Wing-drive

Discussion in 'Sailboats' started by Kjell Dahlberg, Feb 27, 2005.

  1. sharpii2
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    sharpii2 Senior Member

    Checked out your videos.

    I really liked the flapper drive.

    It may be a good substitute for a propeller on a sail boat.

    I can imagine it causes far less drag when its not being used then a typical fixed bladed propeller of the same propulsion capability. It may not be as efficient, but perhaps its other virtues make up for that.

    When I think of a motor sailor, I think of a boat with about 1.0 hp per ton or less. The engine is to reduce the size of the rig and to get through calms. On good sailing days, it is to be turned off.

    1.0 hp/ton will not get you anywhere near hull speed. But I don't see that as an issue, as it takes considerable energy, maybe 4 times as much as it does to go half hull speed.

    For my concept to work, I need a low drag propeller. There are only three options available:

    1.) a relatively inefficient small fixed blade propeller, driven at high rpm,

    2.) a folding blade propeller that can be larger, but is more expensive and more likely to fail to open, and

    3.) a feathering propeller, which may cost as much as the engine.

    Generally, I would go with three. Sometimes spending money on the more expensive option is the better bargain over the long run.

    Your flapper drive opens up a fourth option. One that you might consider yourself when it comes to your wing sail design.

    It looks handy but seems a little poor in sail area.

    I know it's supposed to be three times as efficient as a conventional sail. But what does that mean?

    Does that mean it proved three times as much lift? Or does that mean it proved three times as much lift per given amount of drag?

    The two sound deceptively similar, but they are different.

    My dad's Cessna 150 flew at about 100 kts at about three quarter power.

    To land, flaps were deployed, to slow the flying speed down to make it safer to land. The flying speed dropped to about 45 kts, but required nearly full power for the plane to stay up in the air.

    Except for going up wind, a sailboat is in the second situation. The amount of actual lift is more important than the lift drag ratio. So if a larger sail is one third as 'efficient', it may still sail past a wing sail with one third the area.

    Your rig does not seem all that fast, especially for a multihull, but may be a good rig for a motor sailor.

    It seems a whole lot handier than most sail rigs.

    Have you ever had it out in really blustery conditions?
     
  2. kjell
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    kjell Senior Member

    It is possible to have desmountable wings.
     

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  3. sharpii2
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    sharpii2 Senior Member

    I see.

    But they are extremely vulnerable to wave damage that way. And even though they reduce the capsizing moment quite a bit, they are still sticking up in the air.

    Just that they are low aspect ratio now instead of high aspect ratio.

    All that area can not be feathered except by pointing the bow into the wind.

    IMHO, best to leave them up and find a way to make them self feather.

    Another possible solution is a clever idea I saw in "WoodenBoat".

    Basically the wing sails were really soft sails with the wing ribs acting internal battens. A very powerful halyard was needed to stretch the sail cloth tight.

    Furling happened the usual way. The halyard was slacked and the sail cloth and ribs bunched up at the bottom.
     
  4. kjell
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    kjell Senior Member

    Inflatable wings are one solution.
     

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  5. Kimba09
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    Kimba09 Junior Member

    surely that depends on the eye of the beholder but my first wingsails were rectangular but later used more of the famed "spitfire shape" .
    Kjell is showing a concept here, and also the real thing looks quite good actually
     
  6. kjell
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    kjell Senior Member

    Hi Kim.

    The “America cup” with the new Sails maybe open up new interest in the wing-sail we are working with?
     
  7. masrapido
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    masrapido Junior forever

    I'm going to agree with Kjell on this one. The arguments CT 249 presents are all valid on the paper, but the physics are a little different.

    For example the 4 metres per second wind would surely hit the main sail first and as such affect the AoA and possibly turn over the boat.

    No, it won't. This the misunderstanding Kjell is talking about. For starters, 4 metres per second is fast. Fast enough to reach the rear control flap at almost the same moment and allow it to have it's righting/controlling effect on the rig. Then the usual "sailor working on the deck/cabin would get hurt.

    On which sailing boat that cannot, and has never happened?

    I'm tempted to conclude that CT 249 never sailed a boat. If s/he did s/he would have noticed something very dangerous on standard yachts: a boom.

    Secondly, the negative comments ( of such and similar nature, highlighting possible dangers and high CoG, AoAs etc.) are coming from a racing perspective, although they seem to be from a leisure side.

    When you are a leisure sailor, the safety is more of a concern and the activities on deck are limited to cockpit anyway. You would not want your family to run around on deck while sailing anything, no matter the rig. All your controls are in cockpit, and any problems are for the most experienced on the deck to deal with, not for just anybody.

    Family/leisure sailing happens in a lot more safety-conscious environment than racing sailing.

    And, ironically, the racing sailing boats have their dangerous bits much lower than leisure sailing boats, so where do you think is more dangerous to be on the deck?

    Racing boat, of course.



     
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  8. CT 249
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    CT 249 Senior Member

    No, it won't. This the misunderstanding Kjell is talking about. For starters, 4 metres per second is fast. Fast enough to reach the rear control flap at almost the same moment and allow it to have it's righting/controlling effect on the rig.

