What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Canopy frame fitting questions

N546RV

Well Known Member
I suppose it was high time the training wheels came off...it's been fun seeing the detail of the construction manual fall off a cliff as I start on the canopy. Tonight I started working on fitting the canopy frame for the first time and...yeah, I've got questions.

First up is regarding the C-661 slide block. Obviously this needs to be drilled for the clevis pin that attaches it to the back of the canopy frame, but I'm not seeing any sort of guidance on the plans or elsewhere about locating this hole. Presumably I'd locate it on the fore-aft centerline of the block, but that still leaves the vertical positioning. About the only useful thing I've found so far in searching the forums is to position the hole such that the anchor pin doesn't drag on the slide rail.

I'm guessing this is about all there is to figuring out the hole position? I suppose in the grand scheme of things precise positioning isn't critical, since the canopy and the skirt will be fitted to the fuselage, thus accounting for any variance in height or whatnot?

Next up is the position of the canopy frame when closed. With the frame fully forward, it sits about 3/4" from the windscreen bow; the forward movement is limited by the anchor pin fitting into the anchor block. The reason this gap seems wrong to me comes from me reading ahead in the manual, specifically where they suggest trapping a piece of cardboard between the frame and windscreen bow to provide a straight cut line. There's no way I'm trapping anything that thin in the gap.

Wondering how this worked out for others - did you have the large gap? It seems if I want the frame to slid further forward, I need to maybe remove some material from the anchor block, or the anchor pin, or both.
 
Don’t have the plans in front of me but if I remember correctly, you want to drill the hole high enough to allow the block to pivot on the track as the canopy closes and not interfere with its support.

Totally agree that the 3/4” frame gap is excessive. For mine, the upper forward side skins were interfering with the forward motion of the canopy frame. Rounding those off fixed the problem.
 

Attachments

  • 5BEDCD2D-7409-4583-AA79-28604B243ACE.jpeg
    5BEDCD2D-7409-4583-AA79-28604B243ACE.jpeg
    218.5 KB · Views: 132
  • 09CAA416-AAA4-4DF2-B745-82D93BB78DEB.jpeg
    09CAA416-AAA4-4DF2-B745-82D93BB78DEB.jpeg
    153.3 KB · Views: 137
  • 37F4D13D-EDA3-4B42-A0EF-7F1914F51CFA.jpeg
    37F4D13D-EDA3-4B42-A0EF-7F1914F51CFA.jpeg
    536.7 KB · Views: 119
I suppose it was high time the training wheels came off...it's been fun seeing the detail of the construction manual fall off a cliff as I start on the canopy. Tonight I started working on fitting the canopy frame for the first time and...yeah, I've got questions.

First up is regarding the C-661 slide block. Obviously this needs to be drilled for the clevis pin that attaches it to the back of the canopy frame, but I'm not seeing any sort of guidance on the plans or elsewhere about locating this hole. Presumably I'd locate it on the fore-aft centerline of the block, but that still leaves the vertical positioning. About the only useful thing I've found so far in searching the forums is to position the hole such that the anchor pin doesn't drag on the slide rail.

I'm guessing this is about all there is to figuring out the hole position? I suppose in the grand scheme of things precise positioning isn't critical, since the canopy and the skirt will be fitted to the fuselage, thus accounting for any variance in height or whatnot?

Next up is the position of the canopy frame when closed. With the frame fully forward, it sits about 3/4" from the windscreen bow; the forward movement is limited by the anchor pin fitting into the anchor block. The reason this gap seems wrong to me comes from me reading ahead in the manual, specifically where they suggest trapping a piece of cardboard between the frame and windscreen bow to provide a straight cut line. There's no way I'm trapping anything that thin in the gap.

Wondering how this worked out for others - did you have the large gap? It seems if I want the frame to slid further forward, I need to maybe remove some material from the anchor block, or the anchor pin, or both.

For the sliding block, I just centered the best I could. In the end it didn't matter. The rear frame bow will have to be bent down to about 1" from the slide rail, of if you drilled it high, you have to bend the rear frame down a bit more.

My canopy gap is about 1/8". The frame sits as far forward as the rails allow after the pin bottoms out into the anchor block. There is plenty of space left to cut canopy and the windshield. For the cut guide, I used the thin plexiglass sold at HomeDepot for picture framing. The plexiglass is hard enough so it can guide the cutting wheel and keeping it on the one side. The cardboard material would get chewed up if the cutting wheel gets near it.
 
OK, updates on what I'm sure will be a continuing saga.

First, I think I've found a resolution for the gap issue. I tried fitting the frame without the anchor block to see just how far forward I could get it, and in the process decided that maybe the engagement I was getting between the pin and block wasn't correct. As provided, my anchor pin only wants to go into the block up to the end of the tapered portion:

img_2756-1024x768.jpg


I was thinking this was intentional, that the hole in the block was similarly tapered, but then I pulled off the part sticker and realized it's ust a 1/4" hole all the way through. And if I provide a little "encouragement," the pin will go in further, just not easily:

img_2757-1024x768.jpg


So I'm thinking that the fix for the gap is to slightly enlarge that hole in the anchor block so the pin can freely slide further in. With the pin nearly touching the back of the F-807 bulkhead, I end up with a 3/16" gap between the canopy and windscreen frame, which seems decent to me offhand.

So a question here would be: can anyone confirm that I'm going in the right direction with the anchor pin/block engagement? What does your pin/block interface look like with the canopy closed?

The other fun is that the frame itself seems warped a bit. While tinkering with the gap I discovered it was uneven up front with the anchor pin placed on centerline. In order to get an even gap up front I have to shift the anchor pin basically to the far right side of the receptacle:

img_2753-1024x768.jpg


So I guess this will be my first bending operation - working out a way to clamp the forward frame in place and pull the aft end sideways to get this properly squared up.
 
...
So I'm thinking that the fix for the gap is to slightly enlarge that hole in the anchor block so the pin can freely slide further in. With the pin nearly touching the back of the F-807 bulkhead, I end up with a 3/16" gap between the canopy and windscreen frame, which seems decent to me offhand.

So a question here would be: can anyone confirm that I'm going in the right direction with the anchor pin/block engagement? What does your pin/block interface look like with the canopy closed?
...

Confirmed - the pin needs to go all the way in.
 
Confirmed - the pin needs to go all the way in.

Good deal, thanks for confirming. Now to see if I can rustle up something like an F or G bit. Time to hit up some airport neighbors tomorrow morning...
 
The canopy frame is supported by three points, the side rails (2), and the anchor block + sliding block. You should mount the sliding block to keep the rear cross member aligned at the center.
 
Back
Top