Lumpy leading edge whale fin improvements:
8% more lift
32% less drag
40% greater AOAs before stall
This is new stuff:
Larger/more readable images:
Wow!
Wow is right. Serrated leading edge looks like a lawsuit just waiting to happen.
Aw, geez, my fins already look that way, dimpled & lumpy.
Not intentionally, it’s just my crappy construction techniques!!
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Wow is right. Serrated leading edge looks like a lawsuit just waiting to happen.
Not serrated; knobby. I was thinking rubberized knobs like bumpers. Safer.
Serrated would be bad. Tom what happened with Bassy. Send me a message.
Excellent find!
How’bout the May issue of “Physics of Fluids”?
Patent # 6,431,498
Scalloped wing leading edge
Abstract
An apparatus to modify a wing to provide increased lift over drag ratios compared to similar wings with straight leading edges. For wings extending in a lateral direction, and defining a longitudinal upstream direction, the apparatus forms a laterally extending leading edge facing in the upstream direction. The apparatus forms a plurality of protrusions spaced laterally along the leading edge, the protrusions creating a smoothly varying, alternately forward-and-aft sweep along the leading edge relative to the upstream flow direction along the leading edge.
The present invention appears to function by altering the typical aero- or hydrodynamics occurring over an airfoil. In particular, in cross-section a typical airfoil will have a stagnation point on the leading edge, where the fluid particles have zero velocity with respect to the airfoil. In front of the stagnation point is a stagnation region, where the fluid has negligible relative velocity. The reduction of the relative speed to zero creates a significant pressure on the wing, and therefore, a significant amount of drag. On a typical wing, a line of stagnation points are thus present longitudinally along the leading edge of the wing, creating a line of high static pressures along the leading edge of the wing. Airfoil drag in a viscous fluid can be reduced by decreasing the size and strength of high static pressure regions. In other words, lower leading edge static pressures improve airfoil leading edge suction. In the present invention, preferably one stagnation point exists at each peak and trough along the leading edge, while the remainder of the leading edge experiences lower static pressures.
references
Fish, Frank E., “Performance Constraints on the Maneuverability of Flexible and Rigid Biological Systems,” Proceedings of the Eleventh International Symposium on Unmanned Untethered Submersible Technology, Aug. 1999, pp. 394-406.
Hoerner, S.F., “Fluid-Dynamic Drag,” Leading Edge Devices, 1965, p. 19.
Fish, Frank E., “Imaginative Solutions by Marine Organisms for Drag Reduction,” Proceedings of the International Symposium on Seawater Drag Reduction, 1998, pp. 1-8.
Fish, Frank E. and Battle, Juliann M., Hydrodynamic Design of the Humpback Whale Flipper, Journal of Morphology, 1995, pp. 51-60.
Bushnell, D. M. and Moore, K. J., “Drag Reduction in Nature,” Annu. Rev. Fluid Mech., 1991, pp. 65-79.
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Excellent find!
How’bout the May issue of “Physics of Fluids”?
I work near MIT so may pick it up next week. Brother works for AirForce and can probably get it faster. Look for the full report next week. The journal’s online but I’m not affiliated with their networks.
http://scitation-alt.aip.org/dbt/dbt.jsp?KEY=PHFLE6&Volume=16&Issue=5
Abstract:
Leading-edge tubercles delay stall on humpback whale (Megaptera novaeangliae) flippers D. S. Miklosovic Aerospace Engineering Department, United States Naval Academy, Annapolis, Maryland 21402 M. M. Murray Mechanical Engineering Department, United States Naval Academy, Annapolis, Maryland 21402 L. E. Howle Mechanical Engineering and Materials Science Department and Center for Nonlinear and Complex Systems, Duke University, Durham, North Carolina 27708-0300 F. E. Fish Department of Biology, West Chester University, West Chester, Pennsylvania 19383
(Received 11 December 2003; accepted 2 February 2004; published online 15 March 2004) The humpback whale (Megaptera novaeangliae) is exceptional among the baleen whales in its ability to undertake acrobatic underwater maneuvers to catch prey. In order to execute these banking and turning maneuvers, humpback whales utilize extremely mobile flippers. The humpback whale flipper is unique because of the presence of large protuberances or tubercles located on the leading edge which gives this surface a scalloped appearance. We show, through wind tunnel measurements, that the addition of leading-edge tubercles to a scale model of an idealized humpback whale flipper delays the stall angle by approximately 40%, while increasing lift and decreasing drag. ©2004 American Institute of Physics
whale fin bumps are good for flapping wings, tic tac? … the bumps are the size of a fin, a fin is a bump?
There it is. Old news, but glad to see someone did follow up. Now can anyone see why I said pimples? A+ Rob.
Tom Carroll did it with surfboard wax on his fins years and years ago. TC’s a rad genius.
Thanks to all who answered my (daddio) post!
Lawless,
Thanks for your input - we’ll try carbon.
Wells,
We’re trying to lose toe-in altogether with that design…
Blakestah,
Do you have a photo of the Bonzer fins from the front - at about water level, OR do you see the outside face, inside face or neither of those four fins?
