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Slider Frame

pmccoy

Well Known Member
All, I have been struggling with the alignment of the slider frame all week. Getting the sides to match the 1/16" clearance to the longeron has been a challenge. Now that I have made progress there, I see the rear bow is also spec'd to match the 1/16" clearance to the upper aft skin. However, where the rear bow is welded at the bottom, it's a full 1/4" in from the outside edge. I can't make the side skin and the top aft skin both be 1/16"?? How did other's handles this area?

 
The plexiglass will change the alignment

When you mount the plexiglass it will pull the frame out at both the front and the back so you have to take that into account when matching the frame to the fuselage. In addition as the frame pulls out it changes shape (at least it did on mine) which messed up the alignment of the forward canopy bow to the roll bar, particularly the height at the center so I would not make final adjustments to the roller height until the end.
I had to tweak mine quite a bit after I had cut and mounted the plexiglass.
In my case the plexi pulled the frame about 3/8 inch.
There are some picture and notes on my blog and Matt Burch has some great stuff on his blog in this area
 
Thanks for the shout-out, Dave... here's a link to my canopy building log entries, and also some notes I wrote up on canopy construction in general:

http://www.rv7blog.com/category/fuselage/canopy/
http://www.rv7blog.com/docs/canopy-notes/

The one thing I wish I'd done a better job of when I was at the same stage you're at, is paying more careful attention to the height difference between the aft bow and the top fuselage skin. In my case, the aft end of the canopy ended up too high, so I had to bridge the gap with a custom fiberglass fairing. But then again, it's hard to comprehend or explain how the fit of the frame affects the end product, until after you've built your first canopy! :eek: Go slow and think ahead, and you'll come out okay.

good luck,
mcb
 
canoopy

I have done quite a few canopies now and have adopted a fiberglass skirt method. It is still very hard for me to clearly explain the process, and I do suffer from creative spelling, but.

the canopy frame must fit well

the canopy frame must slide and key into the plastic blocks perfectly!
The biggest problem is the "dogs" on the canopy frame need to be aligned (bent) so they parallel the centerline of the fuselage.

the downward angle of the "dogs" must be equal to the rear slider angle (the one with the 1/4" all thread that sets the angle.

As the canopy frame dogs key in the the plastic there can be NO sideways pull.

the Plastic blocks need to be drilled with a drill bit that will allow free movement. the dogs are 1/4" with powder coating & paint if you chose. This increased the diameter.

After the canopy has been completely fit it will pull the dogs outboard so you will then need to modify as necessary the entrance on the plastic block so the dog will make proper (I need to be careful about wording here!) well you get the idea.


tips
Don't worry about the canopy latch until EVERY thing is done

Do find a plastic snap bushing that will fit into the hole on top of the canopy frame where the canopy latch goes. You have one of these in your kit somewhere. It will keep you from scratching it during one of the 50-60 times you will need to install & remove

A 4" grinder works great to cut the canopy, you can buy very thin disks for them. there is no waiting for an air compresser

The 4" grinder can also be fitted with a sanding type disk. this makes the first step of polishing edges easier.

Do NOT use scrapers, blades, or any other metal cutting device to de-burr edges USE only sandpaper stuff! canopies are expensive (ask me how I know!) I still cry at night.

for a bad, blurry, not quite the angle that will let you see what you are looking for you can visit my website, I have an rv-9a and a -7a you can look at the canopies.
 
The 1/4 " gap where the rear frame tube is welded to the square horizontal part of the frame is for the plexi to "nest" in. In otherwords, the plexi sits above the square tube, and on top of the round rear tube. I found it harder to pull the lower skirts against the fuselage than the rear skirt. The hardest part is the bottom aft corner of the skirts. My advice would be to fit the square tube to be 1/4 to 3/8" inside the fuselage side, and then expect the plexi to pull it out when mounted.
 
Peter-

In my opinion, Matt Birch has, by far the best website for a step-by-step guide to the slider canopy (links above). I followed his steps and came out with a canopy that I'm really pleased with. It fits so well that it's a little tight opening actually.

BTW, if you're planning on using a metal rear skirt, take heed of the above advice re: making the rear bow fit the rear skin perfectly. The top of the plexi must be in line with the top of the aft skin. If it doesn't fit perfectly, it's going to be really hard to get the rear skirts to fit nicely. I've seen very few metal rear skirts that look nice. I suspect that those who do end up with nice metal skirts had that rear bow perfect. I ended up going fiberglass and have no regrets. Had to learn another new skill though!

Good luck with yours.
 
