Marc,
It is starting to look like a wing. How did you choose the shape of the sail?
I’ve started working on the internal setup to switch to a swing rig type of arrangement, and add another servo for the flaps. I don’t have much room so the servos are very small, perhaps too small. I’ve also added a dual rudder setup. I’ve basically started using this boat as a test rig to try out ideas for the next boat.
I can hear Claudio groaning at the quality of the build :D.
Jim.
Jim,
I have not epoxied the wing shape yet…that just blue painters tape to do a mock up for the photo shoot…
I will use the naca 0012-64
so i was thinking last night. about how to do do the pivot. since this is on an RG65 I won’t beable to adjust the flap on the fly since i will only have two channels. one for rudder and one for sail control… so since I can only control sail in/out…I need to be able to set the camber… Unless I figure out a way to make the drum winch do double duty as sail control (in out) and camber…
I was thinking about using graupners tunbuckles as my “hinge”
this way I can fiddle with the gap…
still not sure how I’m going to limit travel on the flap…
Mark - you can always do what the big boats are doing, and that is to build a “cup” on the bottom of the rig (mast ???) and have a simple pin of nylon or metal pin with nylon ball or (???) that is deck mounted on which the wing sits and rotates. Then a forestay and two side shrouds to support the wing. Just run side shrouds back to about the first 1/3 of the wing along gunwales.
Using a ball & cup (I ran mine up from the dolphin striker and through front cross tube) there is no bearings, rust, etc. to worry about, it has low friction, quick to step mast very little friction - and the entire base could be mounted on a thin piece of wood with one pin fitting in your “normal” mast hole in deck, and the mast pin attached to other end of of the wood and sticking up to fit into bottom of your mast. The pin going into the “normal” mast tube should fit tight and not rotate. Moving the nylon pin forward or back would allow change to weather helm. Thus no permanent tubes or extra holes.
Sorry for drawing - but am on my way out. Hope you understand idea.
Dick
PS - you could run light lines to each side shroud location to prevent wood from swinging to one side or another.
I think my biggest issue(besides building the wing) is to get the wing to rotate smoothly. and miss the shrouds… I think my mast is stiff enough that i can have the shrouds go from the deck to the top the mast only… which will eliminate the need for them to go through the sail…
thats where a keel stepped mast like a swing rig would make more sense with a small bearing to help the rotation…and no real need for shrouds… but I’d hate to loose the jib…
Marc,
I’ve been thinking about other methods to put together a simple wing sail. I’ think that there are weaknesses in the approaches that we are each taking. For my method control of the aerofoil shape is a bit difficult, particularly for the flap; for your method, I think that the wing might end up on the heavy side. I’ve had another look at the way that model plane wings can be made, and I noticed that there are many suppliers of foam cores, either pre-cut or custom cut to a specific shape (seem to be quite cheap). This might be an easier starting point, simply purchase pre-cut foam cores and then work out how to get the mast in, join the flaps, apply a coating etc. Because we are both working on fairly small boats I think that the foam should be strong enough on its own, perhaps with some sort of tape or film coating. Any thoughts?
Jim.
jim
good thoughts. with with a hot knife you could cut your own wing out of foam… I measured out my wing ribs, and I only plan to have 4, 1 at the top, 1 at the bottom and two in side. one at 600 mm and one at 300 mm wings is 900mm tall… My initial thoughts were to have the leading edge of the wing “plumb”, as I pictured, with the mast this will make shroud placement much easier but balancing the rotating wing much harder… After staring a the wing I may have the leading edge raked aft a bit… as the tip is raked back the root will move forward so this will give the CE a boot forward as well.
too many options…confusion is setting in 
https://www.flyingfoam.com/ 60" wing (30") each side was about 20 bucks for naca0012. not bad, depending on your profile. you may have to reinforce it…(monocote is pretty impresive)
if you mounted it like a swing rig. you’d probably not have to go too deep into the wing root to get it so its strong enough… the key is of course is to get the hole for the pivot plumb… the company above can do that on a custom quote… as well as slots for reinforcement… I emailed them a question about wing weight… to see how it compares to mine.
