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Valkyrie?s Turn?.

Ironflight

VAF Moderator / Line Boy
Mentor
Almost a year and a half ago, I reported one of the saddest things that can happen to an -8 builder/pilot – a big crack had appeared in that big canopy. Not the first to experience it, I knew that the cause was very cold temps and sharp turbulence – and that long canopy that builds up significant thermal stress. Fortunately, the stop-drilling worked, we flew home fine….and proceeded to fly fine ever since. You see, we had this RV-3 project going, and I just never could find the time to take the Val out of service. Heck, we had the new canopy delivered two weeks after the crack – it’s been in the garage ever since!

Well this week, it was finally time. I didn’t want the Val to go to Oshkosh with that crack, and in order to fix it, I knew that the skirt was going to have to be repainted. I arranged some time with Grady at GLO Custom to do the pant work in between other jobs if I could get it to him with a couple of weeks for him to work with, so I needed to get hopping! Here are a few pictures of the job on “night 2” – I have about four hours total in the job since I started. Basically, once I bit the bullet and realized I had to mess up the skirt paint, it was easy:

1) Use a pop center punch on all the rivets to punch the rivet mandrels inward.
2) Drill al the rivets with a #30 drill.
3) Use a countersink cage and bit to drill off the rivet heads – the cage prevents you from going into the fiberglass.
4) Since I had used some sealant between the canopy and skirt, I had to drill ALL the skirt rivets, then slowly peal it off, using a razor blade as I went to break the bond.
5) Take the old canopy and lay it upside-down inside the new canopy. Slide it around until it finds it’s natural spot.
6) Use a fat Sharpie to trace all around the old canopy onto the new one.
7) Use a cut-off wheel to make the “big cut” – it is nowhere near as traumatic as the first time – you just want to get rid of the windshield. Leave extra to trim off.
8) Strap/clamp the frame to a table. Place the canopy on the frame, and line up the front edge so it sits nicely on the bow. The edges are too long – just cut notches (for the vertical tubes) with a sanding drum on a Dremel to allow it to settle onto the frame. Check to make sure you have extra overlap on the back, and it stays centered.
9) Drill the canopy to the front bow, starting in the center and working down each side. Cleco. You drill into the old holes – super easy through the plex – use a plexi drill (1/8”).
10) Clamp the canopy to the frame about 2/3rds of the way back, where the frame necks down behind the cross-bar.
11) Drill down the sides into the old holes, alternating sides. Keep checking the rear alignment.
12) Once al the clecos are in, use the Sharpie on the inside to trace under the frame where you want to trim the plex. You’ll trim to this line.

That’s as far as I got in about four hours. Tomorrow I’ll trim, fit the skirt, then up-size the holes and use a new “soft grommet” trick that Danny King and I have been talking about. More when I get to it. Here are a few pictures:

Rivets center-punched and drilled (painful to do that to a nice skirt!)
IMG_6698.JPG



A Dremel sanding drum is the perfect radius for notching tube clearance
IMG_6699.JPG



Cargo straps used to clamp the frame to the table so it doesn’t move. Leading edge is drilled to the canopy bow. Trimming comes later.
IMG_6705.JPG


Anyone need a windshield?
IMG_6706.JPG


Ready for trimming, then comes a fit check with the skirt!
IMG_6708.JPG


Speaking of the skirt….it looks a little empty, doesn’t it?
IMG_6709.JPG



Paul
 
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Walking us through the process

Paul,
Thanks for taking us through it. You're right: We all hope to avoid this pain, but I've got your post filed away in case I need to deal with the same misfortune. Can't wait to see it finished! (although it should look like the original, eh?)
 
Uh oh, I see a potential problem here;are you gonna be able to salvage your name/callsign stencil on the skirt when it gets painted? That thing's kinda unique since it's flown waaaay up there.... hope Grady can work around that.
 
Uh oh, I see a potential problem here;are you gonna be able to salvage your name/callsign stencil on the skirt when it gets painted? That thing's kinda unique since it's flown waaaay up there.... hope Grady can work around that.

Yeah - that has been a bit of a stumbling block...they'll see what they can do!
 
Thanks!

Paul,
Thanks for memorializing this. No one wants to think about replacing their canopy, but if it happens it will be great to refer back to your narrative to help remove some of the pain from the process!
 
Paul, how will it fit around the roll bar, the tolerances are very close. The thought of my canopy cracking seems like one of the hardest things to fix, when people get in the back seat I make sure they don't lean on the canopy or frame.
 
Paul, how will it fit around the roll bar, the tolerances are very close.

The new canopy is the same thickness as the old, and I simply made sure that it draped over the bow on the canopy frame the same way - it appears to be a good fit, although I haven't gotten far enopugh along to fit it on the airplane.
 
Aren't you glad you riveted?

I was just thinking how much more interesting this project would have been had you sikaflexed the canopy and skirt. I did and shudder to think about what would be needed to replace the canopy. Pretty much toss the whole assembly and start from scratch, I think.

