Fin Keel vs. Full Keel

[keelbolts]

I guess it was a leading question, or whatever you call them, meant to lead to a point. An aircraft wing creates lift while moving directly thru the air. A keel requires leeway to make lift. That's why I maintain that a wing, thru it's precise asymmetrical form, creates lift, while a keel is merely shoved to windward by the lateral component of the forces acting on it as it falls off.

[Hiracer]

Originally Posted by keelbolts

Observation: no aircraft could fly with wings whose tops matched their bottoms.

But isn't that true because symetrical wings would not produce enough lift, which is to be contrasted with no lift. Symetrical wings would still produce lift, just not enough to support the plane in air.

Keels don't have the problem of supporting the weight of the boat.

[keelbolts]

Next thing you know, you guys will be telling me there's no Easter Bunny.

[Hiracer]

Originally Posted by keelbolts

Next thing you know, you guys will be telling me there's no Easter Bunny.

No, it's Santa Claus who does the heavy lifting. Easter Bunny just lays eggs.

[hellosailor]

"Observation: no aircraft could fly with wings whose tops matched their bottoms."
Then equally obviously, no aircraft could fly upside down.

Yet it is down every day by stunt and military pilots, and at every airshow you'll see aircraft flying upside down and somehow, not falling out of the sky because their wings now have the "wrong" shape up top.

Reflect on that and you will realize that having the two sides of the wing matching--or even REVERSED--does not stop the wing from working as a part of the aircraft. In the same way, a boat hull has a keel, yes, but also a rudder AND the 3D shape of the hull itself. The lift (and other aspects) of the entire underbody also vary as the boat heels over, making it into a very complex art to balance the forces on the hull, especially when the boat heels and now the wetted hull area and shape CHANGE as more of the hull length gets into the water as well.

Once you appreciate the complexities of trying to design a hull that works and works well through all of those changing positions, you should quickly be able to realize why designing a good hull was more of a black art than anything else--especially before computers.

[Hiracer]

Originally Posted by hellosailor

Then equally obviously, no aircraft could fly upside down.

Yet it is down every day by stunt and military pilots, and at every airshow you'll see aircraft flying upside down and somehow, not falling out of the sky because their wings now have the "wrong" shape up top..

Excellent example!

[cal40john]

Some aerobatic planes have symmetrical wings and they do fly.

Pitts Symmetrical Wings VS Non-Symmetrical Wings

John

Originally Posted by keelbolts

Still trying to learn - not simply arguing.

You state that a keel and a wing function in the same way.
one question, one observation:

Question: does a keel create lift without leeway?

Observation: no aircraft could fly with wings whose tops matched their bottoms.

[keelbolts]

The lift on a wing is created by the wing itself. As I have always understood it, as the wing moves thru the air, the differing shapes of the upper & lower surfaces produces different pressures above and below the wing. Lift is created. The lift on a keel comes solely from forces working on it.

Having said that, I never did know what caused the experimental lifting bodies to fly, so maybe that indicates a flaw in my understanding.

[Hiracer]

Originally Posted by cal40john

Some aerobatic planes have symmetrical wings and they do fly.

Pitts Symmetrical Wings VS Non-Symmetrical Wings

John

Now, I'm in the learning mode.

[keelbolts]

I spent several years working on Navy jets so I know that aircraft can fly upside down for varying lengths of time. Questions: does that ability represent the triumph of power over gravity. Put a jet engine on the front door to your house and you can make it fly, as long as you can control its attitude. Was the asymmetrical wing shape of earlier aircraft unnecessary? If not, why is it necessary then, but not now?

[Hiracer]

Originally Posted by keelbolts

I spent several years working on Navy jets so I know that aircraft can fly upside down for varying lengths of time. Questions: does that ability represent the triumph of power over gravity. ?

No, see Cal40john's link. Them be low powered aircraft.

Originally Posted by keelbolts

Was to asymmetrical wing shape of earlier aircraft unnecessary? If not, why is it necessary then, but not now?

Asymmetric is preferred, I'll guess, for both stability and efficiency. Only stunt planes go with symmetric.

[daedaluscan]

Originally Posted by keelbolts

The lift on a wing is created by the wing itself. As I have always understood it, as the wing moves thru the air, the differing shapes of the upper & lower surfaces produces different pressures above and below the wing. Lift is created. The lift on a keel comes solely from forces working on it.

Having said that, I never did know what caused the experimental lifting bodies to fly, so maybe that indicates a flaw in my understanding.

It is a bit more complex than that. Angle of attack allows symettrical airfoils to supply lift. A flat plate will do fine with sufficient power.

[keelbolts]

Pitts are low powered? I've seen 'em fly & I assumed they must be fairly high powered. Aren't stunt planes usually high powered?

[daedaluscan]

Did I mention a Pitts?

[keelbolts]

I think that's what I've been saying. I believe that here's a difference between an object creating lift & being lifted. Am I mistaken?