how fast must a plane go to take off?

Question

I was thinking whilst I was taking of on a airoplan how does the piolet know what 2 pull the wheels in and lift the plan?surely there must be a speed the aircraft must reach when on the runway.

Answer 1

Well there are many of factors that play into this, here are a few.

1) Weight of said Aircraft
2) Wing Loading
3) Airfoil / Eppler
4) How many feet above sea level is the runway
5) Ambient Temperature
6) Wind Speed / Direction

Basically the wing generates lift as the airplane moves forward.Once the wings have generated the same amount of lift as the weight of the airplane, this is called it's "Stall Speed" this is the speed that the plane must stay above in order to stay in level flight. When taking off from the runway you want to be well faster than your stall speed before you "Rotate" (this means to pull back on the yoke).

A pilot knows when to rotate because he/she knows the set speed to do so and because you can feel, in the seat of your pants, when the plane is ready to take flight.

I was on a J3 Cub in Key West back in the 80's when I was training for my Pilot license and we were on the runway waiting for clearance to go. We had a very strong & steady headwind coming straight down the runway. We were able to lift off at under 30 mph because the airspeed over the wings was well over the stall speed, due to the headwind. Boy was that fun!

Hope this helps

Answer 2

This is an answer that I posted to a similar question a day or two ago. It's more than you asked but here ya go.


Answering your question is not unlike answering the question, "how long is a rope?" Don't mean to be a wise guy so forgive me. We must compute the takeoff speeds and landing speeds prior to every takeoff or landing. The speeds vary allot depending on things like the wieght of the aircraft, the elevation of the airport, how hot or cold the air temperature is and the list goes one. We have several performance charts for both take off and landing where we can account for all of this data, which is different for every takeoff or landing, and come up with the appropriate speeds.

There are a number of speeds that we must calculate just for the takeoff. The first is what we call "V1". This is commonly known as the decision speed but it is more complicated than that so let's just call it that for brevity. V1 is the speed where it would take as much distance to stop the aircraft on the remaing runway or to continue the take off to thirty five feet with one engine out. So if the captain is making the takeoff and he has not heard the co pilot call "V1" if the engine fails, he will decide to abort the takeoff and stop the airplane. If the copilot has already called "V1" he is now commited to the takeoff because there is no longer enough runway to stop.

The next number that we calculate is "Vr" or the rotation speed. This is the speed that we lift the nose off the ground to begin the takeoff. Vr is always higher than V1.

"V2" is the next speed and is called the takeoff safety speed. In theory, if you were to loose and engine precisely at V1 and elected to continue the takeoff, you would accelerate to Vr, rotate the airplane and you would continue to accellerate so as to reach V2 at thirty five feet. You would then be precisely over the spot on the ground where you would have come to a stop had you elected instead to abort the takeoff. The landing gear would be retracted now and you would then hold as close as possible to V2 until you get to four hundred feet or clear all obsticles.

All of these speeds assume the loss of an engine at precisely V1. If everything is working ok then everything would happen exactly the same except that you would continue to accelerate past V2 to an airspeed that allows you to retract the flaps and get to a more efficient climb speed.

Before landing we must again compute our approach speed or "Vref" This is a reference airspeed that will keep us nice and slow prior to touchdown without getting dangerously close to the stall speed. Like the takeoff speeds, every approach is different depending on the weight of the airplane primarily and assumes that the landing gear and flaps are fully extended. Obviously the lighter the aircraft, the slower the approach speed and the less braking energy is required to stop after landing.

There is quite a bit more involved in all of this but my fingers are getting tired.

Answer 3

The "quick and dirty" answer to you question is that the liftoff speed depends on the airplane. The pilot either looks it up in the Pilot's Operating Manual (similar to the owner's manual of a car) or on TOLD (takeoff and landing data) cards.

The airplane will be capable of flight any time the lift produced by the wing is equal to the weight of the airplane. Light aircraft have very small variations in weight so the liftoff speed (rotation speed) is fairly constant. In the Cessna 172 the Pilot's Operating Manual says to lift the nosewheel off the ground at 55 knots (about 63mph) and to climb out at 65-75 knots.

On larger aircraft the weight can vary tremendously depending on how much fuel and passengers are being carried. On the Dornier 328 jet (32-seat regional jet) that I fly the weight could vary as much as 8,000 lbs from one flight to the next. This, of course, will vary the rotation speed so use a TOLD card to determine rotation speed. In most cases it varies between 111-120 knots (127-137mph). Larger airliners will have even more of a variation.

Answer 4

Depends on the aircraft, every aircraft has a windspeed that the wings start producing enough lift to leave the ground. Cessnas and pipers need very little wind speed to take off around 50-60 knots, and I'm pretty sure jet fighters need about 70-80 knots to take off. You basically feel the aircraft loosing its grip on the ground and you should generally know how fast your a/c needs to be going to get off the ground in the given load configuration. With small non computer flight control assisted aircraft it's up to the pilot to feel when it's time to take off, in commercial airliners the AFCS or autopilot figures out these parameters of flight when you input the weight and balance of the a/c for that flight.

Answer 5

Fast enough that the wings can generate more lift than the weight of the plane. The airspeed indicator usually has a marking that tells the pilot how fast they have to go to reach this point.

Each model of plane will have its own takeoff speed. This is set by the weight of the plane, and the design of the wings. Different airfoils (the profile of the wings) will generate different amounts of lift. Some generate lots of lift at low speed, but are inefficient at high speeds. Others will generate a lot of lift only at high speed, so they need a powerful engine to get them going fast enough. The designer's job is to match the wings to the rest of the aircraft so that it fits the intended mission of the plane.

Answer 6

Depends on the plane!! A lightweight, wooden Bi-plane, (WWI Type) may lift at 30mph or so, a heavy, hispeed jet fighter may need close to 300 mph . It's a factor of wing area, design and weight. The smaller, thinner wins good for high flight speed need speed to generate lift. A large, straight, thick wing, good for lift and slow speed, needs less speed to get enough air over the wing to lift easily. A modern passenger jet needs 150 to 200 mph to lift off.

Answer 7

depending on the aircraft: smaller the aircraft (depending on company), the less the speed to lift up

if you use a Boeing 737 or 757, takeoff roll is at least 130 KIAS
747 takeoff roll is 165 KIAS
777 takeoff roll is 145 KIAS

if you use a Airbus 320 series: 145 KIAS
330 series: 145 KIAS

Cessna 172SP Skyhawk would be 55 KIAS to lift up
that is just some examples

Answer 8

I was wondering the same thing. I think maybe they think if you have it on and plugged into your ears, you might not hear any announcements they would make. Maybe there is a better chance of an emergency during take off and landing, so you would need to be paying attention and not listening to your mp3 player. I hope you get a valid answer to this question.

Answer 9

Each plane is slightly different but most commercial jets reach "v-one" (the speed at which you generate enough lift to take off) at 160-180 mph.

Answer 10

Commercial jets usually take off at 150 knots (165 mph). Small planes usually take off at 65 knots. Private jets, 130 knots.