Time for a custom wing?

I'm the proud owner of a RRD alu (high aspect) foil, which with it's 120 fuse is fast, stable and reasonable early flying capabilities, but stalls sooner than I'd wish. Therefore I'm thinking to DIY another wing in my quiver. It appears to me however that you have 2 types of wings: low aspect with the wing close to the mast and high aspect where they are well in front.

Why isn't there some cross-over? The longer fuses help with early lift and stability, so what would that give if I slap a low aspect foil (like the ss i99, 84 or 76) onto my long fuse?

Check RRD website. They offer moderate aspect 1200.

I got the 80/726 front and 38/214 rear so nice to see there is a 100/1053 front. I think however that it would be crazy expensive, especially if I also need the bigger 50/281 rear, so I might just have a throw at making my own carbon wing. Not that worried about crafting a good fitting seat tbh, I'll get my head around that.

Still not sure why there aren't low aspects on long fuses. I might have a throw at it to see how that turns out. I'm happy with the long fuse because the lift sits right in between my feet, gives me earlier lift than if I had the same foil on a shorter fuse and has plenty stability.

Also, it turns out to be bull**** but according to SS the i99 has to be mounted all the way forward on a board with tracks, hence the wing further forward. Ofcourse it also effects the position of the rear wing but that seems to be of less importance. This makes me wonder even more why low aspect wings aren't by default more forward than they are on today's models

Some context: I mostly surf on a tiny, gusty and flat lake (gusts are always twice as strong as the average wind) and I would love to fly with a 6.0 and smaller instead of a heavy 8.0, as well as have more drive through the lulls

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PatK said..

NicoDC said..
... so I might just have a throw at making my own carbon wing.

How do you plan to do this? Im also very interested in making my own wings.
Inspired by

This thread is very useful: www.seabreeze.com.au/News/Kitesurfing/How-to-make-your-own-Hydrofoil_8649403.aspx
There is also this facebook group called "board & hydrofoil building" with awesome peole and inspiring projects

I'd go for plywood sins I think eps is just to weak for windfoiling. A rigid foam like pvc should be great, but I think it is trickier to shape sins it is more fragile when sanding so more likely to sand to much, plus it is more expensive. If I master the plywood I might switch.
For my first foil I'll glue-laminate the layers of plywood with thin 80gr/m2 glass and probably 2 layers of 200gr/m2 each side with another layer of glass so I don't have to sand the carbon. If I get skilled I'll switch to glue-laminate with 45 degree carbon and 1 layer on top and bottom. The reason I don't start of like this is that if I don't like the shape before carbon glassing, I can throw the cheaper glass glued foil away and start again.

My fuse has an easy enough mounting to copy it onto the foil. Like that I'd only need to change the foil if the wind de- or increases.
The first shape is probably a 1150 flatwing (100 span x15 chord). Still keen to find out if a lower aspect would work aswell.

The reason you don't see low aspect wings on longer fuselages is because they become too stable in pitch and yaw to be useable for the carving moves they are designed for.

Some are designed to be used with the wing closer to the mast and with a standard fin box location but only with larger stabilizers. Most are built so the mast has to be moved forward on the board to create a setup that can carve tighter.

When I run my Supercruiser with the wing in the forward position its almost too stable to ride swell, it would be better with the mast moved forward on tracks instead along with a smaller stabilizer.

Rather than building a new wing I would consider if you can adapt an existing one. Or adapt an entire fuselage.
What does the current fuselage connection look like?

Go with that.bigger front. For flat water efficiency reducing drag seems to be more important than increasing lift.

My only reasoning for running a big front wing is to be able to carve swell. Which I'm now moving towards winging for.

