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Fitting Tip-Up Canopy Skin to Frame?

tx_jayhawk

Well Known Member
I know lots of others have had this problem, but the canopy skin doesn't fit worth much. The gap at the corners is HUGE. I've done some searching to see what others have done, and I've seen some that use a single shim.

Based on the size of the gap currently, I need much more than a single shim. What have others with a huge gap done?

Any help is appreciated.

Thanks,
Scott
7A Finishing
 
Clarification?

Are you talking about the gap between the forward canopy top skin and the arc of tubing below it, about 4" in from each edge?
 
yes. Sorry, should have been more specific. I am referring to the gap at the rear of the canopy skin between the tube (near the arc as you mention).

Thanks.

Scott
 
My approach was, who cares. I left two rivets out and just put two -3 rivets to nowhere in the skin to fill the holes. I don't think the big gap is going to bother me a bit.
 
Leave out rivets

Yeah, the fit sucks. Just leave out the rivets that would cause the skin to deform.

Underneath, I scuffed and cleaned the skin and tube and filled the area with epoxy and micro filler. Looks clean and finished this way and eliminates oil canning of the skin.

Makes me wonder why the tube frame can't be retooled for the proper arc.
 
I did similar to Darwin

I filled the gap with JB Weld. If I was going to do it again, I'd use the stick type stuff from JB. The stick stuff comes in a concentric roll. You slice some off and knead it and let it harden. When I used the stuff in tubes it had a tendency to sag and run.

Just fill the gap and the holes. If you want to, you can drill and rivet or tap the JB after it's cured. I did see another builder make tapered, curved shims. Great craftsmanship, but could not be a better fit than a paste anyhow.
 
THanks all for the advice. Vans provided the same advice to fill it with an epoxy/micro mixture. Seems like there ought to be a better way, but whatever.

Another question on the fit. The pre-punched skin holes don't line up with the centerline of the round tube (at the rear of the frame). Drilling it as-is won't leave enough edge distance. I don't think bending that tube is the anwer, as I won't be able to get a length-wise offset due to the design. Any others encounter this?

I wonder if I have a terribly mis-shapen canopy frame. ; )

Scott
7A Finishing
 
I think to be fair to Van's, they achieve a huge amount without resorting to any compound curves.

This area is where a lot of angle changing is going on and we have the same gap - we tried a rivet but the buckling was to much so we removed it and will fill later.

I guess this is one of the prices for design simplicity in 2 dimensions !
 
Yeah, the fit sucks. Just leave out the rivets that would cause the skin to deform.

Underneath, I scuffed and cleaned the skin and tube and filled the area with epoxy and micro filler. Looks clean and finished this way and eliminates oil canning of the skin.

Makes me wonder why the tube frame can't be retooled for the proper arc.

RV7Guy (or any others that filled the gap with resin or JBWeld),
Got any pictures to show how you approached this? I've started the forward canopy frame build and the gap is HUGE! Figured I'd walk away and do some research before I tried bending metal in the frame.

For reference: RV-7A, tip-up
 
Last edited:
Here is what I did.
IMG2439-M.jpg


More pictures and dialog on what I did on my website under the Canopy section.
 
I don't understand what went wrong with the 7 with that part. My 6 tilt up has what looks like the same weldment and skin and it was a perfict fit. No gap at all.
 
Three time the same!

Hello

On mine, and on two oter frames of my buddy's airplanes, it is the same, the bow is to low and looks ugly :( :mad:

I do not understand this, instead of doing it right, it ends up, that everyone is calling the support and asking how to fix.

I can understand, that 1-2mm the shape can be of or not correct. But here it looks like, the tube is to short and is going a shorter route. So there is not enough tube to correct this ....

I will fill mine also with epoxy and glas.

Dominik
 
Hello

On mine, and on two oter frames of my buddy's airplanes, it is the same, the bow is to low and looks ugly :( :mad:

I do not understand this, instead of doing it right, it ends up, that everyone is calling the support and asking how to fix.

I can understand, that 1-2mm the shape can be of or not correct. But here it looks like, the tube is to short and is going a shorter route. So there is not enough tube to correct this ....

I will fill mine also with epoxy and glas.

Dominik

If my frame was not lined up to accept the skin, I would cut the tubing about 1.5 inches from the top brace and hand shape it till it fits, then splice it back in at the cut.
 
How crazy must I be to have spent the last half hour looking at this?

I mean, SERIOUSLY Bruce, I normally wake up, walk the dog, make some coffee, and plop down at the 'puter to catch up with VAF every morning. Today, your canopy latch photo series kept me from actually drinking any coffee and now I'm late for work.. So thanks dude! (and good work!) ;-)
 
1000 words...

Here is what I did.
IMG2439-M.jpg


More pictures and dialog on what I did on my website under the Canopy section.

Bruce,
Perfect! OK, that is a huge help. I see that you used a short length of tube radiused on one end to conform to the frame's aft tube. Looks like you filled that tube with the aluminum epoxy putty, and drilled using the skin's hole.

Question: How did you attach this to the frame tube? Did the putty bond to the tube frame strongly enough?
 
Simple process

Hi Col,

First, thanks for your service to our GREAT Country.

