Wing-drive

Ecocat Wing-drive

Hi
A friend filmed my ECOCAT some year ago and I have converted the film in a Video Clip. Here is possible to se how the WING-DRIVE works in light wind and in combination with motor. The use of Spinnaker in combination with a Wing Sail is unique.

http://video.google.es/videoplay?docid=3982200825306107225
Kjell

 

and very amusing!!

 

The Spinnaker has no connection to the deck and follows the wind shift with the Wing-Drive
Kjell

 

self trimming spinnaker

How about this self trimming spinnaker? Course changes and wind shift doesn’t affect the trimming of the spinnaker.

 

So the only tests have been done on a tiny beachcat?!

 

Kjell Dahlberg Wing-Drive is a wind propulsion system. A safety simple sailing system for Catamarans.
http://www.youtube.com/user/wingdrive#p/u

 

Hi
A friend filmed my ECOCAT some year ago and I have converted the film in a Video Clip. Here is possible to se how the WING-DRIVE works in light wind and in combination with motor. The use of Spinnaker in combination with a Wing Sail is unique.

http://www.youtube.com/user/wingdrive#p/u

 

I don´t know what you means with tiny, but I was sailing with my Eco-Cat for 3 years with good result. To day it is possible to navigate with a fully automatic tacking device adapted to wing sails.
Kjell.
http://www.youtube.com/user/wingdrive#p/u

 

Tord.
Prova dena linken.
http://www.youtube.com/user/wingdrive#p/u

 

Wing-Drive is a wind propulsion system. A safety simple sailing system for Catamarans.

 

With respect, Kjell, that boat certainly doesn't seem to be showing a handling advantage over a conventional rig of equal area and less complexity.

 

If you are a cloth sailor. You know that nobody can handle a sailing boat before learning how sails can produce forward drive force.
The Wing-Drive is the easy way to use the wind propulsion. My caramaran is only a floting test bench.

 

It only takes a minute or two to explain the basics of trim in a cloth sail, especially if you could use the wind indicator and marked mainsheet that Garry Hoyt created. It's a small proportion of the total knowledge needed to sail.

I'm still very unsure about the safety of the rig. I have looked at the pic you posted in this thread, at http://www.boatdesign.net/forums/attachments/sailboats/5653d1144178896-wing-drive-4603.jpg

It appears that;

* at no stage could anyone get onto the cabin top without lying down, or they will be in danger of getting hit by the rig which could swing around at any moment.

* there is a projection forward of the sail that sweeps across almost the full beam of the boat, therefore endangering anyone taller than the distance between the deck and the bottom of the rig. It also endangers anyTHING in that area; if you walk forward with a boathook it could be snagged by the rig. If you step backwards while tending to the anchor, you could be smashed by the fast-rotating forward projection of the rig. If you reached up to attend to the bimini, you would be within a few centimetres of being smashed in the fast by a piece of GRP or alloy, propelled by a tall rig. We rig windsurfers on the bows of our boats, and sometimes they get blown around a bit. That's no problem when they get blown into a fixed mast, it would be a major issue if they were struck by a swinging rig.

The danger seems even greater on your proposed twin-rig mono, where it would be utterly impossible to go forward and tend an anchor, step onto a dock, sunbake, varnish or do any other boatwork without the risk of being struck by a spinning rig, even at the dock.

It seems that all the dangers of a swinging boom are being projected over a larger area and (most importantly) that danger will be present at all times. We all know what happens if a mainsail (even a very rigid fully-battened one) is hoisted without the sheet being pulled on - it flogs back and forth and is a danger to those around.

I may be missing something, but if a version of your rig that has a 4m long base is sitting head to wind in a breeze coming from 0 degrees true at 4 metres per second, what happens when a sharp gust from 45 degrees true hits?

As far as I can judge, the following would occur;

1- the starboard-side leading edge would be struck by the new breeze. This would travel down the foil at an angle of attack of 45 degrees, causing the starboard wing to develop lift;

2- a fraction of a second later, the port-side leading edge would also be struck by the new breeze and develop lift;

3- after about four seconds, the new wind would strike the control tailplane. Only then will the tailplane start to have an effect and only then - after the rig has been developing power for four seconds - will it start to turn. I assume that the rig will take a second or two to overcome its inertia and turn, which will mean that it will be creating lift for another second or two.

4- inertia means that when the wing slows into the new position, head to wind at 45 degrees, there will be further forward motion imparted to the boat.