Last edited:
Canopy

All, I have been struggling with the alignment of the slider frame all week. Getting the sides to match the 1/16" clearance to the longeron has been a challenge. Now that I have made progress there, I see the rear bow is also spec'd to match the 1/16" clearance to the upper aft skin. However, where the rear bow is welded at the bottom, it's a full 1/4" in from the outside edge. I can't make the side skin and the top aft skin both be 1/16"?? How did other's handles this area?

Pete,
I beat the heck out of my slider frame for a week and to no avail. Those square side tubes just will not bend without creasing. Concentrate on the aft bow-width and height. Remember that they can be moved fore and aft also, not just up and down/side to side. Find the best compromise. Spend your time on the metal side and aft skins. You can really work them to shape if you take the time; to correct for some misalignment. Mine came out really nice, I think, with them being very flat against the aft skin when closed. FYI-the side of a wood work bench really works well to twist and curl the aft skins, leave yourself plenty of overlap when cutting them out and trim to fit AFTER they are shaped, drilled to bow. Also don't cut the front roll bar height on the slider until AFTER you have fitted the windshield-ask me how I know. Back on the slider frame-if I had just made some minor aft bow adjustments and concentrated on the skins I would have saved myself two weeks of work that resulted in zero improvements. I think that those instructions were written when the entire slider frame was round tube, and have not been updated since they went to the square sides.
Mike H 9A/8A
 
Slider Fram Gap

Gents...

Thanks for the advice. I have walked away from bending the slider frame two or three times already. It's has been frustrating for me so far.

It seems a bit weird that the plans harp on the 1/16" edge distance, then tell you to bend it back in 1/2" for the canopy spread. I think I will take the advice above, and try to make it as straight and smooth as possible. However, the side rails will be 1/4 to 3/8 off of the edge to allow for the spread.

Thanks.
 
Very timely

Boy, is this thread helpful. I'm at exactly the same point in the build. We spent the better part of a Sunday afternoon struggling with how to bend, what is the right positioning, etc.

We will try again in a couple days, but armed with the information from this thread, I think we have a chance now.

Thanks, everyone.
 
Shim It

"However, where the rear bow is welded at the bottom, it's a full 1/4" in from the outside edge. I can't make the side skin and the top aft skin both be 1/16"?? How did other's handles this area?"



You progressively shim it on top of the frame with three pieces of progressively shorter overlapping .032 aluminum picking up 3 rivet holes building up to.096 at the weld area.
 
Really good advice here ! The RV-9 I am building has just gone to the paintshop - I am still not happy with the fit of the rear skirt - I cannot seem to get it close at the rear aft corners - I might need to tweak the frame a little in a bit on a very hot day and see if that helps!
 
Cut the canopy!

Well, we struggled with the frame for a while. At one point we thought we might have to order a new one. We just couldn't get it to line up. Specifically, the rear bow of the pilot side looked terrible. We decided to give it one more go. We gave it a good twist in the direction we thought it needed one and voila! It sooo much better. Now the pilot side looked better than the passenger side. A few more twists, and it looked very good.

Yesterday, Mother's Day, we made breakfast for the moms in the family then adjourned to the garage. We had already completed some of the initial trimming of the canopy and were ready to drill the latch hole and get ready for the big cut. We were using a pneumatic angle grinder that worked ok, at best. It was hard for the compressor to keep up with it and it lacked adequate torq. I own an Ace hardware store, so we went there and bought a RotoZip. What a difference it makes. We tried a few practice cuts and trimmed a little closer to the frame so we could clamp it to the frame. It was much easier to work with than the angle grinder.

With renewed confidence in our ability to actually cut the plexiglass, we clamped the frame in place and marked the line for "the big cut." Than we removed it, put it back in place and double checked the alignment. It looked good. We put the duct tape on to keep the canopy from flopping around after the cut. Then it was time. I followed the blue line as precisely as I could and in short order, we had a windscreen and canopy bubble.

There is still much work to do to get it attached to the frame and get the skirting right, but the cut wasn't too big a deal. I do recommend having the right tool for making the cut. It made a huge difference.
 
Rotozip and canopy cutting

Can you share a bit more detail about using a Rotozip - what bits you might have used, whether you used a full depth cut or a scoring type cut, and how you supported the bubble when you cut it? I had thought about using this tool but wanted to learn more from your experiences.
 
Bosch

I used the Bosch version of the Roto-Zip tool. I purchased it at Lowes for $99. I used the supplied metal cutting disk on the included 90 degree adapter. Worked great. I used a belt sander and the Avery scraping tool to clean up the edges.

