Wayne,
that makes perfect sense. Creative way to continue enjoying downhill skiing!
Klaus,
thanks for writing up that info.
I always thought the ideal was to have ellipitcal pressure distribution over the foil, not neccesarily to have an elliptical foil. Reading what you wrote I think that is still valid.
Doing anything but a parallell sided rectangular foil is prone to errors without a CNC. I found this link which looks like my best shot with no CNC. Especially as a good friend offered to laser-cut templates on a CNC laser cutter.
http://www.duckworksmagazine.com/09/howto/foils/index.htmDoing a cut after routing and then sanding/fairing before pulling off moulds is a real option. The same for rounding off the tip by hand at the bottom. Getting the proper section in that area will be hard. Dont know if the gains outweights the extra drag and loss of lift I will make with my unskilled hands.
I have done three sets of foils earlier by hand. Wood, plane and sand. Free hand.. None of them turned out really well. Partly becouse of design and partly becouse shaping wood by free hand is difficult.
Tornado rudders from Marstrøm was pretty good compared to my homebuilds. Yes, they did cavitate some times. Not a pretty sight when double trapeezing. I always thought the class overloaded the rudders with the mast rake. We sailed with less rake to overcome cavitation problems. They still happened, but not so often. Sheeting out a handful reattached flow.
I am really really surprised that you think the T rudders were designed for a speed much higher than obtainable by the T. With the amount of resources invested in producing a faster T around the course the foils is a very logical place to do research. The centerboards were of course very hard to optimize due to the class rules defining their planform.
When you mention forward sweep, you advocate installing the foil with a bit of forward sweep? Not seen that in a while
The idea is to produce elliptical pressure distribution or to delay ventilation? Cavitation should not be an issue with a daggerboard operating in turbulent flow under the hull?
Looking at the "state of the art" daggerboards in the F18 class, they have gone for higher AR and shorter chord. I think the Wildcat from Hobie have daggers with an 180mm chord! Effective length when fully down 1130mm. Pretty extreme compared to older designs and probably a handful on the starting line.
What I really would like is to buy something ready made with reasonable performance for a reasonable price
I have been unsuccessful in finding that and nobody is sending me plugs or moulds in the mail so it looks like I will have to shape something myself. A "good enough" planform that is easy to shape with a relatively robust profile (building in the garage, able to handle the starting line, tacks and jibes) with adequate lift and reasonable drag. Hmm, sounds like mission impossible..
I would be very grateful for any suggestions or help on this
PS: I definately would prefer to live long and happily!
