Canopy Missing a Chunk

Jamie · #1 08-07-2008, 11:37 AM

A while back while fitting my Koger sunshade, I had my tip-up canopy propped open on the secondary latch. I was standing on the wing, leaning over the canopy trying to put a piece of tape down the center of the canopy to be able to properly center the shade. I leaned into the canopy with my thigh a little bit and cracked the canopy about 2 inches or so. It was along the rear bow, and although I was royally ticked I didn't worry about it after about a week. :-) Yeah, I stop drilled it but figured I could live with it.

Last night I went out for a nice little flight, still flight testing my autopilot and trying to get it to track smoothly (new unit on the way from Trio). Long story short, I opened the canopy but it wasn't open all the way. I went back out to retrieve something from the plane. As usual, I placed my left hand on the roll bar and stepped up. The canopy came down on my hand. The downward force caused the canopy to twist enough that the already cracked area impacted the roll bar. I was horrified as I watched a chunk of canopy skid across my left wing and onto the ramp.

Here's the damage. The broken piece of plexi is wedged back into place in this photo. You can also see where I stop-drilled the original crack.

Now the good news: I am going to place a strip over the rear of the tip-up canopy (a la the -7A factory demonstrator and others). I have a 'whistle' from air coming in here anyway so I figure it will actually have a benefit of reducing and hopefully eliminating the noise.

I plan on using an acrylic adhesive to get the broken chunk back into place. I may also use some sort of adhesive between the plexi and the bow. Anyone have a recommendation for which adhesive to use? JB-Weld? I called JB-Weld and they say it's safe on acrylics.

It looks like I have a couple of options:

1) Do an aluminum strip. Although certainly the easiest and least messy, this would not provide as good of a fit as the fiberglass.
2) Do a fiberglass strip using a release agent on the tip-up canopy so that it can be removed for paint, then epoxied into place. This is the easier glass method because I don't have to worry about getting a straight leading edge on the plane...I can just cut and sand a straight leading edge on the bench.
3) Do a fiberglass strip with no release agent, mask everything and paint on the plane. This is the more difficult glass method as I would have to do the black electrical tape masking thing, then sand down to the tape, etc. I think this would have the added benefit (at least in my mind) of having a stronger bond than method 2.

So, VAF...what say you?

kentb · #2 08-07-2008, 12:00 PM

I haven't done the targa strip on my tipup. I am still trying to decide, but if I do, I would want to do it in place.

I would mask off with black electric tape. Sand the plexi. Place wax paper on the roll bar. Cover the rest of the plane in painter plastic and then start laying up fiberglass.

Good luck.

Kent

fstringham7a · #3 08-07-2008, 12:58 PM

Jamie

I did the FG targa this past month. It turned out great. I used Bi/uni...six layers. Scuffed the forward plexie/cleaned with kerosene......put the universal RV attachment tape (duct tape) over the rear baggage canopy then applied the six strips of FG. Not flying yet so I am still without real world data.

URL=http://imageshack.us]

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Sorry for your problem. The canopy ...at least for me ...has been a real challnege.

Frank @ 1L8 ....RV7A....paint prep....

Brantel · #4 08-07-2008, 01:02 PM

Like Kent says, that is what I would do. Still not sure if I am going to add one or not but if I do, please post your progress so I can copy you!

As far as adhesive, pro-seal would work just fine for that.

Brantel · #5 08-07-2008, 01:03 PM

Frank,

What are those parts of fiberglass I see on your side skirts?

Quote:

Originally Posted by fstringham7a

Jamie

I did the FG targa this past month. It turned out great. I used Bi/uni...six layers. Scuffed the forward plexie/cleaned with kerosene......put the universal RV attachment tape (duct tape) over the rear baggage canopy then applied the six strips of FG. Not flying yet so I am still without real world data.

URL=http://imageshack.us]

[/url]

Sorry for your problem. The canopy ...at least for me ...has been a real challnege.

Frank @ 1L8 ....RV7A....paint prep....

fstringham7a · #6 08-07-2008, 01:11 PM

Brian.

On the port side the canopy sat in about 1/32 of an inch....So I added some FG while I did the Targa top to get the canopy side skirt to match the fuse better.

Frank @ 1L8 ...RV7A.... paint prep....

RBrinkerhoff · #7 08-07-2008, 01:14 PM

Jamie,
I broke my canopy in the same spot on the right side last Saturday. Sunday was spent completing option number two that you listed. It took only a few hours for round one of fiberglass work. Monday another hour of sanding and applying filler. Tuesday another hour and now it is ready for primer and painting this weekend. I wish I had done this during the original canopy build since this appears to be a common problem. Lots of luck with your repair.
Richard

Jamie · #8 08-07-2008, 01:28 PM

Quote:

Originally Posted by RBrinkerhoff

Jamie,
I broke my canopy in the same spot on the right side last Saturday. Sunday was spent completing option number two that you listed. It took only a few hours for round one of fiberglass work. Monday another hour of sanding and applying filler. Tuesday another hour and now it is ready for primer and painting this weekend. I wish I had done this during the original canopy build since this appears to be a common problem. Lots of luck with your repair.
Richard

Ha, a kindred spirit. Thanks for the post, Richard...it does provide some encouragement. I'm been in a rather bad mood today. Did yours completely break away like mine? If so, did you end up gluing the broken piece back in?

I know that others have done it when starting their engines and the engine kicks back so I've always been very careful to fully latch my canopy when starting the engine, then prop it open once running. I am usually very careful to fully open the canopy, but this time I guess I screwed up.

RBrinkerhoff · #9 08-07-2008, 01:54 PM

I plan on gluing the Targa strip and broken piece on at the same time using Sikaflex (226 cleaner, 209n primer, and 295 UV Adhesive). I have cut/fit the strip and will complete the final painting before gluing/installing. I'll take a few pix's of the process.
Richard

PS: This is my second canopy!

GregM · #10 08-07-2008, 09:45 PM

I managed to crack mine when my shirt snagged a cleco. I'm also a model aircraft builder and have CA glue lying around. This is "super glue" (cyanoacrylate) available where models are sold. They have varying thicknesses. The thin is watery, and will seep or wick into the cracks. For broken pieces the thicker glue works better. They also sell an accelerator that will instantly set the glue. It appears to have worked fine and its hard to see the crack if you take your time and use the glue sparingly. I'm going to sikaflex underneath and wrap the edges of mine with fiberglass to avoid any further damage when mine is up and running. Good Luck!