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Old Mar 10, 2015, 07:17 PM
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Build Log
Syner J Foam Build

Here we go.... A bagged version of the airfoils Gerald published here:

http://www.rcgroups.com/forums/showt...6&highlight=gt

It will be a three panel wing, with the first break at the inboard flap. It's only about a 44" center panel, but it simplifies the build for me and will also fit on my pylon fuse.

Hopefully, the plane will finish in the low 50 oz range.

After about two days of XFLR to Cad to foam cutter software, I started to build the foam beds that will support the airfoils (to maybe within a county of accuracy).

All said these pictures are about a week of work.
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Old Mar 10, 2015, 07:32 PM
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End Caps

I used Profili and my neighbor's CNC to cut the endcaps. They are 5-ply birch from balsa USA.

Like the foam beds, this took a day of tinkering to get everything lined up perfectly.

I know, I know, I should be doing molds....
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Old Mar 10, 2015, 11:39 PM
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Now that's an interesting way to build the spar. Wrapping in-situ rather than bagging the spar first is new to me, please tell me more.

For example how many layers of UD (I presume its not constant across the span) and I presume you leave the finished thickness less than the full thickness of the spar slot so you can cap it with balsa or foam or filler. How do you do the maths to compute the final thickness?

Do you intend to winch the finished toy, or is it for F5J (or Ales)?

Looking good, love your workmanship. Its top notch.

Hutton
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Old Mar 11, 2015, 02:05 AM
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Very nice build techniques
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Old Mar 11, 2015, 07:21 AM
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Thanks for sharing the build Will. I love to see these come together from bits off foam and wood, fabric and epoxy. Fascinating!
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Old Mar 11, 2015, 10:05 AM
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Old Mar 11, 2015, 12:44 PM
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Mylar and fabric.

I'm using the carboweave CW30 for skins with an extra doubler on the flaps.

The Mylar is split for the top and one piece for the bottom. The Mylar from CST is my favorite, it's really makes for a shinny finish.

I use frekote for the release. Here's what I've learned about frekote:

1. If your part feels tacky, throw the can away.
2. If the parts just didn't come out like normal, throw it away.
3. Always test your paint glue combo
4. Do a tape test, if basically any tape sticks to the surface, throw it away.
5. I can't find an expiration date on the spray cans....
6. I've never been comfortable going up to the expriation date on the liquid cans.


With all that said.... I've never had a part stick. (Knock on wood) I really do love the stuff.
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Old Mar 12, 2015, 06:46 AM
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I'll edit my grammar in a bit so bear with me

Straight forward bagging. I found that laying down the carboweave down dry is the best. Normally, I wet the mylar and drop the fabric on, re-positioning CW is really difficult.

After the fabric is wet, I debulk the skins for about 5 mins. That gives me enough time to wet the leading edge, hinge and fiberglass facing.

Pulling the bag over the dihedral is a little challenging, Its best to have the bottom bed with the wedge in place so the mylar is resting on something. I pull about 22" then position the beds. After everything is in place I remove the vacuum to give the weight a chance. Then I turn the pump back on.
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Old Mar 12, 2015, 06:51 AM
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Out of the bag, 12oz.

Tips are next....
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Old Mar 12, 2015, 10:57 AM
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Very cool and beautiful work. Thanks for sharing.

Bruce
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Old Mar 13, 2015, 04:58 PM
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This will be a TD ship.

I use a excel sheet from Anker to determine the spar layup. I have been using 9oz T700 uni, to get something lighter I went to the IM7 6oz. with a similar layup. The foam is hi-load 60 and the wrap 3K plain weave on the bias.

Here's the tapers for the center panel:

Top Cap:
3 full layers
36"
29"
24"
22"
12"

Bottom Cap:
2 full layers
36"
24"
22"
18"
12"

Tip layup:

Top & Bottom Cap:
1 full layer
28.5"
16.5"

Quote:
Originally Posted by VHO View Post
Now that's an interesting way to build the spar. Wrapping in-situ rather than bagging the spar first is new to me, please tell me more.

For example how many layers of UD (I presume its not constant across the span) and I presume you leave the finished thickness less than the full thickness of the spar slot so you can cap it with balsa or foam or filler. How do you do the maths to compute the final thickness?

Do you intend to winch the finished toy, or is it for F5J (or Ales)?

Looking good, love your workmanship. Its top notch.

Hutton
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Old Mar 14, 2015, 03:20 PM
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As you noted once the Carboweave gets wet with epoxy resin, the binder disolves and repositioning can be difficult if not impossible.
I generally wet my mylars and have some help me when I put the CW on them. I just want to be sure I have good saturation, but I'm sure your method of wetting out works good as well as long as you get good saturation.
I've made leading edges on DLG's with CW and 3/4 ox class cloth similar to what you do. I put the class on the outside to give me a sanding guide so I know when I'm hitting the carbon. I generally 3M77 it in place.

I'm thinking of using some foaming agent with resin on leading and trailing edges (overhang past he foam) on future builds.

Nice work on your new plane.

Terry
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Old Mar 17, 2015, 07:52 AM
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Wingtips

Same build process. The tips finished at 7.9oz. That puts the total wing weight around 28oz.

The spar layup seems plenty strong even for a moderate winds. The last panel is supported by UHM 100gr uni along with the dihedral break. That area has some pretty high stresses, I extended the wrap just past that point.

You can see the panels line up pretty well. I wanted to do square joiners, but the alignment would be really tough. One good thing about the round joiners they limit the stress on the joiner box on landings. Since the center panel is so short that might be a good thing.

Terry is sending more carboweave, I'm just shy of finishing the other side. Another couple days work to go!
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