Finishing Kit

February 25, 2012

Forward Canopy Stops - 8.0 hrs.

Well, after a lot of looking around online, I found a couple examples of a forward canopy stop, so I decided to make and install a pair of them. I see no harm in it, except for adding a few more ounces of weight to the aircraft and investing more hours of my time. It's worth it if I can solve the problem of a poor-fitting canopy, made so by the installation of the lift struts. So over the last week or so, I have done some trial-and-error fabrication and a lot of thinking about this issue. Here's what I finally came up with. I found some leftover angle in my inventory, so I cut and fitted a couple of pieces and tapped them for 1/4 - 20 threads for the joint connector bolts seen below. I found these at a local Ace Hardware store for less than $2 each. They have a nice flat surface to push against the canopy frame. The curvature of the bracket is needed to reach up and over from the longeron a ways to position the bolt in the middle of the forward canopy frame, where it will push against it, allowing it to only go forward so far. It will be adjustable, so it can be fine-tuned once in position, and held firmly in place with a typical lock-nut. The extra holes are lightening holes.

Here's the right one, primed and riveted in place on the longeron. A small hole is drilled in the sub-panel for the bolt to reach through from the aft side.

Here's the left side. You have to think this through and leave enough room for a bucking bar to fit between the bracket and the sub-panel, for when you rivet the top skin on. You want to be able to easily reach those rivets while lying on your back under your panel! You're also going to be putting the bolt back in place afterwards from the aft side of the sub-panel, so you'll be underneath to put the stop-nuts on, and tighten them when you get it positioned.

I put some UMHW tape on the surfaces of the joint connector bolts, where the flat surface will be rubbing on the canopy frame as it closes. Here's how it looks from the other side:

And here's the one on the right side:

After some tinkering and adjusting and all that work fabricating and installing them, did it work? Well, here's the final result. I now close my canopy and once again, the gap at the aft end of the side skirt is less than 1/32". Perfect so far.

On the forward end, the gap was caused by two factors. The canopy frame was pushed forward, and also being slightly lifted upwards by the pressure from the lift struts. The forward-push error has been corrected, but the canopy frame still wants to lift up slightly. It's just due to the geometry of where the lift struts are positioned and how the forces affect the canopy frame. This is only a problem in my case on the right side. The left side fits perfectly once again. I don't know why this is the case, but it takes very little pressure to push the frame down so it fits correctly. I'm hoping that the weight of the canopy, once it's finally installed, will push this down and eliminate this gap. I don't know what else can be done. I guess all I can do is press on and move forward and see what happens.

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