Wing Sails on Proas!
Even though there’s been a steady evolution of the concept, seems like there is always room for improvement. My current canoe, EasyB, is the end result of about six very good similar designs plus a multitude of other paddle craft and the very first that I thought “there’s nothing that I want to change”.
It has been said that necessity is NOT the mother of invention but dissatisfaction is…
That dissatisfaction shows its face once the first bloom of ‘this is fantastic’ wears off and the little voice of ‘I just wish it would’ starts to whisper.
I was referring specifically to the mechanical system devised by Peter Worsley (we need to get this guy on this forum!!!).>
Peter’s email is Peter “at” sailwings “dot” net. Please do invite him, he’d be thrilled.
Well, if you have been corresponding with him already, maybe you can ask him to have a look at what we are talking about on this forum, or at least this thread?...> If you look at one of his earlier videos here:
> http://www.youtube.com/watch?v=HhUllUd-QUA
>
> At 45 seconds, you see clearly a “conventional” jibe.The crux of your answer is in your statement, “earlier.” Peter’s been working on this for many years, there are vids of several earlier iterations, which behave in various ways.
You are correct. I have been thinking about it, and as the boat goes dead down wind, the wing should transit through a neutral position, pointing directly into the wind, before building up camber and angle of attack on the new tack. The trick is that the cam will seem, relative to the wing, in the opposite position, (fully “aft” instead of forward), but it gives the same end result! All elements lined up, in neutral.
I believe the thing you identify as a “tail flap” is more of a trim tab,
Correct.
also that the entire tail plane likely does move, just isn’t moving enough to see on this vid
I don’t think so. Look at the picture on post #55. That tail seems solidly attached to the pole going through the wing.
Turns out that the “standard” way the R/Cers (and land yacht wingsail guys) do it is with an in-mast push-rod, actuating a control horn at the top of the stub mast. This was pointed out by someone earlier in this thread. Peter’s bottom-of-wing cam and follower are a clear improvement over the pushrod(s), in my opinion
Agreed 100%
No fiddling. Honest.
I saw the light! I believe you now! ;o)
Laurent
Peter Worsley’s wing-sail test platform is a catamaran and it has a control lever somewhat similar to an aircraft throttle control. This is not necessarily ideal for a proa, particularly a small one, where the steering location varies widely as the proa shunts - and as the ama flies. :o) It has occured to me that it may be possible to use a control line to position the cam. It is shown in the image below.
The black, circular cam is shown at its full-power position. It is mounted on a carriage which is spring-loaded to the neutral position and is pulled in either direction by a control line. Only one line (shown here as green) is shown fully; the blue line is shown only at its ends but follows a similarly-wrapped course. The working line, in this case the green one, is held in position by being wrapped a few turns around a locking pin. The inactive (blue) line is not wrapped around its adjacent pin.Each line is tensioned lightly by a bungee, or something similar, to keep the lines tidy and to provide locking.
When the proa is travelling the other way, the blue line is the active one, wrapped round its locking pin and the green line is not wrapped around its adjacent pin. Pulling on the active line moves the cam to increase the angle of the sail-wing. Pushing the line from the other side of the locking pin allows the cam to return towards its neutral position.
The key feature of all this string is that there can be as many pairs of locking pins as you want, placed conveniently to the various steering positions. Cheapskates and lightweight enthusiasts can have a single pair of pins and a bunch of holes to put them in….
It has been said that necessity is NOT the mother of invention but dissatisfaction is…
That dissatisfaction shows its face once the first bloom of ‘this is fantastic’ wears off and the little voice of ‘I just wish it would’ starts to whisper.
So true, so true. My father took it yet another way, “Mother is the necessity of invention.” 😉
Dave
Peter Worsley’s wing-sail test platform is a catamaran and it has a control lever somewhat similar to an aircraft throttle control. This is not necessarily ideal for a proa, particularly a small one, where the steering location varies widely as the proa shunts - and as the ama flies. :o) It has occured to me that it may be possible to use a control line to position the cam. It is shown in the image below.
