Slider frame height......

[J-Dub]

Afternoon all,

So I have done some searching and plenty of reading re canopy and frame set up. From all that I have been able to gather, the front height of the slider frame is always set after the plexi is installed. Can someone provide as succinct answer as to why? The plans clearly show a 3/8" height difference between the canopy frame and the roll bar, and if I put a straight edge across the two like the plexi would want to sit in an ideal world, the 3/8" dimension is perfect. So if that's the case, why not trim each leg now to set the desired height?

To the contrary, you are supposed to lay out and drill the aft track but I am going to wait to do that until the canopy is glued to the frame so I can set the height of the aft end more precisely to account for the extra height of the adhesive instead of the rivets. Any issues with that plan?

 

[PaulvS]

Afternoon all,

So I have done some searching and plenty of reading re canopy and frame set up. From all that I have been able to gather, the front height of the slider frame is always set after the plexi is installed. Can someone provide as succinct answer as to why? The plans clearly show a 3/8" height difference between the canopy frame and the roll bar, and if I put a straight edge across the two like the plexi would want to sit in an ideal world, the 3/8" dimension is perfect. So if that's the case, why not trim each leg now to set the desired height?

To the contrary, you are supposed to lay out and drill the aft track but I am going to wait to do that until the canopy is glued to the frame so I can set the height of the aft end more precisely to account for the extra height of the adhesive instead of the rivets. Any issues with that plan?

If the slider is too low at any point where it meets up with the roll bar then it will be more difficult to fit the plexi windscreen to match the plexi on the slider. Even if the height difference is 3/8" at the centre, the profile of the roll bar and the slider bow may or may not be the same all the way around the circumference.

The aft height of the slider is mostly determined by how far forward is the slider when it is closed. There is a tiny amount of up/down adjustment by changing the position of the nuts on the threaded rod that secures the T track as well as the fore/aft position of the track. There is a limit to how far aft the track can be attached because of interference with the baggage bulkhead and tailcone skin. Once the roll bar is drilled in position it very much determines the height of the slider at the rear.

 

[rapid_ascent]

Its a little bit hard to determine from your comments exactly what stage you are at. It does appear you are going to Sika the canopy to the frame. In my experience it is difficult to say exactly how much the glue gap will be. So the windshield and canopy gaps may not be exactly the same. If you are better at Sika than I am then maybe yours will work out perfectly.

The position of the rear track adjusts the height of the rear bow as Paul said, but is also adjust the tilt of the forward bow. You want it positioned such that the front bow is parallel to the roll bar. If you are able to tape it in place and feel confident with that setting then good for you. I decided I would prefer to eliminate one of the variables in this problem.

My canopy is currently glued to the frame and the rear track is riveted in place. The slider is operational, but I still haven't drilled the two from canopy frame bolts. I'll wait until the windshield is glued to the roll bar.

 

[J-Dub]

Its a little bit hard to determine from your comments exactly what stage you are at. It does appear you are going to Sika the canopy to the frame. In my experience it is difficult to say exactly how much the glue gap will be. So the windshield and canopy gaps may not be exactly the same. If you are better at Sika than I am then maybe yours will work out perfectly.

The position of the rear track adjusts the height of the rear bow as Paul said, but is also adjust the tilt of the forward bow. You want it positioned such that the front bow is parallel to the roll bar. If you are able to tape it in place and feel confident with that setting then good for you. I decided I would prefer to eliminate one of the variables in this problem.

My canopy is currently glued to the frame and the rear track is riveted in place. The slider is operational, but I still haven't drilled the two from canopy frame bolts. I'll wait until the windshield is glued to the roll bar.

Thanks for the feedback guys. The roll bar is bolted in and I thought I had the slider all bent up and had it in the basement for about 4 months while I finished the fwd fuse. Now it seems like it needs a little more tweaking, booooo......

I figured it would best to set the rear track after the canopy was glued for the very reason you mentioned, the variation in the thickness of the glue. Then I could get the surface of the canopy flush with the aft skin instead of trying to guestimate the stack up and that would smooth out the rear skirt installation. No pun intended. Thanks for the feedback Paul. I hear what you are saying

 

[wirejock]

I write an article on the subject in Kitplanes. One thing I learned was canopy first. That way the roll bar can be shimmed a tiny bit (yes, I cleared it with Vans) to match the canopy bow. My roll bar wasn't perfect so it took some bending and shims just to get it vertical. That also meant a new brace was required. Ultimately I got it vertical.
The forward legs on the canopy are easily trimmed with a tubing cutter and dremel. It's much easier to get perfect if you wait till the canopy is attached.
The aft adjustment also sets the level of the canopy in relation to the aft deck. Too high or too low will make the trim difficult to transition.
Just my humble opinion.

