If we're using multiple struts then I'm wondering if I can't just get away with using longboard style channel boxes and building the struts like a fin. Maybe rout in a couple of longer mini-stringers on either side of the box to stabilize it so the torque doesn't rip them out under load. That would eliminate any excess drag on the hull itself. Get a little fore/aft adjustability in the process.
No stringer needed but interesting point about riding a foil with the wider end forward or back.
It's going to be a matter of personal preference but I think it's connected to the ' front foot/ back foot' surfer style. Some people prefer the width at the back but I routine.ly spin the foil around and it's a similar performance but you have to change your weight distribution.. if you move most of the area forward, you don't get much with a strong back foot.. I prefer the width at the back.
Gdaddy, I left the mast/ struts conversation for last as it's more complex. Just like the foil design, I'll offer up what I know and you can do it however you choose.
This thread is the best thing to happen to swaylocks for a while.
Sunshine Coast (hoax) Queensland Australia
What foil does the foil have?
How come it lifts the board and rider up, rather than pulling them down into the water?
I'm just trying to understand what creates the lift force towards the water surface.
Is it just a flat foil and the AOA is controlled by the surfer so that it created upward lift, or does it create upward lift at any (or most) angles?
This is my favorite discussion here in years!
@MrMik, the foils surffoils has shown here all look flat.
The edges are more rounded than sharp as you can see from how the wood plies run.
Since the foils are thin, and have some struts forward and some aft, they will bow upwards when ridden, creating a camber/foil between supports to give lift. The lift made this way is especially effective at low (paddle-in) speed. Positive angle is still required for lift. This is a cool approach to the problem, with out a lot of carbon or a heavy, very thick wing (found in expensive commercial foils like aguera or takuma etc)!
MrMik and bwd, we've all experienced the rising water up a wave face and it's a much gentler effect further away from the breaking section. Further away is where the other foils are king, they use a highly effective foil cross-section to get great lift further away from the break. Closer to the break that effective foil section becomes unstable because there's too much lift.
Closer to the break there's tons of lift and you don't need to encourage it so a simple flat foil works very well. It's just AOA regulating the massive lift just under the wave face.
On a simple flat foil you won't be able to charge 50 metres away from the break but you will be able to surf in the same zone that you usually do. Drop in, pull in, tube, spat out silently onto the shoulder at warp speed, cutty and repeat. The silence and smoothness is surreal and you can pull off one wave and link into the one behind or one in front.
The other foils and mine perform at different ends of the spectrum of wave energy. It's definitely possible to take a foil design like mine, add some foiling similar to theirs, and create a foil that covers a wider range of conditions.
Bwd, you're right about the edges, you're not making a samurai sword so just rounding all the edges is enough for good performance without creating a safety issue. Bringing the foil width in from 23 inches to 16 or 13 inches also halves the danger of slashing someone or yourself. The thinner foil does flex to create camber and it does add to the overall lift. All the forces are up, pushing the foil towards the board creating drag that lifts the foil and with such thin foils there's little form drag slowing the foils acceleration.
I didn't think anyone would understand foiling physics, but it seems many of you understand how it works far too well !!
Aha, it's that force in the water that snaps off fins when they are not strong enough.
I think I would build a strong thin core for the foil and 3D print exchangeable foiled additions for experimentation and later (once known what works when) for adapting the foil to different conditions on the day.
Do you think 2mm holes in a flat foil would cause any issues?
Maybe SS nuts could be in-layed from the top, and screws inserted from the bottom to close the holes when they are not in use for attaching 3D printed foil parts.
MiMik, there's a lot of room for experimentation here to customise foils for certain waves and riders and 3-D printing certainly would make it easy for people to create, share or sell a file.
Some of my foils have 20 x 4 mm holes all over them for testing new mounting struts and they seem to work just fine so I don't think a few 2mm holes will be a problem.
Brett, I see some Bernoulli foil guys pumping the foil to connect to waves behind. Does this flat AOA foil allow that as well?
Thanks for doing this Brett. This is really exciting.
all the best
Personally I'm always ready to learn, although I do not always like being taught. - Winston Churchill
Greg, yes you can pump the flat foils, the shorter ones are easier, even riding prone you can pull the nose up and down to progress the foil. The Bernoulli foils have a quicker 'fall and rise value' so they are more suitable to pumping.