Wingsail Catamaran Model - Page 5 - RC Groups
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Sep 09, 2011, 07:43 PM
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Dick L.'s Avatar
There are 4 pages of posts to this thread about wing sails. I have not posted any pictures on this thread - so perhaps "Disabled" or "Salazar" could tell me the thread or post number you are asking about?

All of my wings are symmetrical in design, since the wing of an airplane (in most cases) is asymmetric. If you are referring to the "pink" wing for my 65cm multihull (65M Class) it is shaped foam and is a two section wing design. The leading edge and the yet to be attached "flap" - or trailing edge. Without the flap, you have no control over the camber you add or remove from the overall wing design to control the amount of power in the wing.

Would love to answer specifically if you would let me know which photo and where.

Regards, Dick
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Sep 10, 2011, 11:49 AM
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Another way to possibly make good use of a wing sail on a monohull would be to cant the mast itself, not to keep it vertical, but to keep the center of effort directly over the center of resistance... like a windsurfer. I have sailed small "pond boats" with an adjustable rig (on shore) that at almost every point of sail with no rudder input at all. This would also have the benefit of actually lifting the hull somewhat.

Check out the new "Speed Rocket 2" photo http://www.sail-world.com/Newsletter...cfm?nid=461365
Sep 12, 2011, 06:12 PM
Registered User

photo


On DISABLED link information, http://www.rcsailing.net/forum1/show...onohull/page11, the photo I'm asking for is this one.
Sep 12, 2011, 08:24 PM
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Dick L.'s Avatar
This is a wing that was being assembled by Magnus Clarke of Toronto (now in New Zealand) and is based on his experiences both on the two-time C Class Champion Canada's boat, as well as being chief wing-sitter for BMW Oracle in the last America's Cup (2 boat) race.

If you look closely, the leading wing (flap #1) is being built in two halves. I base this on the leading edge of the flap where the carbon fiber mast tube is not fully covered. It looks like only 1/2 of the leading edge is built and the second half is yet to come. Meanwhile, the middle flap and the trailing flap both appear to be symmetrical.

You are correct, however - in that the wings used by both the AC boats, and the smaller r/c boats are symmetrical and have the same profile on each side when done. A wing sail being asymmetric would need some devices or hardware to make the curvature of the leading section "pop" to the other side. In the mid 1980's an idea was tried with an asymmetrical wing that was fastened in the middle of the wing to a tall tube type of mast. The concept was to stay asymmetrical and when tacking the wing would flip over the top of the platform to the other side like a big "teeter-totter" rather than swing in the vertical plane much as we are used to seeing.

I believe I have a photo of the boat during initial testing with the wing mounted on an 18 Square Meter class catamaran platform. Will see if I can find and post it.

Regards, Dick
Sep 22, 2011, 01:16 AM
Registered User
Well!
Thank you to all of you for your teachfull comentaries.
Finally, for our 92x18x9 and 3kg RC-boat, we are going to draw an articulated wingsail with 165cm heith, 2x 9,5cm width (main and secondary) smoothly rounded in its back part, 2cm thick and desplaced 3cm from the mast axis to the bow.
Then we will built it: rigid Balsa-structure and ribbs covered with transparent plastic sticked and fixed. The new mast will be sheated in the half existing mast.
The wingsail has only one "servo" so that the curve that forms the sail has to be solved with only one controlled operation with rigid fixings (like a pantograph).
After that, we will try it (we think that it will work).
Sep 30, 2011, 04:10 AM
Registered User
My goodness!!!!!!, "high "homemade" tech" - nology.
Good ideas and better results, but the section is rounded and not wingshaped. Is it not a problem?
This weekend we begin to buid our wingsail with balsa-wood, in a "rustic" version.
Of course it will not be as nice and effective as yours, but it's a good beginning, it's our first attempt.
In some days we will send the plan and some photos.
PABLO
Sep 30, 2011, 08:17 AM
Dan Elliott
The leading edge is rounded, a result of my construction technique. It would be best if it where slightly pointed I'm sure, but it doesn't seem to hurt preformance. In this 60" wingsail version I am making the back sections wing shaped too, it was simply flat sections in the 48" wingsail.
Oct 01, 2011, 10:01 AM
Kraut
very nice dan.
Oct 01, 2011, 02:14 PM
Registered User
Hey Dan,

NICE work...I like your method of bending the PVC without applying direct heat. Very smart...

