Foiling C-Class

[tspeer]

I suspect you could get the the same benefits with less parasite drag by simply extending the span, but that would take you over your allowable area because the winglet does not have any projected area on the wing planform.

The owner says the wings "were an end plate experiment gone wrong" and they won't be used in competition. Might also be disinformation...
PS RG, thanks for the sketches!

[DSmith]

What software are you using there RG?

[Retired Geek]

Its called XFLR5, and its free. Its basically XFoil with some extra's added on.
you can get it at http://xflr5.sourceforge.net/xflr5.htm
RG

Just saw on SA that Clive Everest designer of the RS 300, 600, Tek-Kat and the hulls for Invictus is building another C-class -and a foiler at that.

There is an excellent on-going thread about the foiling C class on SA with contributions from Magnus(blunted,Fred Eaton, Steve Clark and others. There is a photo of a foiling 18² tri designed by Dr. Sam Bradfield
looking very much like a mini hydroptere with a wing mast:
Foiling C Class - Sailing Anarchy Forums
Address:http://www.sailinganarchy.com/forums...=59168&st=100&

Good luck to everybody but best of luck to the Foiler Dudes in the racing starting tomorrow....

[DSmith]

Originally Posted by Retired Geek

Its called XFLR5, and its free. Its basically XFoil with some extra's added on.
you can get it at http://xflr5.sourceforge.net/xflr5.htm
RG

Would it be able to handle multi-element wings?

[tspeer]

No. XFLR5 is basically a "2 1/2 D" code. It uses the section properties from XFOIL with a vortex lattice to get the finite span effects. It may be able to handle widely separated interacting surfaces like a board and a rudder, but it won't tell you what's going on in the boundary layer of a multi-element section.

Canada leading with Alpha. Cogito second . Foils not a factor-all displacement sailing with relatively light wind. Foiler "Off Yer Rocker" third or fourth both days against Patient Lady VI
which I think has used "banana
boards"(foil assist).
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edit 9/22/07: Well, the Canadians have won with Alpha. Congratulations Fred and Magnus!

[high on carbon]

Hey gang, Magnus here.

a quick summary of the I4C event and how things shook out.

Alpha won, as you all know by now, we were able to squeeze a lot out of the boat and it returned the favour with great performance.

She has assy dagger boards in each hull which are lifted on the windward side on each tack. out rudders are a 64 series section, and as short as we felt we could make them and still be in some modicum of control at low speed.

For the heavy air day we pulled out a new set of rudders which were the same as our short ones but they had some small stabilizer winglets on them 90% of the way down the span. The winglets were about 4" out on either side if the rudder, had about 1.5" chord and were about 1/4" thick. They were set to run neutral in upwind trim. The winglets were simply designed to reduce pitching in the boat in waves, and they work quite well. The boat pitches a lot without them and with them, they added a little extra security donwhill which meant we could push harder.

We did not bother making them adjustable as it would be more weight and one more toy to distrct us in conditions that require a huge amount of focus by the crew and helm. Overall I think they worked quite well.

The foiler, Rocker, was slow, period. Being too narrow it could never get enough intial righting moment to go fast and create apperant wind. It also had basic balance issues to be sorted out, that needs a good deal more work to become as quick as a classic C. In total, Rocker simply had way more drag than Alpha, a huge amount more drag.

[high on carbon]

Originally Posted by Erwan

Hi Dough, Hi High On Carbon,

I love the rear beam of your C-cat, do you you think the same kind of beam can be used with a boat with a normal rig ? (ie: a main sail with a track on the beam), or is it possible on your C-cat because there is no leech tension on the rear beam ?

Thanks

You could try it, but you might have issues, it's really a matter of how much carbon you jam in there. we are able to build the total platform much lighter because we have no leech tension from the main being transmitted into the platform so we can go with less carbon as a result.

Word is that the old C-cats had bloody huge beams to deal with exactly this issue of major loads on the boats from the sails.

[bcv99]

Are there any new conclusions regarding the curved boards or Banana boards on PL6? Looking at the videos of ORMA 60 tris, these (little) boards they use seem to work quite well. Getting good overall performance out of the foil-borne Rocker seems to be very hard in contrast.

Is any research planned on refining this semi-flying apporach?

Anyway, congrats the Canadian team for the I4C title and one of the most exicting sailing event of this year, IMO.

Regards, Bernd

[high on carbon]

We're not pursuing banana boards right now, they were a correction for a problem with the boat in the first place, we'd prefer to have the hulls work correctly out of the box.

They are not bad but they do induce a good deal more drag then the other smaller boards.

As for reducing wetted surface, yes they do, but again at a cost of induced drag. On PL VI they are more for keeping the boat from pitch poling as much as anything.

Research, well right now we're planning on taking a breather for a while, go back to mowing the lawn, running the business etc etc.

Here is a link to the International C Class Rules:
Canadian C Class Cats - Class Rules
http://www.cclass.ca/index.php?optio...d=12&Itemid=26