Canopy Frame

[sellis]

Hi all, I need some advice. I'm trying to fit the canopy frame to a QB fuselage. Vans says it just needs some slight tweaking. However, after a LOT of effort to make this fit, I finally realized that if the rear pin and slider block attach bracket were actually centered on the frame, the majority of my issues would be resolved. After measuring a half dozen ways it appears to be off to the right about 3/16". Moving the bracket both shifts the front bow so that it better matches the rollbar/windscreen support, which has a significantly different gap from left to right, and more importantly, it fixes the gap at the rear bow. Before my "tweaking" the rear bow was rubbing the skin on the right side and had 1/2" clearance on the left. After all the bending (ratchet straps, bottle jacks, etc.), it now has a gap of 3/8" on the left and 3/32" on the right, which I do not think is acceptable, but is all I can manage to get from bending. Again, moving the rear pin and bracket to center evens out both of these issues. HOWEVER, my welding skills are not sufficient for such an important piece and I'm having a hard time finding a welder who can do this. And, it's a little (a lot actually) frustrating that to have this cut, welded and re-powder coated, will cost a fortune- once I find someone.

Vans says these gaps are tolerable and covered by fairings and fiberglass, and that all weldments are off slightly due to the welding/heating/cooling process, but this seems to be a quality control issue, not a welding issue, and I'm not comfortable with these gaps. Am I missing something? What other solutions can you offer? I'm sure my canopy frame isn't the only one that has been off.

 

[rv8ch]

However, after a LOT of effort to make this fit, I finally realized that if the rear pin and slider block attach bracket were actually centered on the frame, the majority of my issues would be resolved.

Very observant! I know that when I was doing this I was quite disappointed with how much bending of the frame was needed to get it close to being in the right place, but for some reason I didn't measure it like you have. It would be interesting to know if this problem exists with all frames and we've been bending around it, or if it's just yours.

 

[jmra72a]

The more time you spend on this making it fit correctly the better. I ended up making new plastic parts from UHMW. The top sliding part as well of the one on each side that the pins go into. I used some floral Styrofoam to place into the holders. I then slid the canopy rail into the foam. From this I could remove it and install a dowel pin to measure the angle. I then set up my drill press's compound tilting table to replicate that angle, and drilled the new UHMW plastic blocks. I was pleased with the outcome.

 

[sellis]

Very observant! I know that when I was doing this I was quite disappointed with how much bending of the frame was needed to get it close to being in the right place, but for some reason I didn't measure it like you have. It would be interesting to know if this problem exists with all frames and we've been bending around it, or if it's just yours.

I have a sneaky suspicion that this is a known and recurring issue. Hopefully Vans can get it fixed for future builders.

 

[sellis]

The more time you spend on this making it fit correctly the better. I ended up making new plastic parts from UHMW. The top sliding part as well of the one on each side that the pins go into. I used some floral Styrofoam to place into the holders. I then slid the canopy rail into the foam. From this I could remove it and install a dowel pin to measure the angle. I then set up my drill press's compound tilting table to replicate that angle, and drilled the new UHMW plastic blocks. I was pleased with the outcome.

Interesting approach. I haven't considered that but it might be a better way to offset the canopy without having to move the pin and bracket.

 

[PhatRV]

The more time you spend on this making it fit correctly the better. I ended up making new plastic parts from UHMW. The top sliding part as well of the one on each side that the pins go into. I used some floral Styrofoam to place into the holders. I then slid the canopy rail into the foam. From this I could remove it and install a dowel pin to measure the angle. I then set up my drill press's compound tilting table to replicate that angle, and drilled the new UHMW plastic blocks. I was pleased with the outcome.

This is true. The canopy frame is somewhat flexible and I had to handwork the frame from the front roll bar to the rear bow as in the build instruction. The rear bow in the OP need to be bent down further from the picture. In the end, the goal is to ensure a smooth operation of the canopy. The fiberglass skirt will cover the frame from the external view.

 

[wirejock]

Shop around for a really good Tig welder. Some charge a minimum hour.
I got lucky the one time I needed a part welded. He was fascinated with the airplane project and only charged me $20. Some won't touch it because it's an airplane.
Consider this an opportunity to powder coat the frame any color you want.
In the end, a fiberglass skirt will hide everything.

 

[scsmith]

I wonder if the set-up/jig has changed over the years? Mine fit quite well out of the box. The rear bow needed tweaking to have a constant gap, and the same left and right, but the forward hoop and side rails were very good as-is. This was 17 years ago, of course. (how did that happen?) So just wondering if something has changed. The welding vender for Van's hangs out here on VAF, I think his name is Ross McKutchen or something like that - memory fades. Maybe he will chime in with advise.

 

[vlittle]

I wonder if the set-up/jig has changed over the years? Mine fit quite well out of the box. The rear bow needed tweaking to have a constant gap, and the same left and right, but the forward hoop and side rails were very good as-is. This was 17 years ago, of course. (how did that happen?) So just wondering if something has changed. The welding vender for Van's hangs out here on VAF, I think his name is Ross McKutchen or something like that - memory fades. Maybe he will chime in with advise.

Here’s a tip from 2006:

 

[sellis]

A quick followup on this: Vans has evidently just recently taken the fabrication of the RV8 canopy frame back in-house. After a lot of communication and numerous pictures they said they believed mine came from a "bad batch" and the required work was beyond what could be done in the field. They also stated they made some adjustments to the jigs when they began fabricating these themselves. Thankfully, they sent me a new one at no cost. I just received it and have not had time to get back to work on it, but out of the box, it is light years better than the old one. This one appears to only need minor adjustments. Grateful for Vans support!

 

[sellis]

The welding vender for Van's hangs out here on VAF, I think his name is Ross McKutchen or something like that - memory fades. Maybe he will chime in with advise.

I reached out to him (Russ McCutcheon) a while back, and I think he said he did not do the RV8 canopy, but I can't remember that for certain. I asked about a couple of things and I know he did not do some of what I had asked, although he has done a lot of fabrication for Vans.