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Tipup canopy advice needed

J

John Courte

Well Known Member
Hi.

I've probably gone a little far before I felt the need to ask this question, but I think I may have messed up. Considerably. I have a gap on the right side where C-702 meets up with the forward deck skin, and an overlap on the left side, probably best explained by these two photos.

What gets me is that it wasn't like this when I had everything set up to drill the hinges, and now that the frame is riveted together, I'm losing more and more sleep about the fit.

IMG_1142.JPG

This is the right side.

IMG_1143.JPG

This is the left side.

Add this to the fact that I've got the usual air scoops outboard of the gooseneck hinges, and that I had to do some odd things to the C-702 skin to keep it from catching on the forward deck skin. The air scoops aren't that bad, I was able to mitigate them by rolling the forward edg of C-702 in a little bit.

What should I do here? is that gap too big to be acceptable, even if I make it match on the other side? I haven't drilled any holes in the canopy bubble yet, but I have made the cut. I know I probably should have thought of this before that, but I think the canopy plastic is still good, even if I redo the frame.

Thanks in advance,
-John
 
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This post makes me feel ill.

John, I feel your pain. I went through similar issues in the 9 months it took me to complete my tip-up. Every time you fix one thing on the frame, a couple of other things seem to get out of whack. Many days it was one step forward and two steps back. Clecoes tend to allow a lot of shifting, so maybe if you pull all the clecos and reinstall you might get things closer (I always wondered if I had drilled everything using #41 drill instead of a #40 if things would have been easier to manage). If not, you may need to weld-fill the holes on your goosenecks and drill them again. Any welder who deals with aluminum should be able to do this for you in about a half hour. I ended up doing this a couple of times. In fact, it might be best to drill the goosenecks after everything is riveted. How is the frame aligned? Is this just a skin issue or the whole frame? Are your braces installed? Everything with the frame is so flexible eventually you just have to rivet things together, see how things changed as a result of riveting, and then deal with the consequences.

I ended up making custom shims of varying thickness to lift the fwd skin where the air scoops are. In doing this, the skin hole spacing on those holes near the air scoops needed to change, so I had to fabricate a new forward skin from scratch, using the original skin as a pattern to drill most of the holes. Those holes at the air scoops, however, were match drilled from underneath, up through the rib, the shim, and thru the new skin. A HUGE P-I-T-A!

Just expect this to be a difficult and arduous process, but don't give up! Once the canopy is done, its all downhill from there.

Well, until you get to the cowl and baffles. But that's a much smaller hill than the canopy:rolleyes:.

Good luck. Persevere. Don't let the inanimate object get the best of you.:D
 
The frame seems fine. Nothing rubs, the gaps between the frame and fuse are good for the thickness ofthe seal, and the same on both sides. It seems to be OK in every way except for mild air scoops and that huge, asymmetrical gap in the skins.

Braces are not in yet either, and the skin isn't riveted on.
 
John,
Are all the pieces of your subpanel riveted? If they're clecoed in, do you have LOTS of clecos holding it all together? I found that the clecoed subpanel assembly allowed things to move around. Every time I R&R'd the canopy it would fit a little different. I finally riveted in the the subpanel side pieces ,and clecoed in just the center subpanel with clecos in every hole. that helped "rigidify" things a bunch ...and then the canopy fit was more consistent. BTW .... put me down as another 9 month tip-up guy. (a VERY frustrating process.)
 
You can always drill a bigger hole in the left hinge, plug it with some new material (possibly weld in place), then redrill the plug with the correct position. Basically the brass bearing will be in another bearing. I know of at least one other builder that did this after their final fit was less than ideal. It only needs to be good enough to hold the weight of the canopy, so there is room to play.

Every element of this canopy seems to be solving one problem after another.
 
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All the subpanel structure is riveted in. I made sure to do that before I drilled,and I did put clecos in most of the deck skin holes as well as C-702. Has anyone ever figured out a way to extend (somehow) one of the skins or use filler to somehow hide that gap?
 
Make a new forward canopy skin

Hello John,

Don't give up...make a new skin just slightly larger than the factory skin and trim as necessary. I used the factory skin as a template as shone in the photos below.

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Result:
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You will find that the side joint can be very close, but the area between the hinges may need up to an 1/8" gap.

Best wishes,

Bill
RV-7 N151WP
530 hours since 11/2009
Lee's Summit, MO
 
John,

I had the exact same issue as you. When I clecoed everything up it looked perfect. I drilled the hinge, disassembled, debured and reassembled only to fine it had a big gap. I haven't gone any further at this point but my plan is to install an .020 aluminum strip under the fwd skin and the canopy skin. To which I will apply a thin layer of ProSeal, which will be allowed to cure completely before installing, but will serve to prevent water from entering the gap. (this is how the wing access panels are sealed on UAL Boeing AC.).

