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Re: [PSUBS-MAILIST] Re:
And as a seccond note :) Bernuoli's princapal is not dependant on compressable fluids (aka gasses) It works in all fluids. airfoils aren't about compressing a liquid. they are about making the liquid on top of the airfoil move a longer distance (read go faster) than the liquid on the bottom. Faster moving liquid on top = lower pressure = lift :)
*********** REPLY SEPARATOR ***********
On 2/28/01 at 9:57 AM Carl Kem wrote:
>Dale, excellent query! While the principle is similar to aerodynamics,
>hydrodynamics is indeed a bit different with a twist. The twist is
>while you really cannot compress the water with the airfoil design, keep
>in mind that you are acting against a liquid object. Water has more
>mass than air does. So when you use the airfoil, you are not
>compressing it as much as you are directing it. You may be able to
>direct it in a ditch or canal, but in a lake or ocean, you are directing
>yourself. You are moving, and you are by far smaller than the ocean
>itself. Therefore when you direct the water with the rudder/plane
>you're telling the water, "Hey, I wanna go over here!".
>Carl
>
>
>Dale wrote:
>
>> I have a question for the group.. I am a pilot, and know the theory
>> behind lift on the wing..I noticed on some posts, that there were
>> airfoil shapes being used, to produce lift (in a downward direction)
>> on submarines, submersibles etc.. my question is , how does that
>> work?? Water will not compress, or expand, being a liquid, therefore
>> the pressure difference between the top of the "wing" and the bottom
>> of the wing will be the same, there fore no lift.. or am I missing
>> something?? dale.
>
>--
>"In times like these, it helps to recall there have always been times
>like these."-Paul Harvey