Bonding the Canopy Skirt--Long

Hi all,

I am getting ready to bond my canopy skirt in place. I bought a Todd's canopy (after cracking the Van's canopy) and sikaflexed it on. Process was much helped by all the posts here.

Van's canopy skirt didn't fit well at all. I tried a bunch of cuts and slices and eventually cut off the enter rear (past about where it jogs up) along with all the area that bonds to the canopy on the sides. Laid up new fiberglass so it fits like a glove.

I drilled about eight holes on each side and then clecoed it to the canopy frame. No holes in the canopy plexiglass. I put it back on the plane and the fit is very good. Now the question arises, how best to bond the skirt to the frame and the canopy.

In bonding the canopy, I put in a spacer of about 1/8-3/16. I am very confident of the strength of the bond. The skirt is a much tighter fit to the frame. If I put spacers in, then it will not meet the fuselage correctly.

I had thought that I would put a layer between the canopy and the skirt, with the standard roughing up of the plexi. I was going to basically build a filet around the junction of the canopy frame with the fiberglass skirt, going about a third of the way around each side of each upright and the long runners. Also a filet along the bottom of the plexi/skirt line.

This will be a substancial amount of adhesive, hopefully not a significant weight gain. Does this seem like a reasonable approach? How have others applied the adhesive?

The second question is what to use for a bonding agent. I could go with sikaflex again. It is expensive and has a very short shelf life. I could use 3M 5200, which was recommended by Todd to bond the canopy. Yahoo RV listers have advocated 3m Scotchweld 2216B. Any experience with any of these?

Thanks, as usual for all the help I get here.
,
Michael Wynn
RV 8 Finishing
San Ramon, CA

Hi Michael -

I bonded my canopy to the frame with Sikaflex. I decided to use the same Sikaflex to bond the skirts to the canopy. I did not use a gap for the skirts as I don't think that it is needed. I only used Sika between the canopy and the skirts, not between the skirts and frame. For that, I used pop rivets. It turned out great and it is holding up great after 100+ hours and a year of flying.

Good Luck

Micheal;
I bonded the canopy and skirt both.
I like Ericwolf's way of using rivets on the bottom of the skirt, it surely must be lighter. In my case, some spacers were required to get the skirt to 'lay right' on the canopy and fuselage. That would have been a bit harder to do with the pop rivets, so I forged ahead with the SIKAflex and it worked out fine.
There has to be more than one way to skin this cat...

I also bonded the canopy to the frame but only used Sikaflex to bond the top of the canopy skirt to the plexi and rivets to the lower portion.

I think if I did it again I would cut off the entire 1 inch lip the goes against the plex because I wrestled with it to get it to fit, added some glass in places several times with a lot of the usual sanding etc. I think putting it on without it and then laying one up the would fit perfect would save a lot of work.

At the rear of the canopy where there are no places for rivets if one bonds the canopy skirt and doesn't drill the plexi I believe there needs to be some reinforcement to avoid stressing the bond too much. At the very back of the canopy I left a significant excess of plexi extending beyond the frame. I then glassed that "extension" to the frame with a few layers of epoxy. This helps take the stress of opening the canopy with the ring I put through the skirt at the back.

50 hours and so far so good.

Skirt Bonding

Thanks for your insignts, guys.

I experiemented with 3M 5200. I put a thin coat between a powdercoated metal piece and a fiberglass scrap, powdercoat to plexy and plexy to fiberglass. What I found is that 3M 5200 is firmer than sika. It is somewhat flexable, but less so. The bond was extremely strong--which is to say that I couldn't get the pieces apart without pliers.

One of the nice things about Sika is that if you get it on an unprimed anything, it comes right off after it sets up. Not so the 3M 5200. It stuck pretty well to unprimed plexy so careful masking would be the order of the day. The real attaction to 3M 5200 is that a tube is about $13 and it has at least a year shelf life. The sika outdates really quickly and is really expensive.

I have read elsewhere on the site about people experiencing problems with rivets in the skirt so I am inclined to go ahead and glue it all. It is heavier than riveting and I know that all the little additions to the airframe add up, but I would like to finish the skirt and have the final surface be flat and attactive.

I think I am going to move forward with gluing the skirt this long weekend. I will report back on how it goes.

Michael Wynn
RV 8 Finishing
San Ramon, CA

Fishing Line

I used some fishing line, 50lbs test IIRC, to get a small gap between the skirt and the canopy. I got the technique from a previous post here. I cut some 1inch sections and glued them around the bottom of the canopy...the sika filled in around the line...can't see them at all.

Best of luck.
JC