Blackstah, I have to agree about with you about the notion that the MVG on the tapering part of the tuna's body are there to reattach that trailing edge to the water. What seems to be going on to me is a very sensitive steering device along with the MVG affect for the tail -- a double function if you will. I thing there is a tremendous amount of multi tasking going on with the fin cominations that cannot be approached effectively on a surfboard. Herb's supercharger placement seems an attempt at both vortex generation and sloting, which makes perfect sense to me. Mahalo, Rich
For an MVG to work effectively doesn't it need to disrupt flow on both sides of the foil? All the flight, and the tuna, analogues do this. I look at the superchargers or twinzers and see the smaller fin directing somewhat disrupted flow into the lee side of the fin. As a micro-vortex generator it is not very micro. But improving lift:drag ratios at steep angles of attack is clearly the benefit. It could be that the central fin acts as a canard on tri-fins, making the supercharger benefit less desireable there. It will stall before the outside fin will, and it's stall will serve to prevent further increases in angle of attack. (I understand a canard is normally in front of a wing, I was just making the analogy that the canard stalls before the main wing, and in doing so rotates the body so the main wing will not stall. And the central rear fin on a TRI has a similar effect).
Mark are you still around with those fins ?
We really would like to get that fired up again.
Thanks Coastal Surf Supplies
Please call us asap
I was given a set of finlets some years ago by Glenn DeWitt at Rainbow fins, and I finally recently stuck the pair in front of one of my TunaFlex Fin.Drive.System. single fin retro models. I’ve been working on developing my surfer driven fin design for some time, and I am approaching an entry into the market place. The fin system makes use of the basic physics involved in the turning of a surfboard and transfers the force applied to directional change directly to the fin. A flexible fiberglass rod housed in a sleeve at its forward tip and dressed with traction tiles acts as a pressure plate tiller. The harder you apply a force to turn the board, the more directional ruddering you get out of the center fin, up to about 3*. I think it is the real deal; enough so to have undertaken the time and expense to get a patent.
anyway, I really like the way the board with the finlets feels. I’d like to revive the idea.