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Sliding canopy side rail distance

joew

Well Known Member
I read the plans and the instructions. I've reviewed the forums for some info and seen some older posts. Although the instructions say I should see a width of 40 13/16 distance between the two side rails, like others before me, I'm seeing the distance of 41 1/4.

My frame sides are about 1/16 inboard from the skins and my canopy frame is higher than my roll bar. So far, so good.

The rails are parallel 41 1/4 front and back. I've only drilled the front screw hole in both rails. The aft screw hole (if I drill it) on the side rail would hit the edge of the longeron. My other screw holes are all fine. Is this a problem? What photos I been able to fine show that the aft screw is not on the longeron.

The aft bow of my canopy frame is hitting the skin. I'm anticipating the canopy would pull that away. Has anyone had the need to trim the skin back?

The plans show the screw no where near the longeron. Considering how the plans weren't very reliable, what have you guys seen. Am I on the right track, or am I screwing it up?

Appreciate any insight
 
I beat this to death with measurements and mathematics. Short answer: mine measures 41.0" inside to inside of the vertical walls of the D shaped canopy rail. The canopy rail mounting flanges are inboard of this measurement.

Long answer. The big variation from builder to builder is the shape of the longerons and the width of the fuselage just aft of the roll bar at the centerline of the canopy frame. This is somewhat controlled by the spar carrythough vertical angles, but it is not as precise as the seatback bulkhead.

First I measured the outside distance from the LH side skin to the RH side skin at the centerline of the canopy frame 3/4" tube. Then I subtracted the width of the canopy side skirts, the canopy thickness, the 3/4" tube and the distance from the centerline of the canopy rail to the inside vertical wall.

Fuselage width 42.8125 (outside side skin to outside side skin)
C660 skirt -0.032
C660 skirt -0.032
Canopy thickness -0.188
Canopy thickness -0.188
Half frame tube -0.375
Half frame tube -0.375
Canopy track -0.306 (centerline of track to inside wall)
Canopy track -0.306 (centerline of track to inside wall)
41.01

The holes at the aft end of the canopy rail mounting flange come nowhere near the longeron on my airplane.
 
Slider measurments

Thanks for the tip. I did the calculations as well.

Outside to outside (behind roll bar): 43"
Rt skin. -.032
Lt skin. -.032
Canopy. -.188
Canopy. -.188
Half frame tube. -.375
Half frame tube. -.375
Canopy track. -.306
Canopy track. -.306


Total: 1.8 inches. Final 41.2

Same as I had measured. Seems wide, especially in the rear. Both tracks overhang about 3/16 on both rear sides, and rear screw hole on the edge of the longeron.

Makes me wonder if I should do more bending
 
Vans response

Spoke with Vans. All measurements are a swag and vary from plane to plane as everyone has said. The fact my aft hole in the slider side rail hits the longeron in no big deal. Was told to build away....so I am.

Just don't want to screw it up
 
Canopy Track Aft Screw

I know that this is an older post but I am now in the process of fitting the canopy frame and locating the position of the slider tracks on my RV-7 quick-build fuselage. My measurements are coming out exactly the same as Joe’s when everything is fit up and in position, that being 41¼” between the roller track inside vertical surfaces.

It appears that I will be calling Van’s tomorrow with the same question as Joe did. On my fuselage this will center the aft screw hole of the right in the edge of the longeron. This means that when I drill down through the canopy deck the longeron will be nicked by half the screw hole diameter; I’m not sure if that was the case with Joe’s. The longeron is sandwiched between a lot of other structure at that point; perhaps that's why it's okay?

Has this been the experience with any other builders lately? If this screw is indeed to be located at the edge of the longeron, how should the spacer under the canopy deck be held in place since the screw would not capture it?
 
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Fresh from Vans. Guess it varies on who you get as this is a different answer.

Moving this screw location forward far enough to clear the longerons would be the best solution. Notching the longerons at this location would be less than ideal.

I have not final drilled the holes yet.
 
Fresh from Vans. Guess it varies on who you get as this is a different answer.

Moving this screw location forward far enough to clear the longerons would be the best solution. Notching the longerons at this location would be less than ideal.

I have not final drilled the holes yet.

