Cotton Waiex 191 - N191YX

[Bryan Cotton]

Adam and I did some driver's side canopy reshaping. One of us pushed on it with a board, while the other heat gunned it.

There was a little distortion when we were done, but all down low.

The latch works awesome now though. Totally worth it!


Here is our canopy restraint. We used a nutplate on the bulkhead.

[Bryan Cotton]

Today we finished drilling the canopy bows to the joining elbows. Also we drilled and tapped the bows for 6-32 and countersunk the screw holes.


Question - the plans say to drill the holes to 9/64", which is less than the normal recommended clearance hole for a #6 screw. What size is otherwise recommended?

[Darick]

I didn't want to put my pictures on your page, so if you go to page 15 on my photo album, you'll see that I didn't tap the bow, but instead used locknuts. And I did use a larger clearance hole for the #6 screw than suggested on the plans.

[Gordon]

Canopy.........#6 screws

I used #8 screws for my Onex canopy. Having built 3 RV's over the years....#6 screws are just too small for ANYTHING on the airplane, much less the canopy. Sounds like your already committed on that one. 2nd choice would be like the other builders comment...........run longer #6 screws with a fiber nut on the back side.

On the RV canopies we used #8 screws with a fiber nut and never had any problems after hundreds of hours flight time (and the cold weather). Also I use #8 screws (flush) to attach fiberglass wing tips.......the #6 tend to twist off, especially if they are stainless steel screws.

Don't be afraid to go a bit bigger with the hole in the plexiglass than what Sonex says, your going to use a large area countersunk washer with your #6 screw so there is no worry about it pulling through. Also don't torque them up too tight....that defeats the purpose of the oversize hole.

Gordon.........Onex........Hummel 2400

[sonex892.]

There is nothing wrong with using longer screws and locknuts for the canopy bows, but it can always be done later if need be. I drilled and tapped the bows with 4mm stainless screws. Been flying for 7 years with 277 hrs now on the original canopy, these threads and the canopy are still holding up. All holes are in the perspex are countersunk and well over sized.
I agree with Gordon on the #6 stainless screws if used in nutplates. They gall and break quite often. That said, I doubt you will ever snap a #6 stainless screw in a hole tapped in relatively thin aluminium as in the canopy frame.
Steve
Sonex 892

[Gordon]

Last Comment on Canopy Machine Screws..............

Steve.........your thinking lines up exactly with my thinking. I drilled and tapped the canopy bows for the machine screws (although I upsized to #8) with the notion that if and when one or more fail (strip out) I will then drill straight thru and install a longer screw with a fiber nut.

From time to time I go back to the old adage.......if it ain't broke don't fix it. Although some of the things Sonex has done will test you on that one. I still shake my head at the fuel filler issue on the Onex.......ugh.

You are also exactly right about twisting off stainless screws in steel nut plates......they gall and jam up. Stainless screws with a fiber nut is perfectly fine.

Gordon........Onex........Hummel 2400

[Bryan Cotton]

Thanks for the discussion guys!

My canopy bow strap was not wide enough. In the center I had less than 1/4" of overlap with the canopy when it was closed. So, I am making a new wider one.

[Bryan Cotton]

Well, we have joined the cracked canopy club. Got one of these on each side.


I volunteer at the Explorer post at the museum. They let me use the spray booth since my normal one is too cold.


Painting in progress!

[Gordon]

Cracked Canopy..........Opps

Bryan.........I am curious what you used to enlarge the holes on your canopy?

I used the "plastic drills" from Avery I bought years ago to make the initial holes.......then to enlarge them I use a "single flute step drill" (mine is fairly dull). This is the safest way to enlarge those holes. I have done 4 RV canopies over the years and my Onex canopy recently and have never cracked one.

I guess this advice is a bit late for you at this point. Sorry about that.

Gordon......Onex........Hummel 2400

[Bryan Cotton]

I used an acrylic drill for the initial holes, then a super dull 11/64" bit. We drilled a few holes in a handy cement block to dull it.