Tissue on bottom of wing?

You sure know how to open a can of worms. Stand back--the stuff is going to hit the fan shortly. ;o)

For a flat wing, the Bernouilli effect, much loved by many amateur aerodynamicists, is not the cause of lift.

All of the lift comes from the angle of attack.

Imagine taking a flat piece of balsa and holding it out a car window while traveling at 30 mph. (Please do this as a passenger, not as the driver of the car.)

As you rotate the flat surface into the "relative wind," you will feel the difference made by angle of attack.

By putting the structure on top of the wing, you have eliminated drag on the most important side of your wing--the bottom.

Years ago, someone reported that they took the wing off a trainer, strapped it on backwards, and flew the plane. I wasn't there, but I don't doubt that they got the plane to fly. I'm from the religion that says the Bernouilli effect, though real, is negligible in explaining how wings fly.

And I'm not claiming any professional credentials in the debate, although I do know a lot about religions.

YMMV.

Marty

R O T F L O L !

Which debate was it that you claim not to have credentials in?

Your comment about eliminating drag is on target.

| You sure know how to open a can of worms. Stand back--the stuff is | going to hit the fan shortly. ;o)

I doubt that ... though some might feel that this post is the beginning of the fecal matter/air turbine collision ... | For a flat wing, the Bernouilli effect, much loved by many amateur | aerodynamicists, is not the cause of lift.

I'm generally of the `the Bernouilli effect is optional. Obeying Newton's second law is not' camp. Which probably means that I generally agree with you, but I'm not going to completely discount the Bernouilli effect.

I haven't carefully watched the flows in a wind tunnel, but it wouldn't surprise me if the air does take a longer path on the top of a completely flat wing with a positive angle of attack than it does on the bottom, which would suggest that even here Bernouilli has some involvement.

| All of the lift comes from the angle of attack.

Yes.

| By putting the structure on top of the wing, you have eliminated | drag on the most important side of your wing--the bottom.

I'm not so sure that the bottom is more important. The top of the wing is just as important in generating lift, unless you're talking about an extreme case like a shuttlecraft entering the atmosphere or a rock skipping across a lake.

Perhaps by having the structure on top it's acting as a turbulator?

| Years ago, someone reported that they took the wing off a trainer, | strapped it on backwards, and flew the plane. I wasn't there, but I | don't doubt that they got the plane to fly.

Strapping the wing on backwards isn't really that impressive. Putting it on _upside down_ would be more impressive, and even there, I wouldn't doubt that the plane could be made to fly as long as it had minimal dihedral.

But you don't have to flip the wing over to see that -- just fly your trainer inverted. It can be done, and lift is obviously generated. (Dihedral makes it difficult to keep it inverted, but doesn't really interfere with the generation of the lift.) It's also inefficient, and you'll need a lot more power to keep it aloft when inverted than you will when it's right side up.

| I'm from the religion that says the Bernouilli effect, though real, | is negligible in explaining how wings fly.

It's not negligible. Ultimately, the purpose of a wing is to deflect air downwards, and to therefore generate lift upwards. The Bernouilli effect merely is a way of doing so that is quite efficient -- it allows a wing to generate much lift and yet little drag.

It's also not a religion, though some do blindly follow certain aspects of it it like it's one -- perhaps because they don't understand it? The problem there is that this is all predictable, measurable and quantifiable -- unlike most religions. It's even understandable without too much effort, but many don't bother.

If you haven't read it, `Model Airplane Aerodynamics' by Martin Simons is a good book to read, and I suspect you won't have much trouble grasping what's inside.

Yes, you can explain how a wing generates lift pretty well without even mentioning Bernouilli -- but in the real world, wings are shaped the way they are because the Bernouilli effect is a very efficient way of generating lift. So it's well worth mentioning, even though it's not the entire story.

| And I'm not claiming any professional credentials in the debate, | although I do know a lot about religions.

If I must claim some credentials, I do have a degree in physics. Though you don't need a degree to understand in general how this stuff works.

Interesting posting.... Years ago I used to design my own models. I drew my airfoils 'TLPG' ."..That Looks Pretty Good". Flew fine. Pete Baylinson "Six_O'Clock_High" >

snipped-for-privacy@frenzy.com (Doug McLaren) wrote in news:vNRKd.80278$_56.16477 @fe2.texas.rr.com:

I just know I'm going to regret this, but -

But that whole 'longer path' thing isn't directly relevant, if you really think about it. The fact that the top of the wing is "longer" than the bottom doesn't mean that the air has to go faster - there's no magical physical effect that says that the two bits of air have to go from the front of the wing to the back in the same amount of time if one goes over the wing and the other goes under.

Actually, in normal flying conditions (more-or-less level, positive gravity, airplane weighs more than air, etc), the air *does* go faster over the top of the wing than over the bottom. Quite a bit faster, really - the air going over the top of the wing actually gets to the TE *sooner* than the air going under it, despite the longer path length.

The Wright Brothers didn't get a plane in the air until they put an airfoil in the prop. Do your props have an airfoil? mk