Mainsail leading edge slat.

[Omeron]

We know that masts are always a problem as it is not an ideal
leading edge form for the mainsail.
STOL aircrafts (short take off and landing) and indeed all commercial aircraft
deploy a leading edge slat where high lift and high stall angles (30 degrees)
are required during take off.
How about doing the same with our masts. If a section all along the mast,
forward of the mast, and hinged to the mast, so that it pivots and tacks
itself arond the mast is deployed, would that create a better infow
into the mainsail, by sucking some of the air windward of the mast, and
regulate the otherwise turbulant air entering the mainsail.
Has this been tried before?
How would this contraption be viewed, in terms of sail measurement?
Would it be wieved as part of the sail, or as part of the mast?
I am unable to draw a picture here, but if you google STOL aircraft,
you get all the facts and benefits of a leading edge slat.
This is ofcourse all about windward work, but i do not think it would hurt
downwind, as it would be just another surface creating additional drag.
What kind of shock and horror this would create for IRC measurers i have no idea.

[tspeer]

Leading edge slats already exist for conventional rigs to do what you describe. Sailors call them "jibs".

[yipster]

on cats i've seen the jib placed more windward
model boats on sailing channel with aerorigs use
a short extra pivoting boom on top of the fwd coming boom
to ofset the jib as well but havent seen that live sized yet.

I used a rectangular 2.5" X 75" "jib" on a model cat. It had a ball bearing pivoting, articulating boom set up top and bottom to place the slat in the position Marchaj said would be ideal in his first book(I think-could have been the second book).The thing tacked well and seemed to have an effect greater than it's area would suggest. I was mainly interested in working out the physics of mounting a "soft" slat. Light air performance of the boat was improved considerably. Hope to experiment with full size versions soon.

[Omeron]

tspeer, very clever. i like it.
It is one hell of a slat though...

In this case i am proposing a mini slat in between.

With a chord length no more than twice the longitudinal axis of the mast.

How about that?

[yipster]

Originally Posted by Doug Lord

I used a rectangular 2.5" X 75" "jib" on a model cat. It had a ball bearing pivoting, articulating boom set up top and bottom to place the slat in the position Marchaj said would be ideal in his first book(I think-could have been the second book).The thing tacked well and seemed to have an effect greater than it's area would suggest. I was mainly interested in working out the physics of mounting a "soft" slat. Light air performance of the boat was improved considerably. Hope to experiment with full size versions soon.

Doug, that’s good to hear and makes me look forward even more to Marchaj’s books

[brian eiland]

Have a look thru these discussions

Sail Aerodynamics
http://boatdesign.net/forums/showthread.php?t=457

and these starting on page 4:
Mainsail Leading Edge Slat
http://boatdesign.net/forums/showthr...p?t=457&page=4