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Mar 18, 2012, 12:25 PM
CasualSoCalFlyer
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Garnet DLG electrical system and Supra wing repair both completed!


This is a summary from Thursday to today.

Please note there are some repair tips from West Systems regarding composite wings that that I am passing on for the benefit of others, though I decided not to go this route.

This morning, I finished sanding my Supra wing. Pictures of the entire project and finished surfaces at the bottom. Please keep in mind, this is my first composite repair, so this is more documentation than a “how to”. Though the new surfaces are not 100% smooth, it is close enough for me to start painting, though that is low priority. I disassembled the entire airplane from tip to tail over the last few days, and confirmed it is ready to fly!

Last night, I finished soldering the mini Futaba connectors to the wing and tail servos in preparation to receive the 616 FASST receiver that is back-ordered. Things to do when the receiver comes, mount the battery pack and re-check the CG 62mm from leading edge. My radio already has the basic settings, just need to fine tune at the field. Will be nice to finally have all my planes airworthy and on 2.4g FASST, which has proven it self to me time and time again. What an improvement from the 72 mhz days!

Last Thursday, I had a day off again! Early morning, I started repairs on my Supra Wing. I contacted West Systems the other day about the best way to make my repair; for the benefit of others, and my future reference here is a copy of the transaction:

Me: “I am trying to repair my radio control glider's molded wing after a crash. There is cosmetic damage to my wing that requires some "filling”. Everyone recommends West Systems, but not sure what exactly I need. All I can tell you, needs to be extremely light weight and stiff after its dried. Needs to be sandable to contour to the wing's curvature.”

West System's Rep: “I would recommend using WEST SYSTEM® 105 Resin and 205 Fast or 206 Slow Hardener with 410 Microlight Filler.  The epoxy mixture with the 410 filler is very light weight and sands easy, but when fully cure is stiff. Sand all damaged areas with 80 grit sandpaper before applying epoxy. The epoxy can be thickened to a putty consistency that can be squeegeed on the damaged areas and when cure sands easy to the shape of the wing’s curvature.”

I looked at the price of the mentioned solution, and decided to just use my own supply of inexpensive finishing “laminating” epoxy and micro balloons. I couldn't see spending all that money (about $80!) for 1 quart of resin, hardener and filler unless I were to start another building project.

What is interesting the tech said the minimum shelf life of those components should be about 5 years, though those numbers are “not published”. If true, then this is a great deal for someone who flys frequently.

Before applying epoxy, I pushed in all the damaged parts with an exact o knife so the surface would be flush, and applied thin CA to stiffen the loose parts. I taped around the damaged surfaces as to keep other parts of the wing clean when the epoxy goes on. I also had to sand a bit to make a good contour for the epoxy to set in.

The next morning, I mixed up some laminating epoxy and micro balloons to a thick creamy texture, then allied it onto the damaged wing surfaces. At one point, as the texture got real thick, I was able to shape the filler to the contour of the wing with my gloved finger.

Then I decided to go fly my AVA e in the afternoon at the Rose Bowl, where the field was nearly empty; perfect for RC. Unfortunately, I punched a hole through the solar film as I was securing the stabilizer. Easy fix with clear packing tape.

I had a rather short 10 min 20s flight at the Rose Bowl. It was around 1pm, powerful thermals, wind and lots of sink, so the incentive to explore was just not there. I had hoped to fly around 11am, but this mornings project didn't allow me.

After running some errands, the epoxy became hard enough to start sanding the wings. It was then I discovered that wing also had some damage on the tip, some minor delamination. I decided to apply thick CA to the separation, and it seems to have restored the integrity of the wing tip. I'll have to keep an eye on that. Also, after sanding the wing, I looked closely at the horizontal stabilizer as I was reviewing the radio program, there was also some delamination on one side. Again, I applied CA to the area that was starting to separate, and it seems stronger.

The repaired wing weights 4 grams more than the other wing, due to filler material, though regrettably, I didn't weight the wing prior to the repair .

Though the surface is not yet flush, more sanding will be required after the epoxy has hardened.

My Supra electric is becoming a handful! All up weight just short of 92 ounces!
Last edited by mechmove; Mar 18, 2012 at 12:31 PM.
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