###### Asked in Airplanes and Aircraft, English to French, Boeing
Airplanes and Aircraft
English to French
Boeing

# How fast does a plane have to go in order to get off the ground?

###### 09/12/2011

planes can take off when the lift produced by the wings exceeds the weight of the plane - some variables that determine lift are the speed of air moving over the wings, angle of the wing to the air movement and the shape of the wing which can be changed with the flaps or slats

so its not the ground speed that determines when a plane can lift off but the air speed which can vary with wind speed and direction - and it differs depending if flaps or slats (flaps on the front of the wings) are deployed as they increase lift

another factor that can change lift is air temperature and preasure - higher temps and lower preasure reduce lift and so require more air speed to lift off

the amount of lift required for each plane is determined by not only the weight but the amount of drag from shape of the aircraft and the shape of the wing - which is why take off speed can vary greatly from plane to plane

take off speed can vary from about 32 knots (about 37mph) with a piper cub to nearly 180 knots (about 205 mph) with some supersonic jets whose tiny wings don't produce much lift at slow speeds

some small light high lift aircraft like the piper cub if taking off into a headwind that is equal to their takeoff speed can take off like a helicopter straight up with no ground speed at all