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Where the canopy fairing meets the road... err.. side skirts

LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
I've spread the little fillet of epoxy along the bottom of the front of the tip-up canopy, so I guess I'm committed to finishing this darned airplane now.

What I'm having a wee bit of trouble visualizing, however, is where the fiberglass windshield fairing meets the side skits. I'd appreciate folks posting any pictures they may have taken when they'd marked off the electrical tape indicating the top edge of the fairing... specifically where the tape meets the "ears" (if you didn't lop them off).
 
Bob,

I'm just working on this fairing on my 9A. I stopped the fabric right at the notch in front of the ears. Top of the fabric is right at top of ear level, bottom overlaps by about an inch (for a total of about 2 inches of fabric width on the final layup). I have then gone back with microballoon filler and smoothed over the fabric, the notch joint, and slightly aft of the notch so the fabric is completely hidden/embedded. I did bend the ear enough to be tight against the plexi, but did not put any sealer under the ear (may regret this, but can always squeeze some sort of sealant in there later, if necessary). Sorry, don't have any photos available right now.

greg
 
Some possible photos...

Hi Bob

Lots of photos, some with words from around -

http://www.rvproject.gen.nz/canopy.html#ID3403 onwards....

Web_Img_5922.jpg


Web_Img_5923.jpg


Web_Img_6600.jpg


In general I found it difficult to get a good form on both sides, but it is just trial and error.... A large grid did help, then just lots of by eye work.

HTH,

Carl
 
Greg Arehart said:
Bob,

I'm just working on this fairing on my 9A. I stopped the fabric right at the notch in front of the ears. Top of the fabric is right at top of ear level, bottom overlaps by about an inch (for a total of about 2 inches of fabric width on the final layup). I have then gone back with microballoon filler and smoothed over the fabric, the notch joint, and slightly aft of the notch so the fabric is completely hidden/embedded. I did bend the ear enough to be tight against the plexi, but did not put any sealer under the ear (may regret this, but can always squeeze some sort of sealant in there later, if necessary). Sorry, don't have any photos available right now.

greg
Click to expand...

I'll have to see some more RVs up close. The point at which the fabric on the top edge hits the top of the ears would seem to create a bit of a bump, since the ears (or side skirt) is a fairly thick piece of metal.
 
Really interesting, Carl. Thanks!

Here's a few questions on your process:

* If you were only to lay up a layer or two of fiberglass a day, do you put peel ply on it each day? Or just the top layer at the end of the process.

* Between layers -- or between each day of laying up layers -- it looks like you sanded and shaped? Is that normal procedure? From the instructions, it sounds like Van';s didn't sand until the last layer. On the other hand, it sounds like they did all the layers in one "sitting."

* How did you clean the fiberglass after sanding between layers? At OSH, they said acetone is best used for cleaning fiberglass, but that wouldn't react to plexi very well (or rather, plexi wouldn't react to it very well) and there seems a high probability of contaminating the plexi with it. Did you just use air and a damp cloth?
 
Bob, another picture for you.

I trimmed the ears back a lot. I needed to do a lot of filer here. I just used micro because this is a cosmetic area.



I didn't use peal-ply, but I should have.

Kent
 
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One more question. I've heard of a few people who -- after a few layers of fiberglass are installed -- pop rivet the fairing into the aluminum and then add the final few layers. How prevalent a practice is this and how many pop rivets do people use?
 
Bob,

Don't know how much of a bump the ear will be, but not more than approximately the thickness of the metal, if it's bent to properly lay down against the plexi. Mine is still covered with electrical tape while I finish the micro stuff and make it look all smooth. I'm actually amazed at how easy the micro is to sand - about like drywall (I am mixing quite dry batches as filler).