Steve
N345SF
 
RotoZip

It sounds like I used the same model RotoZip as Steve did. It comes with and angle adapter and a metal cutting blade which worked great for cutting the canopy. I didn't make a scoring cut. After we marked the cut line with a Sharpie, I just followed the line and cut all the way through. It really did work well. I practiced making some trim cuts with the RotoZip before the big cut. It helped to get a feel for the tool and boost my confidence.

To support the canopy, we used duct tape from side to side, two strips aft of the cut and two strips forward of the cut. I had two sets of eyes watching me and the canopy as I made the cut.
 
Peter-

BTW, if you're planning on using a metal rear skirt, take heed of the above advice re: making the rear bow fit the rear skin perfectly. The top of the plexi must be in line with the top of the aft skin. If it doesn't fit perfectly, it's going to be really hard to get the rear skirts to fit nicely. I've seen very few metal rear skirts that look nice. I suspect that those who do end up with nice metal skirts had that rear bow perfect. I ended up going fiberglass and have no regrets. Had to learn another new skill though!

Good luck with yours.


Just a thought here. I think my metal skirts came out very well but the fit of my back bows was too low in places ,... meaning "not perfect". It is way better to be low than high in my opinion as the fix was pretty easy. After a rough fit on the metal skirts, I used felt drawer stops to shim up the canopy to the flush fit height required to make the metal skirts fit well. Then I "fitted" them a little more. (Here is where access to an English wheel really helps, see streaks in the aluminum finish)

Now I had pretty nice fitting skirts (second try) but lots of gaps between the skirt and the canopy that were taken up by the felt drawer stops. That would have made the canopy skirt loose or fit funny after riveting. Too fix that, I mised up a mess of West Epoxy and filler and laid it on the canopy just a skosh above the level of the felt stops, covered it with saran wrap, and then clecoed the skirt back down, then shut the canopy. After the epoxy cured, I took the skirt off, removed the saran wrap and had a perfect fit around the bows which makes fitting the skirt much easier.

I had the George Orndoff videos and he had to fit them twice as well. He also mentioned putting a 1/4 inch spacer between the front canopy bow and the roll bar when fitting the skirts. If they are pretty tight with the spacer, they will be really snug when you pull them out.

If I were ever to do it again, I would make the bows close to even or low all the way around, then build up the canopy to a perfect fit and only then start to fit the skirts. This would be perfectly backward from anything I've seen but having done the build up now, I think it would be a lot easier almost foolproof.

Also painted the inside 3 inches on the back of the canopy so that the glass work wouldn't show from the inside which acutally makes it look very finished.





I also wonder if all the "plexiglass pulling the frame out" isn't about the skirts being fitted in tension instead of fit to "fit". It took two large guys and some 2x4s to bend my frame to shape and I just can't see any way the flimsy plexi can "pull" it out of position. Did not happen in my case but I have heard a lot of folks who say it has.

Just a different look at it.

Bill S
7a
 
Rear Bow Adjustment and "Precision Frame Tools"

This is a picture of the fiberglass build referenced in the post above to make a low bow fit well. Be sure to skuff(?) well. The little semi circles were halves of the felt drawer stops that I stacked up as vertical spacers on the initial fit. Just made the glass fill level with them, covered with saran wrap, clecoed down the skirt an shut the canopy. When it came back off the rear of the canopy was a stress free "perfect" match to the rear deck contour. The build up was a 1/4 to 3/8 in places but I just had to give up "adjusting" the frame bows and this solved the problem.



Here are a couple of precision adjustment tools that were helpful in fitting the frame. The big clamps give plenty of leverage and you need it. Be careful with the cargo straps,... when you release them, they are under a LOT of pressure. :eek:





Hope this is useful.

Bill S
7a finishing up the mistakes :eek:

.
 
Bill,

I wish I would have come up with the idea of the cargo straps, that would have made the bending of the rear bow much easier! Good tip, but to late for me.

Regards, Tonny
 
I used a combination of cargo straps and a pick-up cargo bed spreader lock bar. Straps to crank the sides in and the the cargo bar to force them out in the center. Things work but, it's not fun nor easy.

Jekyll
 
Conundrum...

Working on the slider frame for my 7. I've gotten it to fit "fairly" well. Close to the 1/16th gap all around (with exception noted below). My two problems keeping me from going further are:

1) Top of the rear bow is at 1/16th inset from the skin. Bottom of the rear bow is 1/16th inset from the sides of the fuse. Along the bow, however, the gap is greater (both sides). I can't go up without screwing up the top dimensions, and I can't go out without screwing up the side dimensions. Not sure how to deal with this, or if it can be dealt with by doing an FG rear skirt?