On your rounded section problem, why could you add a profile to the leading edge using PVC or something similar? A 90 angle extrusion would probably work well?

Brian
Oct 02, 2011, 05:56 PM
Registered User
Hi,
First of all DAN, sorry for thinking that you where british and not american. Reading the texts of the photographs of the forum, I thought that the museums where you built the bazins with the fans were in England. Big mistake!

http://www.desktop.aero/appliedaero/...ractiveaf.html

In this page we can analyse the wing section.
What is the best shape for our wingsail? How should the diagrams be?
Do you know if there is a page in Internet where to calculate the shape of the most efficient wingsail for the RC-boat?
Something like http://www.se-technology.com/wig/htm...?open=airfoils, but free.
If I take a NACA 0010 shape, is it OK?
PABLO
Nov 06, 2011, 06:20 PM
Registered User
Hello everyone

I've just come accross this thread which really interests me as im working on designing my own wing sail currently for my Bayer based MINI40 trimaran and my new Nightmare VIII MINI40 that im building. I had been following "Hydroptere" thread on the german rc site with interest but hadent posted their as I dont speak a word of german.

I graduated from Oxford Brookes University this summer where I studied BEng Motorsport Engineering and did my dissertation based on wing designs , primerily for blown wings and diffusers as used in Formula 1.

I'm currently carrying out CFD simulations on a couple of wing designs which are pretty basic two part wings but im going to be moving on to more complex designs as I find the limits of what I can make with my basic tools in my
garage.

Their is data available for a veriaty of wing designs using the NACA shapes but I would be very suprised if it is much use as I would expect the majority of the data to have been gathered at much higher speeds than wing sails so wont really be relivent at slower speeds. A NACA 0010 will work and will generate lift but is a pretty in efficant way of operating and as far from extracting all of the potential available. A NACA 0010 is a symetrical wing which will generate lift which as previosly stated are used on aircraft. However an passenger jet is traveling at very high speeds 400mph + and the angle of attack is at aproximatly 3degree. Whilst this doesent sound a lot at the speeds aircraft are operating even a small angle of attack will create considerable lift. Further because the angle of attack is low the drag im kept low as well at the frontal area of the wing is the same as if it was at 0 degrees angle of attack.

A far better option is to make a two part wing sail with a movable rear section at the rear as has been discussed here in quite some detail. This has the effect of giving the wing a chord curve so the lower side is much longer then the upper side. Utilising a movable section gives the wing a much closer reseblance to something such as a NACA 8412 or similar which quite obviosly will generate more lift than a basic NACA0010. The whole reason for the movable section is so that the sail can work in both directions. If you were building a boat to travel in one direction it wouldent be required but with the need for the boat to be able to travel with the wind on either the port or starboard sides a adjustable wing is required.

Note I havent called this movable part a flap as in my oppinion it is not a flap in a convential sense.

Some basic bits ive carried out CFD simulations on in the past.





Last edited by yogibear; Nov 06, 2011 at 06:57 PM.
Nov 11, 2011, 03:20 PM
Dan Elliott
Excellent work, I can't wait to see pictures of your first run. Good Luck, and have fun.
Nov 12, 2011, 02:08 AM
Registered User
Dan, thank you for your BEST WISHES!
As you can see we have adapted the existing fixed mast to the design of our new REDDEVIL-wingsail. The original mast has a fixed part to the hull (65-70cm length) and a take away secction. We have used this fixed part as the mast shaft. As we thik it's a very good solution and suporting point: the sail doesn't need shrouds!!!!!
You manage to see the union between aluminium shaft and wood mast in some photos more or less in the middle of de wingsail.
In our hands, the 3 kg bulb keeps the boat in balance (with the 170 cm sail dimension).
Some questions:
Do you think it's a good solution for RC models? What forces are
And, as you have had a look at the pictures, can you tell me please (as an advanced comentar) what can happen?
Thank's again!
PABLO


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