Roy,
You inspired us - mini tunnel fin at the top!
Halcyon,
After reading your post - the tuck-in fin will be in the keel position and with pressure on the rear footpad will drop down to pivot fin position (if I can draw it - it can be made!)
ps. I saw your first shape on the other thread, yeah man.
You know who,
When I was a young’un (same age as my son) I asked my father, who never surfed, about fin designs, what would work and etc. He said, “Let’s take your old belly board for a ride in the Mercury wagon.” We got up to 25-30 miles per hour on a back road, he had me open the side windows and told me to stick it out there. Even at that slow speed I had trouble keeping control of it and it banged the side of the car before I could pull it back in. Then he took it up to 50 mph! Stick it out now…as soon as I poked it out the window it ripped out of my hands, spun up into the air at least 20 feet and flipped over and over with a series of shattering crashes. My dad was laughing his butt off so hard he was crying - “Did you learn anything son?” Duh…
If I was thrown out of a tall building I’d rather be a rat than a human.
If I was an ocean mammal I would rather be a Dolphin than a Humpback.
If I was a surfer I’d rather ride a …
Mark,
I noticed that the “CONCEPT of bumpy leading edges is patented by Mr. Fish”
For a vortex generator that you could use see drawing…
So next time I’m at my local break and see the humpback detotees making those 30 percent sharper turns to hunt herring and sardines, my hats off to ya.
Bert,
What is the planning width, length and thickness for a 240 pound shortboard surfer? (small and larger waves, if you please)
Mark,
You do of course realise the story about Tom Carroll with wax on his fins was just a cruel hoax played on an impressionable grom/future surf journalist don’t you?
yeah Ben was amazing we would test the fins sizes etc and he would spend time on the small things the leading edge had to be right…yeah the americas cup was his peak I think anyway…the star-fin was his contribution to surfing…I love it is still a major part of my quiver…Im using 1 of his designs at jaws that goes fantastic…so far zero hydro planning which i havent had before…this gives me confidence to getting deeper…are yu still in perth…were u near the shark attack last week?
Hi Cheyne
I left Perth back in 88 sailed north and around oz
built a new boat in Darwin then headed north again this time indo ended up in England via the French canals
worked there for two years,after all that cold and not enough waves I told Julia it was time to go
So we did the rest of the world and are now in Auckland NZ .we still have the boat (ready for a quick getaway)
but now have two kids that have seen the world a house and land two cows five chickens etc
The good part is I got to surf all over the world and now live just 5 mins from the beach so I still get a wave 3 to 4 times a week
Life has been pretty good to me i think
regards Mike
"Post: Mark,
You do of course realise the story about Tom Carroll with wax on his fins was just a cruel hoax played on an impressionable grom/future surf journalist don’t you?"
Paul, I quote from the forum rules:
Finally, a few good ideas:
- Substantiate your claims.
-m
http://www.appliedfluids.com/UUST01.pdf
http://biomechanics.bio.uci.edu/_html/nh_biomech/whaleturn/whaleturn.htm
http://www.pratt.duke.edu/Newsletter/story156.html
So the question is: construction techniques???
Aren’t those tubercles like 6 inches to a foot wide each?
I’m getting humpback whale lengths of 12-14 meters, and main flipper lengths of 25-30% of that, or 10-12 feet.
I guess this would pose a substantial challenge - does the micro-vortex generating function of the humpback tubercles miniaturize?
Also, humpback speeds are not so far off for surfing, a little slow, but covering most of the smaller wave range.
Mark,
Would love to see you substantiate the claim.
How about a photo of Tom Carroll with the wax lumps on his fins?
But seriously Mark, don’t let my snide remark distract you from working on this idea, I feel that it may have great value.
I would just rather see you looking to nature, the previous work of Tom Morey, the scientific data that I know you have and your own intuition rather than on a little trick played on (I seem to recall) Jamie Brisick, who ironically went on to become great friends with Tom Carroll. And on the numerous times I saw them surf together and checked out their boards, there was certainly only wax on the decks.
PS We have all seen the commercialy available fins with lumpy trailing edges as per the humpback whale around over the years, does any body have any feedback from trying them?
"I guess this would pose a substantial challenge - does the micro-vortex generating function of the humpback tubercles miniaturize? "
I’m thinking it’s more a question of degree not of kind. How about you? Perhaps the term “Vortex Generator” is sufficient.
I was more thinking the efficiency of the micro vortex generation would have some dependency on tubercle size. Those on the humpback are certainly too large to be expected to work similarly on a surfboard fin. However, you could try to scale it down, it might work.
By chord length, maybe 1/2 inch tubercles for fins?
As a fraction of foil length, between 1/2 and 3/4 inch?
If rolliges makes one, and it is rideable, I will follow suit quickly.
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If rolliges makes one, and it is rideable, I will follow suit quickly.
Hah, don’t hold your breath! This is the year of cancelled (or hurried) projects for me.
Plus, almost anything is ridable. I could put some gum on my existing fins. OR some finmaker could allow resin to drip off the leading; sand and go. Somebody come up with something for the SA meet.
Sorry, it’s not on my plate.