An update concerning the layup after talking to a very experienced guy:
- corematerial: pvc (lighter) and plywood (easier) both work. No need to use carbon in the core.
-shape it
- 'separate' your wing in 4 zones (each getting 1/4th bigger so for a 100cm span, starting from the middle: 1. 12,5 cm to each side 2. 25cm to each side 3. 37,5cm to each side 4. 50cm to each side). Use 200gr/m2 UD carbon to make a 'sandwich' that is 4 layers thick in zone 1 (so basicly 800gr in total) and diminish towards 1 layer in zone 4 (so only 200gr on the tips). This gives you flex stifness.
- 'separate' your wing in 2 zones (the full wing & the middle 1/3rd, so for a 100cm wing, starting from the middle: 1. the full 50 cm 2. 16,666cm). Use regular carbon all over zone 1 with an angle of 45 degree and another layer in zone 2 again at 45 degree. This will give torsional stifness.
- you can finish with a thin layer of glass for sanding, but that's not mandatory.
- give it a nice epoxy coat and start sanding (150 dry and 300 wet, or higher grid wet for a more glossy look)

Sidenote: almost everything will fly, so use whatever layup you like. The above mentioned makes the most out of the composites and should be topclass. Use a big strong chunck of wood and just paint it if you don't want to overcomplicate. You'll have great fun too.

Hope this helps and motivates!

Ordering the carbon and epoxy this afternoon. I should be able to make the big lifty lightwind 100x15 wing and a small and fast highwind 65x11 wing for about 90 euro. I think these along with my RRD front wing would make a great quiver

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WhiteofHeart said..

NicoDC said..
I'm the proud owner of a RRD alu (high aspect) foil, which with it's 120 fuse is fast, stable and reasonable early flying capabilities, but stalls sooner than I'd wish. Therefore I'm thinking to DIY another wing in my quiver. It appears to me however that you have 2 types of wings: low aspect with the wing close to the mast and high aspect where they are well in front.

Why isn't there some cross-over? The longer fuses help with early lift and stability, so what would that give if I slap a low aspect foil (like the ss i99, 84 or 76) onto my long fuse?

Im sceptical, I think you get too much oncontrolable power. Low aspect wings have a tendency to create exponential lift as speed increases, couple this with a 120cm fuse and I think you'll be overpowered very very quickly.

You'd think it would add in low end power, and I'm sure it does, but you'd need the technique to get it going earlier. If you dont have that I think you'll only be decreasing the usable range immensely, with maybe a knot or so extra early flight.

A relatively flat medium aspect wing (aspect ratio 8-9) of around 1200 is the biggest I'd go.

Something else to consider is that the RRD is quite a flexible foil (mostly in the mast), I think there's a structural reason they opted for a 750ish wing. I tried the V1 and V2, and both are quite flexy (too wobbly to my taste), wouldnt want to put that under more extreme loads. The fuselage is also quite thin if you compare it to the racing models of Phantom, Starboard or Moses. I've bent (I think 5-6) and broken (3) enough fuselages to know when you're attempting something which might be too much strain.

My advice would be go for the big carbon wing first and see what it gives you, I wouldnt immediately swap the stab, the one thats on there already is small enough. I expect that 1150 to be able to fly in 6 knots with an 8.5, or 8 knots with a 7.0 and good technique. If you can afford it, you might want to consider getting the carbon mast.

Thanks for your input, appriciare it and I share your concerns. The RRD foil is a nice bottom-end, easy entry orientated foil. Fairly early lift and plenty stable, but just not solid enough in the high-end. I tried pairing it with my gun sails 8.0 (3-cam) and when fully loaded pushing the rig, the foil becomes less predictive due to a lack of (mostly) torsional stifness I think. It could be worse, but it led to 1 big nosecrash and haven't had the conditions to use this rig again. 6.0 (and below) works fine.

Anyway, since using my 8.0 is actually exceeding the foils' limit, I'd love to try a liftier wing with a smaller sail to get similar low-end. Money is however an issue (I'm a student) so buying an of the shelf full carbon wing is no option for me. I rather have fun trying to craft something and learn along the way. Will it be as good as a standard RRD foil that had lots of R&D? Most likely not but it might be just enough to fulfill my needs. Will it overall be great fun? I think so. Besides, for the price of 1 shop wing, I can make like 5 front and 2 backwings (altough not planning on making one) out of very decent materials.

You're right that due to the weak construction of the RRD I better don't make crazy big wings. My current plan would be to go for 95cm span with a 12cm chord for a +-1000cm2 surface, which is 1/3rd more than my current wing. Chord % thickness would be around 12, maybe a little less and I'm gonna go for a similar angle of attack as the RRD to make them somewhat comparable (I think the RRD has an overall nice wings btw). That wing would be for 7-13knts conditions, the standard for 12-22. Maybe another smaller and speedy wing for 18-28 could follow, but for now I prefer my freestyle gear in those conditions.