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Feb 19, 2015, 11:06 PM
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Got the canopy/lip area glassed today with 5 x 6oz (180gm). tight- weave S-glass layers. Probably overkill for strength, but I want the FG canopy to to equal the thicknss of the .040 or .030 PETG clear canopy plastic I have, with a little smoothing filling & sanding . The roll of 3" plastics stretch wrap is shown, and used to wrap and bind the laminate tight to the fuse. This is the stuff similar to what Woo used to wrap his Diana fuse boom (thanks WOO). I got it from EBay, sold as "JPack handheld 3" wrapper", around $9 w/ free delivery. Works great, and the laminates release from it easily. Hotbox set for 85 degrees, so it'll cure all night.
Last edited by flyingfever; Feb 20, 2015 at 12:43 AM. Reason: glass weight
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Feb 21, 2015, 10:41 PM
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canopy


Canopy released. turned out fine, but too many laminations. I misjudged the thickness totals, and ended with . 055-.060", too thick and heavy. Maybe it can still be used for a clear canopy buck, or?? It's a good experiment to judge the fuse lamination schedules, etc.. If it were sanded smooth, would it be close enough to size to use it as the buck or form for the clear plastic canopy, or would it be necessary to make the clear canopy form by using this one as a mold, and laminate the exact-sized smaller canopy buck, or form, on the inside of this canopy? Suggestions? I'll use Mike B's method of pulling heated plastic over a form, and not use a vacuum form box. I might need to just chalk this one up for practice. Oh, when I laminate the fuse, I'll do another canopy that matches. Thanks.
Last edited by flyingfever; Feb 22, 2015 at 12:23 AM.
Feb 22, 2015, 08:39 AM
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The way I do my canopys is by glassing the fuz in one go and then cutting the canopy line then hot wording along the line. Then I have a plug to pull a clear canopy the same way as mike b does. the glass does need to be thick to stop the foam melting.Name: t6304763-237-thumb-jan5.jpg
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Feb 24, 2015, 08:21 PM
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Earlier in the thread I showed a picture of some carbon/Kevlar sock that I bought to make the wing joiner sockets for a project I'm working on.......I got one of them finished.....
I first had to fill the lightening holes in the joiner with fast set drywall mud and the waxed it.......I then took 1 mil plastic and waxed that and wrapped it around the joiner two times. The sock was put on......wetted out with epoxy and then pulled tight and wrapped with plastic wrap......the same wrap that is shown being used here.
Model airplane Joiner (0 min 29 sec)

Model airplane joiner 2 (0 min 35 sec)
Feb 24, 2015, 09:51 PM
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Joiner & boxes


I then took 1 mil plastic and waxed that and wrapped it around the joiner two times. The sock was put on......wetted out with epoxy and then pulled tight and wrapped with plastic wrap......the same wrap that is shown being used here." SZD16

Thanks for the video and info.. I ordered the CF/Kevlar sock you suggested earlier for the joiner boxes. Thanks.
Last edited by flyingfever; Feb 10, 2018 at 11:19 PM.
Feb 24, 2015, 11:01 PM
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Another way to make the joiner is do away with the aluminum and just use wood......MDF makes a excellent form.......... use a good quality packing tape and tape the bottom base piece and then tape the edges wrapping around all three sides of the two sides pieces....... screw them down to the base and then make a top piece that will get screwed down to that. No clamps, no wax, no mess. When it cured just unscrew everything and your done.
With all that said why not just use aluminum for the joiner? The one you see in my video cost me $107 and is 1/2" x 1.5" x 40" .........if it didn't have the dihedral in it the cost would have been half that.
Carbon makes sense if there is a double crank in the joiner...... if it can be flat then aluminum makes more sense from a cost and the PITA factor of fabrication ........that and when you have a "Ohshit" moment.... aluminum bends..... carbon breaks!
Feb 24, 2015, 11:15 PM
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6061-T65 Aluminum 48" x 3/4" x 1.5" is $23.00


http://www.onlinemetals.com/merchant...97&top_cat=60#
Feb 24, 2015, 11:44 PM
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["screw them down to the base and then make a top piece that will get screwed down to that. No clamps, no wax, no mess. When it cured just unscrew everything and your done.
With all that said why not just use aluminum for the joiner? The one you see in my video cost me $107 and is 1/2" x 1.5" x 40" .........if it didn't have the dihedral in it the cost would have been half that.
Carbon makes sense if there is a double crank in the joiner...... if it can be flat then aluminum makes more sense from a cost and the PITA factor of fabrication ........that and when you have a "Ohshit" moment.... aluminum bends..... carbon breaks! [/QUOTE]

