keven doesn’y know it yet but Akela is about to become the worlds first McCormack Ketch - as well as transmogtifying Little Gull into a McCrmack Kittiwke.
Im Amt
Richardson
Oberflottenmeister
Brett, As you know, I’ve built a unarig according to one of your early designs & have become an advocate of it’s simplicity,balance & gust absorbing
qualities. When I saw this new version, all I can say is BRAVO!!!
Now I need to build one before I go up to the event in Sheboygan next month.
Bill
How to; Part Two…First a disclaimer…
This is only the first of these McCormack rigs that I have built so I am definatly NOT an expert.
All information is provided for general interest only and no responsibility is accepted for your version if it does not work. OK.:scared:
[SIZE=2]1. The photo shows the wire with carbon rod 1.5 mm x 340 mm partially wound with kevlar thread.
- Fully wound and glued using super glue (cyno) Mast or spar or whatever you want to call it 3mm tube fitted at 460 mm length.
- Complete with sail made from old plan tracing paper (mylar) :zbeer: (450mm luff x 300mm foot)
This really is a quick and easy method. Thanks Brett for sharing your knowledge, if anything looks dodgy please tell me.
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Thanks both to Brett & Ian for sharing all this info; it’s great! Just one question that I don’t believe has been asked. You bot mentioned raking the “mast”; is there a particular angle you chose, or was it a that looks good decision?
Bob
Bob, I don`t know the “official” answer but for me so far it has been a “looks right” decision.
However because it is so easy to change the rake it could be used to balance the centre of effort for individual boats.
Recutting the foot angle is so quick or you could make a new sail in about 3 minutes.
My “Official” rake is the top of the “B” rig mast directly above the pivot.
The larger masts extend further up on this same angle.
The angle is easily tweaked by merely bending the wire.even at the pond.
This whole rig came about by taking things away that where not required to make a functioning rig.I will admit that part of it was driven by a commerical desire to build a rig at absolute minimum cost and minimum time.
Happily I found that by taking things away and making the bits that were left do the job of the things taken away I managed to get a nice solution.
Many Footy projects have stumbled at the rigging stage,a “normal” rig has to be built very very well to function well at this size,many of the rigs I have seen pictures of are pretty awful,at this size fittings have to be made very accurately in order to perform.And even then we were struggling.
So I got rid of all the fittings and moving parts.
Sometimes less is more!!
[LEFT]Bill suggested a 1/3:2/3 ratio of the fore-to-aft areas of sail, so that means to me to bend the wire to make the two sail aareas of that radio, using the pivot as the dividing line.
thx
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Ian, realizing the above, what type/guage of wire are you using?
Does the bend appear to be happening at the front corner, or is it a torsional twist along the horizontal section where the boom is glued on? Or both?
I like the sail planform alot.
Brett, any recomendations?
Just looking for a starting point, thanks
I can’t think of anywhere to get the 3mm tube and the carbon rod, unless the hobby store has that- I don’t remember, and my Jag is in the shop. 
Maybe just soldering on another straight wire will work?
Great Planes Flatouts arf airplane kist have the perfect components for one of these rigs… try this http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJYS1&P=0
its kinda hard to justify purchasing an entire plane to make a rig, but the thing costs 24 bucks, and the foam makes decent rudders…
just a thought!:graduate::devil3:
you might not need that Jag after all!
I’m getting some good excercize on the bike lately.
Hi Bill.
I am using 1.6mm s/s wire ,thats 1/16th in your terms.
The wire twists with torsion,this is the single most important part of the rig.
You can tune the ammount of torsion in the wire with the ammount of thread or
carbon used to wrap the boom in place.
There are other tricks to vary the stiffness as well which will become obvious once you start playing around.
I wouldn’t use anything smaller than the 1/16th wire,perhaps a little bigger would be better even but I have used what I have got and also the weight saving with the lighter wire is quite a bit.
I managed to obtain the carbon tubes and rods in a hobby shop here in NZ,we are not known for our well stocked hobby stores so I don’t expect you guys will find it differcult locating this stuff.
This design is not much different in practice to the version you built earlier Bill,the bendy boom is the only real difference.
Bill, my wire is about the same as Brett`s.
I have built another with something a little thicker to try as well.
I like the idea of bicycle spokes mentioned previously and shall be investigating these next week.
I made a few sails today including a B rig.
It is so quick to do that I can see that having a whole wardrobe of different cloths will be the go.
The angle of rake of that front upright is the most critical component of these rigs and can be used to tune the twist to be optimum.
Have you considered using a bent or curved mast? having a bend in the mast should allow one to keep the sail area low or change the proportions of the fore- and aft- sections. Possibly even to control the amout of lift from the sail or the vortices flowing around the luff.
Tomo…I have considered a lot of things…I even manage to build some boats and go sailing once in a while.
I do all that too.
Curved masts are a pain to get the sail attached and setting right.
With a straight mast you can build a pocket luff sail in about 3 minutes and it sets beautifully. (If it aint broke don`t fix it )
A curved mast would remind me of the Polynesian sails- or is it Egyptian?
Mine will be straight anyway, or at least until I figure it out.
thx
I think he’s trying to slow you down Brett.
Just kidding Tomo.
Ian,
My thoughts exactly!!!
Tomo,
Since you like to contribute so many suggestions & comments, how about showing us something you’ve actually built. That way we’ll know you’re a “doer” & not just a “talker”. Not just kidding…
Bill K