deseely,

Most of this has been covered and to my mind, the Coanda effect as a "how" or cause for the downward deflection is not only DOA, it's a misnomer. Effects can't cause things! Try this.

Bob: How does the air get curved downward going over a wing?
Joe: The Coanda effect.
Bob: How does the Coanda effect curve the air?
Joe: It's like water from a faucet flowing over a glass.
Bob: Ahhhh... But how does the air or water curve?
Joe: (head explodes)

That's pretty much Raskin's argument in a nutshell, but instead of his head exploding, he waves his arms around and says we don't need to know how it works, leaving us

As for the crack smoking circulation theory, as Wouter said, circulation is just a mathematical and visualization tool, not a conspiracy. Check out Section 3.10 of See How It Flies for a very clear description of circulation. Circulation doesn't state that air moves from the trailing edge to the leading edge while an airplane is flying, it states that this kind of flow plus that kind of flow produces the same flowfield as a wing. In fact, circulation assumes that the forward flow under the wing from the TE to the LE is exactly cancelled out by the linear flow passing under the wing from the LE to the TE. You don't need a jet engine to cancel that forward flow, it's already done.

Ironically, a jetstream improperly placed under a wing could decrease lift in that region because of the...



...Coanda effect.

I wish I was kidding.