2) When I slide the frame back, the point at which the rear bow is welded to the square side bar at the bottom touches the rear skin on both sides. I don't know what to do here, other than welding an extension to the rear center tab where the UMHW block attaches, and place the center track aft a bit to keep the "in place" dimensions stable, which should make the back end "climb" more when sliding back. Reason I think of this is because my center tab is a little short compared to when it was shipped... don't ask:mad:.

Looking for any advice...
 
Third dimemsion

Jase, there are really three directions to go with the bend. You might be able to resolve that by bending the bow back/down which will drop it below skin height maybe as much as 1/2 inch. Then if you squeeze the sides in it should just get closer to the skin but the height alignment will be a little off. What should happen is that the bow gets closer to the skin on the front to rear axis but which means that something else has to give which we hope is the side dimension.

Hopefully, if the bow goes down and the side doesn't go out, it can only go back or up. Up is no good, but back isn't too much of a problem. I do think that it doesn't hurt at all to be low anywhere along the bow as long as you plan to even it up with glass as shown in pictures above.

Not sure this makes sense directionally but getting the bow correctly fitted on the sides will make life a lot easier as there is no way to allow for a bad fit there. You can allow for a slightly low fit at the rear bow by building it up after the fact. Obviously, you can't build it lower ;-)

Hope this helps, bending the canopy frame is like trying to pop a balloon by sqeezing it. Squeeze it at the bottom and it goes out the top.

Bill S
 
I just finished mine up, at least to the point that I'm content with it. Remember, there is some height adjustment in the height of the top rear bow to the top rear skin. Sliding the track foward and back will change that adjustment. The weight of the canopy is going to cause the sides to bow out. I bent my frame to allow for that, 1/2" narrower in the front, and 3/8 in the back. I made bars to spread the canopy frame to equal the distance of what the weight will do, and it barely touches in the back. Next step is to get the Plexi on and see how much the actual change is
 
I've got my canopy frame pretty close to where I want it with it inset 1/16 of and inch around the fusalage skins. If I mount my my roller track rails to corespond with the canopy frame in this position they are 41 1/4 inches apart. The instructions say they should be approximatly 40 13/16 appart between roller track inboard surfaces. This seems like quite a difference when we are talking 1/16 of an inch here and there.

Also with the roller tracks at 41 1/4 inches the aft hole in the track will be going through the longeron and the track itself sticks out past the side of the fusalage a 1/2 inch or so. Should I be worried about this measurment? Any suggestions would be appreciated (I'm building a 7A)

Thanks,

Steve
 
I've got my canopy frame pretty close to where I want it with it inset 1/16 of and inch around the fusalage skins. If I mount my my roller track rails to corespond with the canopy frame in this position they are 41 1/4 inches apart. The instructions say they should be approximatly 40 13/16 appart between roller track inboard surfaces. This seems like quite a difference when we are talking 1/16 of an inch here and there.

Also with the roller tracks at 41 1/4 inches the aft hole in the track will be going through the longeron and the track itself sticks out past the side of the fusalage a 1/2 inch or so. Should I be worried about this measurment? Any suggestions would be appreciated (I'm building a 7A)

Thanks,

Steve

Your problem is not the frame, it's the fuselage. Van's fuselage widths are not well controlled at the roll bar position. My data shows up to 1 inch variation between varioius builder's fuselages.

This means that Van's measurements should not be taken literally, and you should just follow the 1/16" inset requirements.

Vern
 
More observations

...Also with the roller tracks at 41 1/4 inches the aft hole in the track will be going through the longeron and the track itself sticks out past the side of the fusalage a 1/2 inch or so. Should I be worried about this measurment? Any suggestions would be appreciated (I'm building a 7A)

Thanks,

Steve

The position of the aft hole should be the same with respect to the longeron regardless of the measurement between the tracks, since in all cases the track setting is based off of a reference to the side of the fuselage (barring shape or curvature differences, which I suppose could be a factor). Whether going through the longeron is a problem or not, I can't say (but will go check mine now that you mention it). If there is edge distance enough on the track to put the aft hole more inboard, I'd probably do that to leave the longeron untouched. There should be zero load at the aft of the track in flight (rollers at the front when closed), so I'd rather there be weakness there than in the longeron. I'm no engineer and I didn't stay at a Holiday Inn Express last night, so take it for what it's worth and call Van's for the horses mouth version.

The track sticking out past the fuselage (I assume you mean the aft end of the track) can be fixed by scalloping the outside of the track. It's in the plans if you look close.

I know your pain... :(
 
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