Canopy

RV-6A Project Website

Canopy

Working with the plexiglass is actually much easier than I expected. I used a kerosene heater to warm the room to 80 degrees along with an electric heater in the cockpit to warm the plexiglass from the inside to 100 degrees.

Cutting the plexiglass is easy using the cutting disk supplied in the Finish kit by Vans. I used my air drill and ran the pressure at about 45 psi to turn the disk more slowly. I cheated heavily using all the ideas on Eric Newton's excellent page also. I first cut off the excess plexiglass by cutting where the sharp bend in the material was evident. Then just keep trimming, mostly the front, until the plexiglass sits on the latch nub. Mark and drill that, then enlarge using a unibit.

Next check the fit again and trim as needed, then go on to cut the canopy in half. By this point, you have made enough cuts to know how to proceed, but it is still nerve-wracking to cut this expensive piece. As everyone says, it gets much easier when it is two pieces.

I found, after all my careful preparation, two areas where I could have done better. While the pressure on the tape I had over the nub for the latch showed that the plexiglass was sitting on it prior to drilling it, after I drilled it the plexiglas still didn't sit down exactly on the bar. It was resting on the nub, yes, but it was also resting on the bar. I think I should have taken 1/2" more off the front to let it sit down more, which would have shifted the canopy forward and changed the angle that the inside of the canopy hit the roll bar/canopy front bow.

Secondly, when I checked the fit prior to splitting, I would push on the front windshield and the side at the same time. On the right side, the right front windshield curve hugged the form of the fuselage. On the left side, it pushed out a bit. I thought it was close enough. After I split, the windshield is more flexible and now fits the fuselage perfectly, but with too much material overhanging the roll bar. That is okay, but it means that the canopy has too LITTLE material to reach to canopy bow. Now mine was really close, so I elongated the hole for the nub, allowing the canopy plexiglass to slide forward slightly to have enough material to drill the bow. The shape of the plexiglass still matched the top, middle, front-to-back support.

I next drilled the windshield and then the canopy, again using Eric Newton's detailed instructions.

In the following photo, I am just getting started. I am cutting off the front of the plexiglass at the sharp bend. You can see that I have scored the material with a light-pressure pass to define the cut line. Next I will deepen the cut with a second and third pass. The last pass will cut all the way through the plexiglass. I'm holding the drill rigidly so that if the cutting wheel binds, it can't pull the drill and put stress on the plexiglass. Cut in the direction that the turning wheel wants to pull you or you risk the cutting disk binding as it digs into the cut line.

Since I did this without assistance, you can see hold I supported the canopy for cutting. I slipped a piece of metal under the canopy and kept the soft canopy from spreading by using the clamp that you see. This lifted the front enough that I didn't cut the fuelage skin underneath.

In the following picture you can see that I trimmed the rear of the canopy as little as possible so that it fit within the turtledeck skin. After final drilling to the rear bow, I made one more cut to leave only 1/2" overhang and a nice smooth edge.

Here is the side skirt for the right side. I pre-drilled it according to the dimension on drawing SC-1A and it worked out fine. If you look closely you can see that the hole drilled through the canopy into the front bow turns out to be too close to the edge of the C-660 side skirt. I'll have to fix that.

Here is the early stage of the left side skirt. Note that the aft edge of the canopy has now been trimmed. This side skirt is overhanging the fuselage skin about 3/16". I don't know if that will pull up using the C-791 brace. Be careful in your alignment of the canopy with the fuselage side. My canopy side bow perfectly matched the shape of the fuselage, and was inside by a uniform 1/16" to 1/8", but either it moved outward slightly with the weight of the plexiglass, or that was not enough to start with. In any event, the overhang takes time to deal with.

After reading the caution (threat?) in Van's instructions about the rear skirt being the most challenging task to the RV builder, I leaped into the task. Here is the right skirt. The simplest way to summarize the following photos is to describe what worked and what didn't.

Good things:

1. Trim the fore and aft edges of the C-666 so that they are smooth. I didn't change the shape much as drawn by Van's on the aluminum sheet.

2. I pre-bent the skirt by placing a slight crimp about 1" aft of the foreward edge. My plexiglass seemed to curl up slightly at its aft-most end and the crimp in the skirt left the aft 4" of skirt bending downward at a sharper angle which helped tighten it on the skin.

3. I raised my canopy capturing block 0.1" before starting this process. The hope is that removing that spacer will pull the rear of the canopy down an extra 0.1" and make it fit tighter.

4. Pull down and forward HARD as you drill each hole. Cleco as you go.

5. Twist the C-666 HARD before you begin drilling so that the trailing edge will be turning in toward the fuselage. It seems like it would also help to pre-roll the piece so it does not try to straighten back out into a sheet. As you'll read below, I was not too successful at this.

6. Measure everything three times before you drill.

Bad things:

1. It is tough to pull down and forward, keep the strap duplicator in the right place, and drill the holes by yourself.

2. My biggest complaint was an error I made near the end of installation of the right skirt. Where it attached to the skirt just did not seem to be pulling in very well at all. I got the idea to roll the skin a bit because the tendency of the skin to straighten back out to a sheet seemed to pulling the side skirt open. Rolling it helped, but I induced some bumps from over-zealous rolling and that made it worse on the trailing edge. It did help tuck in the bottom at the side skirt.

Finally, on July 1, after 117 hours work, the canopy is done. I'm pleased with how it came out, and ready to start wiring the panel.