I agree that buying a ready made product is fast and easy…but I also enjoy building and learning…
got my replay back form the above company… the wing in it current shape in owens pink is 1.53 ounces 43 grams… which does not include spar or covering…
Marc,
You move quickly! I also prefer to build and learn, but the simplicity and cost of this approach is attractive.
Continuing to look for solutions from model planes, I’ve been looking at hinge options. There are a few options available, Robart hinges look like they might work, but will require some modification to enable variation of the gap.
I have gone for the swing rig approach, but in retrospect I think Dick’s suggestion may be a better alternative to begin with. With these sails I have no idea how you would go about working out where the mast should be, so I think that it might be a matter of trial and error. With Dick’s approach it would be much easier to trial different positions.
Jim
I looked at the robart hinges when i was at the hobby shop. almost bought some. but it won’t put the pivot point far enough inboard as the folks reccomend… plus I don’t think it was “free enough” for my purposes…
I did not buy any wings, but I had a nice discussion with the wing guys… tons of options… and if my wing works… I may purchase a professional built one…
Sounds like a good option. I’m also planning to get the best out of my current method and work out appropriate wing shapes and sizes (and use up my foam sheet) before purchasing a pre-cut wing.
You have probably opened the wing guys eyes to a whole new market. You might be able to convince them that it is development work (perhaps don’t tell them it may only be a market of 2)?
I forgot to mention: I set my winch up to do double duty, which worked, in that it allowed you to tack (jibe in my case) and switch the flap to the correct side of the wing. However, there was no control of the position of the flap, ie it was basically set at a particular angle for each position of the main wing. Consequently, when sailing I was constantly hunting for the best angles and sail positions to get the best performance out of the sail. You could really tell when you hit it, and I got better at finding it, but it certainly restricted your course options. This may have also been a result of my imperfect aerofoils, but I think that control over the flap would have helped the situation. I might experiment with having the main wing set, and varying the flap. That said, I’ve bitten the bullet and purchased a 4-channel controller.
Boat now setup with servo for flaps and second wing ready for testing:
The gap is probably a bit big, but it is easier to make it smaller rather than bigger. The aerofoil is better than the second photo suggests, it is just lost at the top of the sail.
The flaps seem to work nicely:
well here is the cad of the proposed wing…
will end up with a mast crane with the first version having shrouds, forestay and back stay from the top of the mast.
here is the mast pivot image
my thoughs are to use a thrust bearing from an RC chopper on the bottom pivot and a radial bearing from an RC car at the upper pivot. currently no plans for any bearings at the other two locations.
here is the flap hinge setup
a thrust bearing on the upper pivot with a radial bearing on the lower
my flap with have pivot stops on the boom, much like the outhual on a soft sail to control the camber so on each tack the main wing will “flop over” like a soft sail. with the main sheet pulling on the boom
maybe I am over thinking the bearings do I really need them? in light air…I think so… but I could be wrong…
Jim nice looking set up… the hard part will be being able to see the wing to tweak the flap. it will have to be fairly close to shore…
did some work yesterday…not real happy with the bottom pivot on the flap… but it is smooth.
110 grams… so far…
the wing rotates very easily
I have enough space at the top for my shrouds, backstay, ect…
One of the element I have noticed from the softsails vs wing (from videos) is that the acceleration seems even quicker and so the reaction time is reduced. you already have to be quick to react with a softsail boat I see the risk of capsizing more apparent and also the ability to depower less evident. A softsail would absorb some of the energy of the wind and gust in it whereas a wing would transfer it into power and speed quicker. well that’s my view - to be proven.
So though I have seen Mini40 trimaran initially built for softsails sail with a wingsail they are yet to prove their added benefit in a race amongst softsail multis.
nice thing about the mono hull with a wing sail… as the wind puffs, the boat heels over and dumps power…
Following Claudio’s suggestion I’ve tested the gap size in my new wing sail with tell-tales. Fairly rough experiment, but reproducible. I’m guessing the gap is too big:
And yes, I need different coloured tell-tales.
jim, also if you are using moving air from a fan, it is already turbulent IE non laminar which could contribute to the turbulence you see…
hopefully I’ll get my sail mounted this coming weekend…
Marc,
Do you know of any methods to produce a simple non-turbulent test system?
By the way, I’m impressed that you kept the weight quite low. How tall is the sail?
Jim.
