You may have followed my efforts at developing mast aft wing sails on the Technology Board. Rather than continue the thread there I’ve decided to start a thread devoted to these sails on the RG65 Board. I’m doing this because I am now convinced that this type of rig is particularly suited to this class, and if developed further has the potential to out perform conventional sails. The reason that I think that they suit this class, is firstly because I think that they should fit within the open RG65 class rules, and secondly because the scale of these boats enables light wings of sufficient strength to be made. When you look at my mast aft wing sails, keep in mind that I have made only a handful of these, so there is significant potential for their performance to be improved.
To begin this thread I’m going to show some of my better efforts, a couple of these are probably repeated from the previous thread, but I will repost here for convenience:
I have some questions for you, according to your tests and experience with this concept:
1.- Which is the best hull for this type of sails? narrow hull with low displacement or wider hull with higher displacement?
2.- What about the lenght of the keel, larger, let´s say 45 cms or more; or shorter like soemthing near 30 cms?
3.- And what about the bulb weight? near 500 grs or better near 700 grs or more?
4.- Which hull design would you suggest to start experimenting with you these concept?
5.- Is there any place with some plans to start trying to build a boat with the concept?
6.- After trying the three options shown in your videos, which is the one you see with better performance: single, double or canting mast?
Thanks for sharing your ideas. Congratulations for your contributions to RC sailing.
Regards.
Mapache CHI - 65, Victoria
Mapache CHI - 65, RG - 65
The wing sail is somewhat heavier than a conventional sail and therefore I think that a higher displacement hull is better suited. For the canting rig, from a very practical perspective, a wider hull makes it easier to implement the canting arrangement.
As for point 1, the extra weight probably favours a longer keel.
Once again, heavier would be better.
I selected a DF65 because it has sufficient strength to cope with the stresses associated with the aft mast arrangement, and also because there are identical boats around for comparison. However, I’m sure that this rig would be best used with a hull designed specifically for it, but hull design is not something I really understand and there are others on this forum better placed to comment on this.
When I get a chance I will provide some details on the designs that I have used. To the best of my knowledge the only other info on rc mast aft sails is the thread Claudio refers to, and there are no other examples of mast aft wing sails.
I really like the canting mast and I think that it combines very well with this mast aft arrangement. However, as Balderdash has suggested, this arrangement requires a third servo so it infringes the RG65 class rules.
The double wing configuration is also very interesting, I have only made one of these and I was impressed with how well it performed. I believe that there is lots of room for improvement here, not necessarily limited to two-element sails, multi-element wings could be configured to better optimise the interaction between the different elements.
Is your double element sail, 1 solid pieces? the fromt bit looks like a wing, with a soft sail back?
I’ve been thinking AC cat style wing sail for a lightweight footy…
Got any more details
For a Footy I suggest that you use 6mm Depron foam for the front element and 2 mm for the flap. The mast will need to rotate like a swing rig. Simply tape the front element to the mast, and use thin tape pieces to attach the two elements (a strip on each side). The boom should rotate around the mast, and should slide through a ring on the rear of the flap (the boom should protrude some way through the ring and is not attached to the front element). The end of the boom should be attached to the ring by a chord, the length of which will set the angle between the two elements. To give the front element some profile, gently sand the rear edge with very fine sand paper, or alternately gently compress. I made a wing like this for a small lightweight cat and it worked quite well.