The "floating" joiner top was to make sure under compression, all excess resin was squeezed out, and then, if it was below the tops, I could add more tows. I could still do that, tho, and just use a wider top with screws for the final compression as you suggest. I chose the CF for the joiner, as most of the 7-10 meter sailplanes I've seeen use cf or composites, or steel or alum. tube filled with cf or other composites. I haven't seen any this size using a solid alum. rod. The 7-8+ m. ones have used a dia. of 20-25mm. or equivilent. The .75" x 1.5" size = approximately a 25mm dia. rod. I don't know if a solid .75" x 1.5" would be stiff enough. This joiner has to lay flat, not on edge, to allow for the 3* wing dihedral. My plane will probably weigh around 45 lbs. Maybe it depends on the grade of aluminum? . If anyone out there knows if it would be safe enough or comperable to the solid CF one, laid flat, advice is appreciated. It would certainly make it easier. I'm no engineer, so unless I know for sure, I'll go with the CF. The alum. bar is 6061 grade, 6511. 4' is only $25. Is it strong enough laid flat?? Could I be so lucky? Thanks. szd.
Last edited by flyingfever; Feb 24, 2015 at 11:58 PM.
Feb 25, 2015, 12:23 AM
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Did some research. Forget the 6061, it's only 45,000 psi.. The two highest grades are 2024 t351, which has a tensile strength of 70,000 psi, 4' costs $60., and 7075 aircraft grade, 83,000 psi, 4' costs $75. Big thing is the weight, which is 5 lbs. for the 40" piece, compared to 2.2 lbs for the solid CF one. The question still is, is it strong enough? I'm thinking it probably is, even flat. Thanks.
Feb 25, 2015, 03:12 AM
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Quote:
Originally Posted by flyingfever
Did some research. Forget the 6061, it's only 45,000 psi.. The two highest grades are 2024 t351, which has a tensile strength of 70,000 psi, 4' costs $60., and 7075 aircraft grade, 83,000 psi, 4' costs $75. Big thing is the weight, which is 5 lbs. for the 40" piece, compared to 2.2 lbs for the solid CF one. The question still is, is it strong enough? I'm thinking it probably is, even flat. Thanks.
My thumb suck gut feel still says go with the carbon fibre option.
Feb 25, 2015, 10:50 AM
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After going back and looking at your pictures I had forgot that your joiner is laying down on its side and not vertical in orientation. Therefore I believe you are better off with the carbon joiner. My application has the joiner in the vertical orientation and 1.5" is more then strong enough in that position.
Maybe get some thin wall aluminum rectangular section and fill that with carbon...... My decision to use aluminum came after thinking of what was involved time wise in laying up that large of a carbon joiner........lots of carbon...lots of epoxy....lots of time...even using slow setting epoxy you still will have different cure rates between the "bottom" and the "top" of the layup.....
Feb 25, 2015, 06:55 PM
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Carbon


Quote:
Originally Posted by mikegbogh
My thumb suck gut feel still says go with the carbon fibre option.
Yip carbon I reckon, it is way stiffer than Al Alloy too and lighter. By the way, the values you are quioting for the different alloys are way too high for ultimate tension or compression in bending. Ultimate is also when they break and you need to think of values for when they stay bent, have yielded in other words.
Wet laid epoxy /uni carbon joiners made with as much carbon as possible in the matrix will yield at about 100,000 psi. I have experinental results from my local University lab that support this for 5/8 inch diam round bar joiner. I put one in the beam bending rig. Failure was soft too with a gentle yield so they shouldn't snap like a carrot if overloaded.
For what its worth.

Allan
Feb 25, 2015, 06:57 PM
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Quote:
Originally Posted by mikegbogh
My thumb suck gut feel still says go with the carbon fibre option.
Seems a long time since we were treated to one of your great builds Mike, what's going on in your workshop????

Allan
Feb 25, 2015, 11:19 PM
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Quote:
Originally Posted by AllanK1
Yip carbon I reckon, it is way stiffer than Al Alloy too and lighter. By the way, the values you are quioting for the different alloys are way too high for ultimate tension or compression in bending. Ultimate is also when they break and you need to think of values for when they stay bent, have yielded in other words.
Wet laid epoxy /uni carbon joiners made with as much carbon as possible in the matrix will yield at about 100,000 psi. I have experinental results from my local University lab that support this for 5/8 inch diam round bar joiner. I put one in the beam bending rig. Failure was soft too with a gentle yield so they shouldn't snap like a carrot if overloaded.
For what its worth.

Allan
Thanks, as I said, I'm no engineer. I'll stick with the original plan of CF, using Mike B's tried and proven method, with a few changes. I now plan to make the receiver boxes with the CF/Kevlar socks and wraps instead of building them out of ply & aluminum, with wraps. I'l probably get an aluminum bar of the joiner size to use as a form for the boxes. Thanks again SZD, MikeB and AllanK.
Feb 26, 2015, 02:17 AM
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Quote:
Originally Posted by AllanK1
Seems a long time since we were treated to one of your great builds Mike, what's going on in your workshop????

Allan
Hi There,
It has been awhile, I have been involved in another hobby ,

I am also busy rebuilding a few old 70's motorbikes.

So with only 24 hours in a day not much happening with the scale gliders , but I did layup a Nimbus 4 fus last weekend for a friend so all is not lost. ha ha.
Really nice to watch another masterpiece unfold from a safe distance.
reagrds
Mike gbogh (B)?
Humblest apologies for side tracking.
Last edited by mikegbogh; Mar 02, 2015 at 09:05 AM.


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