good day


--Insects have been arguing over four wings or two for millions of
years. In their case I have been told vortex lift is important.

an " aeroplane or helicopter " is a lot different situation
then a sailboat ...


It would be interesting to put some smoke over the sails and some
strain guages on the rigging and mast for the various successful twin
masted arrangements such as the J7 to see what is happening.


it has already all been done
what we need here
is to accept these facts

regards fritz


importnt- In harryproa@..., "Mark Stephens"
<stephens@o...> wrote:
>
> Hi,
>
> Regarding point 2 below. There is a common misconception amongst
sailors about the slot effect between sails. As I understand it the
mainsail does not benefit from an increase in wind velocity created
by the slot but rather experiences a detrimental effect. The main
experiences a 'higher pressure' from the windward side of the
foresail. It is the jib which gains due to it operating in the
upwash of the main giving it a higher flow angle. The net effect is a
gain as the foresail gains more than the mainsail loses. I can't
imagine there could be any gains from slot effect in a two masted
fore and aft rig.
>
> Mark
>
>
> *************************
> Mark Stephens
> www.harryproa.com
> stephens@o...
> (int. 61) 02 66552016
>
> ----- Original Message -----
> From: fritz roth
> To: harryproa@...
> Sent: Monday, September 01, 2003 8:43 PM
> Subject: Re: [harryproa] Re: twin masts
>
>
>
> good day robert
>
>
> >I am curious about the difference between the dirty air from a
wing
> sail with minimal standing rigging and the slot from a jib.
>
>
> not much
>
> in both cases you have
> depending on the individual settings
>
> 1 a deflection of the wind
>
> 2 a proportional increase in the velocity
> on the leeside of the following sail
>
> 3 a general decrease of velocities
> from surface friction
>
> 4 turbulence created by unformaties
> and separation of flow on the leeward side
>
>
> all these effects diminish after
> 1 cord lenght at the keel line
> to almost none
>
> straight downwind for much more
> at right angles to a lesser extent
>
> but are added
> if there are already sails
> in front of it
> as with a traditional schooner
>
>
> regards fritz
>
>
>
>
> [Non-text portions of this message have been removed]


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