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View Full Version : OT Now for something completely different- aerodynamically



Thruthefence
08-19-2010, 03:39 PM
Had such fun with shock waves, anyone want to discuss this 'new' theory?

http://knol.google.com/k/the-spell-of-kutta-zhukovsky-s-circulation-theory#

http://knol.google.com/k/why-it-is-possible-to-fly#view

Evan
08-19-2010, 03:54 PM
The primary contributor to lift is the simple changing of the direction of the flow of air over the wing. As an aircraft passes through the air it accelerates the air downward from the trailing edge of the wing. That is where the majority of the lift comes from. A minor component is the production of a lower pressure area above the wing caused by the velocity difference above and below the wing. That component is entirely absent in a flat plate even though a flat plate flies just fine.

Forrest Addy
08-19-2010, 04:07 PM
Put another way, it takes a force to accellerate a mass. Pass a wing with an angle of attack through a mass of stationary air and it will acellerate the air within its influence producing a force - lift. A perfect wing has infinite span, infnite rigidity and strength, a finite chord, and zero parastic drag. The wings you see on airplanes are the products of balancing theory with practicality.

Bruce Griffing
08-19-2010, 05:57 PM
While it is true that the wing accelerates air downward, the wing has no connection to the air except through friction (viscous forces) and air pressure. All of the lift is accounted for by air pressure differences. However, the cause of the air pressure differences is much debated.

J Tiers
08-19-2010, 11:38 PM
The circulation theory has no basis in reality..... but the theory of two oppositely rotating fields in a single phase electric motors has no such basis either.....

There are many such abstractions...

They end up being at best a "way of looking at the problem", which if they are any good, provide the right answer despite not being exact descriptions of what is physically occurring.

At worst, they are just BS.