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Jul 06, 2009, 02:50 PM
Master of the Wind
G Norsworthy's Avatar

Joining the fuse halves


A few words about joining the fuse halves. Start with the halves open on the bench. Cut some 4 mil plastic bag material in strips 1" wider than the joiner tape. Measure and cut the joiner tapes, top and bottom. Lay out the tape on top of the plastic sheet.

Mix a batch of slow hardening laminating resin. We are now using the US Composites with the 2:1 hardener. Plenty of working time but needs a couple days and heat to really harden.

Wet out the joiner tape on top of the plastic using a small roller. It should be on the wet side, just for this part.

Mix a side batch of resin with cabosil or microballoons. Not too thick, just enough to fill any open weave on the fuse layup.

Paint the bond area with pure resin first and then the resin/filler mixture using a short paint brush. Paint enough on to ensure a good bond between the fuse and the joiner tape.

Place the joiner tapes on the fuse sides, top on one side and bottom on the other side, lining up the center of the tape with the seam. Pick up one side, turn it over, and place it over the other side, offset until the flanges touch. Now slide the two halves together until the keys lock. Bolt or clamp the two sides together.

Now use a combination of stick, gloved finger, and small tailwheel on the end of a stick to roll down the joiner tape. Because we are rolling on plastic, there is no danger of unravelling the tape, or sticking it to the wheel/stick and pulling it back up. Keep rolling periodically until the resin get a little tacky to ensure there are no bubbles.

The last step is to take the slightly tacky resin and mix in a little microballoons. Stand the mold on its nose and pour some thickened resin to cast a solid plug in the nose.

Tonight we unbolt it and see what kind of troll pops out.
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Jul 07, 2009, 12:26 AM
yyz
yyz
Registered User
yyz's Avatar
Putting the seam tape on the plastic and then rolling the plastic is a hot tip! Joining the halves is the step that drives me to drink.

Where in the world are you obtaining the blue foam in California? I looked all over for that stuff. It's relatively cheap and easy to find in cold parts of the country; not so much in the warmer climates.




Quote:
Originally Posted by G Norsworthy
A few words about joining the fuse halves. Start with the halves open on the bench. Cut some 4 mil plastic bag material in strips 1" wider than the joiner tape. Measure and cut the joiner tapes, top and bottom. Lay out the tape on top of the plastic sheet.

Mix a batch of slow hardening laminating resin. We are now using the US Composites with the 2:1 hardener. Plenty of working time but needs a couple days and heat to really harden.

Wet out the joiner tape on top of the plastic using a small roller. It should be on the wet side, just for this part.

Mix a side batch of resin with cabosil or microballoons. Not too thick, just enough to fill any open weave on the fuse layup.

Paint the bond area with pure resin first and then the resin/filler mixture using a short paint brush. Paint enough on to ensure a good bond between the fuse and the joiner tape.

Place the joiner tapes on the fuse sides, top on one side and bottom on the other side, lining up the center of the tape with the seam. Pick up one side, turn it over, and place it over the other side, offset until the flanges touch. Now slide the two halves together until the keys lock. Bolt or clamp the two sides together.

Now use a combination of stick, gloved finger, and small tailwheel on the end of a stick to roll down the joiner tape. Because we are rolling on plastic, there is no danger of unravelling the tape, or sticking it to the wheel/stick and pulling it back up. Keep rolling periodically until the resin get a little tacky to ensure there are no bubbles.

The last step is to take the slightly tacky resin and mix in a little microballoons. Stand the mold on its nose and pour some thickened resin to cast a solid plug in the nose.

Tonight we unbolt it and see what kind of troll pops out.
Jul 07, 2009, 12:32 AM
Master of the Wind
G Norsworthy's Avatar

Remove the fuse from the mold


This is the rewarding or frustrating part, depending on how it goes. I saw this done with something like a 40 foot boat mold, and those guys knew what they were doing. Some water, compressed air, a few popping noises and it slid right out.

After unbolting the flanges, use a hose to run some water down the crack to start dissolving the PVA. Wait a bit, go to dinner, and come back later. Now start prying the mold apart wherever it appears loose. In this case one side just lifted off. Then the other side peeled out. This was the first time I brushed on the PVA and I must admit it was easier than spraying. The finish was just as good or better.

Success. I'll take it to work tomorrow to weigh it. Not as good as Europlastic, but then I only do one of these every few years and the mold is not perfect either. Next step is to fill, sand, and paint the seam to your level of satisfaction.

The jury is still out on the US Composites with the 2:1 hardener. For this amount of time the MGS was much harder, but I will give this some time in the hot box. The scrap kevlar in the wing saddle is much stiffer than previous versions but still may need some plywood for the wood screws in the cross pieces.
Jul 07, 2009, 12:38 AM
Master of the Wind
G Norsworthy's Avatar
http://www.whitecap.com/\

They stock it in San Fran and brought it to the local branch for me. if there is no local source I might be willing to make a deal. Will PM with details.

I'm using hiload 40, which seems to be fine given the thickness of the skins. Word is hiload 60 is even better but the learning curve for cutting is longer. I built 5 and 6 from spyderfoam. Again hard to cut and the source has dried up.
Jul 07, 2009, 01:04 PM
yyz
yyz
Registered User
yyz's Avatar
Greg,

Did you paint the mold prior to layup or using a coloring agent in the gelcoat layer? The white looks really nice in the photos.

Mike




Quote:
Originally Posted by G Norsworthy
This is the rewarding or frustrating part, depending on how it goes. I saw this done with something like a 40 foot boat mold, and those guys knew what they were doing. Some water, compressed air, a few popping noises and it slid right out.

