Single fin with superchargers

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Anonymous (not verified)

This question is for Herb or anyone else who has experience with this, What do you think about using superchargers on a single fin setup? I'm about to shape a 7' egg and am considering fin options. I'm thinking a 9" Greenough 4c, possibly with side fcs (it's what I have available) or single tabs for superchargers. Another option would be fcs and superchargers, plus the single box. I'm trying to think of a way to be able to use the 2+1 setup or just the chargers and the single. Any thoughts? Thanks- ryancg

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Anonymous's picture
Rob Olliges (not verified)

I'm using MVGs (micro vortex generators) a few inches in front of my single fin box. MVGs are a stick on (super strong 3M tape) small double fin about 3/4 of an inch high. They come in flexible and rigid material. On my son's first board the MVG will replace the center fin and Herb's Supercharger's will be side fins. Rob Olliges http://gosurfgear.com/nscgi-bin/gosurfgearcom/catalog.cgi?Cartid=18481068414958&Department=MVG%20TURBO%20SYSTEMS&Merchant=gosurfgearcom

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ryancg (not verified)

Hey Rob. What are the MVG's meant to do? I know little about the technical aspects of the way fins function. I use Herb's chargers in my shortboard and think I will probably use the box, side fcs, and chargers in my 7'. Many options. Thanks- ryancg

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Anonymous's picture
Rob Olliges (not verified)

The MVGs are supposed to set up very small vortices (swirls) in the water as it approaches the fin. This may allow for a smoother flow of water around the fin and behind the fin. If it works, it reduces drag. Herb's superchargers probably work in the same way by setting up the water to approach the fin and also provide a smoother release and flow of water off the fin. I can see how this effect may be more noticble with side fins which are towed in and are producing a lot more drag than a single fin. The MVGs have been used on the front (nose) of air boards as mini-fins when coming down backwards ("fakie" I think it's called). In that set up two MVGs are used as a center fin (4 mini-fins) and one MVG on each side as side fins. For information on the physics of vortex generators just type in "Vortex" in the Swaylock's search box above. Rob Olliges

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Anonymous's picture
Halcyon (not verified)

Ryan & Rob, Any fin set-up with lead finlets seems to me a credible idea -- singles or otherwise. Here's a few photos the referen the naturals points of in nature. http://www.taxidermy.net/reference/fish/tuna/69a.html http://www.chambers-associates.org/Big-Marine-Fish/photos_yellowfin_tuna_pg1.html I'll spare you the pitch on how long ago she invented it. Sometimes regression is a damn good idea because it yields progress. Mahalo, Rich

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Anonymous's picture
Dale Solomonson (not verified)

You`re right, Rich! Sometimes the fastest way to gain headway is by tacking into the wind... you can get where you want to go, but almost never in a straight line.

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Anonymous's picture
ryancg (not verified)
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Anonymous's picture
Sluggo (not verified)

Dave Parmenter makes a board called the Widow Maker. Basically a single fin with superchargers, works great. Sluggo

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Anonymous's picture
Mark Vin .... (not verified)

That’s not a vortex generator. This is a vortex generator. (See the F18 pictures from the 2003 Dayton Air Show in the link below) A vortex generator for a fin needs to look more like the wing-strake of the F18. The strake is simple, light and effective. The strake promotes attached flow over the wing, which results in a high lift capability and high stalling angle. The strake should work just as well for a fin in water. Such strakes have been water tunnel tested and their performance has been shown to be unaffected by the low Reynolds number flows typical of surf fins. The strake is effective to some degree with all fin planform types, and is most effective for moderately swept planforms. The strake is shown to be just as effective on a thin or a moderately thick fin. The strake may at times develop a cavitation vortex off the fin, but I do not expect this vortex to be detrimental to the fins performance or general capabilities. (We will see about that.) The existing vortex generators and canards used for surfing fins are not very well designed. The vortex generator needs to have a span about 0.2 to 0.3 of the main fin, and it needs to be of very low aspect ratio so that a strong tip vortex can be generated. If the fin-strake works as promised, it will be a major step forward in fin development. I wonder why the kiteboard fin manufacturers and surfboard fin manufacturers haven’t worked this one out, as some companies actually make both kiteboard and surfboard fins. Try it for yourself. A strake is simple to make. Get a “T” section alumin(i)um extrusion of 2mm section width. Shape the strake with a file. It is not necessary to make the strake edge sharp, just rounded. Thanks, Mark http://www.richard-seaman.com/Aircraft/AirShows/Dayton2003/F18f/