I'd make a new skin, but I figure the same thing might happen again. And the gap still remains, whether large or small.
 
I'm now leaning toward the replacement skin method. A sheet of aluminum and some elbow grease seems more efficient than replacing/redrilling the forward frame.

"Canopy Support Group" should be its own category. :D
 
If the canopy is aligned and only the cap is the issue, you can always add a few layer of glass and fill the gap with glass, this is of course if you are going to paint.

Building a nicely fit canopy is one of the hardest part of the project and as others have pointed out, there is a lot of flexing in all parts with only clecoed together
Another part to watch for during your alignment is to install the struts before you make your final fit as those will shift the whole thing once again.
 
Tipup Support Group ...

... is a great idea. :) The other day someone asked my how many hours I had in the project... I said "1350. That's 900 on the canopy, 300 looking for tools in my shop, and 150 on everything else." :(
 
From the original post, looks to me like the L hinge is not drilled quite right (hole is too far aft) which is shifting the skin too far forward. I don't think that a new skin will fix this problem, only hide the problem. That in itself is *maybe* ok, but I would check your fit of the canopy at the rear - do you have more gap between the canopy and the roll bar on the L side when the canopy is closed (I'm betting you do)? If this is the case, then you will end up with other issues to fix on that part of the canopy.

Yes, I've been there, and ended up buying a new welded frame (don't remember the part number now) and redrilling those holes. Fixed a lot of issues (but be assured that there will be more issues). In the end, my canopy is not perfect, but I don't notice it so much any more now that I'm flying.

greg
 
When I assembled my canopy, I kepted in mind this is a pre-punched kit for the most part. The gap is going to be there. I believe mine is a slightly over 1/8 inch. The seal should close the gap. Yours looks ok from what i can see on one side, but there is no gap on the otherside. My hinge pin holes are centered just like the drawing shows them. Remember, the kit is pre punched, and every thing should align up very close to the drawings.

The air scoop on each side of the canopy frame can be adjusted using the hand fluting pliers to tighten the radius of the prefabed/welded canopy structure. Similar to what was done when fluting the wing ribs. I did this to my canopy, and it came out perfect. I did it a little at a time, use light pressure on the fluting pliers. I would make one flute, then install the canopy frame, check how the flute effected the curve, and repeated until I got both side to seat flat (no scoop).

Hope this helps
2mwdksz.jpg


Here's a link to the tool I used.

http://www.aircraft-tool.com/shop/detail.aspx?PRODUCT_ID=7070
 
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Looking at these pix and comments, make me feel so greatful to be pass this section of the build. I remember those days when I wondered if this will ever come out OK

It did :)
 
He said the frame fit fine, so this is a skin problem, and redrilling the goosenecks will not help.

Here's an idea: Is one of your skins installed upside down? Try flipping one over and re-clecoing, then try the other (if they're not marked and you're not 100% sure that it is installed the way it was initially drilled).
 
Tipup Side Gap fix

My looks the same. I just drilled my canopy frame hinges and now one side (pilot side) looks the same as yours. Co-pilot side stayed nice with small gap, but pilot side ended up with a 1/8 gap. I've been examining and looking at what's going on and I do think the 1/4 hole in the hinge got pushed forward a bit. When I pull out the hinge pins I can push the gap out with just slight preasure.

So, I'm considering moving the 1/4 hole slightly aft when I enlarge it for the bushing. I think this will close the outboard gap, but it will worsen the skin to skin interference on top.

So I'm also thinking of moving the hinge hole slightly down as well as aft to lift the skin slightly.

Please let me know what you did and how well it worked. If you have more photos that would be appreciated.

thanks
 
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If you are going to paint your plane, there is a very good likelihood that will need to do some glass work here. As others have mentioned, things will change each time you take the cleckos out and put back together or if you add other things. Adding your canopy to the frame will make things more rigid and probably change things a bit.

If all other things line up and is good, specially the curve on the side that matches the fuse, I would build on and just fix this issue with glass once every thing has been riveted. I had mine nearly perfect (at least the gap) and once added the canopy, things changed again and actually had to shave off some from the front since it was catching the forward skin.
 
Following up...

As it turns out, I'll be glassing/filling the front edge of the canopy anyway, because like a complete maroon, I was so eager to test out the struts, I opened the canopy while the forward deck skin was clecoed on. This bent the canopy skin along the front edge and I had to bash it back into shape with a flat set and a back rivet plate. So now it looks, um, not great. However, this area is going to get a lot of glass and filler, so I'm not terribly concerned about it anymore. And sure enough, with the struts on, the canopy was pushed forward enough to make that gap less apparent. So I think I'm in business. Now I just have to solve the problem of the aft latches being just a couple thousanths short of where they need to be lock in easily to the detents on the latch fingers.

I dislike the canopy. I dislike it more than I dislike paint, and that's some grade-A dislike.
 
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