Step 22: Canopy Stop
A few years after finishing the canopy, I finally installed the canopy stop. Even though my turtleback bulkhead and the headrest are different, the geometry was still the same. So I basically followed the methods shown in the plans. However, I ran into a problem with the 25.5-inch dimension on the turtleback bulkhead shown in Figure 83. I blindly followed the plans only to find that the 25.5-inch location was BEHIND the port headrest! So I had to relocate the ball socket one inch more inboard. You'd think by now I'd learned to trial fit everything. :-(
The gas spring and ball sockets are available from Service Plus Distributors (SPD Part #: SPD-GS-5150-40), or you can get them from your local NAPA store (NAPA Part #: 8195587). I made my own elbow bracket from some aluminum and riveted it to the shear web on the starboard headrest. I also bought the Stop-Lock device. As the name implies, this spring-loaded lever locks into place once the canopy is fully opened. It keeps the gas spring from being compressed. To close the canopy, you pull the lever out of the way and pull the canopy down normally. The Stop-Lock is a must have device. You won't realize the necessity right away, but as the spring gets older it loses pressure and has a harder time keeping the canopy open. Just ask anyone who's had their canopy blown onto their head by the wind!
By the way, I found the geometry and the approximate 69-degree opening angle to be about right. I had always wondered why the canopy doesn't open up higher. (It would be easier to get in and out of the plane if it did.) It becomes crystal clear once you actually sit in the pilot's seat -- any higher and you won't be able to reach up and grab the canopy in order to close it. Also, any higher and the starboard edge of the canopy starts to impinge against the upper longeron.