Select to expand quotekeef said..
Hows the head swell fagman that NM is as good as it gets , all the passion and pain on a project that finally paid off, living the dream man??
www.gpsteamchallenge.com.au/sailor_s
Absolutely Keef! I am totally stoked to get to 35 knots any time, but to do it for a NM! Still buzzing a couple of days later 
( Thank goodness most of the doors in this house are double doors, otherwise it would be expensive getting my scone inside atm)
Look at at all those PBs!!
35 nm Fangy
thats what I call a payoff for all that effort and well deserved!!
Select to expand quotewaricle said..
Look at at all those PBs!!
35 nm Fangy
thats what I call a payoff for all that effort and well deserved!!
Damn it, my head just exploded Thanks Waricle
Very interesting Ross, I lasted 10 minutes of the video. When I put a fillet on this fin the other day I thought I would leave the excess bog at the back and sanded it up as part of the fillet. Do you think think this will act as a cut out or part there of without cutting into the fin and weakening it.
Swindy, I don't know the answer. My thoughts are that the extended fillet is a good idea and beneficial. It possibly maybe as effective as a cutout. Certainly in the situation of a steady flow state and angle of attack, I think a well formed fillet aft extended will be quite effective. Maybe under 'shock loads' that might occur in chop hopping its ability to tame flows maybe challenged.
The faux cut out that results from the extension of the fillet aft, will not have any positive affect. The cut-out must occur before the trailing edge in order to shunt ventilated flow through to the leeward side before it gets attached to the trailing edge.
My only concern with the extended aft fillet is durability. In my clumsy hands I would be likely to snap them off when rotating the fin out of the box at the end of the day.
Well explained mate that makes things much clearer. If it works well I will re enforce with some glass as resin and q cell mix isn't very strong.
I have been having some issues with Starboards and their tuttlebox bolt placement being slightly different from the patented design. This results in the bolts being loaded at an angle, exacerbated by the fact that the fangyfins are threaded immediately from the surface down and Starboards' with short bolt length. If anyone orders fins with a Starboard in mind, I will discuss with you personally how we will address the issue.
I have also been pondering whether the level of finishes on the fins that I offer is the best it could be. I have changed the Standard finish from a 400 grit to 2000 grit. I hope to get my hands on some 5000 grit soon and will use that as well.
I am happy with the performance of the Delrin bolt nuts, so I will continue their use in addition to directly tapping the aluminium itself.
Details here: ( but beware of my super slow server - patience grasshopper :-)http://www.fangyfins.com/assets/player/KeynoteDHTMLPlayer.html#9
To finish: A MASSIVE THANK YOU to all those people who have supported Australian manufacturing and design jobs. I don't know of any other comercially available fins that are 100% designed and made here, so feel proud that without your support it would still be just a good idea, and more importantly, the foundry I use may not have survived. As always, I am totally committed to putting smiles on dials, so if you ever have an issue with one of my fins, I will sort it.
I had to map out the ideation and analysis process of Fangy Fins as part of a Uni exercise. I am sure I missed out a fair bit, but I ended with a pretty picture so I thought I would whack it here, just in case anyone else wants to one ;-)
Select to expand quotefangman said..
I had to map out the ideation and analysis process of Fangy Fins as part of a Uni exercise. I am sure I missed out a fair bit, but I ended with a pretty picture so I thought I would whack it here, just in case anyone else wants to one ;-)
Did your environmental impact study take into account noise pollution to your neighbours.
Select to expand quoteSwindy said..
Did your environmental impact study take into account noise pollution to your neighbours.
Nah. They stopped complaining once the concrete shoes set.
Select to expand quotefangman said..
Nah. They stopped complaining once the concrete shoes set.
I have a feeling concrete isn't very environmentally friendly. Something about letting lots of carbon loose during manufacture
The FF22 patterns are nearing completion, they have been CNC machined from Necuron by Swoosh.
Same again below showing the two inner core box patterns, next to the core box for the fin foil itself. Stuff is happening, fangyfin22s are on the horizon soon :-)
Somewhat belated contribution to the discussion on page 1 about drag etc.
Not having read the whole thread above, but on the topic, I believe spanwise lift distribution has a whole lot to do with induced drag. i.e. the way the lift distribution "tapers" off towards the tip of the fin, affects the strength of the tip vortice and the amount of induced drag produced (sorry if this is obvious). Three ways I can think of doing this off the top of my head:
- Twist, i.e. what we see in sails, and I believe some aircraft wings also may take into account aeroelastic behavior to benefically reduce drag during certain flight regimes. Also people also try stuff like flexible wings in F1 (although its technically banned). Probably not going to be effective with the aluminium fins, but possibly something worth testing in composite fins, especially with the ability to tune the stiffness with fibre orientations etc, I'm sure this is something they probably do in americas cup foils etc.