The black, circular cam is shown at its full-power position. It is mounted on a carriage which is spring-loaded to the neutral position and is pulled in either direction by a control line. Only one line (shown here as green) is shown fully; the blue line is shown only at its ends but follows a similarly-wrapped course. The working line, in this case the green one, is held in position by being wrapped a few turns around a locking pin. The inactive (blue) line is not wrapped around its adjacent pin.Each line is tensioned lightly by a bungee, or something similar, to keep the lines tidy and to provide locking.
When the proa is travelling the other way, the blue line is the active one, wrapped round its locking pin and the green line is not wrapped around its adjacent pin. Pulling on the active line moves the cam to increase the angle of the sail-wing. Pushing the line from the other side of the locking pin allows the cam to return towards its neutral position.
The key feature of all this string is that there can be as many pairs of locking pins as you want, placed conveniently to the various steering positions. Cheapskates and lightweight enthusiasts can have a single pair of pins and a bunch of holes to put them in….
That’s slick, I think in my case the control lines will just run thru a pair of clamcleats. Spring load to neutral a real positive. Only big decision left is whether to use a ring of 6” or 8” PVC pipe for the cam.
Skip
I think in my case the control lines will just run thru a pair of clamcleats. Spring load to neutral a real positive. Only big decision left is whether to use a ring of 6” or 8” PVC pipe for the cam.
Skip
Of course BB has a real seat and everything… :o)
That’s slick, I think in my case the control lines will just run thru a pair of clamcleats. Spring load to neutral a real positive.
Very slick. We did some experiments with this setup years ago for kite-proas. Same reason, as you need to move about the boat to trim it optimally—then can’t reach the sheet. We found a good compromise was to use an endless loop rather than 2 lines, and to route them right around the trampoline. In that way they’re accessible from anywhere on the boat—and also semi-protected from being stepped on or kicked loose. Slipping it under one horn of an ordinary jam cleat mounted at 90 degrees (if lightly loaded) or through a pair of rope clutches facing each other (if the loads are higher) works well. Pairs of cam cleats or clam cleats, facing each other, didn’t work as well
Centering springs; great idea but there’s a steep price. If there’s sufficient friction in the system to hold a setting (as with Peter W’s bowden wire and no self-centering), then you can leave it un-cleated and adjust it from anywhere on the boat. If there is a centering mechanism—or minimal friction, either one—then you must cleat the line(s) off, as Peter “not Worsley” shows (May we know your last name, Peter? Even an initial!)
If the line(s) are cleated, it means the pilot must be within reach of that cleat any time he wants to alter the setting, and you may as well just move the bowden wire to more convenient place and be done with it. The beauty of the adjustment line is that It can be accessible from anywhere.
A work-around could be to hand-hold the adjustment line, but that’s gonna be a pain—remember this isn’t actually a sheet, it’s more of an auto-pilot setting control, so there’s no feedback or feel to it—and it needs very little movement to go from feathered to full throttle. Plus you still need to steer the hull, so you’re kinda busy.
Only big decision left is whether to use a ring of 6” or 8” PVC pipe for the cam.
I was wondering the same thing. I’m thinking maybe it’s better to go big. Wouldn’t this give you more available bias, therefore more available range of motion, for the flap and/or tailplane? You’d also have a longer lever so more total power available for controlling the rig.
Dave
That’s slick, I think in my case the control lines will just run thru a pair of clamcleats. Spring load to neutral a real positive.
Very slick. We did some experiments with this setup years ago for kite-proas. Same reason, as you need to move about the boat to trim it optimally—then can’t reach the sheet. We found a good compromise was to use an endless loop rather than 2 lines, and to route them right around the trampoline. In that way they’re accessible from anywhere on the boat—and also semi-protected from being stepped on or kicked loose. Slipping it under one horn of an ordinary jam cleat mounted at 90 degrees (if lightly loaded) or through a pair of rope clutches facing each other (if the loads are higher) works well. Pairs of cam cleats or clam cleats, facing each other, didn’t work as well
Centering springs; great idea but there’s a steep price. If there’s sufficient friction in the system to hold a setting (as with Peter W’s bowden wire and no self-centering), then you can leave it un-cleated and adjust it from anywhere on the boat. If there is a centering mechanism—or minimal friction, either one—then you must cleat the line(s) off, as Peter “not Worsley” shows (May we know your last name, Peter? Even an initial!)
