What is the scientific reason why airplanes fly?

Question

i mean why does an aircraft (Commercal) have to run fast before it lifts off the ground? Is it because of bernoulli's Principle? please explain thanks

Answer 1

There are two reasons that I've heard..

1. This is the most common explanation - Bernoulli's Principle where the pressure on the wing's upper surface is less that the pressure on the lower surface. This pressure creates a net lifting force.

2. The wing is a curved surface that forces air down. The air being forced down creates a lifting reaction on the wing. Sort of like a rocket motor where the gas expelled out of the nozzle creates thrust for the rocket. The lift is a result of moment exchange and Newton's Laws.

Answer 2

Aircraft fly simply because Lift overcomes the force of Drag and Gravity, thru the use of Force. How come a rocket "flys" without wings? It goes UP because there's enough FORCE to move it there. Same with airplanes. While wing shape, Bernoulli's Principle, etc. all contribute, if you use enough brute force, you can make a straight piece of plywood fly.
So, the first reason is Angle of Attack, and the Force used to propel the aircraft. If you tilt the wings up some to get the wind to hit the undersurface, and provide enough force, the aircraft will lift off and fly. The shape contributes to the lifting force, but is not the true REASON it flys, only helps it to fly well. The other reason is aerodynamics and drag reduction, and wing design that promotes the pressure differential over the wing to help with lift. The reason it's NOT the main reason for flying? When the USA was doing power dive testing in WWII with the P-38 Lightning prototype aircraft, at around 650 mph or more it would lock the controls, and actually try to dive MORE, backwards, than pull up...a few pilots died while finding out about this killer phenomena. They eventually figured out how to install dive brakes to keep the speed down so the aircraft would respond, but the controls worked backwards after a certain speed. the lift force couldn't overcome the control locking up ... so the wing shape didn't matter after a certain speed in this instance. The main two reasons an aircraft will fly is Angle of Attack, and Aerodynamics. Ask any bird... they don't have a vertical tail rudder!

- The Gremlin Guy -

Answer 3

Ahh, the old Bernoulli vs Newton debate.

They are both correct, and they both need each other to produce lift. You can't have one without the other. (Well, you can. Flat plate lift is an example of Newtonian lift without Bernoulli, but it creates ten times as much drag for the same amount of lift).

The air is accelerated over the wing and decelerated (to a lesser degree) under the wing. Since we aren't adding any energy to the air, the accelerated air takes some pressure away, creating suction (or lower pressure) on top of the wing.

The result of the accelerated airflow on the top of the wing is the turning of the airflow. It is much like a canoe with two paddlers, when one person is paddling faster than the other. The canoe turns.

The down wash is a necessary reaction, but since it is behind the wing, it has already done its job and can't contribute to lift. It is the action that we are concerned with (not the down wash reaction). The action is lifting the airplane.

For more detail on why the air wants to accelerate and the airflow wants to turn, you need to look up the Kutta-Zhukovsky theorem.

Answer 4

Bernoulli's Principle is NOT why planes fly. They fly because the air is deflected down by the wing, pushing the plane up. You can make a plane fly even if you used ordinary flat boards as wings.

The proof of this is PLANES CAN FLY UPSIDE DOWN. If it was all about the Bernoulli's Principle, the plane would head for the ground immediately when you flipped over. And clearly that does not happen. They even had a 707 they did a barrel roll with and when it was upside down, there was no sudden dive for the ground.

This is an example of something that got written years ago and people believe it as faith.

Another example is "normal body temperature is 98.6 degrees" (it is not) Also, there are "seven simple machines." (there are eight. They forgot the bow string.)

Another is that tides are caused by the pull of the moon. Yes, the one on the side of the earth facing the moon. But the tide on the other side of the early is due to the wobble of the earth around the earth-moon center of gravity, which is inside the earth.

Answer 5

I haven't researched the subject for over 15 years, but I thought phone stuff was on 2.4 GHZ. There is nothing on an aircraft in that frequency range. Or at least there wasn't 15 years ago. As the "radio operator" noted, you are probably getting some kind of reflected signal to cause your interference. The FCC used to check these anomalies for free. Call them! If you have a satellite phone instead of cell phone, the aircraft could block your signal.

Answer 6

Hey Jude, LIFT is the key word here. It's created by the differential in pressure of the air flowing under and over the wings. The bigger the aircraft, the more wing area and land speed is required for it to get airborn.

Answer 7

it has to speed up so it can get enough lift to take off and yes bernoullis principle and newtons thrid law of motion ever force there is equal oppositte force so air getting pushed down by wings plane going up

Answer 8

yes, Bernoulli's Principal is a contributing factor. the asymmetrical design of a "wing" causes low pressure on the topside of the wing, therefore allowing "lift".

Answer 9

Simple explanation, the shape of the wing creates negative preasure on the top of the wing and positive preasure on the bottom, creating lift.

The speed of the wing through the air determines the lift created.

Answer 10

In layman's terms, the velocity of the air going over the wing has to be high enough for the pressure to drop. It is the differential between the low high pressure under the wing and the low pressure over the wing that makes that type of flight possible.