Regarding your query about poprivets, I have seen photos of this. My take is that if the canopy contours well with the metal decking, then poprivets are not necessary (I did not use any). I did a small test using some plexi scrap where I set a piece of the plexi on a piece of scratched aluminum and just put a fillet of filler along the edge of the plexi, simulating the fillet you would put at the front of the canopy. After curing, it was possible (not easy, but possible because the aluminum bends) to pry the two apart. Once the glass is in place and overlaps both plexi and aluminum by an inch or so, I think it will be virtually impossible to separate the two. So I decided that there was no need to add rivets, at least for strength. Plus you would have to fill around and over them to get things smooth.

On the other hand, I have a colleague who made a fairing out of fiberglas that is totally detachable (at this point) - its basically just a two-inch wide strip of several layers of fiberglass and epoxy that was formed in place on his canopy but with release agent underneath. He is planning to just rivet the fairing in place and put a sealant of some sort between it and the plexi. The idea here is that he could remove the plexiglass canopy if necessary without destroying it. I am hoping that I never have to remove my plexi now that it is bonded in place....

greg
 
Thoughts

Hi Bob,

Lots of others with more glass skills than I, but the basics of how we did it was multiple sessions, flox bedding + 6oz first, then 9oz (x 'some') then 2 oz layers to finish, then lots of micro balloons. Also had some addition flox sandwiched in there to get the right profile. I've ended up with a 'line' where the glass edge to AL but that is fine for me, I didn't endup blending it completely - just painted it yesterday and looks fine.

Overall I guess the canopy structure is one of the weakest results of the whole project - it is perfectly servicable, works and looks 'great' at first glance, but I know there are a number of things that could be better 'next time' - and more so than most of the major components in the project.

Bob Collins said:
* If you were only to lay up a layer or two of fiberglass a day, do you put peel ply on it each day? Or just the top layer at the end of the process.
Click to expand...
I didn't, and probably wouldn't in one go - just sand / scuff and apply next layer(s). That said, you don't want too many goes if you can help it.

Bob Collins said:
* Between layers -- or between each day of laying up layers -- it looks like you sanded and shaped? Is that normal procedure? From the instructions, it sounds like Van';s didn't sand until the last layer. On the other hand, it sounds like they did all the layers in one "sitting."
Click to expand...
I'm sure Van's / experienced others can do it in one sitting - I don't have the skills! :eek: I did try and do the layups on 'multiple day' basis and prefereably whilst the epoxy is still green and a bit tacky. I think I stopped and sanded on a couple of layers to get the shape somewhere close too (but it is a while back now)

Bob Collins said:
* How did you clean the fiberglass after sanding between layers? At OSH, they said acetone is best used for cleaning fiberglass, but that wouldn't react to plexi very well (or rather, plexi wouldn't react to it very well) and there seems a high probability of contaminating the plexi with it. Did you just use air and a damp cloth?
Click to expand...
Generally just sand, acetone wipe and go. Also used the previous batch of cleaning acetone which has a 'stickness' to it which helped grap the dust out. Remember not to let neat acetone near the plexi.

Bob Collins said:
One more question. I've heard of a few people who -- after a few layers of fiberglass are installed -- pop rivet the fairing into the aluminum and then add the final few layers. How prevalent a practice is this and how many pop rivets do people use?
Click to expand...
I didn't pop rivet a bracket, but I did make a temporary stop during the cutting process to hold the front of the canopy in the same place each time.

Web_Img_5927.jpg



HTH,

Carl
 
Well, I'm slogging along, I put the third layer down last night and will let it cure (I stop at the hangar on the way home each day for some "debrief time" from work). I don't know if I'm doing it right or not. I guess we'll see.

One question I have. Is it better to apply the fiberglass strips dry or wet. I've been putting down a little epoxy... then wetting the fiberglass and placing it on. It's messy, of course. I'm wondering if it makes more sense to apply the fabric dry?

What do most people do?

Update: Pictures here.
 
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Bob Collins said:
One question I have. Is it better to apply the fiberglass strips dry or wet. I've been putting down a little epoxy... then wetting the fiberglass and placing it on. It's messy, of course. I'm wondering if it makes more sense to apply the fabric dry?
Click to expand...

