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Forward tip-up frame question

TCONROY

TCONROY

Well Known Member
I'm working on the canopy frame and have a question to ask fellow -7 builders. I've drilled and riveted the splice plate to the forward frame, but have NOT drilled the 1/4 holes for the hinge pins (release mechanism). I can't seem to get the skin to both have a 0.020" gap around the front AND for the left and right sides to sit perfectly above the fuselage side rails. If I shim for the 0.020 gap between the forward skin and canopy skin, the sides are at a little bit of an angle with probably a 0.5" gap, sitting above the fuselage side rails. If I set the sides correctly, I have a 0.05+ gap at the top portion between the two skins. It seems I can't achieve both. At one point I thought I had this right but it seems to have gotten off. Any suggestions?
http://rv7.conroyair.com/logindex/Finishing/2012.06.06.htm
 
Can't help you specifically, but ...

... my advice is try not sweat some of those front canopy clearances too much. every time you complete another major task on the canopy assembly, it shifts a tiny bit and fits differently than before. I spent HOURS obsessing over those .020 and .030 clearances, only to find it changed every turn in the road. The most important thing is to install those non-provided (by Vans) canopy forward stops , or "snubbers", to prevent the gas cylinders from pushing the canopy forward when you install them. That can easily move your canopy .125 to .250 forward and ruin all your front edge clearance efforts to date.
 
The most important thing is to install those non-provided (by Vans) canopy forward stops , or "snubbers", to prevent the gas cylinders from pushing the canopy forward when you install them.
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What is that about?? I am in the process of trying to make the canopy fit, but I have not heard about Snubbers???
 
http://www.chadandbrittne.com/May 2008/May 10-08.htm

Here's a pic from Chad's excellent website that shows the canopy "stops" or snubbers. They go on the top fuse rail, immediately fwd of the subpanel. The bolt they employ is adjusted tight up against the canopy fwd rail to prevent the gas cylinders from pushing the canopy fwd. Not difficult at all, and you can make them from scrap and a bolt or two from "Ace Aviation supply". :D
 
Tip up canopy pics

I agree with the comments above. It's a floppy structure, even after it's complete. The resulting gap between the forward canopy skin and the forward fuse skin can be a problem spot based on accurate drilling of those 1/4" pin holes. I had binding problems between the two skins as the canopy opened. Ended up having to file back the canopy skin until it adequately cleared. You can address cosmetic issues when it's all said and done.

That top fuse skin is EXTREMELY tight along the left and right sides when getting clecos in.

The Van's folks commented to me slider or tipup, difficulty based on 1 to 10, the canopy is an 11. Ya just have to be patient and logically work through it.

My canopy pics can be seen here: https://picasaweb.google.com/mikerv9a/Canopy
 
PIN 37 said:
What is that about?? I am in the process of trying to make the canopy fit, but I have not heard about Snubbers???
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I agree with Rupester. The installation of the gas struts messes up all your careful fitting work. I thought I'd give you a reference to how I did mine, too. Here's a link to my log page for this item:

Forward Canopy Stops

They made a dramatic difference in maintaining how the canopy fits after installing the gas struts. I made them from scrap that I had on hand. The bolts I used are Joint Connector Bolts found at a local hardware store. I added a layer of UHMW tape to the surface of each one to minimize scratching on the forward face of the frame. The extra holes are just lightening holes.

P1030427%20(Small).JPG


P1030429%20(Small).JPG
 
Canopy

Some thoughts on the tip-up:

The canopy front skin probably is correctly trimmed and punched. That's logical since it is a single piece flat wrap. The weldments are multiple pieces jigged together and distorted from the welding process. No two are likely to be the same. If I is was starting over, I would focus on shimming/twisting/bending/splicing the weldments to fit the skin.

I needed a minimum .036 inch gap at the front of the skin to keep it from hanging up during opening. Even then, I had to carefully bevel both sheet metal edges to allow them to "shingle" a bit. In theory, it should be possible to tighten up that gap a little by nailing the height of the pivot pin holes just right.

