Hi Karl,Some thrust bearing/bushings on each side of the board at the pin and some wheels at the top. There is very little friction.
Nice to see a picture of your system. What section do you have on the main foil, and are you having any problems with pitching moments or low speed flying and take off.
When I was trying to control the foil in a similar way I found that the pitching moment due to the cambered section would cause the CoL to effectively move aft as the speed increased, increasing the loading on the wand. I even snapped a wand at speed. Quite a crash.
I ended up putting a small tailplane on the main foil to counter the pitching moment.
Although I am now just controlling my rudder foil I can set the angle of my main foil on a string to increase the AoA for take off and up wind.
I believe that I am getting a laminar separation problem at low flying speeds and take off.
I am using an RS600FF main foil, NACA 63412 section. It is not really designed for low Reynolds number operation.
At low speeds I find the boat flying very bow up and feeling draggy, then suddenly (as the flow attaches?) it will flatten and fly properly.
It is posible that at the same Cl and Rn the flapped foils maintain attached flow to the flap and only see flow separation from the last 30%.
It is also possible that a better designed section will produce the required lift without separation, or that there is a different problem.
What is your experience?