I won't bother with "how to hotwire" there is plenty on the model 'plane sites I suspect.
So now you have a series of 1200mm long foam wing bits. Woops, forgot. When you hotwire, you take off the trailing edge. Figure this out by having your sailtrack in hand. The back has something for the sail, it can be anything really. I have use alloy sail track, caravan awning track, pvc sail track as used on cargon masts, PVC conduit with a saw cut along it's length, etc. So the back does not come to a point. Moving in from the back you have; the sail track and then a bit of timber roughly 20mm thick. It's easiest to shape this to match your profile before gluing it on, then foam.
Glue each of the bits of foam to the wooded batten and to each other. You don't need glue with any strength,as it will be stronger than the foam anyway. Make sure you are lining this all up carefully and without any twist or curve. You will not be able to take this out later. (Believe me I have been there).
Now take the hotwire again and cut off the whole leading edge back to where the mast is thickest, you will have a long, somewhat delicate "D" section.
Now you again have choices. What you are going to make is a web which goes across the mast. I have made these from; a single long plywood piece with scarf joints and 10mm alloy bars on the edges, the same but with 15mm wooden battens, but the last was fibreglass tri-axial ribbon, very heavy cloth weight.
If doing it again, the glass was easiest lightest and strongest.
I radiuesed off the front edges of the trailing section which was now supported on the wood batten and a couple of full length table. Give it a healthy radius, you have to persuade that glass to curve round for about 20mm along the sides of the wing. Very carefully and with good epoxy glass this on. You need to work at this.
When it has set off carefully sand and smooth.
Now make a base block for the mast step, more wooden blocks for where the boom attachment is, one for the top and another block for where the stays will go They all hang off one fitting on the front.
Now glue all these bits in place, again low strength glue is good enough. (5 minute is fine)
Give it all a bit of a sand, make sure you have there "web" edges well smoothed in.
Glue the front back on. Fasten on the sail track to the timber.
Now you are going to glass the whole thing. You could do a light seal coat and let it harden, some of the surf board guys do, I never have (usually cos I'm in too much of a rush).
I have always left it still standing on the trailing edge, tables etc, but I do know that others have bashed nails in to the top and bottom so you can rotate while glassing. (I have also seen some of these with an inbuilt sideways bend)
Glass layup?? You pays your money and makes your choice! 3 layers of 6oz "S" glass with patches over the hounds fitting and base did not break till a later owner capsized a class 3, so should be fine! "S" glass is a pain to squeegee out, but it does give more strength for weight. The glass has to go all the way back to the sail slit, so you need to think how to achieve that. Do not over resin, it will just float the cloth off the foam.
REMEMBER YOU CAN ONLY USE EPOXY ON POLYSTYRENE FOAM.
Now that it is glassed leave it alone for a day or two.
Fill and fair, paint etc, then put on fittings. I put the mast base 35% back along the wing. If you put the step too far forward it will just rotate too much, too far back and it will oscilate when you tack, and this is NOT fun, it can lift the front of a class 3 over 2 metres in the air if sufficiently violent. I use a standard Ronstan hounds fitting for a bigger mast so that it wraps back as far as the web, and have it welded along the edges of the beak at the front.

kiwi307 said...

I won't bother with "how to hotwire" there is plenty on the model 'plane sites I suspect.

REMEMBER YOU CAN ONLY USE EPOXY ON POLYSTYRENE FOAM.

back in the time of BIGM (before I got married)
I used to make "disposable wings" for my disposable r/c aeroplanes out of polystyrene foam, and it was surprising how much punishment they could take- I used aluminium templates at each end of the wing section and a hot wire made by our sparky (at work) to cut them out- I used a bench saw(at work) to cut a trench in the wing sections, and used plain pva wood glue smeared into the trench to fix the spar in place (20mm x 5mm? timber from bunnings)

The entire wing was covered with brown paper glued on with the same pva wood glue. the final paint job was pva paint (leftovers from work)

At the centre section where there was the most stress I wrapped a layer of woven fibreglass matt- and flood brushed it with woodglue and put them aside for a couple of days to dry.

each wing was roughly 1500mm x 250mm, and cost a total of $8.00 to build.

