hmm, this glue, is it strong enough for fin boxes? does it eat eps?
I am enjoying this thread as well. I have found that the skins and rails add a lot of weight so I am interested to see the next stage. The deck on my most recent project is 1/8" ply and I wish I had put 2oz glass on the inside. Looks like I will need 2 x 6oz on the outside to make it strong enough that will add alot of weight and it won’t be as strong.
So, are you going to put a little chunk of some ultra hard wood in the notched piece of the fin where the screw seats? I didn’t see if you mentioned that before. I suppose glue it in with some CA and then mold the whole thing together? You’ve given me a whole new respect for superglue.
I hadn’t been following this thread until today and I have to say that I’m amazed! Your workmanship and attention to detail really show through. I’m really interested in what your doing with the fin construction - can you explain further?
Tennis matches have been cramping my time… along with school, and looking for a job.
I still gotta come see this…
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hmm, this glue, is it strong enough for fin boxes? does it eat eps?
Most types of CA glue will eat foam. Im sure it will eat EPS. There is foam safe CA glue that probably wont eat EPS foam. HOWEVER, the curing characteristics of CA are NOT favorable when used with foam. Foam is porous as spheres, not grain. CA will soak through the spheres to a surtain depth and make those spheres brittle. There is a boundry line between the saturated foam and the unsaturated foam. I promise it will easily crack there. CA works best on materials with a grain because the grain will bridge the boundry line between brittle saturated material and softer unsaturated material. Resins provide a more flexible joint with a less abrupt boundry line. Stick to epoxy for foams PERIOD.
BUT… I have not tried CA on foams like Klegecell and Dyvincell. Thats the type of foam core I use on skimboards (see attached pic, LP is my nick name, and I found that pad while skimming at vilano beach a few years back, it just washed up). These foams have a different pore structure. It might work great… but it might be too porous and could suck the glue away from the joint. I think a paste of epoxy plus micro-balloons could have potential for joining Klegecell and Dyvincell.
For airplanes I use 3M-77 foam safe spray adhesive to skin wing halves with balsa and mybe some carbon tow in between. (Ive only been able to find foam safe spray adhesive at craft stores) The wing halves are fiberglassed together with a small plywood joiner imbedded in the foam. Then the wing is covered in iron on mylar (see attached pic)… That whole framework was built entirely with CA wing mounts, engine mounts, everything!!
3M-77 is super light, super sticky, You just spray it on both sides, wait for it to tack up, then stick the pieces together and push down for a few seconds. There is no need for long dry time or vacuum bags. Any one want to skin an EPS blank with balsa using 3M-77??
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So, are you going to put a little chunk of some ultra hard wood in the notched piece of the fin where the screw seats? I didn’t see if you mentioned that before. I suppose glue it in with some CA and then mold the whole thing together? You’ve given me a whole new respect for superglue.
The notch molded in and formed from the wood and Carbon tape. I dont think its going anywhere. see pic “surf26” and “surf27”
check out what these planes are capable of…
http://www.toc1.com/Video/Files/13.mpg
Oh duh, my bad. I forgot these are twins, so the fin base is larger than the box and they run over the front. Do you think your wood/tape lamination will be strong enough to keep that set screw from digging in? I find sometimes there is a tendency to over torque the set screw as it is a blind mate and the plastic threading clearance is pretty random from box to box.
Hey, if you want to attach a leash to it, I bet using that black cord in some epoxy and making a small leash loop on the deck would look pretty slick. Then again, maybe clear epoxy on the deck would not take away from the overall wood look. I’ll just sit back quietly and enjoy the rest. Good show.
Im getting a lot of questions of how I plan on doing the rails because they tend to be a weight issue. Well… the airplanes on those videos above are made from molds to produce a hollow fiberglass/kevlar/carbon shell. The shell is supported by a few bulk heads here and there and the wing is hollow with a beefy carbon spar and two ribs, one on the tip and one at the root. Its very stiff, strong and light. How about hollow fiberglass/kevlar/carbon rails?? Ive figured out how to do it and I think I might keep some suspense…
Check out the new mold for the other fin. It came out better than the first, but still a few bubbles that need to be filled in. I have the first fin to pop out of these molds. It came out good, but also it still has a few bubbles that need to be filled in. I need to cut off the edges too.
Any one want to skin an EPS blank with balsa using 3M-77??
Go for it!
just make sure you report back after the inevitable failure…ha!
BIG model!
a little bigger and you could sit inside the thing…
cool link
my older bro was into r/c airplanes…still is part-time
Im gluing the subdeck to the frame lotsa sandbags!!
lpcdefg,
Excellent thread! Just thought I’d post a link to a site that shows a similar process to the tooling you made for the fins. And for a recent post made by someone regarding making foam core fins: http://www.nextcraft.com/j47_sportjet07.html
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lpcdefg,
Excellent thread! Just thought I’d post a link to a site that shows a similar process to the tooling you made for the fins. And for a recent post made by someone regarding making foam core fins: http://www.nextcraft.com/j47_sportjet07.html
That plane kicks ass… It just needs a turbine!!
Check out my fins and boxes. I still need to do a little filling and a clearcoat.
THank you for going through this projecct, good stuff-fun to watch it coming together. I was just wondering, if you had time, would you consider writing a thread about moulding the fins? Been trying to figure this one out for a while, understand the mold making part, it is just from that point forward . . .
Mahalo
Joe~
Interesting construction techniuqe…really. But a six pack of Newcastle says she snaps the first go out…that is if you surf her like a real board.