 

[J-Dub]

I write an article on the subject in Kitplanes. One thing I learned was canopy first. That way the roll bar can be shimmed a tiny bit (yes, I cleared it with Vans) to match the canopy bow. My roll bar wasn't perfect so it took some bending and shims just to get it vertical. That also meant a new brace was required. Ultimately I got it vertical.
The forward legs on the canopy are easily trimmed with a tubing cutter and dremel. It's much easier to get perfect if you wait till the canopy is attached.
The aft adjustment also sets the level of the canopy in relation to the aft deck. Too high or too low will make the trim difficult to transition.
Just my humble opinion.

I have read those Larry, and your blog! Great articles, I will be using them especially for the skirts.

OK then riddle me this!!! I see everyone that sikkas their canopy do it upside down. Why not do it right side up? Serious question. You can screw wooden spacers on the bench at exactly the right width dimension front and rear, put the sikka on the frame and then drop the canopy down on the frame and clamp it to dry. Then the frame will be at exactly the right dimension front and rear when everything hardens up.

 

[wirejock]

I have read those Larry, and your blog! Great articles, I will be using them especially for the skirts.

OK then riddle me this!!! I see everyone that sikkas their canopy do it upside down. Why not do it right side up? Serious question. You can screw wooden spacers on the bench at exactly the right width dimension front and rear, put the sikka on the frame and then drop the canopy down on the frame and clamp it to dry. Then the frame will be at exactly the right dimension front and rear when everything hardens up.

The plan will work. Most do it upside down because it's easier to drop the bow into the plexi. A builder can do it solo. Your method should be fine. Practice it a few times with the helper. It may be tricky to do solo. However, the canopy bow will still flex. It's the tension in the plexi that causes it. Figure 1/2" per side, but best to clamp and measure the deflection. It's different on every one.

 

[J-Dub]

Slow progress but I find myself in a bit of a pickle. I am pretty happy with the frame shape but when I try to slide it open the rear bows touch the aft skin. The obvious solution is to open up the bows but then when closed the lower skirt would be a ways away from the fuselage side skin. I am tempted to leave it and put Chaffe tape on after paint. Anyone have a better idea?

 

[wirejock]

Slow progress but I find myself in a bit of a pickle. I am pretty happy with the frame shape but when I try to slide it open the rear bows touch the aft skin. The obvious solution is to open up the bows but then when closed the lower skirt would be a ways away from the fuselage side skin. I am tempted to leave it and put Chaffe tape on after paint. Anyone have a better idea?

Remember, the canopy will pull the bow inward. It varies, but about 1/4" per side. Clamp the canopy and measure the deflection as insurance. I wouldn't try to get too close to the side skin. A fiberglass skirt will hide "muffin top hips". My Lucy has a lot of "Junk in her trunk" and no one has spotted it yet.

 

[J-Dub]

Remember, the canopy will pull the bow inward. It varies, but about 1/4" per side. Clamp the canopy and measure the deflection as insurance. I wouldn't try to get too close to the side skin. A fiberglass skirt will hide "muffin top hips". My Lucy has a lot of "Junk in her trunk" and no one has spotted it yet.

“Inward”!!!!! I have been under the impression the canopy opened up the frame, not closed it in….. my plan was to do aluminum bottom skirts and a fibreglass rear skirt, but that may change after all this.

 

[rapid_ascent]

It's difficult to tell from your pics, but I think you need to work on the shape of the rear bow. It doesn't seem to be following the shape of the aft top fuselage skin close enough. I had a hard time with this and it took forever to get it right. Others say it dropped right on. I think if you are able to get the upper portion of the bow to follow the skin shape more then It will be able to drop down slightly. You will need to bend the lower portion out more as you already know.

I also can't tell how well the front bow matches the shape of the rollbar.

I used the metal side skirts. They fit very well. I had planned to use the metal aft skirt, but it popped out and left a large gap. I then made a fiberglass one. I still haven't glued it only yet, but the side skirts fit great. I had a friend (DRAKER) help me drill the side skirts it went pretty quickly and I adjusted slightly as needed.

 

[wirejock]

“Inward”!!!!! I have been under the impression the canopy opened up the frame, not closed it in….. my plan was to do aluminum bottom skirts and a fibreglass rear skirt, but that may change after all this.

