@Erik on the Mike Raper episode you said you wanted a bottom mount wing at 0 deg angle(as industry standard) I’m assuming thats realtive to the front wing but where on the front wing? How do you define 0 angle relative to the front wing? 0 relative to flat bottom of front wing? 0 relative to the tip of front wing leading edge to tip of front wing trailing edge?(How George at delta measures)
I’m setting up a CAB 1000 and building a quick and dirty rear fuse for it and i want to get a reasonable starting point so i don’t go crazy trying to get to the 1 deg shim stage(don’t want to start 4 degrees off and wonder why i cant make it work)
I thought he meant the surface the tail bolts to is flat, and 0° to the fuse? I just put my phone’s level on my takuma rig which was set up anyway, and lying on a slant, but it’s the relative angle that’s important. I measured the flat/concave trailing edge of the flat side of both the foil and tail, while it was upside down:
Foil(1210): 6°
Stab(chopped 220): 3°
I wonder if the 178 would be different, since it’s flat side is much flatter.
That’s true, but I’m assuming the whole system is designed to drag the fuse straight through the water at the efficient speed of each foil? But in any case that’s just what I thought he meant, and no other obvious alternatives come to mind.
This is my understanding. There needs to be a difference in angle of the front and rear foil of about, I think I remember Cliffy saying, 4.5 degrees. From my feels most foils are tuned pretty close to that minimum with no shims. Unifoil and Takuma seem to have the fuse angle mount for the tail about 1.5 less lift than needed and the tail comes with about 1.5 degrees of angle (negative for more front foot) built in. KD tails use 1.5 I think, except blunt which is 2 or 2:5. Kane can chime in.
Until the last year I was always adding more negative shim to increase front foot pressure. I’m now tuning to find the fastest most efficient stab angle and moving the mast to get the foot pressures I’d like to feel. This works if you’re on a foil that doesn’t have much forward pitching moment. The lift 170 is a good example of that pitching feel. The nose feels like it wants to drop out in turns. Takuma kujiras are an example of a steady lift. They require less weighting changes.
Setting front foil angle is something we worked on with the Progression foils, and we set it about a degree from what I ride (use a plate shim for that last degree) as it will be easier for most riders. I’m at the extreme of the setup range. I think the foils will come with plate shims. Also depends on what board you’re riding. We’re gonna do a video or tuning guide on setup. What’s interesting is I tune a bit different for downwind. Take out the plate shim. Easier to pop up and can get a bit farther forward on the board to balance out legs. Doesn’t turn quite as tight but that’s not what you’re optimizing for downwind.
Older foils like the cloud, Armstrong surf, vortex required a lot more tail shim. And I think that has anchored tuning to the extreme a bit.
@Erik thanks for that post! Just question with last sentence…what do you mean by those brands require more tail shim and “anchored tuning to the extreme a bit”. Do you mean those brands require more tail shim for more lift ?
Older foil sections had more pitching moment so you had to counter that with more tail (surface area or shim). By anchoring I meant that it’s been normalized. Like in the sales process when you list something at a high price so that’s what’s in everyone’s mind. Th en when it’s discounted a bit it seems cheaper.