I can’t find any head to head comparison for those new very high aspect foils ( Code, Lift, ART, Gofoil, F-one, etc).
Curious to know esp in the sub 1000cm² the comparison for glide, speed, turning abilities, stall speed.
Numbers mean nothing anymore.
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Wow didn’t realize this was even possible… how does this translate to prone?
Even some of the the DW race guys are running tiny kitefoil race gear now. Just wild how efficient some of these foils (and riders) have gotten.
Axis classification by span makes the most sense in comparing. But there’s no comparison/classification for foil profile which is equally important IMHO
What we actually want to compare foils aren’t numbers describing the shape, but numbers describing how it performs.
I think Sabfoil gives the most performance data of any manufacturer, a speed range for a single rider weight.
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I ride Code. sell code.
but also test lots of foils in the range of lift, north, mikes lab, Armstrong,
Lots to talk about, but you cannot look at area of a foil and think its going to be similar to another foil ina different range at the same size. there is so much to look at in terms of how a foil will ride, glide. Testing is truly the only way. Im always free to chat about it.
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If we can’t compare any of the numbers (wingspan, area, aspect ratio, etc), I’m trying to imagine what a quantifiable test would actually look like.
I’m picturing a flume tank, with variable flow speed. The complete foil setup goes in the tank, and you can set downward load (rider weight), measure horizontal load (drag), and control pitch (angle of attack of the board).
So the test looks like:
Set the rider weight.
Start up the flume flow, and slow raise it from zero to some maximum. (The faster you want to flume to be able to flow the more expensive it will be, and eventually you hit cavitation/ventilation limits of the foils.
Auto-control pitch to hold foil depth steady. Probably standardize the board height above the water surface.
Re-run the test with a bunch of standard rider weights.
The output would be a bunch of curves. X-axis is speed. Y-axis is drag. Each line on the chart is for a different rider weight. The start of each curve would show takeoff speed. Lower drag would be what we describe as “glide”.
The hardest part might be designing the mechanical linkage to keep the hydrofoil stable in the tank? The safest thing would be to ditch the board, just bolt the baseplate right to the testing linkage, and fix the setup in roll and yaw. Only allow up/down movement, pitch, and forward/rearward would be fixed by a load cell for measuring drag.
What am I missing? What would control the “top speed” of the foil, for the test? Cut of off when it ventilates/cavitates? Or when drag hits a standard level?
Would we need a way to apply the vertical load through the baseplate at different forward/rearward positions? I guess with two vertical actuators, both along the centerline, offset forward/rearward of each other, you could control pitch, apply the vertical load at any effective balance point, as long as the net vertical of the two actuators is always feedback-adjusted to the target rider weight?
I think a flume tank will be very difficult to build with consistent flow over the entire foil. Much better moving the foil through still water than trying to move the water.
I’ve thought about this before and came to a servo (or otherwise well controlled) motor driving a takeup reel/drum with a long rope. This takeup reel would be mounted on a linear rail with a force gauge. Rig up a catamaran out of two downwind boards, with the foil suspended out in front and between the two “pontoons”. Then start pulling the contraption through the water towards a dock, controlling the speed with the speed of the motor and measuring the drag force.
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I admit that my flume tank would be impractical. We would need to partner with a serious engineering university, and tank time isn’t free. Most university flumes aren’t wide enough, deep enough, or fast enough.
How about we bolt this testing apparatus to the side of a powerboat? Most modern waterski tow boats have cruise control (automatic speed control). I’m picturing a long plank, strapped to the boat, and extending out sideways on one side. Maybe add weight onto the plank, equal to synthetic rider weight, so that when the foil is taking that much vertical load the boat rides level in the water? In that way foil-pitch, vertical load, rider weight, and foil depth could all be combined?