Bruce's process will work. I found the process I used very easy to use and looks great, so here ya go!!

1) Scuff everything aggressively, clean throughly.

2) Mix a very thick batch of micro filler and epoxy. About a half pump of the pumps will do for the first run. I used West Systems and 410.

3) Work this mix into the gap. At this point you are just trying to fill the gap under the round bar. Keep it under the bar by working both sides.
We'll make it pretty later.

4) After this first run cures, mix another thick batch and fill to your desired end. Use your finger and denatured alcohol to smooth as desired. If you get this part down, very little sanding is necessary.

5) Touch up fill as needed, sand to finish and paint prep.

If you are comfortable with working with the epoxy mix, you might be able to get it done in one batch and then only have some minor fill as needed.

The process is quick to do and provides a solid fix. And, it looks great!!!

RV7Guy (or any others that filled the gap with resin or JBWeld),
Got any pictures to show how you approached this? I've started the forward canopy frame build and the gap is HUGE! Figured I'd walk away and do some research before I tried bending metal in the frame.

For reference: RV-7A, tip-up
 
The Plan

Hi Col,

First, thanks for your service to our GREAT Country.

Bruce's process will work. I found the process I used very easy to use and looks great, so here ya go!!

1) Scuff everything aggressively, clean throughly.

2) Mix a very thick batch of micro filler and epoxy. About a half pump of the pumps will do for the first run. I used West Systems and 410.

3) Work this mix into the gap. At this point you are just trying to fill the gap under the round bar. Keep it under the bar by working both sides.
We'll make it pretty later.

4) After this first run cures, mix another thick batch and fill to your desired end. Use your finger and denatured alcohol to smooth as desired. If you get this part down, very little sanding is necessary.

5) Touch up fill as needed, sand to finish and paint prep.

If you are comfortable with working with the epoxy mix, you might be able to get it done in one batch and then only have some minor fill as needed.

The process is quick to do and provides a solid fix. And, it looks great!!!

Darwin,
Thanks for the process, and for the kind words. It is a privilege to serve.

OK, I actually like the looks of Bruce's approach, so I'm giving that a try first. If I can't get that right, I'll flex to Darwin's microfill/epoxy route. Thanks to all...gotta love the Van's Air Force. I'll post results when I've got 'em.
 
I took the simple approach. All I did was buy a packet of #6 stainless washers and fit in enough to fill the gap under the countersink in the skin and pull a rivet through it. The #6 works great with the rivet and the countersink.

If you are real industrious you can slightly countersink the top washer so that it fits better with the skin but not necessary. I don't have a specific pic, but you can see in my canopy section below that it turned out fairly well, and takes almost zero additional time.

http://www.704ch.com/search/label/Canopy
 
Gap

I thought of doing spacers but decided I didn't want to look at the gap. I've seen a couple of them like that and it is not attractive.

For me it was a combination of aesthetics and functionality!!


I took the simple approach. All I did was buy a packet of #6 stainless washers and fit in enough to fill the gap under the countersink in the skin and pull a rivet through it. The #6 works great with the rivet and the countersink.


http://www.704ch.com/search/label/Canopy
 
My RV6A fuselage measures 41 and 1/2" outside rail to outside rail just under the tubing in question. If the 7 is wider in this location, I wonder if the fab team for this part are using the same dimensions for the rear tube used on the 6. Using a short piece here would cause it to set lower and not have the same contour as the panel that it will lay in front (pilots view) of.

Are they all like this? Then they need to fix their jigs. Are some like this? Then send yours back and get a good one.
 
steel epoxy

OK, here's my follow-up question:

I can't find the aluminum epoxy putty, but HD carries J-B Weld steelstick, which has steel in the epoxy putty matrix. My gut tells me this'll work fine, there's so little of the steel in there, and it showed VERY little attraction to a strong magnet.

Any problems using J-B Weld steelstick to execute Bruce's approach?
 
BUMP

Just didn't want my question to get lost, 'cause I do look forward to answers.
 
For the Aluminum Putty, search on Devcon Aluminum Putty (F) 10610. A buddy used to work for one of the major airlines, and they used this stuff to repair dents in the wings and elsewhere.

I used it on the Tip-Up canopy skin-to-forward top skin transition. The L and R sides needed some "blending". I found this stuff sets up within about 30 min, and later sanding is quite difficult as this stuff is quite dense. Once sanded, I used a razor blade as a burnishing tool and the result was very smooth and the surface looked like aluminum.

When you find their web site, click on distributors and see if one is near you. I found one in Raleigh.
 
For the Aluminum Putty, search on Devcon Aluminum Putty (F) 10610. A buddy used to work for one of the major airlines, and they used this stuff to repair dents in the wings and elsewhere.

I used it on the Tip-Up canopy skin-to-forward top skin transition. The L and R sides needed some "blending". I found this stuff sets up within about 30 min, and later sanding is quite difficult as this stuff is quite dense. Once sanded, I used a razor blade as a burnishing tool and the result was very smooth and the surface looked like aluminum.

When you find their web site, click on distributors and see if one is near you. I found one in Raleigh.

Noel,
Thanks. A local store carries DEVCON. I'm in business.
 
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