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Anonymous's picture
mark spindler (not verified)

interesting photo of the f-18 fighter. i cant compare the effect of the strakes on that plane to the mvg (multi vortex generator) i developed. i suspect they work in different ways. perhaps they are vortex eliminators. after all jets work at much higher speeds than surfboards. as i have said all along i got my idea from observing the finlet arrays on tuna and mackerel. i asked my brother, who is a fluid physicist complete with Ph.D., what he thought the finlets on the tuna did for the tuna and he said perhaps they worked as micro vortex generators. this was back in the fall of 97. i got in touch with nasa and harvard and spoke with the top nasa mvg design engineer and the harvard mackerel researcher. i spoke with them both about micro vortex generators and tuna design. from one i was told you cant go wrong imitating the creator. the other i introduced the words "contributing flow" to her research. design and concept wise my mvg is more like the mvgs on the wings of the boeing 737, which are small triangular aluminum finlets about 20 or so to a wing. i put some curves on mine for several reasons. one, though water and air are both fluids water hates a straight line and refuses to stay attached. second, straight fins dont look good on a surfboard and because i figured i had an uphill battle to get a new concept introduced i thought i'd make it look a little familiar. i really didnt think anyone would be drawn to a simple triangle, but that was the shape i used i my first prototype mock-up interestingly, as i have shown mvgs to just about every name brand board and fin shaper in the industry the one remark i most commonly heard was "nice foil". which indicates to me that there are certain things surfboard shapers are accustomed to look for. lastly, i shaped them in much the same shape and dimensions as the tuna finlets. my thinking was if it worked for the tuna who was i to improve on 4 million years of evolution. surfboard speeds have yet to reach 65mph but that information hasnt stopped the tuna from reaching or exceeding that capability. maybe someone should tell them their mvgs are designed poorly. maybe that'll slow the buggers down. however my next generation mvg is much different and sets will be ready very soon for pro testing this winter. btw regarding fillets on glassons, the navy has added fillets to the conning towers of their subs. in fact if you were sitting on your board in the ocean and a sub passed 10' under you, you would not even know. the navy has put all kinds of silencers and turbulence eliminating devices all over their subs. so for glassons as long as the fillets arent gargantuan they are effective at reducing the turbulence of the base of the fin. that will decrease drag and therefore increase speed. maybe not noticeably but conceptually. one more thing, Greg Loehr's Resin Research epoxy has taken all the work out of it. you dont even have to think about it. RR resin is the best thing that has happened to surfboard construction since foam. He's also the best of the best shapers. you should all be totally stoked that he's already done the leg work for you and you should be requesting Resin Research for your next board. and then you should be sitting on the edge of your seat to hear what he's working on next! mark

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Anonymous's picture
Mark Vin .... (not verified)

Mark S. The MVG people and Herb S must be congratulated for developing and promoting the system. I would encourage this work to continue. The field is wide open. Please accept that I am expressing a view. I do not wish to debase your efforts. You may be interested to know that a major surf fin manufacturer rejected the vortex generator fin design which I proposed. They know best. As for water tunnel testing, did you know the Australian Government bought six Collins Class attack submarines off the plan without having done any water tunnel testing at all. The Australian Government then spent hundreds of millions of dollars fixing up the problems because the submarines sounded like "a rock-concert underwater". The Australian Government also then gave Fin Control Systems a research and development concession, reportedly valued at one million dollars, to improve fins for surfboards !! If you are interested to know more about straked-wings/fins then try these articles for starters. The Journal of Aircraft, Vol 17 - No 1 page 20, and Vol 16 - No 11 page 756. Thanks, Mark.

