Who dares to suggest a reason for this?

[trux]

Kars, by using a very wide span and a thick foil, you increase the frontal profile, increasing so the horizontal drag seriously. Besides it, at this span, I suspect the flexing will be still serious - do not forget that even a relatively small flexing wil have impact on the efficiency. As for the surface area - do not forget that at a classical monofin, the blade is active only in its part, so taking the entire area for active is not correct. Also be aware that the forces acting on the foil fixation in the middle will be rather serious, so it risks breaking apart if not properly dimensioned and strong enough. These are just some basic thoughts - you sure need to experiment a lot to find out the right solution.

[Kars]

Thanks Trux,

The design is far from being finished, remember it's just a 5 min sketch containing some general principals explored in this thread. As for dimensioning with wood I think it's better to start out with a little over dimensioning and than shave of the abundant excessive wood. The fixation in the middle will be on two points, about 28cm apart on a solid plate in such a way that the wing will behave as one UNinterupted wing.
I'm confident that about 4 to 5 cm (2"!) wood is strong enough to hold the momentum generated over arm of about 47cm.

The surface area (70 x 60 x 2/3 ) I calculated of traditional monofin was mend to chart, estimate, the FORCE a swimmer could apply. I think the effective fin area of such fin is about 70 x 10 cm.

What I hope to achieve is to have a [much] better efficiency due to a [much]more favourable 'effective fin area' to 'ineffective fin area' ratio.
I think the same thing Ted already has achieved with his inspiring Lunocet design.

Secondary I learned that apparently there were rules in the fin swimming sport limiting the length of the wing, traditionally the width of the monofin blade. This together with maximum force swimmers can have on their ankles, coping with the momentum generated by the length and surface of the fins, limit's 'the growth' of the monofins.

This explains also why I would like to have the wing closer to ankle.

Well just been designing again, and it's great fun, though before publishing I need to sleep a night over it. Just like you trux to get a good grasp of what I want in my aqua foil, WaterWing fin. Hell that sounds like a nice brand name! LOL funny how those neurones get fired up, even at such a later hour!

Love, Courage and Water!

Kars

[zerog]

This explains also why I would like to have the wing closer to ankle

Kars! ... you're building a Lunocet!
Salute!

[HJ]

Hey guys... I've reading the Dr. Fish paper generously supplied by Ted:

"Review of Dolphin Hydrodynamics and Swimming Performance"
http://stinet.dtic.mil/cgi-bin/GetTR...c=GetTRDoc.pdf

This paper is unreal. It's got it all. Including a definition of attack angle that shows me the difference between AA and Pitch: "an attack angle is defined as the angle between the TANGENT of the fluke's path and the axis of the fluke's chord." Complete with diagrams. Ted actually explains this in his Glossary, but it took me seeing the Dr. Fish pages to have it finally sink in.

If you want to learn about cetacean swimming kinemetics, body morphology and control surface design, drag-reduction reduction mechanisms, thrust production and efficiency, et al.... read this paper. And it gives the historical perspective on all this.

Yowza!

[Mullins]

I must have a look at that paper...

Something that's bugging me: This may just be me and my weird physiology, but is anybody else able to keep their knees together if the soles of their pointed feet are held at the angle of the Lunocet footplates? I certainly can't, even with my legs straight - and as soon as I bend my knees, they are forced further apart.

Bring on the website...

[trux]

I seem to have certain angle between the soles. Though the angle seen on Lunocet photos seems to be bigger. Would be nice if it is adjustable.

[purple squid]

In the "History of ForceFin" video -- it looks like the monofin foot pad changes it angle to the fin -- is this true -- is it hinged?