If the line(s) are cleated, it means the pilot must be within reach of that cleat any time he wants to alter the setting, and you may as well just move the bowden wire to more convenient place and be done with it. The beauty of the adjustment line is that It can be accessible from anywhere.
A work-around could be to hand-hold the adjustment line, but that’s gonna be a pain—remember this isn’t actually a sheet, it’s more of an auto-pilot setting control, so there’s no feedback or feel to it—and it needs very little movement to go from feathered to full throttle. Plus you still need to steer the hull, so you’re kinda busy.
Only big decision left is whether to use a ring of 6” or 8” PVC pipe for the cam.
I was wondering the same thing. I’m thinking maybe it’s better to go big. Wouldn’t this give you more available bias, therefore more available range of motion, for the flap and/or tailplane? You’d also have a longer lever so more total power available for controlling the rig.
Dave
I lean to the larger myself, rather than draw anything I’ll probably trial up some of the pieces this weekend and make gofast noises. Since I’m committed for now to a fairly fixed position the dual pull throttle seems to have a lot of merit. A 2/1 setup (1 pulley each way) might be worthwhile to increase “range of motion” (I’ve become very familiar with the phrase) 😉
The line around the pod worked quite well on P52 when using a shunting staysail.
Skip
Very slick. We did some experiments with this setup years ago for kite-proas. Same reason, as you need to move about the boat to trim it optimally—then can’t reach the sheet. We found a good compromise was to use an endless loop rather than 2 lines, and to route them right around the trampoline. In that way they’re accessible from anywhere on the boat—and also semi-protected from being stepped on or kicked loose. Slipping it under one horn of an ordinary jam cleat mounted at 90 degrees (if lightly loaded) or through a pair of rope clutches facing each other (if the loads are higher) works well. Pairs of cam cleats or clam cleats, facing each other, didn’t work as well.
Presumably there needs to be some sort of tensioning spring to take out slack and allow the loop to be ‘pushed’ ? I’d be worried that if the line snagged and parted then the tensioning might drive the cam to full coarse pitch just as you were trying to deal with the mishap.
Centering springs; great idea but there’s a steep price. If there’s sufficient friction in the system to hold a setting (as with Peter W’s bowden wire and no self-centering), then you can leave it un-cleated and adjust it from anywhere on the boat. If there is a centering mechanism—or minimal friction, either one—then you must cleat the line(s) off, as Peter “not Worsley” shows (May we know your last name, Peter? Even an initial!)
see #47 :o)
A work-around could be to hand-hold the adjustment line, but that’s gonna be a pain—remember this isn’t actually a sheet, it’s more of an auto-pilot setting control, so there’s no feedback or feel to it—and it needs very little movement to go from feathered to full throttle. Plus you still need to steer the hull, so you’re kinda busy.
Quite agree.
Only big decision left is whether to use a ring of 6” or 8” PVC pipe for the cam.
I was wondering the same thing. I’m thinking maybe it’s better to go big. Wouldn’t this give you more available bias, therefore more available range of motion, for the flap and/or tailplane? You’d also have a longer lever so more total power available for controlling the rig.
Dave
The power to control the rig comes from the aerodynamic forces on the tailplane - the cam is simply setting its angle-of-attack. The tail should be pivoted about its centre-of-lift which with a symmetric wing without a flap will not shift with A-o-A of the tail. The leverage decisions come from
: how much angle does the cam give you when its acting on a frame of a convenient size
: when does the main wing stall
: how much tail angle is needed to achieve main wing stall
: what is the maximum flap angle at the trailing edge of the main wing
then put multiple fixing points on all the lever arms and tune it under real sailing conditions.
Cam diameter is probably dependent more on mast size than cam travel. I’d be tempted to mount the cam on a flexure platform (see image) than any sort of sliding bearing - particularly in sandy, salty seas. The flexure consists of a couple of chunky square frames separated by two thin (ply? glassfiber?) open square flexible elements. The bottom frame is nailed to something solid (bottom of the mast?) and the top one carries the cam ring and moves in a straight line without friction and is self-centreing.
Peter H
Sorry to be the dim bulb, but I’m still trying to wrap my head around why the maximum tailplane position occurs when the apparent wind is on the beam.
