Re: sailing upwind?

[brian whatcott <inet@INTELLISYS.NET>]

At 13:09 12/29/99 -0800, you wrote:
> Isn't it possible, in principle, to "sail" directly into the wind by
> driving a (submerged) propeller with a wind-driven turbine? It seems
> to me that, while somewhat inelegant, there is no reason this should
> not be possible. Energy is extracted from the airstream (it is slowed)
> and used to overcome wind resistance.
>
> (I consulted also with my son David and he agrees.)
>
> Leigh


I expect that John Denker had in mind an application of Fred
 Lanchester's dictum, that the airfoil acting on the air and that
 acting on the water (a fin, keel or dagger) provide each other's
 reaction force so that the minimum angle with respect to the wind
is the sum of the two 'gliding' angles, or in
more familiar terms:
Aerodynamic angle whose cot is Lift/Drag
Hydrodynamic angle whose cot is side force/resistance

But Leigh's windmill propulsion seems to demand only that the
superstructure and air prop drag due to the wind is less than the
 water prop thrust due to power from the air prop.
Some positive net force will provide
headway even into the teeth of the wind.

The question brings to mind the experimentally confirmed fact that
 an air blower situated on a deck and blowing into the sail can
 provide net forward thrust too.


brian whatcott <inet@intellisys.net>
Altus OK