How do planes take off?

Answer 1

An airplane has to reach a certain speed (which varies depending on aircraft type and gross weight) before it can take off,

There are 7 main stages involved with take off in commercial airliner.

1) Checks - when the aircraft has had its IFR and take off clearence from Air traffic control, the pilots must do a series of brief checks, such as flap configuration, APU setting, landing lights and autopilot, After these are done the aircraft will taxi onto the runway.

2) Power up - At this point the throttles will be advanced and the tubines will power up and the aircraft will start accelerating

3) Final check - The pilots will look at their speed gauges, They should be "alive" and displaying increasing numbers by now

4) V1- The "V1" speed is the speed that the aircraft can no longer stop with the amount of runway it has left and must take off no matter what happends.

5) Rotate - This comes about 2 seconds after V1 is called, When the captain says outloud "Rotate"! the first officer will pull back on the yoke or sidestick and the aircraft will pitch up and lift into the air, increasing in speed and pitch angle until both of the desired are reached

6) V2- This is the speed that the aircraft can safley continue the takeoff if an enjine fails, it is usually called about 2 seconds after rotate.

7) Positive rate- This happends about 40 ft off the ground and is usually around 3 seconds after the aircraft has become airbourne, This simply means that the aircraft is climbing and the alitmiters are correctly working, At this point the crew will raise the landing gear, and raise the flaps 1 stage.

This is what the conversation should look like at take off with a functioning crew

(key)

Atc = air traffic control

fo= first officer

cpt=captain

fo: Heathrow tower,Virgin 332 at runway 27 left has received IFR clearence with delta for departure to the east for KORD, Requesting take off IFR over

(that was the first officer asking for clearence from air traffic control, the capatin would be doing the pre takeoff checks while the first officer does this)

atc: Virgin 332 cleared for take off runway 27 left, climb and maintain 4000, remain on runway heading until you have contacted the controller on the departure frequency, good day sir.

fo: Virgin 332 cleared for take off runway 27 left, good day (this must be repeated so the controller is sure the pilots have understood the clearence.

Capt: all checks complete, power up

fo: power to 70%

capt: Airspeed indicators checked

fo: checked

capt: V1!

capt: Rotate!

capt: V2!

capt: positive rate

fo: gear up

capt: gear up and locked, retract flaps to 2 degrees

There is much more involved than this however this is the basics of the process

Answer 2

Planes use a combination of kite effect and Bernoulli's principle to take off and fly. When the plane nears the runway's end and the pilot judges that it is going fast enough, he will pull the stick back. The nose will come up and the bottom of the wing will be exposed to the oncoming air. The engines supply thrust, and force the plane forward. The bottom of the wing is forced against air, and the air pushes back against the underside of the wing. But because the wing is slanted, air is forced down, and the wing will be forced up by the air. That's kite effect. The only difference is that with a kite, the air is moving and the kite is held stationary. With aircraft, the plane is forced forward into the still air. Haven't we all held a hand outside the window of a moving car and experimented with tipping the hand up or down to feel the force of the moving air? What kid (or adult) hasn't? Bernoulli's principle says that if a fluid (gas or liquid) is moving, it will have less pressure than if it is not. A wing is shaped to take advantage of this idea. The shape of the wing is such that the bottom is mostly flat, and the top is curved. The leading edge of the wing curves up and over and then continues to curve down and back to the trailing edge. Move the wing through air and the air moving along under the wing has pretty much a straight shot to get to the trailing edge. The air moving over the top, however, must travel farther to rejoin the air that traveled along the bottom, and will therefore move faster. And it will have less pressure as it is moving across the top of the wing. Lower pressure on top/higher pressure on the bottom equals a net "up" force called lift. Look! We're flying!