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Windscreen - canopy alignment slider

JurgenRoeland

Well Known Member
There's something I'm troubled about on the manual of the sliding canopy for the RV-7.
When ready cutting the windscreen, you are supposed to adjust the height of the front canopy frame for fitting with the windscreen that's now taped in place.

on page 9-12:
the height of the canopy is adjusted at the roller brackets so the windscreen portion of the canopy is even with, or slightly lower than the sliding portion of the canopy.

I don't understand why they say 'slightly lower'. I would have expected slightly higher. I have no experience with fiberglass yet but I was assuming that it would be better for the transition with the fairing that the sliding canopy would be even or slightly lower than the windscreen.

Is this an error in the manual or am I not understanding the process ?
 
the canopy frame is marginally higher than the roll bar / windscreen hoop.

Drawing 43 shows this.

When you finish the screen you attach a strip to overlap / fair in the gap.

Best wishes,
Ian
 
I understood indeed that the WD-640 frame itself of de slider is 3/8inch higher than the roll bar as in detail B on WD43.

But in the manual they are referring to the resulting top surface of the windscreen plexi to slider part plexi when the bubble is on.

I would have expected that here, the windscreen would stand out a little bit higher or equal. (but not less) in order to make the fairing transition easier.
 
In case it is of use Larry Larson answered some questions on the canopy metalwork on here and has published a couple of very useful articles on the slider canopy - sikaflexing and one piece fibreglass skirt - in Kitplanes which are available online.

Cheers
Ian
 
Tips

I know that guy!:D Sorry. Silly sense of humor.
A couple tips may help.
1. The windshield doesn't meet the canopy at a perfectly flat plane like your car hood meets the fender so don't make yourself crazy.
2. The 3/8" shown in the plans is a good starting point. However, if you haven't cut the two forward canopy legs or installed the roll bar brace, don't make them final. Cut the legs to get close to the 3/8" but don't drill for the rollers. Leave the roll bar brace till the canopy is done. If you're lucky, the canopy will be perfect 90 degree match to the roll bar. If not, you can shim the roll bar a degree or so to match then install the roll bar. Be sure to confirm this is allowed by Vans. Mine was twisted a little so it was impossible to get it exactly 90 degrees to the longerons. They let me shim it a little but I never got it perfect. No one can tell.
3. Once the canopy is done and windshield attached, trim the canopy legs for height then install the rollers.
4. The windshield trim is fiberglass. It was cover the joint.
The rest is way too much to post. Feel free to read the articles. Two more parts are pending so you may want a Kitplanes subscription.:D
 
Even with or slightly higher for the slider frame… even with is desired, but practically impossible to achieve, so slightly higher is preferred so that you shim the windscreeen to match the slider canopy. The reason - you will putting a fillet of epoxy on the back edge of the windscreen and won’t be able to see the shims. If you shim the canopy, it will be visible. However, sometimes it’s unvoidable. After spending two months fiddling with the flimsy pretzel-like slider frame I had to choose what part of it I wanted to fit perfectly, because making it fit perfectly everywhere is literally impossible.
 
Even with or slightly higher for the slider frame… even with is desired, but practically impossible to achieve, so slightly higher is preferred so that you shim the windscreeen to match the slider canopy. The reason - you will putting a fillet of epoxy on the back edge of the windscreen and won’t be able to see the shims.

Yes, Scott has it exactly right here. In spots where the windscreen is too low, it's easy to shim outward and nobody but you will ever know, especially if you use a bead of your favorite sealant along the windscreen/rollbar joint.

The slider canopy is frustrating but hopefully it will all be worth it when you can taxi around with your elbow hanging out! :)
 
reference

It is all in the reference in the meaning of "above"

the windscreen comes up at a sloped angle to the canopy. so if the flow of air over the windscreen to the canopy is to be smooth, then the front of the canopy has to be higher than the back edge of the windscreen. this way the fairing the covers the gap between the wind screen and canopy is smooth.

This is why WireJock says to not cut the canopy side frames until the windscreen is on; he suggests one would want to vary the height of the canopy front side to make an even flow from the windscreen to the canopy, once the windscreen is bonded on.

Of course, i did not follow his excellent advice. I'll let you know how it comes it.
 
Even with or slightly higher for the slider frame… even with is desired, but practically impossible to achieve, so slightly higher is preferred so that you shim the windscreen to match the slider canopy. The reason - you will putting a fillet of epoxy on the back edge of the windscreen and won’t be able to see the shims. If you shim the canopy, it will be visible. However, sometimes it’s unvoidable. After spending two months fiddling with the flimsy pretzel-like slider frame I had to choose what part of it I wanted to fit perfectly, because making it fit perfectly everywhere is literally impossible.

that's exactly how I felt. I messed for ages with that frame and in the end thought I had a perfect match. Now that the slider plexi is on, I notice I'm slightly high (bit more than the 1/16) on the back end at the top rear, but short (inwards) on the downward thin bar legs left and right, making it wider would have made the sides stand out too wide for the side skirts. On the passenger side, the plexi is inward about 1/4 inch from the skin of the top fuselage on the 45degree position. I hope I can bridge this gap with a self made rear skirt of epoxy. I gave up on he hope using the aluminum skirt. wirejock's article in kitplanes is a real eye opener. I never worked with epoxy before but it makes me feel confident that it's doable.

In the front I have a good fit on the front bow of the slider but the roll bar is messed up. It had a twist in as delivered like wirejocks' so I also had to shim it. Now with the windscreen on I have the impression I bent it a little too much leading to the need of couple of washers on the side. No big deal I guess but I worry about the gap between the windscreen plexi bottom and the top fuselage skin.

I already have finished drilling the rollers to the frame now and I'm pretty much locked in. Will probably be using a ton of washers to try to level it out between windscreen and slider. I assume you can't use a lot of washers under de sliding frame as the holes are already drilled in the slider and sliderframe and adding washers would create tension.

I thought the fuel tank was fun... but the canopy beats it all...
 
Last edited:
Juergen,
I’ve drilled mine too, mostly out of frustration, and willing to use spacers wherever needed. I wanted the sides to be right as my first choice for a perfect fit, so I can use the aluminum side skirts and was able to achieve that. I have spacers in various locations to make it all come out right and I will come up with a way to camouflage the spacers. I’m really looking forward to getting this step in the process behind me.

5443F6AC-3115-49C5-9456-748F6472E333.jpg

C9C262D4-21E7-40C2-9C41-6E855D08AACD.jpg
 
A couple of the jigs I made to help with canopy frame tweaking:

49B856E7-6E1E-4D08-A0F3-FF82C9915DD0.jpg

48DB732C-9DC1-4CB7-B778-F514319ED4C4.jpg

0FDADA1A-9C86-4B3D-8D2F-464E7FCD6E70.jpg

The round pieces were pulleys from a modified band saw that I inherited. I rebuilt the band saw with new appropriately sized pulleys to bring down the speed to what I wanted. They worked perfectly to help get that frame into a shape that I could live with. From an entry/exit, operational, and appearance standpoint I prefer a sliding canopy, but it is a challenge to build.
 
I also used that kind of bending setup when I adjusted the frame and spend 2 months getting it better. At some point I gave up and went with the best I could get. I drilled the canopy frame in place some time ago so that part is locked in.

I also drilled the rollers now so the height is defined. Due the form of the roll bar, the windscreen sits slightly higher at the top. From the 11 to 1 o clock position, it's even and from the bend on downwards, the canopy frame is wider so I can use washer shims there. Only the top is higher and that's impossible to solve. I'll adjust the fairing there by puttin an extra bed of epoxy to fill the gap.
 
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