Therefore, the rig will have been producing lift for some 4 seconds - enough to move a boat forward at reasonable speed, more than enough to be a problem if trying to dock, sitting at anchor in a crowded bay, or sitting on dock lines.

I may be wrong about this, but surely there must be such effects in a wing rig? I have been using wing masts for some time and even stepping them you notice the buffeting effect of tiny windshifts; they certainly don't feel to have significantly less drag when being stepped when the boat is facing into the breeze.

Furthermore, as Ggguest pointed out, the effect of wind shear may be profound. In many conditions the apparent wind direction is around 10-20 degrees different between the bottom of the rig and the top of the rig - and that relationship changes dramatically as the boat moves over a large swell. If a rigid wing is in flow that is not uniform in its direction then it cannot be feathered directly into the wind over its entire span, can it?

 

Your comments are vey interesting.
What I understand from your comments is that you don’t understand how the Wing-Drive handles the wind. First of all the freeswinging wings are mounted abow heads and can’t hurt enybody. The 2 important part of the Wing-Drive are.
1. The Wedge Tail, which is controlling the AOA to the wind.
2. The bearing that permit the balanced wings to rotate with minimum resistace.

The Wedge Tail is holding the wings to the AOA, you only adjust this to controll the wing movement. Any windchange is controlled by this tail. The wind is always shifting direction. There are no capzising risks. A 45 degree gust only increases the boat speed.
You don’t need to be a sailor to handle the Wing-Drive. You are not sailing, you are handeling the boat with wind propulsion system.
Kjell

 

I don't think it's necessarily a lack of understanding.

"First of all the freeswinging wings are mounted abow heads and can’t hurt enybody."

But surely they are NOT mounted above heads in your own illustration, reproduced here;





From those illustrations, it seem that anyone who stands on the upper cabin tops on those boats is in danger of being struck by the Wing Rig. Anyone who tries to (for example) work on the cabin-front windows will be in close proximity to the wing rig - if they stand up they could be injured. And since you can't drop a wing rig easily, tasks such as working on the cabin top or the windows will be dangerous, surely.

This is completely different from a conventional boom; (1) a conventional boom only sweeps over the area behind the mast; (2) you can tighten the mainsheet to stop the boom swinging even when sailing; (3) you can work on the centreline by moving the boom out to one side or the other or lifting it high. On the Wing Drive rig, there is always something that may swing freely to a breeze, sitting above your head, and it takes up a much greater radius.

I suppose the bottom of the wing rig could be raised much higher than it is in your illustration, but that increases the heeling moment dramatically.

"A 45 degree gust only increases the boat speed"

But that's the point - what happens on the many occasions in which you DON'T want any boatspeed? What happens when you are anchored, or moored?

Isn't the controlling Wedge Tail aft of the leading edge of the main wings? It certainly looks that way in your illustrations.

If so, surely there must be SOME response time involved in the rig reacting to wind that comes from a slightly different angle, even when it is set to neutral position. The rig cannot swing to meet the new wind instantaneously if it is controlled by a tail at the trailing edge of the rig - that would surely violate some of the basic laws of physics.

No matter how effective the bearings and the Wedge Tail are, a windshift coming from a slightly different direction but towards the front of the rig will strike the forward sections of the main wing before the wind passes to the controlling Wedge Tail at the trailing edge, won't it? Until the windshift reaches the Wedge Tail that controls the AoA, the Wedge Tail cannot react to the windshift. Until that occurs, the main wings will be creating force.

We don't always want this force. We want to be able to moor or anchor a boat without the rig creating force.

Please explain how a wind moving at 4 metres per second from an angle of 45 degrees to the rig's front can strike the Wedge Tail BEFORE it strikes the main wings. Surely this is not physically possible?

In a rig where the main wings have a 4m chord (ahead of the leading edge of the Wedge Tail) and the wind is moving at 4m/s at an angle to the rig, there are four seconds in which the wind is passing over the main wings at an AoA. During this time the main wings will produce lift, surely?

Yes, of course the Wedge Tail will spin the rig into the wind WHEN the wind hits the tail - but that can only happen AFTER the wind has passed over the main wings and developed lift.

On my mooring in a gusty offshore wind, the breeze can go from zero to 20 knots in a second or so, with 90 degree windshifts. While the rig is at an AoA and reacting to these shifts, it will create force and therefore send the boat surging on its mooring, won't it?

I've sailed craft with free-standing easily-spinning rigs for years. For years I have noted that during the period the rig takes to spin into the wind, it is producing force. This period may only be one or two seconds, but that is enough to create forward motion which can be a major problem.