I would imagine you could use the same type of materials to make a landyacht wing.

kiwi307 said...

I have never had the need to have a rotation control, just positioned the pulleys on the boom and on the yacht carefully so that as you sheet harder it pulls the rotation off, as you ease it allows the mast to rotate. A boom with easily moveable blocks facilitates this. Drop them forward on the boom for windier days, back a bit for softer days.

Do you mean you controled the mast rotation just like a mid sheeted class 5.

If you want to go longer than the length of a guitar string, then this is the stuff to get:

http://www1.jaycar.com.au/productView.asp?ID=WW4040

Experiment with voltages and lengths of wire, you want the wire to make a nice hissing noise as it cuts, and you don't want it to bend much as you pull it through the foam.
A spring is a good idea to keep it tensioned, because the wire expands as it heats up...

Great write-up on the construction btw, it almost sounds possible to do in my garage

Clemco said...

kiwi307 said...

I have never had the need to have a rotation control, just positioned the pulleys on the boom and on the yacht carefully so that as you sheet harder it pulls the rotation off, as you ease it allows the mast to rotate. A boom with easily moveable blocks facilitates this. Drop them forward on the boom for windier days, back a bit for softer days.

Do you mean you controled the mast rotation just like a mid sheeted class 5.

Pretty much, except that the gooseneck is attached to the mast.

With solid wings is there any "ideal" thickness ratio for a wing?
and does a wing need control flaps at the rear of the wing or would it operate OK as just a wing profile?

I hate to bring up the weight problen again but 280 x 80 looks a bit fat to me. Would not a 6:1 ratio wing be more efficient?

I am sorry 307, I was being a smart ass.
Serious question though,
Would a thinner wing be better than a thick one. I hear the windsurfer masts are getting thinner these days. Also I notice the Palmer class 3's have quite thin wing masts.

kiwi307 said...

Gizmo said...

With solid wings is there any "ideal" thickness ratio for a wing?
and does a wing need control flaps at the rear of the wing or would it operate OK as just a wing profile?

If you look at Vindicator which Faze5 built and Paul is now the custodian, it has a symmetrical wing (or did when I sailed it). It worked fine, was a bit slow on initial acceleration, but seemed to accelerate almost exponentially, ie seemd to accelrate more,the faster it went. As I was sailing on the mud patch at Gawler (?) it meant that it was becoming interesting, far from frightening though.

In its original form vindis symetrical wing was a wooden frame covered in a "new material called monofilm.. on Port gawler beach it could sail and race quite well against a sanderling rig and had similar aceleration. Im guessing that was because there was some distortion of the rig that made it assymetric enough to work.
It didnt go that much faster than sanderling rig either.
when the wing was filled and faired, it became another creature altogether.
in say 1knts 0-64 kph is slow work carefully winding up, then great accel from 64-85 . this is when the front tyre expands so the first few runs of the season /day will be a bit bumpy .85-104 is a steady smooth acceleration. your now at the peak of what any other yachts on the lake is going to do in a blow. a LLM will have washed out at 85, you'll have scared the #### out of any local 5's and be passing any visiting kiwi YOTT's.
youve just got up to slow cruising speedthe wing seems to sit at that speed waiting for a gust. in a stronger wind it likes to sit at 123-125 waiting for a gust.
On one occasion the yacht went from 0 to 105 in the time it took me to take off a glove, adjust the helmet strap and look up at the speedo!

Now when the yacht gets away in reverse its a different type of acceleration again

Oooooooh , Ive got a big industrial roll of that stuff

my problem is just getting the timing of my time right.
my time is sadly regulated by customers and other peoples shift rosters.
AND wind( of whichthere is 30+knts outside )

got rigged at 4.30 saturday, went out for 1 quick sail...................75kms later came back in at a nice cruising 115kph. managed to do a 2 way run of the length of the lake. thats the second time in 29 years on Lefroy . wind was nice, TP1 was sailng wih my daughters little 3m sail off 'Hummingbird'
had a great camp, did the drink/hangover thing, and got up to a nowind sunday!