As I understand it, the tailplane is to control the angle of incidence between the apparent wind and the main element. By having some angle of incidence, it generates lift—up to some maximum lift angle of incidence. Right? Why should does the boat’s course effect it? Is it like sheeting out (lower angle of incidence) or is lit like easing the outhaul (creating more camber)? Why have the angle reduce as the apparent wind comes behind beam on—like a broad reach? Why have a smaller angle of incidence going upwind than a beam reach?
I know I’m missing something, but I’m not sure what it is.
On a side note, how about that flap on the main element that is tied to the tailplane….that’s interesting. Now we’re getting some camber too.
http://www.youtube.com/watch?v=AArllt2TRZo
Sorry to be the dim bulb, but I’m still trying to wrap my head around why the maximum tailplane position occurs when the apparent wind is on the beam.
As I understand it, the tailplane is to control the angle of incidence between the apparent wind and the main element. By having some angle of incidence, it generates lift—up to some maximum lift angle of incidence. Right? Why should does the boat’s course effect it? Is it like sheeting out (lower angle of incidence) or is lit like easing the outhaul (creating more camber)? Why have the angle reduce as the apparent wind comes behind beam on—like a broad reach? Why have a smaller angle of incidence going upwind than a beam reach?
I know I’m missing something, but I’m not sure what it is.
On a side note, how about that flap on the main element that is tied to the tailplane….that’s interesting. Now we’re getting some camber too.
I’ve also had a hard time digesting the whole thing but it is elegantly simple. Maybe the attached sketch will help, tis almost geometrically correct. I quit doing animations almost two decades ago 😉
In the sketch wind is always from top of sheet to bottom.
Helps to realize the tailplane follows the follower.
My plan is to definitely have a flap on the main section to introduce camber, a lot will depend on actual trials, which come after the cambered panel staysail.
Skip
I was curious about Peter Worsley’s system with regard to how the flap angle changes relative to the wing angle (my concern is that there is not enough flap movement in the close hauled position). So I modelled up a 2D sketch of the system using CAD software and plotted the angles. I used a 100mm dia. mast and a 300mm dia. cam with 80mm of travel either way. I positioned the pivot point for the cam follower as close as practical to cam in the maximum travel position. I adjusted the lever lengths so as to get as large a flap movement I could get in practical terms (about 60 degrees). The results, plotted below, show that as I suspected there is not a lot of flap movement in relative terms at small wing angles (i.e. close hauled). This may be ok if, as I did, you configure it to give large maximum flap deflections. If not, you won’t get any decent thrust out of the system when close hauled.
Mal.
For completeness, below is a screenshot of the sketch I used for the above analysis. This shows a wing angle of 30 degrees off hull centreline, with the cam in the mid range position (half throttle):
The Worsley cam and flap system gives maximum camber and angle-of-attack on a broad reach and steadily reduces both as the wing comes to a close-hauled orientation.
The heeling component of the wing’s lift is small on a broad reach (as with any sail) and the drive component is large. As the boat gathers speed and the apparent wind swings towards the bow then the camber and AoA (and thus lift) are reduced by the cam and the heeling component (which is a large proportion of the lift when close-hauled) is thus kept within bounds. So the system appears to be designed to be inherently user-friendly - although too much throttle for the wind conditions (or heading) will still tip your boat over, I suspect.
So there will still be the requirement for elite sailorly skills in managing heading and power to achieve the desired headway - and for those planning schooners the additional subtleties of power-fore and power-aft to balance and steer the boat.
Those wishing to have more control and responsibility can always design a self-trimming wing-sail without the cam in which the control lever (or sheet) simply moves the flap and tail directly…
Well said. Hi,
I have just found the forum and have read through with interest.
I don’t know much about proas, but pleased to see you may find the system useful.
As has been seen here, it’s quite difficult to convey how the system works on paper, that’s why I made the various videos. I wasn’t sure it would work myself until I actually constructed one. There is another video which maybe has not been seen, which could help make the system more understandable, here: https://vimeo.com/84289428
It works exactly the same as before, but in this instance there is a wing flap connected which works in opposition to the tail movement. (A slight mishap towards the end when the linkage falls off!). However you can still see how it works. These wingsail rigs can be either flapped or flapless, both are quite acceptable, the flap maybe slightly better at the expense of some extra complication. However, the “Saildrone” goes quite well I notice, even without the flap.
Peter Worsley