Canopy frame fit - tip-up rv7/rv7a

[mcgaughy]

I've been forcing myself to work on this tip-up.....it is not fun to see all the poor fit around the front skin (not the plexi fit but the skin to skin mating joints between the hinged canopy frame and the stationary fuselage skins. I've searched and read many posts. Some say using a Shrinker works great in the 10 and 2 o'clock position on the top. Others say shims. Others say fiberglass. Some at Oshkosh looked nice and others very bad. Most that looked nice appeared to use fiberglass / filler.

I'm looking for more input as to what others recommend that have finished this stage of the build. I need to push through this stage or I will never finish.

Ellis

[bill v]

I have shims on about half of the rivets that hold the skin to the canopy frame at the lower edges of the front skin I couldn't get shims into the compound curves of the frame and skin so I covered the skin with plastic and the frame and put fiberglass down and then put the skin on the frame to get the right shape of shim. not saying its the best way just letting you know I had the same trouble and my fix was shims of various thickness of aluminum except for this one of fiberglass.

[Smilin' Jack]

One of the problems I had was the canopy moving the forward top skin area. There are post to put in a canopy stop that will help keep the canopy from forcing the sub panel every time you move the canopy

As far as the shims. I shimmed the top skin next to the canopy. I ran a small shim over the top of the hinge that is held in place with RTV and is under the small tube gasket that runs along the top of the sub panel across the hinges.

It keeps the water out from the hinges mostly except in very heavy rain I might end up with about 20 drops on the cloth skirt from Flight Lines that covers my instruments all the way across the opening between the sub panel and instrument panel.
I do have photos if you email me I will send them to you..
Jethound@comcast.net

[Wingnut]

I am at the same point. Originally, I started it back in June and thought I would have it done before Oshkosh. It's now January and I am still messing around with it. Every time I touch it, it seems to change. I thought it was pretty good and so I drilled the splice plate. After riveting, the frame was way off. It stuck out on both sides. I drilled out the splice plate and purchased a new plate and skin. Two friends that previously completed -7s came over and recommended fluting the heck out of the frame. I thought I would break my fluting pliers. We then slightly rolled the side edges of the skin and added a thin strip of aluminum to the front edge to shim the center. It now looked pretty good again, so I pulled it apart to prime and paint. I put it back on and began fitting the bracing. It looked good, so I pulled it off to prep it before riveting. I put it back on the fuse and now I have a gap between the side fuse skin and the canopy frame skin. I will mess with again tomorrow and it will probably fit differently again. I am going to get it as close as I can and just rivet it. I looked at some at a regional fly in and they looked horrendous. However, they are flying and mine is holding down the garage floor.

[BillL]

Ellis - I am finishing my canopy now, so all this is fresh (or raw) right now. Please either post a picture or say what is riveted and what is not. Then say where you have gaps and offsets. That would help us give some guidance.

I even made this list on my canopy then focused in, and back out to address an action plan. A few thou here and there can make a significant difference.

Just as an idea, I even machined some new pivot bushings with offset bores to tweak the frame and gaps.

[rv7charlie]

Definitely do not use the lift struts while doing the fitting. If the front top skin isn't riveted yet, it should have every rivet hole filled with clecos, but the aft edge will need something flush. I bought some tiny metric screws/nuts that fit like the flush -3 rivets to fill all the holes around the top skin's aft edge.

If you don't do this, everything will move as you move the canopy frame. I guess I got lucky; I did spend some time getting everything lined up but the only significant problem I had was maintaining clearance between the top skin aft edge and the frame front edge, as the frame pivoted up.

Charlie

[BillL]

Good point Charlie, I read all about the stops and installed some angles before riveting the forward top skin. After riveting the skin (sealing with proseal like BruceH). I measured the gaps before and after the struts installed and there was no change. With everything riveted, strut forces seemed to make no difference. If that changes, I will update this post.

I am beginning to think about a whole new philosophy for what the fundamental variables are to yield the proper clearances around the perimeter. More later.

One thing - I have concluded that the canopy frame should not be fitted, or completed, until the front skin is riveted. The contour of mine changed by .020" causing a scoop on the left side. It was literally perfect before that. My theory is that the hammering of the riveting process deforms the 90 deg tabs in the sub panel. That panel is only .025.

We are trying to get the skin spacing within .010", the offset within .005" and side clearances within + or - .010" . That is very tight for such a large flexible structure. If that canopy skin deflects even .010" when closing, it will snag on opening with a .040 gap. I wonder how this was addressed on the 14.

Jay Pratt told me he has never built a tip up he was happy with. I can see why he stopped building them.

[Ray Brunet]

I used my edge roller to pull the canopy skin down to take the scooping out. I am not advocating you do this but it worked for me and if you do it remembers a little at a time.

Ray

[Rupester]

Originally Posted by rv7charlie

Definitely do not use the lift struts while doing the fitting. If the front top skin isn't riveted yet, it should have every rivet hole filled with clecos, but the aft edge will need something flush. I bought some tiny metric screws/nuts that fit like the flush -3 rivets to fill all the holes around the top skin's aft edge...

Charlie

McMaster-Carr sells some 3/32 all-aluminum cheap rivets that can be removed with just a light touch of a drill. I used them all over the front tip-up construction and on the fwd top skin. They give you clearance and working room that you don't get with clecos. (Clearly, these aluminum rivets are strictly temporary during construction ... They are all removed and replaced with solid rivets for the final assembly.)