J

JohnF

Well Known Member
I had the canopy frame hinged on the fuselage. All looked good; almost perfect as far as I could measure things. Side edges lined up perfectly with the edge of the longerons.

I then attached the plexiglass and that went well. Now when I lower the canopy now one side does not overlap the edge of the longeron. One side has the proper 1/8th inch overlap, but the opposite side has interference such that the trim piece on the outside strikes the edge of the longeron preventing the complete "closure"

Its like you want to squeeze the two longersons a bit to narrow the fuselage so the canopy trim would properly slightly overlap the longerons but that seems not a good idea, and I am stuck on how to proceed, and wondered if anyone else could have run into this problem and if so what was done to correct things. Any help would be appreciated.
John
 
How

I agree, Larry, spreading the canopy would do it, but with the plexiglass already attached I wonder if that would be recommended?

I did not yet bolt/nut the aft end, and will do that and see if it 'spreads' the canopy. If no, then something along the line of your suggestion seems to be the only solution.

John
 
Canopy Fit Fix

The folks at Vans recommended using a shim under the side trim piece to push it out a bit and allow the overlap that I wasn't seeing on one side. That was the best fix the local folks who looked at thought too. That's what I will do. (Although I admit the idea of spreading the frame was tempting, but fear of damaging the already attached plexiglass halted any serious plans to do that.)
 
If your canopy frame was the same width as the fuselage, it is too narrow. Page 34-04 diagrams A-A and B-B depict the wd-19 frame rails with a 1/32" overhang on the side skin. Even with the overhang it is a close fit lowering the canopy. I just finished attaching the canopy to the frame and installing the guides. There is enough flex in the canopy assembly that the skins can "catch" as you lower it over the side skins. I wonder if breaking the edge of the canopy skirts would help ensure that they slide over the side skins.
 
canopy fit resolution

Yes, the shim worked fine for me too. Thanks to all for help given.
 
I'm at the same place. The frame lines up perfectly with the longerons, NOT with the required 1/32 overhang. Trying to decide whether to try and spring the frame apart (scary), or use shims. Could someone please provide more detail on the shims? Dimensions, exactly where they get inserted, etc.?
 
Spreading the canopy frame is no big deal. Mine was about 1/8 too narrow on one side and 1/16 on the other. I took one side and a friend took the other. We bent it by hand just a few minutes. Just work slow and check the fit as you go.
 
Tried to spread the frame by wedging it apart as much as I dared. Didn't make a huge difference. Guess I will wait until the canopy is drilled and clecoed and the skirts go on and see how it fits.

Another question. When my unmodified canopy was within 1/32" of the aft window at the top, it had about 1/4" gap at the bottom on both sides. So I removed 1/8" from the rear at the top tapering down to nothing at the bottom corners. Also elongated the hole at the top by 1/8". On re-try the gap at the bottom corners is now about 1/8". The plans say that rear gap should be 1/32". Did anybody else see this? Does anybody think it matters? I don't want to remove any more material because I would also have to move the hole more, and the plans say you can only move it 1/8", which I already have.
 
Hi,

When I trial-fitted my canopy I noted the trimming that appeared to be required and went ahead and made the adjustments. The second trial fit was close to perfect.

I then drilled the front and back holes as per the plans. The plans say it is OK to slacken off the clamps at the rear, and that it is OK if the frame rises up above the cardboard. Mine did rise, by at least 1/4 inch. Not sure if this matters.

More significant is that the 1/8 gap at the front has reduced, and the small gap at the back has become quite big - more than 1/8 inch. Again, not sure whether this matters.

Please can anyone advise whether the gaps I now have will cause an issue going forward. Not that I can see any alternative at this stage...

In retrospect, it may have been better to keep the frame tightly clamped to the roll bar.

Cheers...Keith
 
My experience with this

Keith:

You do have to loosen the clamps to get the aft section of the frame up flush against the canopy for drilling. However, I then put the clamps back in place with the spacers to maintain the distance from the roll bar and then drilled the canopy.

My gap between the canopy and aft window ended up being right at 1/8inch pretty much all the way around. I had read several posts, including one from Scott, that suggested going a bit more than 1/32 for expansion and shifting. I shot for about 3/32 based on suggestions in the posts. I was right there with the final trial fit but once all was assembled, it ended up being 1/8inch. Hard to imagine this would cause any problems.

Jeff
 
More canopy fun

The plans call for pre-drilling #40 pilot holes in the forward bow, then match drilling through the canopy, again I presume #40.

I cannot see any instructuion to open up the holes in the forward bow to #30, but the rivets look like 1/8 inch. Should I just go ahead and enlarge the holes?

The plans also say enlarge all the holes in the canopy to #27. I had no difficulty enlarging the #30 holes to #27. But the #40 holes at the front were not so good. I ended up with small chips coming away from four of the holes. I was drilling slowly, at 70 degrees.

I'm now nervous about countersinking these holes. Do I need a special countersink?

Thanks...Keith
 
Page 34-06 Step 3

Page 34-06 Step 3 says to drill #30.
Page 34-07 Step 3 says to drill all holes #27. I assume the holes are drilled larger to allow room for the acrylic to expand and contract with temperature.
I used the same countersink for the canopy that I used on aluminum. However, I used an egg-beater type hand drill for both drilling and countersinking. It takes longer than a power drill but you can stop if the bit catches.
Joe
MillersFalls1.jpg
 
Thanks, Joe.

Just noticed before you posted this, that #30 is specified in Page 34-06 Rev 1. I was looking at an old version.

Cheers...Keith
 
Thanks, John. In fact I just went ahead with the standard 3-flute countersink. Slow speed was fine. You do have to watch though, because the material is removed quickly, and it's easy to overshoot.

One further issue I had was with the front canopy hole on the port side. The hole in the skirt intersected the edge of the canopy. I elected to drill a new #27 hole in the skirt further aft. Not cosmetically pleasing, but almost certainly better than having a hole breaking the edge of the canopy. Strangely the starboard side is OK and the rest of the canopy appears symmetrical.

Cheers...Keith
 
Keith,

Van's made a change here after early builders noticed this. My canopy skirts came with a decreased spacing in the two most forward holes to prevent this. Your kit was probably earlier so did not have the change, although it is a mystery why one side is different than the other. Maybe you should call Van's.

John
 
I hesitate to reopen this thread but have fitted the canopy and have had some nagging problems.

1. The most aft bolt in the canopy skirt interfers with the C-1212 guide block. Have replaced this bolt with a low profile one, dremeled the screw down flat and still have interference. One person cannot open the canopy as the opposite bolt hangs up. Will file off the interfering forward portion of the guide block and hope it solves the problem.

2. The canopy is quite flexible so when one person opens the canopy from either side the opposite side aft canopy skirt can slightly rub against the roll bar and leads to paint damage. Has this been experience by others and have they tried any sort of a thin wear plate of say sticky vinyl, etc. for protection.

3. Again, due to the flexibility of the canopy, when one person lowers the canopy the opposite C-1206 guide plate will hang up on the sill and has to be bumped from the outside to engage.

Any comments on the above would be appreciated.

John s/n 317
 
Hey John

Its been a while, but as I recall we early guys all had a problem with that. Just grind off what you need to, to get it to work smoothly. I had to take a fair amount off the corners that interfer. Just do what you need to. It is not critical.

John Bender
 
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