Mine is also 41-1/4". No way I'm drilling the aft hole and hitting the longeron. I've already marked the hole location so it misses the longeron. What are you doing with the excess rail that exceeds the side of the deck on the aft end. I've already trimmed per plan, but I'm still 1/4" too narrow on the aft distance (41"). The way I see it, the frame should flex that 1/8" on either side and still slide back. Might bind a tiny bit. I suppose I could spread the rails 1/8" further outboard both sides then move the aft hole forward. Haven't drilled mine either. Thoughts?
 
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Mine is also 41-1/4". No way I'm drilling the aft hole and hitting the longeron. I've already marked the hole location so it misses the longeron. What are you doing with the excess rail that exceeds the side of the deck on the aft end. I've already trimmed per plan, but I'm still 1/4" too narrow on the aft distance (41"). The way I see it, the frame should flex that 1/8" on either side and still slide back. Might bind a tiny bit. I suppose I could spread the rails 1/8" further outboard both sides then move the aft hole forward. Haven't drilled mine either. Thoughts?

Hi wirejock, I'm about at the same stage. Looks like you passed this point a year ago :) Any update how this finally ended up for you and what your final solution was ?

thx
 
Canopy rails

Hi wirejock, I'm about at the same stage. Looks like you passed this point a year ago :) Any update how this finally ended up for you and what your final solution was ?

thx

Feels like 15 years! I kept the 41-1/4. Canopy works just fine. The important dimension is the two rollers need to be centered in the track. To make it even harder, the plexi will flex the bow outboard about 1/2".
 
I assume there's no way you can take into account the flex of the 1/2" while still fitting the tracks. Mine is getting reasonably well (after days of bending) and I ended up at 41" width sharp.

The only thing that worries me is that I do not have the 3/8" distance in relation to the roll bar. I checked the measurements at the front bow in relation to the canopy deck and I'm even higher between the front side bow bottom and the canopy deck. On dwg43 full scale detail E-E the distance is 2" 7/16 according to the plans.
Mine in the front is 2" 1/2. So I'm even higher than the plans indicate. Yet I don't have the 3/8" (I have no shims under the rollbar so sits directly on the canopy deck).

Not sure if this 3/8" is critical on the rollbar and if it won't cause issues later.
The rear now sits at 2" 3/8" which is a bit more than the 1/8" tolerance.
On the rear, my top frame sits perfectly 1/16" below the top skin.

Only thing I can do is lower the front bow by cutting a bit more off from the legs but that would even more reduce the distance from the roll bar. Not really sure what is the best way to go here.

Bending the front bow in increases the height but sets the side bows to far in from the side skins.
 
Pictures

Something is going on here. Please post pictures so we can help you better. Reading just words is getting me confused.
 
Canopy bow dimensions

I assume there's no way you can take into account the flex of the 1/2" while still fitting the tracks. Mine is getting reasonably well (after days of bending) and I ended up at 41" width sharp.

The only thing that worries me is that I do not have the 3/8" distance in relation to the roll bar. I checked the measurements at the front bow in relation to the canopy deck and I'm even higher between the front side bow bottom and the canopy deck. On dwg43 full scale detail E-E the distance is 2" 7/16 according to the plans.
Mine in the front is 2" 1/2. So I'm even higher than the plans indicate. Yet I don't have the 3/8" (I have no shims under the rollbar so sits directly on the canopy deck).

Not sure if this 3/8" is critical on the rollbar and if it won't cause issues later.
The rear now sits at 2" 3/8" which is a bit more than the 1/8" tolerance.
On the rear, my top frame sits perfectly 1/16" below the top skin.

Only thing I can do is lower the front bow by cutting a bit more off from the legs but that would even more reduce the distance from the roll bar. Not really sure what is the best way to go here.

Bending the front bow in increases the height but sets the side bows to far in from the side skins.

Don't sweat the height and don't cut the bow legs yet. Trim those to bring it down after the canopy is done. Before the windshield is attached you can shim it if it needs to be higher or shim the roll bar just a little.
 
Here are some pictures that illustrate my current problem.
I made links to my website for each picture as I wasn't sure how to make them smaller here.

