Select to expand quotesailquik said..
That looks like my kinda fin. Plenty of size for me. 
If you get time off testing on Workers Comp Swindy, I would be happy to continue the testing at LG for you until you are good again. 
I'm sure that can be arranged once the guys here have had a go. It may be a little shorter by the time you get it as the tip is quite thin and our crash test dummy's aren't that careful
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Select to expand quoteSwindy said...
It depends if you have the work ethic of a student I suppose.
My Swoody 20 & 17 side by side for comparison. Just a final sand and coat of paint and its done. Any low points will have to wait till next week to get filled, running out of time.
I didn't weigh it before I started but the other 20 started out at 740g and end up 540g. The 17 is now 510g even with 40 g of resin used for the fin box, so was it worth putting in the wood? I don't know but I weighed the off cuts from the cut out and minus the swarf and grinding dust weighed 120g. All the other cutting and grinding I done probably took off another 140g.
No way is this a commercially viable process but if it gives me more options that work well, to me its well worth the effort.
It looks awesome. Would be good to see a picture from the front to compare the thickness. I was thinking of a 17 a bit like the 20 with the tip cut out and the body made thinner for speed. That would be a lot less work and if there were marks or instructions it could be done more easily by the average person. The main problem I see is how to maintain a good profile when grinding.
Select to expand quotepowersloshin said..
It looks awesome. Would be good to see a picture from the front to compare the thickness. I was thinking of a 17 a bit like the 20 with the tip cut out and the body made thinner for speed. That would be a lot less work and if there were marks or instructions it could be done more easily by the average person. The main problem I see is how to maintain a good profile when grinding.
The limiting factor on taking the thickness down more than I have is that this is a hollow fin and if you take off too much there isn't much ally left either side in the hollow area. Its widest point was 22mm and ended up 18.5. The core box had been put in 1mm off centre when cast so 1 side was 2mm thicker than the other. If you got Ross to do a solid casting you could take off as much as you like. The only question is how far can you go before it looses its FF awesomeness and becomes just another delta fin. This fin is more a scaled down fin that would probably be close to what an original FF would be if Ross was to sell another child to pay for its development.
As a FF20 has achieved over 39kn I'm sure in the right hands this one will do over 40. Its not always about speed, a FF will put a smile on the dial in conditions where other fins will leave you feeling frustrated.
As long as you don't go too far below 8% chord to thickness ratio the FF should still do it's thing.
But with fins, speed isn't just about drag, it's about lift to drag ratio. Going thin doesn't necessarily improve this. If you have to run at an increased angle of attack to get the lift you need, the drag can go up.
The first FF22 off the rank is Sue's Budgewoi special. It has been cut down to just under 17 cm. An important thing to remember if you are doing your own prep ( I forgot and I designed it!) is that the box at the front has the outline of a POWERbox. This box design was to try to make it easier and quicker to grind the casting into a powerbox if required.
IMPORTANT - TUTTLEBOX users - To get the bolt holes to line up with the reinforcing, you need to take 1-2 mm off the very front of the box casting. If you are unsure, put the fin in the board and drill a small pilot hole mark into the fin to see if its correctly aligned, BEFORE you do the bolt hole at 5.0mm.
The second photo is a comparison with a FF20. Sue's Budgewoi special has more surace area and greater foil thickness than the FF20. It will weigh in at approx 750 grams. I am hoping it will provide enough low speed lateral resistance and upwind lift, while keeping the the benign handling charactersitics. I just need to finish it off and get it over to NSW for testing.
Select to expand quotefangman said..
The first FF22 off the rank is Sue's Budgewoi special. It has been cut down to just under 17 cm. An important thing to remember if you are doing your own prep ( I forgot and I designed it!) is that the box at the front has the outline of a POWERbox. This box design was to try to make it easier and quicker to grind the casting into a powerbox if required.
IMPORTANT - TUTTLEBOX users - To get the bolt holes to line up with the reinforcing, you need to take 1-2 mm off the very front of the box casting. If you are unsure, put the fin in the board and drill a small pilot hole mark into the fin to see if its correctly aligned, BEFORE you do the bolt hole at 5.0mm.
The second photo is a comparison with a FF20. Sue's Budgewoi special has more surace area and greater foil thickness than the FF20. It will weigh in at approx 750 grams. I am hoping it will provide enough low speed lateral resistance and upwind lift, while keeping the the benign handling charactersitics. I just need to finish it off and get it over to NSW for testing.
With the level back to < 0.30 I will need that..
My Fangy 18 arrived yesterday. From here on to be known as the FF167. The actually fin length is 167mm
I've spent about 2 hours on it and it is starting to look half reasonable
In the hand and next to other fins it is comically small, but installed in the 44cm board it looks rather pleasing.
