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Window fit

D

dspender

Well Known Member
I purchased the Cee Bailey's windows. When I placed them over the door window opening they were a near perfect fit needing little trimming. However, most of the corners needed a fair amount of compression to settle onto the lip of the window and I anticipated this upward tension would fight against the Lord Adhesive I will use to adhere them. I brought them into the 70 degree house and placed weights over each corner. In less than 24 hours the window edges sat nearly perfectly onto the lip of the opening, needing minimal compression to sit flat. I thinks this speaks to the flexibility of the windows and the influence of temperature. I suspect this is why glass cloth and resin placed over the interface of the window/door can craze or crack.
My question: Is it necessary to place any layers of cloth over the window/door interface? I don't see directions in the plans to apply this cloth. I am thinking the Lord Adhesive is sufficient to hold the window in place and avoid the possibility of resin/cloth crazing or cracking.
 
I did not use the load adhesive, but I did put a layer of cloth around the windows. After 2 years I am developing cracks around the front edges of the rear glass. The corners are trying to straighten out, mainly on hot days. I believe that the use of the load adhesive is probably the best method out there at this point, but I would still use a layer of glass around the edges. It takes quite a bit if body work, but in the end, you will have a stronger bond with less chance of cracking. I have been debating removing my side windows and redoing them, which would require a significant amount of work and hassle to repaint a major section of the fuselage. My advice is do everything you can at this point while it's easy!
 
I used the Lord adhesive and a layer of cloth. It's been over two years and no cracking yet. My opinion is that the layer of glass makes the joint look better.

If you walk around the RV-10s at OSH, you'll see many variations of adhesive, glass, and cracking.

I'm not aware of anyone that has use Lords and glassed that has experienced any cracks or crazing. Nor am I aware of any negative impact of using Lords instead of Weldon.
 
So the answer is...

So after reading many, many threads on this,I would conclude that the extra layer of glass MAY look better to some but it is not required...
 
I used both the Cee Bailey's windows and the lord adhesive. What I did, and what I think would be best for you to do is trim the windows down so that there is a small gap between the outer edge of the windows and the jog in the door. I also had to clean up the inner angle of the door opening a bit, as there were some fiberglass and epoxy "boogers" from Van's. I also put a very slight bevel into the edge of the windows. I didn't want the fiberglass and the window pushing hard against each other when different materials expand at different rates. I have a small (1/16 - 1/8") gap that is filled with lord adhesive to act as a slight cushion between the two.

After the window was bonded, I did choose to fiberglass over the joint. I had originally planned on doing what you are talking about, and not having anything covering the joint (so there would be nothing to crack), and painting the edges of the windows black... but I didn't end up going down that path.
 
I am getting a better understanding. I think without fiberglas over the gap, continuous paint from fiberglas canopy across the gap and over about 3/4 of the window alone, will lead to cracks in the paint. The window will move with temperature variations and the fiberglas canopy will move less. Paint alone would crack. Fiberglas spanning the gap and painting over the fiberglas may lead to less paint cracking. I am thinking the best is to place the cloth/resin over the gap as a lip, intentionally trying to not adhere the cloth/resin to the window. This way the lip of fiberglas will act to retain the window in place should it try to leave the airplane yet not restrict the window movement with temperature variations. I think the paint would less likely crack. Maybe in those installations where the paint has not cracked, the overlapping fiberglas is less/not adherent to the window. Another option could be adhesive only, relying on the adhesive to keep the window in place and paint up to the gap, but not over the gap. No paint can crack then.
 
What about painting a perimeter around the window plexi, not paint the actual joint, and paint the surrounding cabin top glass? No paint across the dissimilar materials and the border around the plexi takes care of aesthetics. Would look like most car windows...
 
I'm thinking, any option that does not place a material (cloth/resin or paint) across the joint will cause no cracks. Personally I would like to place a cloth/resin lip 3/4 over the window edge, without trying to adhere that lip to the window, and paint the lip during the cabin painting process.
 
I used Weldon with fine weave glass tape from a hobby shop around the gap. They've been in over three years and had temperature swings of over 100 degrees with no cracking. One thing to remember is that one of reasons the lip is on the inside and window attached to the outside is to allow for the window to be kicked out in case of the need for emergency egress. Otherwise it would have made more sense to mount the window from the inside.
 
I am not sure what the Sika is. I will Google it. I talked with Geoff at Aerosport. I am going to adhere the window with Lord adhesive and see how it looks. I may leave that appearance or may consider to paint the perimeter of the window where the underlying Lord adhesive shows through as well as the 1/16 gap between window and cabin. I would like to avoid overlying cloth/resin, the chore involved installing it and the risk of future cracks. May have cracks anyway.
 
Bill.Peyton said:
Dennis,
Check out the way that Jan did his windows in his latest -10. This is what I had intended to do, but at the last minute decided to paint on to the glass, after having used Sikaflex adhesive, which I know now is the entirely wrong adhesive.

http://www.vansairforce.com/community/showthread.php?t=1987&page=33
Click to expand...

Bill, what about Sika makes it unsuitable? I'm not there yet, but I did have a good experience with Sika on my -9A canopy. I was thinking about doing mine just like Jan's, which I think looks awesome.
 
Sika flex is a strong flexible adhesive. Flexible is the key word. Unfortunately it allows the joint to move as it is heated and cooled, so much so it's just not possible to paint over the joint and not expect it to crack. My original plan was to not paint across the joint and allow it to flex with heating and cooling. I was going to create a gasket using pro seal similar to how cirrus installs there window. Similar to how Jan has done his windows, but no paint across the joint. Since the SikaFlex adhesive uses a jet black activator on both surfaces, it leaves a nice looking reveal around the glass. I intended painting up to the glass, then creating the gasket in the groove around the glass. After I attached the glass with the sika, I changed my mind and covered the seam with some 6oz. cloth. I should have know better, it only took a year for the cracks to show up in the paint of the rear windows.
 
Understood - it sounds like glass over Sika is a no-go. I'm thinking about doing just as you did, but no glass, and filling the gap with Sika. It looks like that's what Jan did. I think the only real difference looks to be in the aesthetics of having (or not having) the black border around the window.

But I'm still a long ways off...
 
Bill is this what you considered: Lord's for the adhesive and then afterwards Sika in the 1/16 groove as an accent. Paint the cabin up to the groove and paint the window from the groove inward about 3/4 inch to cover the color of the Lord's underneath the window? And don't paint the black, Sika groove?
 
Dennis, Close, but not quite what I did. Use the Sika Flex Adhesive and make pro-seal or sika-flex gasket in the groove. Go look at a Cirrus window install for a good visual. Here are some pics of how I started. I should never have strayed from my original plan.

Activator applied with spacers per specification for Sika thickness

IMG_1487.jpg

IMG_1488.jpg

IMG_1490.jpg


Groove left for gasket. Below is how it looks from the outside after curing.
IMG_1512.jpg


And the inside
IMG_1516.jpg

IMG_1498.jpg
 
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