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As I mentioned elsewhere on this forum, I have a very annoying wobble in the wing-to-fuselage connection. I am able to decrease it by wrapping two strips of soda can aluminum over the flat parts of the fuse but it does not eliminate it completely and it makes it hard to pull the wing off the fuse. So I am looking for a more or less permanent solution to this problem. I am thinking about pouring some epoxy mixed with I do not know what exactly into the barrel of the wing and sticking the fuse in there. Extra epoxy will hopefully get squeezed out. Big question is what release agent should I use on the fuse so that I can still pull it out after the resin sets? Any advise would be appreciated.
I just used a small paintbrush with long handle and put 2 coats of epoxy on the inside of the wing and it worked perfectly. Do 1 coat then tip the wing up so any excess drains to the outside and doesn't pool inside.test the fit after one coat sets and do more coats if needed. The end of the fuse has sharp edges and sliding it in and out will gradually shave the inside of the wing.You can use this to help get a good fit , but once you have it perfect then file the sharp edges off so it doesn't shave epoxy off every time you slide it in .one wing I had needed 2 coats and the other only one coat so be conservative because it is adding thickness to 6 sides.
Have you tried adding a good supply of Lanolin grease on that part of the fuse and all connecting parts of this wing? Next time after wing breakdown / wash more lanolin. This method works for me.
I use plastic wrap for working with epoxy, works amazing somehow as it doesnt stick to the epoxy.
Here is youtube guide for applying tape. I used it to eliminate wobbling on my mast and it worked.
Thank you all for your input. I think I will try epoxy. Will test some release agents on a mock up first.
I did try all kinds of tape and determined that soft tape does not work, hence, used strips of aluminium.
Hi guys i solved the wobbly wing issue for good with an easy modification. I added another 6G screw to the wing/fuse and fitted helicoils to the small fillet that the foil bolts go into as they alway strip as there is only a few threads to tighten the bolts on. Now the bolts go all the way through and i have them cut so they are flush.
Found a good read about release agents and stuff:
www.epoxyworks.com/index.php/what-you-can-do-if-you-dont-want-epoxy-to-stick/
I am wondering now what kind of resin is used in wing fabrication, and what kind of resin I should use. Definitely not one of the fast curing ones.
I also like the idea of helicoils in the fillet thingy. It is so easy to strip the threads in it. Ruined a couple of them in the past.
Epoxy resin, hi quality slow cure like Resin Research ot West Marine.
Fast cure for cosmetic.
Slow cure for structural.
I tried the foil tape. This worked well in terms of eliminating wobble but I had to apply it very flat and only halfway around (applied tape longitudinally). I added a thin layer of grease then carefully slid it on. It fits very tight and no real wobble now. However, I couldn't get the damn thing off to change wings out at the beach! When I do get it off I'm sure that I'll need to reapply tape. So, it's really not the best fix unless you are leaving it on, and even then you need to take it off occasionally to keep from seizing.
Here is a new way to address the wobble. The brass mast cap inserts seem to loose their grip and get easier stripped. I've gone thru 2 of them in 2 seasons. For those who were earlier adopters of the FWIND1 and mulitple masts (short to long), you have a chance to remedy the mast cap problem.
Just take the 15 inch mast (who uses it?) and "slice it" on a band saw or hacksaw, about the same thickness as the orginal. The Slingshot masts are threaded really deep. I got 5 mast caps from my 15 inch mast and still have room for more.
The new mast cap (sliced), has stronger thread's than the brass one. It helped alot.
Like Fast505, I use tape as well. Good luck.
^^^
Cool idea, never thought of that! How many could you make out of that 15" mast?
I wounder if it's stonger aluminum then the SS forged aluminum caps. I have thought of drilling through the top of the alu cap and re taping so you can't bottom out the bolts and maybe get a extra couple threads
But don't think this would solve the wobble some are experiencing since this just stops the wing from sliding back and forth.
I agree, it just provide more threads and eliminates the bottoming out issue.
Still needed some tape for the wobble.
15 inch mast makes +/-6 caps.
I noticed a wobble after de-rigging yesterday. I tried to tighten the front cap bolt and is was stripped. It looks like the bolt only grabs a few threads in aluminum cap. Wonder if it is a corrosion issue. I did not think I had overtightened the bolt. Usually when you strip something you know it right away.
Yes it grabs perhaps 2 threads which is why I've threaded mine through and gotten longer bolts.
Throw this aluminum in the trash(I screwed up the bolts a couple of times and the thread has already deteriorated). it is necessary to use the foot of carbon fiber or as I have a hybrid stainless steel and carbon fiber.
Watch out for galvanic corruption when combining carbon fiber with stainless steel. I've seen it happen in carbon extensions.
Well, finally I found some time to get to it. Rubbed a lot of wax on the fuselage. Packed the bolt holes with wax as well. Wrapped the mast plug insert with thin plastic tape and popped it in. Mixed a tea-spoonful of epoxy without thickener and poured it into the wing tunnel. Slowly inserted the fuselage to proper depth and made sure it is positioned straight. Next day checked how it turned out. Fuse-wing connection is rock solid. Tapped the wing off the fuse with a wooden block. They separated but "unwillingly". I think the tolerances turned out to be too tight for frequent wing changes. Fortunately I have a couple of fuses for other wings. If I have to do it again, I would use a bit of tape over the wax on the fuse prior to insertion into the wing to have a touch more wiggle room. My other wings do not have so much play as this I-84 had.
Next I plan to make a few new mast caps as "alllesad" suggested.
You can't use a standard drill to countersink, the angle is wrong, usually 60 degrees, whereas a countersink is 90 degrees.
The other issue is the drill will grab & bite into the wing & probably drill right through before you can stop it
You can re-sharpen a drill to 90 degrees but clamp the wing down & use a drill press set to the correct depth so it can't grab & go right through.
Not sure but I think the problem is with this system there is only 1 bolt actually threaded into the fuse whereas the other 2 go through the fuse into that spacer thingy which only locates the top of the wing.
If the spacer is not a tight fit into the wing you will get wobble.
If the spacer was slightly tapered it would help or wrap it with some tape maybe.
If there are plain holes through the fuse then these could be tapped out & helicoils inserted to give 3 proper connections & ditch the spacer.
I think that might be what JJ did in another thread from memory.
I may be wrong as I haven't looked at the setup in real life close up but from the above photos that's how I see it & explains why an extra bolt helps.
Hello,
to do it I will start by sanding the inside of the foil to remove any salt hand get clean surface.
after I will put some flash breaker(special composite tape that got calibrate thickness) or use metal shim to define the thickness of the gap to fill.
If you are less than 0.2 put Meguiar's wax release agent directly on the shaft + plasticine for the hole and and mix of epoxy resine with microspheres microballoons get it thick apply a thin surface on the shaft and inside the foil and assemble both use the cap with on bolt full of release agent to get in position.
If it is over 0.2 laminate one or more layer of 200g E-glass on the shaft thickness of one layer is around 0.2.
once you have the form mad, insert it inside the foil with epoxy mix with microsphere and microballoon
