Re: [PSUBS-MAILIST] basic hidrodynamic question

[Kenneth Schulze <aquamari@cruzers.com>]

Hi Alec,
In aerodynamic terms, try using Newtonian Impact calculation to determine the
resulting pressure forces on the dive plane surfaces.

Cp = 2 * sin^2 (alpha)
where;
            Cp = Pressure coefficient = (P-Pa)/(.5*density*V^2)
             and alpha is the angle between the dive plane & flow direction

You can assume Cp=0 for the shadowed surface and that force will act perpendicular
to the surface at the centroid of the dive plane.
Hope this helps,
Ken Schulze

Alec Smyth wrote:

> Hello all,
>
> Over time I've accumulated a fair little sub-related library, but I've come
> across a VERY BASIC calculation I can't find a formula for in any of my
> books. I need to work this out as part of dimensioning the axles for my dive
> planes.
>
> Lets say I have a perfectly flat, rectangular dive plane, with a surface
> area of 120 square inches, and I am doing 8 knots. Suddenly I incline the
> dive plane downwards by 30 degrees. What's the magnitude of the resulting
> force? I do realize the force is normal to the plane surface, and I expect
> one gets to it by calculating the pressure and then multiplying by the 120
> square inches... but that pressure is eluding me.
>
> I wonder can anyone help?
>
> Alec Smyth
>
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