Ok I give up, why are the leading edges of kite and windsurf racing fins sharp?
windsurf fins have been around for ever, so I suspect it's been proven faster just can't figure out why or see any research on the topic.
Each fin I looked at aren't just thin rounded leading edges, they F'n SHARP!
In the aircraft world everything subsonic region is a rounded leading edge, because it has less abrupt stall characteristics. and the laminar flow is less likely to be disturbed by small changes to the angle of attack causing drag. Watching kite board racing, the board is all over the place in the chop and there is no way these things a rocking a steady AofA.
a sharp edge can create low drag but this is typically only at AofA of zero
The fins on a race board are symmetric and generate lift from the drift angle, no way these things are operating at zero AofA
Sharp edges has advantages in supersonic flow by preventing bow shock and wave drag in front of the aircraft in supersonic speeds. So is often what is found on fighter planes and supersonic aircraft but NOT on subsonic craft.
any windsurfers care to elaborate on the evolution of sharp LE fins?
or is this just cuz windsurfers and kite racers are a bunch of monkeys?