Initial Canopy Trim-How Much?

[pilot28906]

Do you just remove the edge up to where the canopy gets a little thicker? Do you remove the plastic film or just cut through it?

Thanks

[rv7charlie]

I started by removing just enough of the base flange to allow the bubble to conform to the frame. Lots of small cuts after that, as it approached final fit.

I'm pretty sure I left the plastic on in the area I was cutting. IIRC, when I did the 'big cut' I ran tape lines over the curve to hold down the loose folds in the plastic covering.

Charlie

[wjb]

Just finished this step. RV-7 tip-up.

Take a look at the photos below. After a rough marking on the fuse, I trimmed the sides a few inchs below the bottom of the joggle along the side of the fuse, and a 1/2 inch in front of were the canopy transitioned from main bubble to the forward clamp area.

As shipped from Vans:



After initial trimming (with my beautiful daughter/assistant):



It's a slow process, doing the fine tuning, but it is not difficult, just time consuming. The "big cut" is actually just a rough cut (BTW, easy!); you'll do lots of fine tuning of the edge after the cut, as the canopy lays down nicely on the frame. The canopy pieces are very manageable solo once the big cut is done.

The first cuts (shown here) were right through the protective vinyl. Later on, I peeled back the plastic, cut off the excess, and then taped it down so the plexi dust wouldn't get blown underneath during the trimming. Be prepared for lots of plexi dust.

I used a Dremel Saw-Max, rather than the angle grinder and Van's cutoff disks to make the cuts; I found it easier to control.

[pilot28906]

Thanks for the info and photos. I purchased the Saw Max and it cuts better than the Van's wheels and die grinder. So far, I trimmed about 1/2" off the front; much more to go!

[CJ in E.P.]

When trimming my canopy for a 9A I started by trimming off the flange from the front end which appeared to be simply the excess material extending past the form. From your picture it appears that you've already done this. Next I adjusted this edge by trimming off just enough to get the fit close to matching the front deck of the canopy assembly. I would suggest not going to far trying to make this perfect at this point because it will change slightly once you make the big cut. Note that at this point I wouldn't trim away any more of the "flange" from the sides or back of the canopy as it isn't necessary and doesn't interfere with the fitting process. Also take note that at the point you're ready to make the big cut, with the canopy aft surface resting on top of the fuselage behind the cockpit and the front edge resting on the forward canopy deck, that the canopy may not be resting on the rollbar assembly. So, once you make the big cut and reposition the two pieces of plexi in the same spots the top cut edges will meet up and the bottom edges along the sides will be separated, which will require a lot more careful trimming and adjusting along the top edge to get a good gap. How you adjust this gap will depend on if you are going to follow the instructions and secure the canopy with screws, or use Sika adhesive. (If using adhesive you'll need to shim a gap between the curved canopy frame rib and the plexi, and the rollbar and the plexi, to allow about an 1/8 inch for adhesive). Bruce Hill did a really nice job of documenting the process on his rv9a project and I'd highly recommend following it closely if you plan on using Sika, which I'd also recommend. Mine came out really nice.