This is the general setup.
At first I put the frame on some woodblocks. this made it easier to see the tilt in the side bows and to determine the width for the rear bow and relative spacing to the top fuselage skin. I managed to get these almost ok. So little or no tilting on one of the blocks. The front bow has the correct spacing 1/16" left and right from the side skin front and back.
http://jursairplanefactory.com/images/vansairforce/20201021_164901.jpg

Then I put the frame on the rollers and on the tracks and positioned the slider bar on the top fuselage.I used a spacer of 1/16 and a ruler to determine the distance from the top skin. As you see in the image below.
http://jursairplanefactory.com/images/vansairforce/20201021_171517.jpg

Now comes the funny part. The side bow is not level at all (front to back). I had already cut off a bit of the front bow legs. In the front I'm very close to the 2" 7/16 what Vans describes in the plans. But in the rear, I'm way lower. Much more than the allowed 1/8". This occurs on both sides (little more on the pilot side)
http://jursairplanefactory.com/images/vansairforce/20201021_185224.jpg

The logical step would be to lower the front bow but there, I'm already below the 3/8" spacing required between the front bow and the roll bar.
http://jursairplanefactory.com/images/vansairforce/20201021_185203.jpg

Looking at it from the front, I can also see the rear bow it a bit too low on the right. No matter how I bent, I can't seem to get the rear line straight. My thaughts are that the frame has been welded a bit off center and this cause the slight bend down.
The next images illustrate the slight bend down on the rear right.
http://jursairplanefactory.com/images/vansairforce/20201021_164914.jpg
http://jursairplanefactory.com/images/vansairforce/20201021_171409.jpg

Bending the right side rear bow up al ittle would be an option but that widens the back again
So my guess is to bend it up sightly and then thighten the curve on the right to regain the width.
I'll tweak that a bit tomorrow.

My biggest concern is the non-level side bow.
I don't see how I can get the rear bow to come higher without being higher than the top fuselage skin. Lowering the front will even more reduce the spacing between rollbar and front bow.
If I would need to make the front shorter, I would have to take of another 9/64 to get the same height as the back and I'm already at 5/16 (20/64) so only 11/64 would remain.
 
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Side bows

You are on the right "track". Sorry.
Yes. Try and get the aft bow a little closer to the shape of the top skin. It will make the skirt easier later If you're molding a fiberglass skirt, it will span quite a bit but it's easier if the canopy is reasonably close to the shape of the top skin.
Honestly, I don't know why the side bow has to be parallel and within a dimension. Mine was way off both sides. The skirt covers it. If it's a bit off, it won't matter. Remember the plexi spreads the bow so you will still have to bend again.

What does matter, a lot, is the side to side dimension of the bow so it clears the aft top deck. You need to clamp the plexi canopy to the bow and measure to be absolutely certain the bow won't hit the top skin.
What does matter, a lot, is the rollers fall in the center of the rails. You need to clamp the canopy to the bow and measure to be absolutely certain they will be in the center of the rail. A bit off may be ok, but if they drag on the inside or outside, it makes it harder to open and close. Now is a good time to look at Supertracks if you plan to install them.
The forward top measurement can be adjusted by cutting the legs, but don't do it now. You can always cut those legs. A tubing cutter will trim the forward legs in very small increments. You actually want it too high so it can be adjusted later.
Same for the plastic blocks. Leave them till the canopy is done. Then you can get the hole perfect and the canopy will lock into position.
 
Plexi flexy

I would not worry about the side bows being parallel to the longeron. This will be set by the front bow height in relation to the roll bar, and the rear bow in relation to the fuse top.

I would first make sure the front and rear bows match the bow curvature and rear curvature as close as possible. than make sure the side bows match the fuselage curvature.

next, decide if you are using sikaflex or rivets/bolts to hold the plexi on.
If using sikaflex, decide if you are using the C759 piece, or just a wide sikaflex bead.

The rear track will have to come forward, or moved backwards to get the rear bow level with the fuselage. I had to drill new bolt holes because I dint take Wirejock's advice, and I pre-drilled these holes.

These are the steps I found very important.
 
John brings up a good point that I had to learn the hard way. It is most important to work on the front and rear bows to match the curvature of the roll bar and aft fuselage respectively. I still don't have mine completed but I spent way too much time worrying about the side bows. The instructions are not really specific enough in this regard. Once I started focusing on this area things at least started going in the right direction.

The other thing I learned during my struggle was that you need to be able to make localized adjustments to the bend to the bows. Don't think that you can push on the side bows and you will get the shape that you need. That just doesn't work.

I went to work on another area for a while.
 
conduit bender

I used two electrical conduit benders to bend my front and rear bows, 3/4 " for the front, 1/2" for the rear. It is important to think about the reactive force and where it will be placed to keep the bends in the right place.
 
It can be challenging to make the frame fit at rear, side and front. Mine was so far off I cut both rear bows and one front bow out bent new ones and welded them in.
 
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