Physics question:)?

Question

Identify the force associated in a lift of an airplane and explain it thoroughly...

What is magnetic lines of force?

Answer 1

Lift is cause by airflowing faster over the top of the wing of an airplane that it flows over the botttom.  Bernoulli's principle tells use that wher a fluid flows over a surface, the pressure on the surface is reduced.  So by having air move faster over the top of the wing, the pressure on the top of teh wing is reduced and is lower than the pressure on the bottom of the wing.  Since teh pressure on teh bottom is pushing upward, it lifts the wing, hence the airplane.

Answer 2

The answer about "air flowing faster over the top...blah, blah, blah" IS ONLY correct in ground effect (flight near the ground).  Those nifty pics you see of wing cross sections in a wind tunnel with smoke streamlines is an example.

At altitude the lift can not be explained by such primitive views of fluid flow.

The principle lift components are..

1) Newtons conservation of momentum.  The air flow is deflected by the wing since it has an angle of attack (or specially designed shape).  This pushes the air mass down resulting in lift.  This view is compatible with Bernoulli (because energy methods and Newtonian methods are mathematically related).  This is still not complete (please keep reading).

BUT THE MOST IMPORTANT REASON WINGS LIFT...can not be explained without a thorough understanding of fluid mechanics...

2) The vortexes that are shed from the wing are the main lift generator for an aircraft at altitude.

This "dumbing down" of flight by talking about "faster air" having a lower pressure does not really explain how airplanes fly.  It is presented as an "answer" because the "real" reasons are much too complex to be fathomed by those who are not aerodynamic engineers or the like.

Here is one of the GREAT websites out there that tackles this issue of the misconception of flight.

I hope you get a chance to review it...

http://www.eskimo.com/~billb/wing/airfoi...

-Fred