Repurposed old wing.
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When I started finishing my Q-200, back in 1985 or so, I was hangered with a QAC dealer. For the finishing phase of his project, Marvin had used a polyester resin, which he mixed with micro-balloons instead of the Rutan recommended epoxy dry micro. The advantage was a very quick cure time, especially in a drafty old hangar in Minnesota. I later found out there were many dis-advantages, one of which was the resin seeping into the Styrofoam and creating pits in the skin. This defect developed over a few years. There was also significant cracking in the filler in places where it was thicker. Over time, I drilled some small holes and injected wet micro, but the dimples were numerous and by this time had I started cross country racing and was flying faster than ever, so I decided to build a new rear wing.
Enter Mr. Sawzall. I cut out the old wing and stuck in a new one. You can look through samhoskins.blogspot.com to learn more about that project. After I completed the aircraft, I got my A&P at the Aviation Technologies program at Southern Illinois University (actually I built the new wing in their carburetor's lab) where they have composite classes, so I donated the old wing. They also have my old canard. They are now using these parts for teaching the painting module of the A&P program. My old wing wing has been powder blue, pink, and they just sent over a picture of it getting painted white again. BTW, never use polyester resin in the finishing phase. I can show you the right way with this here video I made a couple of years ago. https://youtu.be/43K1qwoHbnc Happy New Year. Sam  |
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Chris Walterson
Sam------------- Good report. I don't know if I said before, but I am building a Glasair 2SFT. The airplane came with lots of parts missing, so I decided to build my own style wing tips.
I had some old pink dock foam so I made some templates and hotwired out some tips. Had them attached and sanded and ready for the micro and glass. The Glasair used a Vynl Ester resin, so I mixed up some resin, added micro and did a fill. Waited a while for it to set before I installed the glass. When I came back all the foam was 1/4 inch smaller and had been eaten away. Tore it all apart and on to plan "B" I am so used to using Aeropoxi, I didn't realize the problem Vynl Ester created with the billet foam. I should of know better when I know that bondo, gas, and some thinners eat foam. That's why they say, prior to paint, soap and water wash and no chemicals. Anyway. No harm done, just time and money,and another learning lesson.----------- Chris in Canada -- This email has been checked for viruses by Avast antivirus software. www.avast.com |
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Robert Cringely
I built Glasair TD #102 (the first kit!) and #123. Vinylester resin is why only urethane foam is used in Glasairs. You can’t hot-wire it, either, because it doesn’t cut cleanly and releases toxic fumes. But it sands beautifully and is completely resistant to fuel. I’m using urethane foam for both wings of my new Q1 because they will hold fuel. It’s a feature not a bug. On Tue, Dec 27, 2022 at 10:17 AM Chris Walterson <dkeats@...> wrote: Sam------------- Good report. I don't know if I said before, but I am |
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Hi Chris,
I did some careful testing of solvents when I was building my Q. I ended up using what is called "Fabric Wash". It is formulated and sold by Air-Tech Coatings Inc. They specialize in finishes for fabric covered aircraft. To test it, I put a piece of blue billet Styrofoam in a jar of this liquid for a period of two weeks and I had no change in the foam, either softening or shrinkage. I believe the formulation is mostly alcohol (it is a proprietary formulation), but I know from testing, that it is safe to use on all the materials in a Q. It is also fully evaporative, so it does not leave any residue.
Even soap and water will leave some soap on the surface and in the pores. Soap film can cause delamination and epoxy is hydrophilic, so will soak up water affecting the cure.
If you are concerned about the health of the styrene foam and want to make sure there is no residue that will compromise a lamination after you clean an area, this is the stuff I can recommend. Here is the link to the product it is $39/gallon plus shipping from the US: http://airtechcoatings.com/product/fabric-wash-rf-4020-gal/
Cheers, Jay -----Original Message-----
Sam------------- Good report. I don't know if I said before, but I am building a Glasair 2SFT. The airplane came with lots of parts missing, so I decided to build my own style wing tips.
I had some old pink dock foam so I made some templates and hotwired out some tips. Had them attached and sanded and ready for the micro and glass.
The Glasair used a Vynl Ester resin, so I mixed up some resin, added micro and did a fill. Waited a while for it to set before I installed the glass. When I came back all the foam was 1/4 inch smaller and had been eaten away. Tore it all apart and on to plan "B"
I am so used to using Aeropoxi, I didn't realize the problem Vynl Ester created with the billet foam.
I should of know better when I know that bondo, gas, and some thinners eat foam. That's why they say, prior to paint, soap and water wash and no chemicals.
Anyway. No harm done, just time and money,and another learning lesson.----------- Chris in Canada
-- This email has been checked for viruses by Avast antivirus software.
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