- Plan shape, stuff like elliptical planforms etc.
- Changing aerofoil profiles, i.e. having a high lift profile nearer the root of the fin, and a lower lift profile towards the tip.
For fins, I think most commercially produced fins only tune the plan form. Maybe there is also benefit in tapering the As with everything, there are tradeoffs everywhere and I think a lot of the fine tuning results in single digit % gains.
www.aero.us.es/adesign/Slides/Extra/Aerodynamics/Design_Wing/Chapter%205.%20Wing%20Design.pdf
And just a few words on the CNC moulds.
The CNC is a shapeoko XL, just under $3k landed including buying the spindle (in my case a Makita Laminate Trim Router). Can machine foams, wood, plastic (things like nylon, acetal etc), even engraves aluminium, and can cut aluminium too, but you have to take it pretty slow. I do some engraved rowmark and aluminium labels, as well as some plastic parts for work with it (they were too cheap to buy an engraver, but not too cheap to pay someone else to do it??). ->carbide3d.com/shapeoko/
The CAM software I used is Autodesk Fusion360. Available free for non-commercial use. Use this to tell the shapeoko how to cut stuff. Shapeoko does come with software to make some simple 2D stuff, but once you get into 3D parts you need something with a bit more capability, and Fusion360 has a pretty decent following in the hobbyist arena. I can make the files public for people to view if they are interested (benefits of cloud based software I guess...).
The Material is Necuron 651. It was just under $400 for a 1500x500x50mm board. Its basically a polyurethane modelling board, fairly widely used in the industry. I ended up using a full board for the moulds for Fangy, however there were a few mistakes made etc, ideally next time I'd probably use less than half a board. Or at least use the 25mm thick board.
Main advantages are that it is dimensionally stable and machines really nicely without any dust. Alternatives are to use something like wood or mdf, but MDF is allegedly hard on machine tooling, and the worst thing is the amount of dust produced when machining, and it isn't particularly dimensionally stable.
necumer.com/index.php/en/products/board-materials/modelling/necuron-651
It wouldn't be a really big step to sand, paint with high-build, sand, polish, and then pull composite parts out of moulds made from Necuron. Although they don't particularly recommend doing mass production with something like Necuron 651 (may only last a few parts). The next step up Necuron 702 is specifically designed for tooling for laminates, but its about double the price, and not justified considering what Fangy was after. However, it really isn't that expensive if you think about it, you could probably build tooling for composite fins for less than $100-200 bucks per fin worth of tooling (not including labour). necumer.com/index.php/en/products/board-materials/tooling/necuron-702
The entire process took way too long, but not too bad considering it was the first project of this type I've attempted. Probably about 32 hours total, about 16 hours of machining time total and the same amount of time doing the CAM. Second time around I think I could easily half the programming time, and probably the machining time as well (take out the one major screwup binning a part after about 4 hours of work 
). A lot of time was spent roughing out material, which was a pretty inefficient way to doing things in hindsight.
If anyone is curious on other parts of the process in making the moulds happy to share. End of the day its pretty cool that for not too much money you can buy "tools" (i won't say toys) like these.
Thank you for posting all the info Swoosh. I am still impressed by my electric toaster, so this stuff blows me away. Once I get the FF22 orders sorted, I will need to commence work on convincing the Minister for Excessive Windsurfing Expenditure to fund the FF18 or FF20 reduced foil.
Swindy will have tested an FF20 reduced foil after the first few strong cold fronts. I suspect an FF18 would be a better option for Budgewoi, but an FF20 may hang in better in the winter chop here. I am in two minds at the moment. On one hand, as Swoosh mentioned above, the spanwise flow is a considerable contributor to the drag of the fin. However some of the vortex resolves to lift in a vertical direction, that is lifting the fin out of the water. Anecdotally, my experience with the FF28 ( with negligible flex) is that it can lift a lot of weight vertically at 30 knots!
On the other hand, Dietrich Hanke suggests that when a board is travelling at very high speeds the drag from the fin is close to one-quarter of that produced by the board. With the board being the major contributor of drag by far, my thought with the FF's was to sacrifice some of the fin efficiency to produce vertical lift, and in turn, decrease the board drag as quickly as possible.
But how much vertical lift is enough? And if I make the fin shorter will it simply lift to the point of uncontrolled ventilation, or will it self-limit. At what point does the fin drag from the vertical lift become more significant than the board drag?
Has anyone got any spare time and a desire to do some CFD modelling? 
In the meantime, it's back to Swindy's thinned out foils experiments. Let's see what happens and maybe we can get some comparisons between a thinned out FF24 versus an FF22, or a thinned out FF22 versus an FF20.