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Anonymous's picture
Rob Olliges (not verified)

Thanks Mark (both): Thank you for explaining you MVG development. And thanks to Mark Vin (Fin?) for provoking some decent discussions recently. You may want to search the archives if you haven't done so already. Fins tend to spark the most heated discussions in surfboard design. Very few of us are hydro- or aero- engineers yet we tend hold on to strongly help positions as though we are. We also seek knowledge from nature and from scientific journals. Most of us take aeronautical information designed for a different media and for much higher speeds and misapply them to slow moving surfboards. I suppose the interest in fins is because they stick out. These little appendages hold are attention and define us as a "type of surfer." In 1985 to ride a single fin shortboard was to suffer ridicule. Riding a multifined longboard now sets you apart from the more traditionalist. When you spot a surfer on the beach we unconsiously look to the fins to try to figure out what kind of person this is. Still the work on fins must continue. They are imperfect: they create drag, they can be dangerous, some catch seaweed and leashes, fixing them to the board has various considerations. Let every Swayaholic resolve to create an innovative fin or two in the next year and report our findings for the interest and betterment of our art. Let's get to work, Rob Olliges

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Anonymous's picture
Halcyon (not verified)

Mr. Vin, The strakes on the F-18 -- are these the cylindrical looking affairs protruding off the wing tips or the long low sloped triangular wing protrusions the begin under the canopy and finish at the leading edge of the wing. I'm fairly certain you refer to the later. Put them on surf fins? Ask yourself: How this would affect direction change? The answer is obvious. the board would be impossible to turn. Bullet like appendages on the end of the fin. No, that's not worth considering. Either addition would be hindrance and unneeded. (Consider lapstrak boats yaw less than smooth hulled boats because the strakes reduce this motion, why would a surfboar be any different. Freedom of motion is the theme a surfboard is built around.) Am I completely amiss and the strakes you refer to something else entirely and my questions those of a cave man? On the other hand fin-lets like Herbs superchargers are very sensible way the imitate nature and accomplish more speed in much the same was the most free, and fastest tuna does. To mantain a proper perspective one must remember that airplane wings do very different things than surfboard fins do. Granted there is a crossover because the lift and drag they both produce are what makes them function efficiently but airplanes are propelled by a prop or by trust in a neutral fluid atmosphere while surfboards plain on a viscous fluid surface and are directed and driven by the fins beneath them the hull shape these fins are attached to. These are very different sets off circumstances to address. One might consider the surfboard a much less sophisticated vehicle than an F-18. In some ways it isn't; in some ways it is. The one that charms you best is the one that holds your eye and is hidden under a most graceful skirt. Mahalo, Rich We reveal what we don't know by what we say.

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blakestah (not verified)

I agree wholeheartedly in the limitation of the wing analogy - but the tail analogy with the tuna is a lot closer. The real issue is whether MVG has a substantial impact at the speed in question. They could be critical at 50 MPH on a tuna, but irrelevant at 15MPH on a surfboard. I think they are also different from the twinzer or supercharger design. That is more like a double-wing. It allows attached flow at greater angles of attack by having two fins in parallel. Not the same as the MVG, which sets up flow heading into the base of the tuna tail.

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Anonymous's picture
mark spindler (not verified)