The plans 9 11/16 inch dimension for the closed canopy gas strut length should be treated as a bare minimum. The strut toggles over center by about a quarter inch as it nears closure. If your rear attachments are too far forward, you will be bottoming out the struts during each opening/closing cycle. This forces the canopy frame to flex unnecessarily.

Van's drawing shows the rod ends of the struts forward. My last picture of their 7A shows they actually have their cylinder ends forward. Because of how the oil settles in the cylinders, they function much better that way--with a nice cushioning effect at the end of their travel .

Some people swear by the forward stop mod. Once everything was properly fitted and solidly riveted together, I found I didn't need them.
 
I wrote this article on the canopy stops some years ago. I swear I took the canopy and canopy frame on and off the project 5,000 times and 4,999 of those times, it did not fit the same way when putting it back on.

I THINK -- and your mileage may vary -- that Van's has you adjusting the gap between the canopy skin and the top skin way too early in the process. If I do it again -- and someday I may do it again -- I'd wait until I was about to rivet the top skin on for the last time.

I also didn't like the gaps on the side much. They were OK when viewed from the outside, but from the inside they looked -- as Walter Tondu once famously said -- "like you could throw a cat through them." I ended up extending the sides with fiberglass pieces. So the bad thing about the canopy frame is it's not a very fun design. The good thing about it is you can play with it later to satisfy one's OCD.

I would also be more careful -- and it's not like I wasn't careful to begin with -- in drilling those 1/4" hinge pin holes because that had more to do with the fit of the canopy than anything else I did. In my case, I got it just wrong enough to end up with a higher gap from canopy-skin-to-top-skin on one side, which I only recently solved by building the area up.

Oh, one other thing on those canopy stops. They go in an area where you're going to need to get in with a bucking bar when you rivet the top skin on for good. So you might want to build a little clearance in there.
 
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Charlie is right about the importance of locating the strut rear attach. Nevertheless, the canopy stops are easy and cheap to install, and can be a big benefit depending on the specifics of your install. And BYW, Bruce's canopy stops are the snazziest I'VE seen ... most of us just hacked up a small piece of angle. :D:D
 
What do you all think of the edge distance here? I'm not totally thrilled with it but I understand it is common and doesn't seem to be a big issue. I don't have the exact dimension right now. The other one is a bit better.
IMG_5826_640x480.jpg
 
TCONROY said:
What do you all think of the edge distance here? I'm not totally thrilled with it but I understand it is common and doesn't seem to be a big issue. I don't have the exact dimension right now. The other one is a bit better.
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Trevor, I think this is quite common actually. Mine looked like this, too, but perhaps not quite this close. Check with Vans just to make sure, but my hunch is they'll say "build on". That hole DOES look a little big to me, too. Is it just the photo?
 
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I guess I will e-mail Van's. The hole is 3/8" as the bushings were pressed in without issue. Thanks!
 
Just an update... I talked to Joe at Van's and he didn't like that edge distance at all. I'm going to have it TIG welded and give it another try.
 
My holes on the gooseneck hinges would have ended up exactly like Trevor's if I didn't mark them with a sharpie before I drilled them. The 1/4inch hole as per Van's plans is falsely located and has to be moved about 1/10th of an inch forward to be on the centreline of the gooseneck hinge. I ordered new F-745 ribs and UMHW blocks to and moved the location of the hole slightly forward to rectify this.
There are quite a few gotchas on the tip up canopy apart from the pivot hole and gas strut location. Rivet holes on C-704 splice plate line up with the tooling holes on the aft C-631A canopy frame ribs. The rivet holes on the 613 splice plates conflict with a pre punched hole in the in the C-702 skin. The holes as called in the plans for the angle at the back of the Wd-725's do not line up with the canopy latch lugs and in fact the upper hole also conflicts with the tooling holes in the C-631A's.
It would be nice if the good folks at Van's rework the canopy chapter and change some of the hole patterns and dimensions to what really works.
 
@Mounz: perfect timing, I am working on p. 9-2 (Installing Canopy Release) and will soon come to this part. Any other Gotchas??
 
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