If you've ever watched a jet plane taking off or coming in to land, the first thing you'll have noticed is the noise of the engines. Jet engines, which are long metal tubes burning a continuous rush of fuel and air, are far noisier (and far more powerful) than traditional propeller engines. You might think engines are the key to making a plane fly, but you'd be wrong. Things can fly quite happily without engines, as gliders (planes with no engines), paper planes, and indeed gliding birds readily show us.

Aircraft do not defy the law of gravity, they produce a sufficient force to overcome gravity, just as you do if you decide to jump in the air.

There are four main forces acting on an aircraft, thrust from the engines, drag on the airframe, gravity pulling down and lift generated by the wings.

Once the size of the lift is greater than the weight of the plane then gravity will be overcome and the plane will rise. Once cruising altitude is achieved the lift force is balanced with the weight and the aircraft stays at a constant height.

Airplane wings are shaped to make air move faster over the top of the wing. When air moves faster, the pressure of the air decreases. So the pressure on the top of the wing is less than the pressure on the bottom of the wing. The difference in pressure creates a force on the wing that lifts the wing up into the air.