    If a gust is moving at 4 metres per second across a wing rig where the leading edge of the control surface is 4m from the leading edge of the wing, the wind will be affecting the leading edge for a second before the control surface can even start to take effect. That's pretty simple maths.

    There are many boats that accelerate significantly when the sail is sheeted in for one second; enough to make them bounce around uncomfortably on their lines when in a marine berth. I know people who have experienced this in their wing masted boats and see it as a problem.

    On which sailing boat that cannot, and has never happened? I'm tempted to conclude that CT 249 never sailed a boat. If s/he did s/he would have noticed something very dangerous on standard yachts: a boom.


    I have done five Sydney Hobarts and won seven national titles. That's sailing a boat. I also smashed my front teeth on a Moth boom as a kid, so I am all too familiar with them.

    I have owned and sailed with many wing-masted and free-standing rigs and have a significant amount of experience with them. The fact that a rig can feather does not mean that it does so before it creates significant power. I have also read about people like Loic Caradoc and his last radio call about how Royale's wingmast was taking control although it was feathered. I have read about people like Peter Blake and his issues with the big wing mast aboard the Stienlager tri, even when feathered. I have spoken to people like Nigel Irens and Arnie Duckworth about the problems of the large wing masts they have sailed with, even when feathered.

    On none of the boats that I have sailed is the boom "active" (that is, connected to an aerofoil and free to move) at all times the mast is stepped. When you are standing at the dock, painting the deck, leading a new vang line, or bringing non-sailors aft while under motor on other boats the mainsail can be dropped and the boom secured firmly to the centreline. That cannot be done with this rig.

    My boat is currently moored in a marina. Last time I was there, I watched miniature whilrwinds chase around the water, as a gusty offshore breeze came down from the mountains and swirled around the buildings. There was a 35 knot wind and the gusts were spiralling around in circles.

    How would someone do the things I was doing (taking bags of clothing and other passage gear off, putting on the cover, checking mooring lines) if there was a rig at head level spinning around in those gusts? Yes, the whole rig could be lifted 6' above the cabin roof but that is going to have a significant effect on stability under sail.

    Secondly, the negative comments ( of such and similar nature, highlighting possible dangers and high CoG, AoAs etc.) are coming from a racing perspective, although they seem to be from a leisure side.

    When you are a leisure sailor, the safety is more of a concern and the activities on deck are limited to cockpit anyway. You would not want your family to run around on deck while sailing anything, no matter the rig. All your controls are in cockpit, and any problems are for the most experienced on the deck to deal with, not for just anybody. Family/leisure sailing happens in a lot more safety-conscious environment than racing sailing..


    My family and friend are free to wander from the cockpit to the bow when leisure sailing. So (in normal conditions) is just about everyone else I have ever sailed with, unless they are very young or old or unwell.

    And, ironically, the racing sailing boats have their dangerous bits much lower than leisure sailing boats, so where do you think is more dangerous to be on the deck?

    Racing boat, of course.


    Yes, a racing boat boom is often lower to the deck. Therefore we duck under it when sailing.

    The point is that the boom is not free to move around when the boat is at the mooring, coming into a berth, taking people onboard and aft, being rafted alongside another yacht, etc. When these things are being done the sail can be lowered and the boom secured. This cannot happen with a permanent wingsail.
     
  9. masrapido
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    masrapido Junior forever

    You will have to concede, if you do have all that experience on the sea, that the boat will not roll over 90 degrees in a second. The movement of the ship is a lot slower. And a 4 metres per second wind does not have the power to list the boat significantly anyway, let alone to turn it 90, so the argument is not valid from any point of view.

    And as you confirm that you duck to avoid the boom, how is that less dangerous than Kjells high set up? Hence, that too is not an argument against his proposition.

    As you take the sails down in a marina, you would want to do the same with the wing. And more so because the wing never stops generating the force. So the wing simply must go down.

    Which is what Kjell said that can be done easily.

    If you want to argue Kjell's wing, I'd suggest the lack of efficiency and a cumbersome design. In its' current form his sails would be a lot of work to take down in the best of weather conditions, compared to the standards sails. And it's weight would not be helpful either.

    But the rig, as such, has been in use for a few years now and Kjell is still alive, so not all is bad.

    I personally like the wing as suggested by http://wingsails.com/

    Soft and light. Inflatable modules inside to adapt to the tack and wind /direction change.

    No option is perfect, so one picks what one considers best for his purpose. If you want to race with a wing, current wings on cup cats are probably a good pointers towards the most applicable shape and engineering solution.

    I have seen a better wing somewhere on the net a few years back. If I find the link, I'll post it. It was French design, and it was really nice looking hardware. To my memory, the wing was lighter, faster to take down in a trouble, and more efficient than those used on cup cats currently.

    Which is what a leisure sailor would be more interested in when sailing with family and friends who might be all non-swimming people who have never seen the boat before in their lives.
     