Regards,

Michael Wynn
RV 8 Finishing
San Ramon, CA
 
I was just thinking how much more interesting this project would have been had you sikaflexed the canopy and skirt. I did and shudder to think about what would be needed to replace the canopy. Pretty much toss the whole assembly and start from scratch, I think.

Yeah - I dont' have anythgin against the concept of Sikaflex holding on a canopy (I am pretty sure that it has no flight issues at all), there are aspects of maintenance that could be troublesome. I'd hate to have to uild a new skirt....



Paul, as much as I think your paint scheme on Tsam is great, your personal picture as an avatar is much much better.

Heh, heh, heh.....I guess we'll just keep that "eye" Avatar in reserve for when folks get out of line....;)
 
Back to Flying Status?.

OK, so another seven hours of work on top of what I did in the first post brought it back to flying status ? not finished, because it still needs fiberglass work and paint, but at least the Val is once again airworthy, and the canopy is now pristine!

This portion?s notes:

1) Removed all the clecos and took the canopy off the frame for trimming the sides. I did this with the cut-off wheel and angel die grinder with sanding discs. Dressed the edges with Dremel sanding drum and finished with 600 grit sandpaper to polish.
2) Drilled all holes in the sides of the canopy to ?? with plexi bit. Drilled the front edge holes one size up from 1/8? per standard Van?s instructions.
3) Cut little grommets out of surgical tubing for all the ?? holes. They fit just fine with friction alone, so I didn?t use any adhesive to hold them in place.
4) Replaced canopy and clecoed from front to back, including the skirt. The fit isn?t exactly the same, as the canopy shape isn?t exactly the same. The rear of the skirt was a very tight fit, and I left several clecos out rather than pre-loading the assembly excessively.
5) Riveted the skirt to the frame using CS4-4?s, then used AACQ4-4?s for the skirt/canopy/frame sandwich holes. I gave each hole a swipe of countersink with a deburring handle so that the rivet heads will be a little below the surface ? I?ll fill with micro before paint. This will hopefully keep the rivets hidden.
6) After all the rivets were in place, I turned the canopy upside down and used silicone to fill the gaps between frame/canopy/skirt from underneath (you can?t see this area from inside the cockpit, but this ads some sealing and a little bit of adhesive in the back).
7) After the caulk had cured, I test-fit the canopy on the plane, and found that I have a bit of a gap in the back ? I?ll fix that with glass and micro before paint ? this is art, not engineering, and all it needs is a pleasing shape.
A few pictures (sorry for the focus ? good camera is on a trip ? this is the old shop camera that has problems with it?s macro focus?.):

A sharp razor blade makes it easy to slice washers out of surgical tubing
IMG_6712.JPG


Fuzzy picture, but you can sort of see the surgical rubber grommets in the ?? holes
IMG_6715.JPG


Skirt riveted back on to frame ? not that the rivet heads are over-countersunk
IMG_6746.JPG


The shipping box makes great work stand to hold the canopy inverted! Note the caulking underneath the low frame tube.
IMG_6751.JPG


Paul
 
PD

You have such a beautiful machine, it would be a shame to attend the annual gala event in anything less than perfect order.

I do admire your work, on and off the boards, and mostly with your family fleet!

DB :)
 
Finishing Up

One of the problems with refitting the bubble on one of these airplanes is that no two are EXACTLY alike. Therefore, when you try to match things up with the skirt, you are bound to have to make a few adjustments to the fit. In the case of the Val, once I lined up all of the forward rivet holes, the skirt road just a fraction high on the bubble in the back, and that made it gap across the back ? it was about ?? high in the center rear. This clearly needed fixing. Fortunately, it?s fiberglass, and once I had committed to repainting anyway, it?s just a matter of cutting, grinding, and ?gooping?.

In this case, I split the skirt down the middle and found that if I took out a wedge-shaped piece, I could lay the two sides nice and flat against the bubble and the fuselage. I located the rivet holes in the bubble and frame underneath and drilled two new holes in the skirt to correspond, then popped in a couple of rivets. From there, it was simply a matter of grinding down a bit to create a scarf joint and laying in a few layers of glass. I finishing pass with some micro to fill the weave and get it ready for the paint shop.

Here are a few pictures of the ?flyable? (not painted) job:

I cut a wedge out of the rear, then riveted the edges ot the canopy/frame after wrapping it to a nice fit.
IMG_6753.JPG


A few layers of fiberglass ? more at the back middle where it goes over the track
IMG_6755.JPG


A little Micro?.a little sanding?.
IMG_6756.JPG


Ready to fly?..to the paint shop!
IMG_6758.JPG


Paul
 
All Done!

A week at Grady's GLO Custom for touch-up, a visit to the Vinyl Graphics shop for name tags, and she's all ready for Oshkosh!


IMG_6760.JPG


Now if only she wasn't behind Tsam in the hangar, maybe we'd get out more together.... ;)
 
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