blakestah the physics of the tuna swimming motion is a lot more complex than current physics math allows. i have the reports from jennifer nauen at harvard. however i can say that my mvgs work a little different than the tuna finlets, but with much the same result. the tuna has an articulated body, and nature has accomidated this by allowing the finlets to swivel. that is they can move much like a sail on a mast. they can also move individually or as an array. therefore no matter what angle the caudal (tail) fin is in relation to the finlets they can allign with the tail to contribute flow. this differs on a surfboard as the board is inflexible. but the mvgs are inflexible too so they remain for the most part linear to the flow. what little out of line they do get allows them to produce and contribute the micro vortex to the lee side fin and thus contribute flow in the form of a jet into the turbulent bubble reducing drag in a turn. visualize that. next, here's something to ponder. way back in the 70's scientists theorized that according to what was then current theory of flight the common bumble bee could not fly. well obviously it was the theory that was wrong because the bee could in fact fly. basically what they failed to realize at the time was that to the bee air was like a viscious liquid. so while yes the tuna goes 50+mph and the surfboard 15-35mph one may question the effect of the mvg on the lower speeds. well i say the tuna has to go through a full range of speeds from 0-50 and i believe the finlets assist at all levels of this speed increase and maintenance. maybe it's our theory that has kept surfboards from reaching the 50mph mark. but perhaps everyone is completely satisfied with their current boards. keeping in mind that the tuna has a lot of other things going on that assist in swimming, too complex to mention here, there is one test that would be telling. how fast can it swim without finlets? given that the latest research indicates that fish can feel pain i doubt this test will ever be allowed. but if the tuna doesnt need them why after 4 million years are they still there? regardless here's one statistic for ya'll, the atlantic bluefin tuna has been clocked at speeds in excess of 50mph and water is 800 times denser than air. also, it's not nuclear powered and doesnt require a crew of 200 highly trained sailors and techies to operate. that's enough for tonight, but i leave you with this one final thought, today i got a request from mvg team rider, aerial pioneer, and inventor of the air 360 john holeman who just today asked for more mvgs because he's back in the water and surfing again. honestly i and a lot of people besides myself prayed for this day and i for one couldn't be happier. mark

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Anonymous's picture
Tubedog (not verified)

Do you put your MVGs on the side fins of a thruster? If so, in line in front, or to the side? Or just in front of the center fin?

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Rob Olliges (not verified)

Super stoked to hear John is in the water again. Soon to be seen in the skys above Sebastian. Rob Olliges

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Anonymous's picture
mark spindler (not verified)

tubedog john holeman rides twins, so there is no trailing fin for him to put the mvg in front of. however, a couple years ago john came up with the idea of putting one directly in front of and in line with each of the side fins. he put them about a thumb width in front. john said he gets at least 15% more speed, faster acceleration and better recovery speed after landing an air. i finally tried his set up a couple weeks ago. (i'm a a slow learner. lol.) i have a 2 1/2 year old greg loehr tfs twin fish and i had taken the mvgs off to repair a cracked fin box and decided that instead of putting the mvgs back where greg originally did i would try john's idea. it was fast, tracked high very easily, turned easily (too easily at first but i got it down) and because it tracked high and pulled the max speed off the top of the wave i could see why john liked it set this way. so there you have it, tubedog. mark

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Anonymous's picture
Greg Loehr (not verified)

Mark, Glad to hear John is doing so much better. Somehow I knew he couldn't be kept down for long.

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Anonymous's picture
Tubedog (not verified)

What is your positioning of mvgs on the side fins? In-front in-line, or off to side? If to the side, how much away from main side fins? Thanks-

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blakestah (not verified)

So you'd presume the MVGs on a tuna are there to aid water flow heading into the tail... and not to promote reattachment of flow coming off the rapidly tapering body height in the rear half of the fish? http://www.flmnh.ufl.edu/fish/Gallery/Descript/BluefinTuna/BluefinTuna.html This is kinda important - the vast majority of MVGs are rearward of the leading edge of the foil. They act on flow re-attachment in the draft or rear of the section, where water needs to re-attach. In airplanes, they disrupt flow at the leading edge, so that it is more disturbed coming off the rear of the foil, and separated flow is minimized at steeper angles of attack. http://www.microaero.com/pages/v_howvgswrk.html I kinda think the tuna MVG fins are there to promote re-attachment for water coming off the body, and have little to do with the actions of the rear tail.

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Halcyon (not verified)

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

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Anonymous's picture
blakestah (not verified)

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).

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Coastalsurf's picture
Joined: 12/03/2010

Mark are you still around with those fins ?

We really would like to get that fired up again.

Thanks Coastal Surf Supplies

1-888-569-7038

Please call us asap

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TunaFin's picture
Joined: 11/18/2016

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.

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