There are far better fiberglass people on the forums than me, but I was taught that you always saturate the cloth before putting it on the assembly. I think of it like when I used to watch doctors putting a cast on my arm - soak the fabric in glue or whatever, then put it on.

What I do is lay out a sheet of foil or plastic, and put the pre-cut glass flat on it. I then pour on some mixed resin, and squeegee it all over the glass, saturating it, but making sure that all the excess is removed. TI then pick up the saturated cloth and apply it to the part/airframe.

The really good guys start similarly, but then lay another layer of plastic over the saturated glass, and REALLY squeegee out the excess resin. That's why they use lots less resin than I do. I think DanH has written some really great posts on glass-work before you might check to see if they are in the "tips" forum.

The great thing about glass is that you can always fix your mistakes with sanding and cutting tools....

Paul
 
Ironflight said:
I then pour on some mixed resin, and squeegee it all over the glass, saturating it, but making sure that all the excess is removed. TI then pick up the saturated cloth and apply it to the part/airframe.
Click to expand...

Yeah, that's pretty much the way I'm doing it. Here's the problem I do have with it, though. I generally brush it on but when it comes to removing the excess, how do you do that with fibers separating all over the place and making it a complete mess? So I put it on and then put the Dacron on and then squeegee it out.

So what's the best way to remove excess resin? I use the fiberglass tape for certain sizes, but I'm also following the instructions that call for each layer to be 1/4" larger than the last, so I'm cutting some cloth from a big wad of BID.

I'm also trying to figure out this "bump" thing.
IMG_0096.JPG
 
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Bob Collins said:
I guess everyone is over at the "thread moderation" thread.
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Nahhh....some of us work for a living - and then we go flying when we get home! :p

I am still hoping a real glass expert will step in and tell us how it is done Bob, but I used a chunk of upholstery foam that had been getting in my way in the shop for years. i cut it into little 1.5"x1.5"x3" chunks, and used one every time I mixed a cup of resin. I used it as an applicator, daubing rather than brushing. I know I still used more resin than I should have, based solely on the amount of sanding dust in the shop after getting rid of the excess. The little foamies worked well though, and were also useful for smoothing out little bumps. Squeegees only worked for me if I had something on top of the layup, like peel-ply.

Paul
 
A little different technique

I prefer to brush on coat of epoxy on to the fairing, then apply the dry glass. This allows you to easily position the glass on the fairing. Next, use enough epoxy to so soak the weave and add another layer of glass. Rinse, lather repeat....

I also use foam, like Paul, to soak up the extra epoxy. If you get most of the excess off you can avoid using ply peel. I prefer to not use ply peel on compound curves. Trying to position the ply peel will often cause you to move the glass. Not good. You can get a mess in a hurry.

I have always found that wetting out cloth then moving it is cumbersome. Much easier to move dry. Same end result. Use what works for you.
 
Ok, first I'd like to say I'm no expert but have dealt with fiberglass forming and repair for over 20 years. When you put a layer on and get it shaped like you want, give it 45 to 60 minutes to get tacky, then as Darwin says put your next layer on dry. The tacky layer underneath helps hold and position your next layer. Squeegee it in to the tacky layer, it's easy to lift and reposition if you need. When you like it brush on more epoxy and work it in so there are no voids or bubbles. 45 or 60 minutes later your ready for the next layer until you satisfied. I would keep building over the hump a few more layers. Before the last couple of layers sand the hump and blend it in. The last couple layers over the top will tie thing together nicely. If it's going to be more than a couple of hours before you return, by all means use peel ply. It will save you a lot of sanding. Be as neat as possible to eliminate a lot of elbow grease . It's really not very difficult, just time consuming. I'll post some photos of my RV 8 fairing if it would help. Good luck! Patience is your friend.
 
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