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aeropunk

Active Member
Hey fastback guys,

We're at the point in the Showplanes plans where we need to start thinking about welding components to the WD-808 seat back weldment. One of those components is the little nut which anchors one end of the canopy gas strut. (Pictured below, with arrow.)

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Question: Did you guys drill a hole in the WD-808 behind the welded nut in order to accommodate the full length of the gas strut anchor bolt?

I'd rather not weaken the steel WD-808 if possible, but I guess the only other options would be to cut that bolt a little short, or just leave it sticking out a bit. Any thoughts? What did you guys come up with here?

And while we're on the subject, did you guys try welding everything with the WD-808 installed in the fuse, or just mark and clamp things and then do the welding away from the airplane?
 
Dan made a little bracket that dropped that mounting point down about 1.75-2.5" to improve the geometry. Of course I shamelessly copied him. The only welding I did with the brace on the airplane was to temporarily tack the center tipup bracket in place.
 
Thank you gentlemen, very helpful -- and very nice-looking work. Could I trouble you for a close-up photo of that bracket?
 
Brian,

Had I seen what Dan had fabricated I would have followed his path as the geometry would have been easier. In sticking with the drawings from Showplanes your challenge is finding that exact location point for the nut that will allow the strut to compress just before it 'bottoms out', whilst maintaining the canopy in the open position, at no more than 90 degrees, fully extended. It is achievable, but Dan's way is easier (as always)...

As for attaching, I chose to grind the tip of that nut to exactly match the curve of the WD-808. The curve on the nut allowed for greater contact between the nut and the weldment, and also brought the strut closer to the weldment, allowing for a neater fit. A spot of epoxy held it in position as the weldment was removed from the aircraft for welding off site.

I too added a roll bar, the one that Bryan at Showplanes sells. Like the nut, the contact points of the rollbar were ground into a shape to match the curve of the weldment.

Overall I am extremely happy with my outcome, a lot of work, but extremely happy. (If I knew how to add a picture I would!)
 
Brain, sorry, can't seem to find a picture of the gas strut bracket. It's just a bit of folded steel that drops the mount point below the cross tube center. One or two folks have commented that it might snag a passenger's knee getting in and out, but it never has.

Dropping the mount point makes the canopy easier to lift from the closed position.

Here's mine. The rollbar is not subject to dynamic loads, other than use as a handhold. No need for regular weld inspection, so I used a beautification method known to fabricators as "cheating"... bead blast for tooth, then fill and smooth with dry micro, much like a custom Harley frame. Scott uses enthusiasm and some sort of Zen Method to get pretty welds because he is young and has better eyesight. I will teach him about deceit when he is older ;)

BTW, were I to do another Showplanes canopy, I'd lay a few plies of carbon on the front and rear face of the mid-canopy crossbar. Carbon is high modulus, meaning it doesn't stretch under load. Glass fiber is relatively low modulus. The gas strut, when compressed, is strong enough to bow the left lower edge of the canopy frame away from the fuselage skin just a tad.

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Don't give away all of the secrets Dan, someone just might use them. The carbon is in mine. My welds aren't that pretty at all, but better than many that I've seen. I'm just proud of my work and how far I've come in some of those details. I've sectioned enough fish-mouthed test samples of my progress (months worth) such that even if they aren't perfectly pretty, I know exactly what is under them and they are sound. That darn roll bar was a big slap in the face that I can no longer weld without reading glasses!
 
DanH said:
BTW, were I to do another Showplanes canopy, I'd lay a few plies of carbon on the front and rear face of the mid-canopy crossbar. Carbon is high modulus, meaning it doesn't stretch under load. Glass fiber is relatively low modulus. The gas strut, when compressed, is strong enough to bow the left lower edge of the canopy frame away from the fuselage skin just a tad.
Click to expand...

Since I am going to build a showplanes, this sort of stuff is gold.
 
This is all great stuff guys, thanks a lot. This is the first RV for Dad and I, so it likely won't win any awards, but you guys have definitely given us something to shoot for!

 
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