after building a full scale open 60 here in canada, i decided to build a model inspired by it, for my mantle. i soon discovered there in a class of r/c boat named the “footy”. my model is the same size as the footys, so i’m going to use my composite knowledge, to produce this model in advanced composites. i mostly produce stuff in carbon fiber, but it seams like the footys are an affordable class of boat; therefore i’ll make them from very light glass, and carbon for whomever has the dough. i would like to know what this community thinks of my creation, and when i have a few popped out the mold, i could donate some, to the experienced riggers, to do some r&d.
so, what do you all think?
sorry, i’m having trouble resizing my pics to fit the upload specs.
going to work on it, will upload the pics asap
That was a real tease…can’t wait to see the pics;)
Bill H
I must admit I’m rather sceptical. The relatiionship in the performance characteristics betwwn a moveable ballast 60-footer and a Footy seems rather obscure.
The problem with carbon fibre at Footy sizes is that you get vastly excessive tensile strength but no panel stiffness because it is thin - and that’s if you can get very light carbon cloth. Otherwise it’s just expensive black glass.
We have settled for most Footy applications on a depron/carbon sandwich using 16 g/m2 carbon tissue. I think this is prabably worthwhile. Panel stiffness is better than a simple epoxide coat over the depron.
However, show is what you have!
yah forget the cf. i’m building a footy from a mould i have designed, its slmost done… [actually when i see if it sails i may be willing to create some hulls for others… we’ll see] but i use regular glass, and the boat empty weighs just under three oz. plus the thing is almost bullet proof… [i dropped it off my painting stand -about 5 ft- yesterday, not a scratch! anyway, long story short, it has been said, i can’t see cf being good as hull matieriel…
alright nigel … the challenge of building to the footy size bit me last week … in my case I’ve choosen to riff on a 49er with a lateral ballast track at midships (see Doug Lord’s MicroFoilers) … to build at this size demands an incredible attention to detail and as mentioned, scaling down creates it own hazards … my drawings are a week or so from being finished but for now dispacement is around 230 grams (hmmmmmm … ) … hull weight 15-20g, rig with sails 20-25 appendages 5g, electronics to be researched … the rest for ballast … plug will follow in about 3 weeks … obviously I’m leaning heavily on the rcflight knowledge base for both construction techniques and electronics sourcing … will post line drawings and plug pics when ready
… trevor paetkau
ps … i’m a damn fool and know it …
Angus, are you making hard-chine panels of the depron, or using it to conventionally “plank” a rounded hull? Is the latter even possible?
–Doug
can’t speak for doug however …
Depron becomes pliable with heat making it possible for it to take on complex curves (ie hull shapes) after which it can be laminated with a skin material (cf) using either vacuum bagging or a mould/plug combo …
trevor paetkau
Hmmm…is vacuforming of the depron possible, then?
–Doug
Doug.
We’ve got two techniques. With the Red Fox design, which is hard chine, we have carbon rod chines, carbon strio frames and a very thin depron skin fitting between (not over) the chines but left a little proud. This is then sanded down to fair and then skinned with carbon. The carbon chines are probably not necessary except that their stiffness makes them fair more or less by definition and most of diffiulty of getting boats like a Razor true is eliminated. The process is a bit tedious bit it does enable the not very skilled (like me) to build a very stiff light hull. Pictures when I get the film developed.
The Dingo design is female moulded. The depron is (I hope - the mould is being delivered tomorrow) is cut to reasonably accurate pabnel sizes, scored in a grid pattern (I used to love end-grain balsa full size) and heat fitted to the mould. On trial runs that’s actually much less trouple than it sounds. Depron is removed, lay up 1 layer of tissue, add depron, 1 layer of tissue. Sandbag. Not the quickest or cheapest but very strong and light and a female moulded finish as well.
Hope this helps.
Thanks, Angus. A couple more questions: 1) 3 mm depron? 2) 12 or so mm grid?
–Doug
1.5 or 2mm depron, sanded down to 1 mm finished in the chine boat. Hence the carbon - stiffens it enormously and adds puncture resistance. At 16g/m2 the amount of carbon is probably vaguely in line with the actual strength requirements!
1 mm carbon rod chines. These are initially fitted to shadows set at 50 mm centres using hot glue so that they can be released later (and can easily be adjusted during erection.
Frames set at 50 mm centres alternating with the shadows (i.e, 25 mm gaps). They are built of trapezoidal section 0.4 + 4 mm carbon strip (wing traling edge) to optimise weight v. buckling. Fitted tangentially across the chines/deck edege on the inside and overlaps cut flush. Fitted AFTER the chines are in place on the shadows. This means that there is a consistent, fair 1 mm gap between the outside (skin) side of the frame and the fair line of the skin even if the frame is not true or accurately located.
Then take the skeleton off the shadows, fit the skin and rub down with a sanding block bridging two chines until it is flush (should have to remove 0,5 mm all round).
It sounds complicated, but apart from setting up the chines in the first place everything is as imprecise as you want it to be - and all you have to fair is the chines. Because the carbon rod is very stiff, this is much easier than if you were using, say, balsa.
Hope this helps
Sorry - answered wong question. Grid is 6 mm using a tool made from a block of wood and old junior hacksaw blades, so why not? 2 mm depron.
I happen to have an unrepeatable opportunity to get a CNC machined female mould made for nothing 
but the technique would work as well or better on a male mould.
Hope this helps - but I think the Red Fox solution is rather neat too!
i gotta take more pics of the plug tonight. the pics i have are to big. i only have a phone camera. then i’ll try to upload them to show ya all.
as for panel stiffness, the nice thing about composites is, you can put material where you want it, as well as using the dictional strengths of the reinfocement, to add, or subtract stiffness. you’ll see in the pics (when done) that the vessel is not a hard-chined boat, with flat, flimsy panels.
it wont need sanwich panel construction either.
not only will the reinforcement be placed stratigically to achieve stiffness, the shape will contibute alot as well. compare the stiffness of half a sphere, compared to when you join both halves together…to give an idea of what i’m talkin about.
when some are done, i will send out some to whom ever wants to r&d them, and see if there flimsey or not. maybe 4 or 5 hulls. (glass only)
i’m looking for feedback on my product, so i can then adjust, and re-tool as needed, to make a realy good hull superstructure. anywho bac to messin with pic uploads.
forgot to add that the ballast won’t be movable. the boat will have a full crew, not a solo pilot (just kidding). i could make a canting keel for it. might work on that after some regular protos are done first.
The point I was making is that you cannot get normal carbon cloth light enough to be anything but grossly over strength. The maximum hydraulic force on a Footy hull is roughly equivalent to pouring water from a jug onto the back of your hand from a height of a foot! Cellophane will do nicely, except that its panel stiffness is about 0.
A cantng keel is illegal
i’ll send you the first one to prove you wrong.
not that i’m out to prove you wrong, i would love your feed back, so i can make a good hull. so, when they are ready, i’ll let you know and send one out to you. youl get proto #1.
You guys need two classes … a closed class (as is) and an open, development class restricted to lets say a mono / 30cm hull … see who comes up with what and what shakes out … I’ll re-iterate, the size is appealling in so many ways its brilliant … to get folks thrilled about it, let their geek natures take off and blow their brains on development … the bad will fall by the wayside and the good will be encouraged … in the meantime the closed class can take what’s best from the dreamers and evolve and its own logical pace …
where in Canada are you from by the way Nigel … ?