After unbolting the flanges, use a hose to run some water down the crack to start dissolving the PVA. Wait a bit, go to dinner, and come back later. Now start prying the mold apart wherever it appears loose. In this case one side just lifted off. Then the other side peeled out. This was the first time I brushed on the PVA and I must admit it was easier than spraying. The finish was just as good or better.

Success. I'll take it to work tomorrow to weigh it. Not as good as Europlastic, but then I only do one of these every few years and the mold is not perfect either. Next step is to fill, sand, and paint the seam to your level of satisfaction.

The jury is still out on the US Composites with the 2:1 hardener. For this amount of time the MGS was much harder, but I will give this some time in the hot box. The scrap kevlar in the wing saddle is much stiffer than previous versions but still may need some plywood for the wood screws in the cross pieces.
Jul 07, 2009, 02:28 PM
Master of the Wind
G Norsworthy's Avatar
Mike,

The white is car paint, and it was painted in the mold.

Greg
Jul 07, 2009, 03:08 PM
Master of the Wind
G Norsworthy's Avatar

Fin and Stab


This design will have a T tail. I looked at all the options and with some improvements in building learned from DLG planes it makes the most sense. The stab will be bolted on and the elevator will be hinged. I looked at the Supra scheme, but it gives up a lot of moment arm in front of the fin. Construction borrows heavily from the Supra.

The stabs are cut, trued, and glued at the root just like the wing joint. The top of the templates lines up so that the hinge line is straight. Two pieces of end grain balsa are inset full depth where the bolts will go through. Two smaller pieces of 1/8" thick carbon plate are then inset on the bottom of the wood, where the bolts will go through.

Two pultruded carbon rods are inset in the foam, described well here.

https://www.rcgroups.com/forums/show....php?t=1065719

The hinge line is cut and faced with 1.5 oz glass as described here. I am using the tape over wood filler like Phil Barnes uses on the elevator. The fin is thicker and the triangle cutout is reasonable to deal with. The surfaces are held on with small tabs of 1.5 oz glass (not bias) and double stick. I like the tape better than 3M77 because it is easier to control and doesn't mess up the shop. You also always know how much you have left, and the nozzle does not plug.

https://www.rcgroups.com/forums/show...d#post12386533

LE is wrapped with 1.5 oz glass and double stick tape, and the stab is ready to bag.
Jul 07, 2009, 03:58 PM
Registered User
Kai@UCSB's Avatar
Greg,

Will you use Kevlar as hinge line?

-Kai
Jul 07, 2009, 06:38 PM
Master of the Wind
G Norsworthy's Avatar
The tails will be skinnd in kevlar. Single layer on the stab, maybe double on the fin. The skin is the hinge, same as a Taboo wing. If I double the fin, there will still be only a single layer over the hinge line, otherwise it will not bend very well.
Jul 08, 2009, 02:34 AM
Master of the Wind
G Norsworthy's Avatar
Fuse finished out just under 15 oz. Got the center section and tails in the bag tonight.
Jul 08, 2009, 10:12 AM
Registered User
dbaya's Avatar
Subscribed. Epoxy still sticky!
Jul 08, 2009, 02:57 PM
Master of the Wind
G Norsworthy's Avatar

Stab and Fin continued


A few photos of the fin during assembly. The fin also has two pieces of 1/8"carbon plate embedded in the tip where the bolts will go. They are then covered in end grain balsa, which is cut oversize and fit to the stab after bagging.

The stab layup is 1 layer of 1.7 oz kevlar on the bias. The fin layup is one layer of 1.7 oz kevlar, a second layer of 1.7 kevlar forward of but not covering the hinge, and a 2" layer of 4.5 oz carbon uni over the high point, expanded at the tip to cover the second carbon insert. Something I forgot on this one but will use in the future is to run a 1/2" wide strip of 1.5 oz glass between the kevlar and the paint, poking out past the LE of the mylar, to encapsulate the kevlar should some finish work be required on the LE.

The hinge reinforcement, LE, and balsa inserts were wet out with extra resin for a good bond. The assemblys were packed inside denim cloth with plastic covering on the inside as a vacuum conduit. This is re-usable and conducts very well. The final vacuum was pulled with some weight distributed over the top bed, and me pushing on it as well to ensure that the bottom bed is flat on the table. Once the vaccum is pulled, the TE is checked with a long straightedge to make sure it is not warped.
Jul 08, 2009, 08:00 PM
Master of the Wind
G Norsworthy's Avatar

Center section


A maple block is glued into the center section about 2.5" back from the LE to make a hard point for the bolts. It is deep enough to take countersunk bolts if we go that route.

The layup is 1.5 oz bias glass, 2 layers of 6 oz uni glass top and bottom, one layer of 6 oz top and bottom over the middle 12", and cross direction uni patches over the brass tubes. Took a mix of 15 oz of resin, and a little was left over. The final vacuum was pulled under a bit of weight to verify that the beds are down on the bench. The alternate is to use double stick but then you have to clean it up. The TE was checked with a long straightedge to make sure it is not warped. So far this is the best looking XC wing I have made at this point. I credit Anker's idea not to remove any skin thickness so that the wing is supported by the bed all the way to the TE. The parts are scheduled to come out Sunday.
Jul 14, 2009, 12:49 AM
yyz
yyz
Registered User
yyz's Avatar
What the hell, Greg? It's like you quit building and went back to work. What's up with that? Seriously though, watching this and learning a ton.

Thanks again,

Mike
Jul 14, 2009, 02:08 AM
Master of the Wind
G Norsworthy's Avatar
Social service, actually. Plus I bagged the center section last week and uncertain of the US Comp slow resin I asked dbaya not to open the bags until the weekend no matter how many times I begged. Not to fear I have the centers and tails in my posession and bagged the tips tonight. I'll post it all as soon as I can get some time.


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