.

pressure

The force acting on a unit of a surface.

propeller

A curved blade that, when spun around quickly, forces an aircraft forward. A propeller is a twisted airfoil.

ramjet

A type of jet engine designed to work at high speeds. It does not need a compressor since the very fast-moving air compresses itself as it enters the engine.

rotor

A set of large twisted blades that provides both the lift and the thrust in a helicopter. The main rotor is attached horizontally and the tail rotor vertically.

rudder

The upright panel on plane's tail that is moved to the right or left to help the plane turn.

scramjet

A special types of ramjet designed to work over 8 times the speed of sound and at very high altitudes.

streamlining

The shaping of an object so that a gas or liquid will move easily around it.

swing-wing

A wing that can be swept back as a plane gathers speed to reduce drag.

thermal

An updraft of warm air found over a hot patch of land.

thrust

The forward-acting force, supplied by an engine, that allows a plane to take off and remain airborne.

turbine

A series of blades that are turned around by the hot gases rushing out of a jet engine. As the turbine spins around, so does the compressor to which it is linked.