Fangy. I'm still worried by your vertical lift theory.
Vertical lift behind the rider, can be advantageous at low speeds, and help to start planning.
But it's the last thing you want to go fast.
Vertical lift behind the rider has to push the nose down, actually increasing wetted area and increasing drag. I think what you are experiencing, is strong sideways lift, supporting your weight on the rail, allowing a windward rail lift, which in turn produces aerodynamic lift, with the wind getting under the board.
Select to expand quotedecrepit said..
Fangy. I'm still worried by your vertical lift theory.
Vertical lift behind the rider, can be advantageous at low speeds, and help to start planning.
But it's the last thing you want to go fast.
Vertical lift behind the rider has to push the nose down, actually increasing wetted area and increasing drag. I think what you are experiencing, is strong sideways lift, supporting your weight on the rail, allowing a windward rail lift, which in turn produces aerodynamic lift, with the wind getting under the board.
I reckon there is an element of both. The way I see the spanwise flow down the taper, vector resolution of the opposing forces will give rise to some vertical lift. I can see the vertical lift being an issue at higher speeds, hence making the fin shorter and/or thinner. I have to admit I have not ever travelled at a great enough speed for the lift to be a problem - me and the Barge are well anchored to the water! The other thing that may just be me, but when I am fully powered up and leaning back on s speed run, I extend my front leg fully straight, and I feel I have the fin under my back foot, so I perceive the lift is not coming from behind me, (and pushing the nose down) but under my foot. This may just be my perception, and in reality I am positioned further forward. Something for me to take notice of in the near future.
All my best speeds have occurred when I accidentally find the Goldilocks amount of lift that gets enough of the board out of the water to reduce drag but keeps just enough in the water to maintain control.
Because making these fins never goes to plan, the FF22 has hit a little funding hurdle. To get this project to pouring stage, I need to have six prepaid fins and I can cover the rest. On top of that, the foundry has increased the cost of the castings 10%. The cost of a DIY FF22 will be $150. If you are interested, please pm me, and if I can get the numbers I will organise to have them poured.
Sue loaned me a Fangy 20cm fin today. Budgie was super deep (50cm) and choppy so it seemed like a good day to try I out.
I was on an 2015 Isonic 90 with a Maui TRX 7.0m. The wind was 5-25 kts. The fin felt pretty good cruising around in the moderate 10cm chop. It definitely had more grip than the 18 Delta I would normally use at Budgie. I had the mast track set as far back as possible which is my norm for all delta fins.
I only had 2 or 3 decent speed runs. My best at 36.9 kts felt very strange indeed. The nose of the board felt like it was glued to the water. It felt super stable and boringly safe. Normally in 10cm chop conditions I would have trouble keeping the nose down. At the end of the run I was a little disappointed that I had not made the best it and hadn't got the board to release properly. I was surprised to see how fast the run was.
I am a relative light weight and I don't think I have ever gone over 37 kts on a 7.0 sail. So this fin is fast in a very strange way.
Select to expand quotetbwonder said..
Sue loaned me a Fangy 20cm fin today. Budgie was super deep (50cm) and choppy so it seemed like a good day to try I out.
I was on an 2015 Isonic 90 with a Maui TRX 7.0m. The wind was 5-25 kts. The fin felt pretty good cruising around in the moderate 10cm chop. It definitely had more grip than the 18 Delta I would normally use at Budgie. I had the mast track set as far back as possible which is my norm for all delta fins.
I only had 2 or 3 decent speed runs. My best at 36.9 kts felt very strange indeed. The nose of the board felt like it was glued to the water. It felt super stable and boringly safe. Normally in 10cm chop conditions I would have trouble keeping the nose down. At the end of the run I was a little disappointed that I had not made the best it and hadn't got the board to release properly. I was surprised to see how fast the run was.
I am a relative light weight and I don't think I have ever gone over 37 kts on a 7.0 sail. So this fin is fast in a very strange way.
Thanks heaps for the feedback tbwonder. I am find my self with a long layover in a tiny Botswana airport. So I have time to kill:-)The fins were primarily designed to produce some lift vertically to ensure the board is lifted clear of the weed drag and planing ( not so much to be out and out speed fin. I cannot use the fin in the combination above and remain impressed by those who can!! I think I the solid nose down feeling is explained by the vertical lift from the fin occurring behind the mast foot, independant of board rocker/tail, and thereby pushing the nose down.
I would love to hear any feedback on combinations that work and especially the ones that don't!
Select to expand quotefangman said..
I think I the solid nose down feeling is explained by the vertical lift from the fin occurring behind the mast foot, independant of board rocker/tail, and thereby pushing the nose down.
How does that compare to lift generated by a pointer fin?