You're right "outward". Sorry.

 

[fr0gpil0t]

Don't mean to hijack this thread, but it sounds like we are doing a similar task. I thought I had a good fit and taped the canopy on the frame, and I feel the front bow width could be reduced by 3/8. It slides okay, but the front bow is pushing the wheels out in the rails, and would slide smoother if narrower. This must be the 3rd time I've bent the bow in and then a few days later found it is too wide and tight.

I had success when I stood on one side bow and pushed down, but the challenge with this method, while I might have reduced the overall width of the frame, it wasn't; even on each side, and then the bow didn't match the roll bar. I have tried ratchet straps so I am applying pressure evenly to both side , but it always seems to spring back out.

Any other methods - I’m keeping to bend the side of the front bow in 3/8 (3/16 each) without changing the shape of the top of the front bow in the from 10 to 2 region,

Robert

 

[wirejock]

Don't mean to hijack this thread, but it sounds like we are doing a similar task. I thought I had a good fit and taped the canopy on the frame, and I feel the front bow width could be reduced by 3/8. It slides okay, but the front bow is pushing the wheels out in the rails, and would slide smoother if narrower. This must be the 3rd time I've bent the bow in and then a few days later found it is too wide and tight.

I had success when I stood on one side bow and pushed down, but the challenge with this method, while I might have reduced the overall width of the frame, it wasn't; even on each side, and then the bow didn't match the roll bar. I have tried ratchet straps so I am applying pressure evenly to both side , but it always seems to spring back out.

Any other methods - I’m keeping to bend the side of the front bow in 3/8 (3/16 each) without changing the shape of the top of the front bow in the from 10 to 2 region,

Robert

Conduit bender works for localized bending but put a shim in so the bender doesn't make a kink.
I found my 200lbs and my sneakers worked better than any other method. Might as well squeeze it an additional 1/4 each side for the canopy flex.

 

[fr0gpil0t]

On the OP's question, I found trimming to close to 3/8's worked well. But then when you have both parts of the canopy in place, it's much easier to see how good the fit is between the two halves vs measuring 3/8's. I then used a file on the frame legs to adjust it closer to the final fit. I will adjust it again after gluing.

 

[J-Dub]

Don't mean to hijack this thread, but it sounds like we are doing a similar task. I thought I had a good fit and taped the canopy on the frame, and I feel the front bow width could be reduced by 3/8. It slides okay, but the front bow is pushing the wheels out in the rails, and would slide smoother if narrower. This must be the 3rd time I've bent the bow in and then a few days later found it is too wide and tight.

I had success when I stood on one side bow and pushed down, but the challenge with this method, while I might have reduced the overall width of the frame, it wasn't; even on each side, and then the bow didn't match the roll bar. I have tried ratchet straps so I am applying pressure evenly to both side , but it always seems to spring back out.

Any other methods - I’m keeping to bend the side of the front bow in 3/8 (3/16 each) without changing the shape of the top of the front bow in the from 10 to 2 region,

Robert

I tried straps a couple times and in the end kinked it. My issue was side to side as well. Didn’t have a conduit bender either. Made a paper template of the “best” side and the bent the other to match using several blacks of wood in my vice. It’s kind of a poor design built to a price point. If you run your hand around the inside, it comes with a bunch of small kinks already in it, so it doesn’t take a whole lot of force to make one of them bigger. I am “happy” with my shape and will be gluing tomorrow….. my plan is place a piece of dowel the correct width between the front and rear bow while the sika cures hopefully ensuring the correct dimension. Not sure how much will change once the dowel is removed after curing, or if it is more like a composite and locked in……

 

[wirejock]

I tried straps a couple times and in the end kinked it. My issue was side to side as well. Didn’t have a conduit bender either. Made a paper template of the “best” side and the bent the other to match using several blacks of wood in my vice. It’s kind of a poor design built to a price point. If you run your hand around the inside, it comes with a bunch of small kinks already in it, so it doesn’t take a whole lot of force to make one of them bigger. I am “happy” with my shape and will be gluing tomorrow….. my plan is place a piece of dowel the correct width between the front and rear bow while the sika cures hopefully ensuring the correct dimension. Not sure how much will change once the dowel is removed after curing, or if it is more like a composite and locked in……

If I understand you plan to set the fore/aft distance with a dowel. Don't add too much tension. Once it sets, the plexi and Sika is holding that tension. Add expansion and contraction and it may be too much. Just sayin'.
Engineers on here know more.