Time: 10 Hours
Yesterday and today started my canopy/frame work. The first thing to do is get the canopy tweaked by bending and stretching so that the side rails and canopy fit just right. This was a long process as I put the frame on and look then removed it to bend a little followed by putting it back on. This happened a bunch of time to get it just right. I was able to do all this since my buddy Glenn let me borrow his frame rollers and slider block from his frame since mine are still back ordered. There are several measurements you need to adhere to but overall you need the sides of the frame to match up to the fuselage sides so the canopy fiberglass skirts will match up nice.
Once I had the the frame almost perfect I clamped down the side rails and checked to make sure all the measurements between the left and right side, keeping the spacing equal. Once I had them set I drilled the holes followed by a screw and nut.
Before I do anything I needed to mark out a few measurements. First was to draw a centerline on the fuselage at the leading edge and aft edge. Then I needed to draw marks on the canopy marking centerline. These marks will hep as I cut the canopy down in order to keep the canopy straight as I cut.
I also made some measurements on the fuselage. There is a mark the the forward top skin marking centerline as well as the 3.25″ mark back from the bulkhead giving you a mark for the forward/aft placement of the canopy. I also marked the aft canopy slider for center and marked the top of the canopy frame for center. Now as I remove the canopy I can return it just where I needed. Getting the center line on the top of the canopy proved to be a challenge with the curved surfaces, hopefully it won’t cause any problems. The cutting process is time consuming as you want to really take your time and do small changes. It is tempting to make big cuts as it is needed to get the final shape, however every little change effects the entire shape and how it sits on the frame. So it has been done many times before and I’m following the guidance of other builders as well as my in-house guy, Glenn. To start I made a scribe out of a large popsicle stick drilling a small hole for a fine point sharpie pen at 1/4″ distance from the edge of the popsicle stick. With this scribe I can run the edge along the forward skin and use the sharpie to mark the canopy at the same shape of the skin. So essentially the largest cut you will have a will be 1/4 inch with the rest being less than that all the way to no cut. The idea is to start at the forward edge and cut that down until you have the canopy just touching the roll bar. You can cut just a little bit off the aft end, but you need to be very careful as the aft end will shift as the forward and is cut and lowered. As the canopy shifts forward the amount needed to be removed at the aft end is reduced. You do need to remove some but with caution. As you get closer to touching the roll bar you can trim the aft end as needed with the goal for the canopy to be supported by the frame and not touching the slider rail anymore at the same time leaving plenty of link for you to work with later. So with the help of Glenn I move the canopy over to a pair of sawhorses outside in the nice warm air to do the initial cut.
I used Glenn’s air tool with a cut off disk to make the cuts using extreme caution as you do not want to screw this up! After cutting the initial 1/4″ I cleaned off the canopy and we returned it to the frame and aligned all the marks.
As you trim the front the forward end of the canopy begins to drop. The edges are long on purpose for you to trim later, however as it drops those edges start to touch the canopy frame. These need to be trimmed now so that you can get a good fit and will eventually be trimmed off. So I marked those locations and trimmed with my Dremel drum sander which made easy work of it.
So this process went on for several hours marking the canopy removing it and cutting it and returning it to check location and fit. Remember how I said earlier that I was hoping my measurements on the top of the canopy wouldn’t cause me issues? Luckily Glenn was in the shop helping me and noticed that I was slowly shifting the canopy to the right side, meaning my canopy was leaning to the right just a hair. We were able to verify this by the factory cut lower edge and making sure the spacing on left and right in reference to a rivet was the same. As we returned to canopy to the center position I found that my initial centerline mark on the canopy was off a 1/4″. Not a major deal at this point and I course corrected and all was well. Thanks to Glenn’s experienced eye I caught it.
So I repeated these steps 8 times for a scribe, mark, remove, cut and replace until I got the forward canopy to touch the roll bar and the aft edge to just be supported by the frame with about a 1/8″ clearance.
I’ll say that cutting this stuff is messy and nerve racking because the cost of an error on this part is really expensive and it is very unforgiving. So what now? Well it’s time for the “big cut”! That’s where you separate the windshield from the rest of the canopy. However I can’t do this until I get my backordered parts, as there is a spacer block that will get riveted to the top aft skin receptacle that has a hole in it to accept the pin on the canopy frame as it slides forward. I need this to determine the actual final position of my frame as it slides forward. That’s important for this big cut as I need to cut dead center between the frame and roll bar so I have enough spacing on each side. So I’m done with the canopy for right now and will move on to other stuff this week until parts arrive. Sounds like Van’s is having a supplier issue and it may be a couple weeks. Hopefully sooner rather than later as I need the warm weather for cutting on the canopy or I will have to heat the shop as you definitely don’t want to work on this below 75° as they become very brittle so I have read.