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  #1  
Old 01-11-2018, 12:26 AM
Scott Chastain's Avatar
Scott Chastain Scott Chastain is offline
 
Join Date: Jan 2005
Location: KMCE
Posts: 52
Default The Unhappy Cracky Club

How long, O Lord? Will you forget me forever?
How long will you hide your face from me?
How long shall I take counsel in my soul,
Having sorrow in my heart daily?
How long will my enemy be exalted over me?

Consider and hear me, O Lord my God;
Enlighten my eyes,
Lest I sleep the sleep of death;
Lest my enemy say, "I have prevailed against him";
Lest those who trouble me rejoice when I am moved.

But I have trusted in your mercy;
My heart shall rejoice in your salvation.
I will sing to the Lord,
Because he has dealt bountifully with me.

Psalm 13
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RV-8 N898W Descending Dove

Last edited by Scott Chastain : 08-26-2018 at 10:54 PM.
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  #2  
Old 01-11-2018, 01:21 PM
jklusman jklusman is offline
 
Join Date: Feb 2013
Location: Lafayette, IN
Posts: 7
Default

Thanks for the super documentation, Scott. The canopy on my RV-8 has a 5-inch crack in almost the same location. It has been stop-drilled twice and seems to be stabilized. This canopy was installed using machine screws. I didn't build the aircraft, and when I bought it, the crack to the first stop-drill was covered with a decal. After the crack extension, probably caused by temps near zero in the hanger, I paid more attention to closing the canopy and noticed that latching it caused a slight distortion of the frame to the left. So, I now close the canopy the final 1/4 inch when getting ready for T/O by pushing on both sides of the front frame. Don't know if that will make a difference, but it sure can't hurt. I leave the canopy open 1/2 inch when it's in the hanger. I've bookmarked your page just in case...
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  #3  
Old 01-11-2018, 09:43 PM
Captain Avgas Captain Avgas is offline
 
Join Date: Oct 2005
Location: Melbourne, Australia
Posts: 1,656
Default

Quote:
Originally Posted by Scott Chastain View Post
As the polishing progressed, small occlusions became visible along the upper edges of the V-groove.

The cause of the occlusions was unknown. Great care was taken to clean the plastic prior to bonding. Nevertheless, whether or not the imperfections would develop into full-blown cracks was yet to be seen.
Scott, a fascinating and instructive post with great pix. However a couple of questions for you.

Can you tell me why you used the PPG DX330 Acryli-Clean to prep the canopy. My understanding from reading the product tech info is that the DX330 is not suitable for acrylic (despite the name). The PPG SX103 might have been the more appropriate product. Is it possible that the occlusions you developed arose through using the wrong cleaner.

I am surprised that when you were using a Polyvance adhesive (ie Plastifix Clear) you did not use the Polyvance cleaner (1000-A Super Prep Plastic Cleaner) to maintain compatibility.

And finally, the fact that the Plastifix Clear was not in reality clear at all (but translucent) must have been disappointing. Is it possible that a Weldon Product might have been more transparent.
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  #4  
Old 01-12-2018, 08:48 AM
Rupester Rupester is offline
 
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,196
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Great post, Scott. A practical and innovative solution to a relatively common problem that doesn't offer a lot of fix options. If I were faced with the same problem, I'd go the same way. No way do I want to look at all those hours for building a second canopy in its entirety.
Thanks!!!!!
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  #5  
Old 01-12-2018, 11:57 AM
RV7ForMe RV7ForMe is offline
 
Join Date: Jul 2015
Location: Europe
Posts: 366
Default Thank you!

Hope I never need this but I have downloaded it with pictures and put into my folder for future reference if the pictures were to disappear!

Thank you for writing it up.
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RV7 - Wings Started...
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  #6  
Old 01-12-2018, 12:07 PM
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mfleming mfleming is offline
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 276
Thumbs up

What a great write up. I've saved this post as a webarchive for the future.

This should be a sticky!
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Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Started 11/2016
Empennage completed 11/2016 (sans fiberglass)
Ailerons and flaps completed 3/2017.
Wings completed 12/2017 (sans fiberglass)
Started on QB fuselage 01/2018
Donated 2017
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  #7  
Old 01-13-2018, 08:18 AM
Captain Avgas Captain Avgas is offline
 
Join Date: Oct 2005
Location: Melbourne, Australia
Posts: 1,656
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Quote:
Originally Posted by Scott Chastain View Post
From the PGG DX-Series Data Sheet: "PPG DX Cleaners are specifically designed to remove waxes, grease, silicones, road tar, engine oil, overspray, adhesives and other contaminants. They can be used on bare metal, primers, automotive finishes or to clean plastic parts <emphasis mine>.
Hi Scott, PPG DX330 cleaner is a general purpose auto refinish wax and grease remover. It may be safe to use on some auto plastics such as thermoplastic olefins etc as used in bumper bars and other trims but I wouldn't use it on an acrylic aircraft canopy. I suspect that the fact that your gas inclusions are occurring mainly along the interface of the acrylic and the Plasti-Fix adhesive points to a problem with the cleaner.

But I'm also amazed that the Plasti-Fix instructions called for the use of denatured alcohol as a cleaner. To me, denatured alcohol is methylated spirits which generally contains products that are certain to cause stress cracking.
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Last edited by Captain Avgas : 01-13-2018 at 08:25 AM.
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  #8  
Old 01-13-2018, 02:57 PM
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snopercod snopercod is offline
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 1,322
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Awesome job, Scott, and a very helpful writeup. It gave me chills looking at you gouging out the crack with a Dremel tool. I could just see the tool skittering across the canopy I don't know if this information will be of any benefit to the RV Community but on my Lancair, I used Hysol structural adhesive to bond the acrylic canopy to the fiberglass frame. IIRC, I cleaned both pieces with automotive wax and silicone remover, and lightly sanded the canopy in the joint area. On the inside, I reinforced the joint with BID tapes. No cracks in 220 hrs. (knock on acrylic). I have nightmares about cracks in my canopy...
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  #9  
Old 01-16-2018, 05:45 AM
Tooch Tooch is offline
 
Join Date: Nov 2011
Location: Amelia, Va
Posts: 194
Default Heat Pad?

Hey Scott,
In the third picture down, what is that orange pad with the 2 wires going to it?
Looks like some kind of heat pad
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  #10  
Old 01-16-2018, 08:09 AM
RV8 Tom RV8 Tom is offline
 
Join Date: Nov 2005
Location: New lenox , Illinois
Posts: 58
Default

I'm guessing light strip for the panel.
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