Just need a nice 35 knotter to test it out
Looks damn good! But that must be a tiny board, or there is some Hollywood trickery with the camera, because the fin actually looks big enough to be useable Bring on a howling breeze, I am super keen to see what happens 
Select to expand quotetbwonder said..
...the board is 26cm wide just in front of the fin.
I have toothpicks wider than that!!
Select to expand quotetbwonder said..
No trickery was intended, the board is 26cm wide just in front of the fin.
Now you just need wind..
What are people using to fill & cap the void? I was considering using expanding foam but thinking I may end up with an eruption of foam everywhere. Just normal silastic to cap or a particular type?
Select to expand quotemorts said..
What are people using to fill & cap the void? I was considering using expanding foam but thinking I may end up with an eruption of foam everywhere. Just normal silastic to cap or a particular type?
Morts I have been using a wedge of polystyrene packing foam, jammed in to make a plug and then a thin layer of Silastic (Selleys Bathroom version, but I dont think this is critical) over the top to seal it. So far, it's been fine.
Select to expand quotesputnik said..
Here it is Ross
1000 grit finish, good enough?
Compared to Tricky's that is the Crown Jewels :-) Looks very nice Jeff - damn good job! Now use any means possible to nobble Tricky in any 'head to head' contests in future.
Good grass too!
I have just finished a little R&D project for fangy. I was given the task of taking one of his original solid 24 fins and making a speed version. So out came the grinder and hacked into it making it about 5mm thinner just above the fillet and tapering it down all the way to the tip while trying to keep a decent foil shape equal on both sides. Then undone most of my hard work by cutting out the centre of the fin for the balsa wood insert. Having done this a few times now it doesnt seem to get any easier or quicker. Shaping the balsa back to the foil shape is probably the quickest operation. Then 3 layers of glass each side, sand, bog and sand again. Then a coat or 2 of spray putty and a wet n dry. Its now ready for TheFangman to add his finishing touches to it, as he did with the previous project i done for him. (Butcher)
Hopefully we get some wind soon to get some feedback on how it works.
Looking good Roger. The very skinny FF 22mod I did is slippery and fast but quite unpredictable on the small downhill chop once I get past 32 knots. More experimenting to be done...I am really looking forward to seeing how your modified FF24 behaves...and then butchering it
BTW my other Swoody is still perfecto, with no sign of fibreglass separation from the aluminium.
Wish the same could be said of my 22 swoody. Twice now one side has completely ripped off. I put it down to the glass sold in bunnings doesnt soak up the resin properly. I think the ones holding together well are from when i had some decent glass. Dont worry i got some more decent glass for yours and to re do my 22. It also lifted on the 17 swoody so Mike re done it as its in his fin collection.
Swindy, maybe use coarser sandpaper before you glass? Itll leave a rougher surface for the resin to key onto n grip.
Worth a try.
Select to expand quoteolskool said..
Swindy, maybe use coarser sandpaper before you glass? Itll leave a rougher surface for the resin to key onto n grip.
Worth a try.
I use 80 grit, that should be ok. The problem is even though i soak the glass with resin and roll the living daylights out of it when you sand down the excess it goes fluffy. The ones i have done with glass from west systems haven't been a problem either sanding or coming appart.
^^ Ahh, any brandname linked to the glass matting? So it fluffs up like sanded Kevlar??
trouble is, rollers don't work so well with resin on top of the cloth, they are much better with resin under the cloth. Squeegees work better with resin on top, you can force the resin down, rollers force the resin up.
I had some carbon that just wouldn't wet out, no matter what you did. I was told it was meant for resin infusion systems, may be there's glass in that category as well.
Yes better quality glass is good. Plus Re roughen the aluminium with fresh epoxy on sandpaper just before adding glass. It improves the bond. Think this is mentioned somewhere in the west system manuals
cheers Jeff
Select to expand quotejirvin4505 said..
Yes better quality glass is good. Plus Re roughen the aluminium with fresh epoxy on sandpaper just before adding glass. It improves the bond. Think this is mentioned somewhere in the west system manuals
cheers Jeff
Good tip jirvin, i will try that next time.
Select to expand quotedecrepit said..
trouble is, rollers don't work so well with resin on top of the cloth, they are much better with resin under the cloth. Squeegees work better with resin on top, you can force the resin down, rollers force the resin up.
I had some carbon that just wouldn't wet out, no matter what you did. I was told it was meant for resin infusion systems, may be there's glass in that category as well.
I put resin on liberally first then lay the glass on and roll it with a metal roller till it soaks through, add some more resin and repeat for 3 layers.
Select to expand quoteolskool said..
^^ Ahh, any brandname linked to the glass matting? So it fluffs up like sanded Kevlar??
Cant remember brand name but assume bunnings only sell one brand nationwide.
I havent sanded kevlar as yet but its obvious the resin hasnt soaked completely into the glass. Once sanded i give it a brush coat of resin then sand it again but still dont get a 100% satisfactory finish.
No issues with the new glass though.
