An aircraft is a vehicle which is able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.

Although rockets and missiles also travel through the atmosphere, most are not considered aircraft because they use rocket thrust instead of aerodynamics as the primary means of lift. However, rocket planes and cruise missiles are considered aircraft because they rely on lift from the air. From jOOzONE.cOM.

The human activity which surrounds aircraft is called aviation. Manned aircraft are flown by an onboard pilot. Unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Target drones are an example of UAVs. Aircraft may be classified by different criteria, such as lift type, propulsion, usage and others.

更多飞机介绍请见维基百科：http://en.wikipedia.org/wiki/Aircraft

有关飞机历史的英文参考：

http://www.34restoration.org/AircraftHistory.htm

http://www.joozone.com/daxue/20100517/3001.html

http://www.joozone.com/daxue/20100517/2996.html