Mini Transat Foils - canards

[fng]

I have a saying that real knowledge is limited to ones own ignorance.

So here goes, I have designed a mini transat 650 and am researching the aysmetrcal canards.
The big thing is that they need to have a huge working range. to windward they are slow and sail on a heeled water line around 8 - 10 degrees before you add yaw. Then reaching and running they often reach speeds in the late teens and early twenties with little or no angle of attack.
Structurally we need a cord width around 12%
My initial research is leaning towards the Eppler 67, and 68, the 66 is also good but we would need to have longer cord length canards.
The next two of interest are the clark V and Y smoothed, after that the HQ 2.5, 3, 3.5 - 12and 13% look good the come a few odballs fx84-w-127, psu-90-125wl, and the E201.
I have seen many similar foils but without data, e.g. H105

If any of you could shed some more light on my quest - great

[fng]

some images

[Doug Lord]

Have you considered something like this-gets rid of any boards/trunks in the hull. I have a friend- and NA/Marine Engineer(who posts here) -that did a preliminary study of the KFOIL for a client who had a mini.... Offers less weight and ,overall, less complication.

[fng]

Hi Doug,
minis have box boundries and the winglet would exit the box. Secoundly the keel fins are generally as small as possible ( just to carry to bulb and canting pin ) there are wild times when both canards are raised and you want drag down to a minimum, so the increase in cord width to accomadate the hinge and links for the winglets may well out way the gains.
If you consider the keel fin and bulb only for righting moment ( some even have the hinge raked upward aft to get negative angle of attack on the fin to aid in righting moment).
If you also look at the open 60's and the fact that at times there bulbs exit the water the winglets would then be redundant.

In the case of our design the foils are virtually centred in the heeled water plane ( see the preliminary picture ) the canard has been moved inboard slightly and the rudder outboard slightly and the angles in the boat parrelled

[Doug Lord]

Originally Posted by fng

Hi Doug,
minis have box boundries and the winglet would exit the box. Secoundly the keel fins are generally as small as possible ( just to carry to bulb and canting pin ) there are wild times when both canards are raised and you want drag down to a minimum, so the increase in cord width to accomadate the hinge and links for the winglets may well out way the gains.
If you consider the keel fin and bulb only for righting moment ( some even have the hinge raked upward aft to get negative angle of attack on the fin to aid in righting moment).
If you also look at the open 60's and the fact that at times there bulbs exit the water the winglets would then be redundant.

In the case of our design the foils are virtually centred in the heeled water plane ( see the preliminary picture ) the canard has been moved inboard slightly and the rudder outboard slightly and the angles in the boat parrelled

----------------------------
My recollection was that it was legal when it was first looked into. Without too much trouble could you give me the dimensions of the box?
Good luck with the project!

[Paul Kotzebue]

You can see the Mini Rule here.

See J-2-c. Adding foils to the bulb will require reduced draft to avoid going out of the box when heeled.

[Doug Lord]

Thanks for the rules Paul-I appreciate it very much.

[fng]

the box is 3000mm wide buy 2000mm deep, also note that 2000mm deep is at any angle of heel. So sorry Doug as the keel cants and or the boat heels the winglets would pass through the draft max or the gunnel line max width. yes rule J-2-b and c say it all

[tspeer]

Originally Posted by fng

...I have seen many similar foils but without data, e.g. H105

Coordinates attached.

I would use XFOIL to analyze candidate sections for your conditions. 1 < Ncrit < 3 would probably be appropriate, based on the experience of others in designing keels.

[fng]

Thanks

[Doug Lord]

Originally Posted by fng

the box is 3000mm wide buy 2000mm deep, also note that 2000mm deep is at any angle of heel. So sorry Doug as the keel cants and or the boat heels the winglets would pass through the draft max or the gunnel line max width. yes rule J-2-b and c say it all

---------------
Offhand, do you know when these rules became effective?

[fng]

Hi Doug, As long as I can remember. If you google Leo V and mini transat 650, you will find Leo's site, there is a very good history record there.

[Doug Lord]

Thanks-good idea...

[Questioner]

fng,
try talking to Rob Shaw, he used the AQ foils on "Karma Police" which seems to be going rather nicely at the moment, attached picture is a comparison for the AQ sections that I have verses a couple of the ones you mentioned.