Windward ability
- Thread starter deep denial
- Start date
prv
Well-Known Member
Standing lug (the yard crosses the mast) and it's a yard not a gaff or a sprit
Pete
snowleopard
Well-Known Member
If you look closely you will see that the yard crosses the mast and the luff of the sail is in front of the mast. Technically it's a standing lug.
scotty123
Well-Known Member
Obviously not a balance lug of course.
snowleopard
Well-Known Member
The way to reduce drag is to eliminate stays and make the mast (i.e. leading edge) an aerofoil section aligned with the luff like this...
Little Rascal
Well-Known Member
Yep it's a standing lug...
But aerodynamically, because the yard is so high peaked it's acting like a load more luff.
But aerodynamically, because the yard is so high peaked it's acting like a load more luff.
scotty123
Well-Known Member
The way to reduce drag is to eliminate stays and make the mast (i.e. leading edge) an aerofoil section aligned with the luff like this...
So why, don't more boats have wing sails/
prv
Well-Known Member
Yep - very Spitfire-wing-y and elliptical, which I'm told = efficient. She does look nice to sail.
Pete
Little Rascal
Well-Known Member
Cos you can't get the sail ties on so easily!
Pete,
Yeah the Spitfire is a good example...
Twister_Ken
Well-Known Member
If God had meant boats to fly, he'd have invented the aeroplane.
Errr, hang on a minute...
snowleopard
Well-Known Member
scotty123
Well-Known Member
Even for 'commercial' vessels?
Little Rascal
Well-Known Member
Wing sails are more complicated than they look.
The difficulty comes from the need to provide camber and twist.
A simple solid wing would have to be of a symetrical airfoil section and have no twist in order to work on both tacks.
All of a sudden you've given away all your advantages. Not efficient and with poor aceleration.
A wingsail in which you can control camber and twist, like BMW Oracle which has multiple trailing edge 'flaps', is very complex and expensive and more or less controlled by computer.
And then think about what you'd have to do to reef or even ride out a gale at anchor!
In 99% of cases the performance gain is not worth the money and practical problems. The 1 % is usually confined to the extreme racing machine or the esoteric home built boat...
But following the aerodynamic principles, even with soft sails, can improve things.
The difficulty comes from the need to provide camber and twist.
A simple solid wing would have to be of a symetrical airfoil section and have no twist in order to work on both tacks.
All of a sudden you've given away all your advantages. Not efficient and with poor aceleration.
A wingsail in which you can control camber and twist, like BMW Oracle which has multiple trailing edge 'flaps', is very complex and expensive and more or less controlled by computer.
And then think about what you'd have to do to reef or even ride out a gale at anchor!
In 99% of cases the performance gain is not worth the money and practical problems. The 1 % is usually confined to the extreme racing machine or the esoteric home built boat...
But following the aerodynamic principles, even with soft sails, can improve things.
snowleopard
Well-Known Member
Not only are solid wing sails complex but they are always up and that can be a pretty scary thing when there's a lot of wind. What I was talking about is an aerofoil as the leading edge to a soft sail - see my diagram and this...
Little Rascal
Well-Known Member
Sorry, got distracted by wingsails. Thats a wing mast really.
They have to rotate to be any good though.
That one is on a swing rig - another story also! They're much more common on models yachts.
This link shows the effect of a standard mast:
www.wb-sails.fi/news/Stallpics.HTML
Picture 2 shows the seperation bubble caused by the mast. Pretty cool...
They have to rotate to be any good though.
That one is on a swing rig - another story also! They're much more common on models yachts.
This link shows the effect of a standard mast:
www.wb-sails.fi/news/Stallpics.HTML
Picture 2 shows the seperation bubble caused by the mast. Pretty cool...
Woodlouse
Well-Known Member
Wing masts are not more popular because they are heavier than normal masts, more complicated than normal masts, and contribute a fair amount of sail area which cannot be reduced after the sails are taken down. The advantage you get from them is not great enough to outweigh the disadvantages for most sailors.
You only really see big wingmasts now of the big ocean going tri's. Even the Open 60 boats these days generally opt for a more conventional rig, though there are some skippers who prefer wing mast.
You only really see big wingmasts now of the big ocean going tri's. Even the Open 60 boats these days generally opt for a more conventional rig, though there are some skippers who prefer wing mast.
Little Rascal
Well-Known Member
Also, the contribution of profile drag (the sort made by a conventional mast) increases with rising airspeed.
As such faster boats (multis) benefit more from wing masts than 'slower' boats (monos).
As such faster boats (multis) benefit more from wing masts than 'slower' boats (monos).
snowleopard
Well-Known Member
snowleopard
Well-Known Member
"Wing masts are not more popular because they are heavier than normal masts,
But as there are no stays the total weight is pretty much the same as a conventional rig but windage drag is greatly reduced.
more complicated than normal masts
no rigging attachments, spreaders, topping lift, spinnaker gear, backstay tensioner, massive winches, deck tracks
and contribute a fair amount of sail area which cannot be reduced after the sails are taken down.
ready-set storm canvas with drive adjustable down to zero by altering angle of attack.
"
Now look what happens when you're on a broad reach...
The rig is still in laminar flow mode with slot effect, as opposed to a conventional rig that is partially stalled..
But the killer argument is what you do in a rising gale and you have to reef. No rounding up and driving into wind and sea, just let go the sheet and the rig rotates over the bow and lies docile while you pull a reef down.
But as there are no stays the total weight is pretty much the same as a conventional rig but windage drag is greatly reduced.
more complicated than normal masts
no rigging attachments, spreaders, topping lift, spinnaker gear, backstay tensioner, massive winches, deck tracks
and contribute a fair amount of sail area which cannot be reduced after the sails are taken down.
ready-set storm canvas with drive adjustable down to zero by altering angle of attack.
"
Now look what happens when you're on a broad reach...
The rig is still in laminar flow mode with slot effect, as opposed to a conventional rig that is partially stalled..
But the killer argument is what you do in a rising gale and you have to reef. No rounding up and driving into wind and sea, just let go the sheet and the rig rotates over the bow and lies docile while you pull a reef down.
Little Rascal
Well-Known Member
Snowleopard.
I posted that smoke test link as support for the wing mast... If you can get rid of the seperation bubble behind a normal mast, you save a chunk of drag.
Jon
I posted that smoke test link as support for the wing mast... If you can get rid of the seperation bubble behind a normal mast, you save a chunk of drag.
Jon