  10. Kimba09
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    Kimba09 Junior Member

    lets have a little look at effects of wind gusts, this comes from sailing with 9 different wingsails over the last 18 years.
    1/ the wind isn't digital, As you get an increase of wind it may be quick but not instant. The pressure gradually increases and the Tail begins to react straight away.
    2/ the wind gust you speak of of 4 mtrs a second is around 7 kts .Not really dangerous and the wingsails adjust to this before you realise that something might have to be done. $mtrs /sec wind taking 4 seconds to have effect would mean the tail is mounted nearly 16 mtrs back from the centre of pivot? An unusual rig . Also if the there is a change in angle of attack the distance is shortened so the wingsail will react quicker.
    3/ From experience was sailing at Malpas with a group of disabled sailors, one was at the tiller of my boat, a great day , light winds relaxing and chatting . When we got back one of the guys in charge came up and said "that was amazing" We were unsure of what he meant and he said "that wind gust" . We again looked blank and he said "there was 11 boats sailing in a line, and then there was 1 and you missed it? well there was a gust but the wing handled it so we kept talking.....
    4/ mooring drag. A fellow in Spain did some wind tunnel tests of wingsails versus a bare mast (just rigging) He said you will like this , the wingsail because of its shape only has about 10 % of the drag of a conventional rig.
    5/ Over the years with these rigs we have been hit with many big wind, never a problem but boats next to us have "rounded up" and gone over. A wingsail may not be perfect but its way ahead of other rigs for performance , cruising safety and mooring
     
  11. kjell
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    kjell Senior Member

    The differense when sailing with Cloth sails or Wing sail.

    Sails are controlled by Sheets. When there is a change in the wind direccion. The sails have to be trimmed for the new direccion by the crew. In gusty wind, the crew must be trimming the sails or changing the course. Or the risk for capzising is eminent.

    Wing sails are controlled by the Wedge-Tail. When there is a change in the wind direccion. The wing sail is automaticly trimmed by the Wedge-Tail. The crew can do other things. There is no risk for capzising.
    Wing Sailing is safety.
     

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  12. kjell
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    kjell Senior Member

    This is my floating test catamaran. During 3 years the Wing-Drive has been tested in all different wind conditions. The Wedge-Tail has demonstrated the exact controlling the wings AoA.
     

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  13. CT 249
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    CT 249 Senior Member

    I agree that no option is perfect. I have spent years sailing with "alternative" rigs (ie those that are not standard sloops) and grew up with people like Frank Bethwaite testing radical rigs in front of my house.

    Wingsails work very well in certain situations, as do wingmasts and other devices like extended aerofoil luff pockets - I own about a dozen of them. But they also have problems. Interestingly, after years of testing of captive kite style rigs, lateen rigs, etc Frank earned a new respect for the modern sloop rig.

    I would be very interested in a scientific test of wingsails, but those who promote them very rarely seem to do such testing. They have been tried in some classes for over 50 years, since people like Bee McKinnon had one on an IC, but only in a few (namely multis) have they come up with the performances claimed for them.
     
  14. CT 249
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    CT 249 Senior Member

    In one post I made a typo with the windspeed - mea culpa.

    If a gust at 90 degrees to the "old wind" is moving at 4m/s and the leading edge and control surface are 4m apart, the wing will still be producing drive for about a second and in a strong wind, a rig that drives the boat forward for 1 second can be a major problem when mooring or moored.

    I still can't work out what will happen if someone is, for example, coming into the dock I came into a couple of weeks ago. Gusty 35 knot westerly. Marina building to windward. The results? Blasts of wind from all directions, hitting with very solid force.

    I have spent years with freestanding rigs that can be free to pivot and in such conditions the rigs do spin around. If a wingsail cannot be dropped and can only feather into the wind, in such a situation it will spin around and no one in its swept area will be safe.

    Yes, you can lift the rig higher but on my 28' boat for example you would have to have the foot of the rig about 11' above the waterline to be able to cross all of the deck and cabin roof safely, as you need to be able to do when mooring singlehanded. That is sure to have a significant effect on heeling moment.

    There have been many wingsails of different types. When they have been built, raced and won, they were adopted. Sailors are very quick to adopt technology that wins and is practical.

    It would be very interesting to see proper trials, in a scientific and objective format. Until such trials are carried out surely we can ask questions.
     

  15. Kimba09
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    Kimba09 Junior Member

    I have been hit many times by 30+ knot gusts, one example of only around 20kts was when we were coming to shore and my 2yr old daughter was playing on the lee outrigger. When it hit my eyes went to her and the outrigger dipped about 2-3". a Corsair next to us went over, Really at the time with the 2 boats so close the difference was truly remarkable.
    My wingsail is very light, all the load is carried on the mast so the wing is about 8kgs including tail and it reacts to windshifts very fast. have moored the boat for extended periods a few times, rig up and down and up has never been a problem unless the boat is beached, then the rig must be lowered.
    the new boat will have 2 wingsails, fore and aft and be raised with small wiper motors, counterbalanced by springs, most of that has been done and hopefully my health holds and we can launch in a few months.
     
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