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Canopy Frame questions

Don

Well Known Member
I've spent a couple of hours per day for a week bending the canopy frame (slider). The directions are clear that you need to understand what your doing and that you need to think about what you're doing. In that case, the directions could be just a tad clearer about reasons for some of the measurements.

After a week of back and forth - closer, closer, almost there....how the heck did that happen? - here's were I am.

1. My front bow is a bit less than 3/8" taller than the roll bar and it follows the shape of the roll bar pretty well. The manual says this should be 1/4 to 3/8" taller at the center and the latching mechanism should be centered. I think I've got this covered.

2. The side rails should be inset 1/16" and closely follow the shape of the longerons. This is the easiest measurement to capture in my opinion and I'm there...most of the time (and currently).

3. The side rails should be level with the longerons within 1/4" - I'm close but not perfect. If I could get the aft bow bent the way I want I'd likely be almost perfect - within 1/8".

4. The aft bow is supposed to be 1/8-1/16" lower than than the turtle deck at the center - I'm there. This is a snap to capture by sliding the C-762/C-763 rail forward or aft as needed. The problem begins as you move off the center line of the aft bow. The instructions simply say, the bow should follow the curve of the turtle deck. My does...but not within 1/8-1/16". It was out by about 1/2 an inch or more and I've gotten much closer but at the bend of the cone in the turtle deck I'm out at least 3/8". Above that - in the flatter areas of the turtle deck, the bow is from 1/16" to 1/4" low.

How big of a problem would I create if I called this "good enough"? When I attempt to fit the aft skirts to the turtle deck, I'm guessing I'd be in for some pretty difficult sessions getting a decent fit. I'm just not sure how to get the frame to match the skins any closer.

I know if I could somehow flatten and raise the aft bows some as they move away from the center, the match would improve. In addition, the side rails would raise on the aft end and the rails would parallel the longerons better.

So, in short, how close is close enough when it comes to matching the curve in the turtle deck skin?

And one other question - when I start drilling the plexiglass the directions say start with a #40 bit and open the holes to final size (5/32) with a unibit. I understand plexi loves to crack - is the #40 bit just a standard bit?
 
I struggled with the canopy too! After bending it perfect in one spot and messing up another over and over I finally decided it was good enough. I too ended up having the most discrepency in the aft bar.

I ended up building the rear skirt to plans with Van's supplied skin, and I was able to close up the differences. Being the rear skirt is a complex curve, you're able to pull it into place if you will. Another option is to make the rear skirt out of fiberglass either way you can cover up you're differences in the rear bow or at least I was able too. Just get the center where you want it by sliding the rail, and build on.

I also drilled my pilot holes beginning with a #40 size bit and then using a unibit to enlarge the holes. I think the key is to do this when the canopy is warm, above 80F and use a dull (well used) bit.
 
Thanks Steve. I find that after 30 to 90 minutes of bending - evaluate, cogitate, frame off, bend, frame on, examine, and repeat ad nauseum, I will hit a point where I ran out of ideas and/or patience. Then, in a hour or the next day, an idea would hit me about how to move forward. Yesterday I figured out a bending too that has been a big help - it can tighten a radius or loosen it but it only works a little at a time (usually a good thing). Right before dinner I was taking a break and it occurred to me how to bend the left bow up about 3/8". That one bend has got me close in every dimension (but I needed to rebind the right bow back into shape). I've been tweaking the aft bows since and I'm probably going to move on tomorrow and fire up a space heater and cut the canopy. Knowing the skirts allow for some adjustment makes me feel better.
 
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