Is one difference that if a pointer fin generates a lot of lift, the board becomes hard to control, because the fin pushes the windward edge up, while FangyFins make the board easier to control because they push the nose down?
Fangy on studying your fin on my desk I see it differs in four obvious ways from other Delta style fins ( A built in chamfer, the strange cut out at the back of the fin, overall extra thickness and the centre of effort is much further back than traditional deltas) . You have probably explained all this before in the previous 300 posts but perhaps you could explain in simple terms your theory behind these differences. In particular which things push the nose of the board down.
Any plans to make a 16cm?
I think Fangy hasn't got it quite right. It's vertical lift behind the center of gravity of the board as a whole, not just behind the mast track.
When I queried Fangy before about this, his reply was with his weight, and leaning back onto his back leg, the lift of the fin was more underneath him.
But if you are light, like me, you'd have to have your back foot behind the fin's center of effort, to get it's vertical lift underneath you. So if it's behind the board's center of gravity, it pushes the nose down.
In chop, this can be a good thing, as it allows the board to ride over the chop instead of slamming into it.
Maybe this is why you went faster than expected.
But if you are on dead flat water, I think you'd be slower.
As Fangy explained it to me, it's the thicker leading edge at a high rake that produces vertical lift.
These fins have effectively no flex, they are incredibly stiff.
A pointer can produce vertical lift when it flexes, as it then becomes more horizontal as it bends to windward.
The rear cutout and fillet at the fin board junction, are there to limit cavitation and ventilation. The thicker foil, enables greater angle of attack, allowing bigger sail sizes on shorter fins.
In heavy weed, the greatest drag is from depth of fin in the weed, a shorter thicker fin at a high angle of attack has more drag in deep water, but less in heavy weed. Well that's the theory, anyway.
Fangy is sure to correct, any points I've got wrong or missed.
Select to expand quoteboardsurfr said..
How does that compare to lift generated by a pointer fin?
Is one difference that if a pointer fin generates a lot of lift, the board becomes hard to control, because the fin pushes the windward edge up, while FangyFins make the board easier to control because they push the nose down?
We don't use pointers much here, but you could be right, pointers being longer, they have more leverage over the sailors weight, so it's harder to control the windward rail coming up.
Fangy fins being a lot shorter have less leverage, so it's easier to control the windward rail.
But the amount of vertical lift, as far as I'm concerned is an unknown quantity. With pointers, it varies with the fins flex, with fangy fins it's the leading edge thickness?
Swindy has modified his Fangys, by thinning out the leading edge, in an attempt to get more speed. I would be very interesting to hear what he has to say about vertical lift comparison between thick and thin leading edges
Stuck in Maun, Botswana atm. Wifi drops out every time I move my eyelids. Will post when I get to Jo'burg...hopefully
The thinner of my 22 F Fins is definitely quicker but has sacrificed a bit of its upwind ability especially in chop. Across the wind and down wind has great acceleration and still 100% confidence that it wont let go. I took the other one out last week in some pretty gnarly chop and it didn't let go once even pushing hard up wind but it is definitely a bit slower. I haven't had enough chance to test them both much as yet especially in the smooth to see how the board sits in the water. If it is the vertical lift created by the thick leading edge and the foil width that make them so grippy up wind in chop it works and works well.
TB Wonder, I have made a 17 out of a 20cm FF but no one has tried it yet. I will give it to one of the team lightweights to try out on a suitable day.
Select to expand quotedecrepit said..boardsurfr said..
How does that compare to lift generated by a pointer fin?
Is one difference that if a pointer fin generates a lot of lift, the board becomes hard to control, because the fin pushes the windward edge up, while FangyFins make the board easier to control because they push the nose down?
We don't use pointers much here, but you could be right, pointers being longer, they have more leverage over the sailors weight, so it's harder to control the windward rail coming up.
Fangy fins being a lot shorter have less leverage, so it's easier to control the windward rail.
But the amount of vertical lift, as far as I'm concerned is an unknown quantity. With pointers, it varies with the fins flex, with fangy fins it's the leading edge thickness?
Swindy has modified his Fangys, by thinning out the leading edge, in an attempt to get more speed. I would be very interesting to hear what he has to say about vertical lift comparison between thick and thin leading edges
So, in simplified terms, the Fangys create lift from the water hitting the front edge; since it's angled, that imparts an upward momentum (lift) onto the board. Thick edge = lots of lift.
In a pointer, the lift comes mostly from the fin flex, which creates an upward force vector from the hydrodynamic lift. Water hitting the (almost) vertical front edge would mostly impart backwards momentum (drag), so front edges are thinner.
Does that sound right, Ross? And what are you doing in South Africa now? You're a few months to early for Luderitz!
