35th Americas Cup: Foiling Multihulls!

Doug the bump on the leading edge of the foil could be from the work of Dr Fish (true name) http://www.whalepowercorporation.com/p/tubercle-technology_24.html

 

That Oracle video was an abysmal and beyond embarrassing sort of 1950's Soviet newsreel propaganda.
However the leading edge foil bump is sort of interesting amongst all the cringeworthy defecation.
Seeing there was zero humour, just smiley faces and vacuous BS, maybe the bump is the real deal, and not a joke plant (although it appears a last minute addition) to play on the minds of the uninitiated?

 

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Thanks! I've seen some of his work and/or copies-for instance on one of the new IMOCA boats rudders.(see PRB rudder below below) But I have never seen just a single tubercle used on a foil until that Oracle video?

click for better view:

 

A single tubercle ist only to be used on very fast boats to limit a cavitation bubble in speeds over 35kn.

 

Thanks, Manfred-do you have a link that discusses a single tubercle for that application?

 

German "YACHT" Nr. 6:
The tubercle has to avoid the sudden and total loss of lift at the foil.

 

Wow! Thats impressive-thanks very much!

 

Hi Doug, I was busy to look for scientific research comparing a foil with tubercles with a normal one without them. Here it is what I`ve found: http://buckelwalflosse.de/Docs/SA_Bruno.pdf .
You will find there some CFD figures indicating the flow of water and air on the foils at different angles of attack:



Compared with a normal foil (please have a look at the pic) the one with the tubercles has 6,5% more drag.
At an angle of attack of 10° the lift to drag ratio of the foil with tubs is 30% worse compared to the normal one. At 20° the ratio is 24% better. There is no remarkable difference in water and air.
For a hump back whale traveling in very high Reynolds numbers of 10*8 (10 hoch 8) and a lot of spare energy the 30% at 10 deg are no problem.
I think there has to be a lot more research to decide where to use tubercles (rudder, foil, helicopter, turbines, wind energy and so on.).



The importance of the other tubercles at the head, body and tail of the whale has not been researched.

Here you will find a lot interesting publications: http://darwin.wcupa.edu/~biology/fish/pubs/index.html and
http://darwin.wcupa.edu/~biology/fish/pubs/pdf/2004PF-Megaptera.pdf
http://darwin.wcupa.edu/~biology/fish/pubs/pdf/2011ICB humpback.pdf
http://darwin.wcupa.edu/~biology/fish/pubs/pdf/2004PF-Megaptera.pdf and more!

 

35th AC---tubercles

Great stuff, Manfred-thanks!

 

I think that when the hulls are over the water is greater air resistance. Little foils and planing hull with transverse stepped shoud be better.

 

35th America's Cup on Foils---Oracle

Jimmy Spithill interview from Scuttlebutt and Esquire:
http://www.esquireme.com/content/15347-interview-jimmy-spithill

 

For the show better would be if the boats could sailing in all power of the wind. It should be possible reefing sails. I have some drawings for planing and foiling proa with canting (flying) keel and reefing soft wingsail:

 

Living life to the fullest.

 

35th America's Cup on Foils! UK

Jack Griffins "Cup Experience"-- check out the new rudders on the new UK test boat:
http://us5.campaign-archive1.com/?u=5b22acb550cbb7053ea617522&id=46376e91bf&e=bd814531ed

 

35th America's Cup on Foils!

Martin Fischer(Team France) on foil design for the AC:
https://translate.google.com/transl...fisher-une-choregraphie-du-vol-coupe-america/