Jeff R

Jeff R

Well Known Member
I started working on the canopy for my slider. The roll bar is supposed to be stretched or compressed so that the ends are 7/32" from the outside edge of the F-721 aft canopy deck. For stretching, the instructions say "It can be adjusted quite easily by hooking one end behind something and pulling....Go slooowly. It is easy to do too much."

Well, mine was off about a quarter inch, and I pulled and hooked and pulled some more and it didn't budge a bit. I got out my truck's jack and stretched out that baby, reach a full inch of deflection, and it snapped right back and is still 5/32" off. This is not be "easy" at all.

Any ideas?
 
I had the opposite problem and had to bend mine in about 3/16". I used a ratchet strap to bend it progressively inward and then released it until it maintained the right width. Based on the marks I made on my bench as I did it, it took 5" of bending to get the 3/16" of permanent deflection.

See my April 6th entry: http://www.mikesrv9a.com/canopy.html

Not quite so easy as Van's suggested.
 
Before adjusting the roll bar width, call Gus at Van's. I've convinced him that poor slider canopy fits are the result of the fuselage width not being correct at the roll bar position.

He thinks that some large pipe clamps could be used to adjust the fuse width at this point (if too wide).

If you think about it, this point in the fuselage has nothing to key in the width during assembly. Van's provides measurements in the instructions for the canopy frame width that were way off on my kit. I've seen up to 1" variation in this width between a/c.

One way to check is to lay your canopy tracks down the longerons and see if they can be made parallel without cutting a large angle (fishmouth) at the aftmost position.

You can see the large fishmouth in the track in this photo:

117_1740_1.jpg
 
Thanks guys. I did call Van's and spoke to Bruce, who built a tip up and wasn't real sure. I mentioned Vern's post so he put me on hold to confer with Gus, and he reported that Gus said it was fine to to put a big clamp on the fuselage sides and bring it in to conform to the roll bar.

I do have a wide clamp, so that is what I will try.
 
I widenned the fuselage about 3/16" to match the roll bar using a 2X4 (rather than trying to bend the roll bar to match the fuselage) on my slider RV-7. I don't have the canopy done yet, but I got the canopy frame to match the fuse within Van's specs without too much adjustment. We'll see how it turns out in the next few weeks.
 
Adjusting the fuselage width

Jeff R said:
Thanks guys. I did call Van's and spoke to Bruce, who built a tip up and wasn't real sure. I mentioned Vern's post so he put me on hold to confer with Gus, and he reported that Gus said it was fine to to put a big clamp on the fuselage sides and bring it in to conform to the roll bar.

I do have a wide clamp, so that is what I will try.
Click to expand...

I'm just wondering how this all turned out. I'm getting ready to install my roll bar. At first it looked as though I wouldn't need to adjust anything but upon further examination, the roll bar looks to be about 3/16" too narrow. I have a couple of long clamps so I am able to squeeze the fuselage if need be. Does anybody have any tips on how to do this? I'm thinkiing of distributing the load on the outside of the fuselage by clamping on a couple of 2X4s.

Thanks.
 
Now that I have started on the canopy frame, I understand better what Vern, above, was saying. Thus, I recommend that before you do anything to the roll bar, skip ahead and do the preliminary work on the slider roller tracks and put the canopy frame in place and try to work out the fit as a system. As Vern says, the fuselage width at this point is not tightly controlled, and it would be a shame to spend hours getting the roll bar to meet some arbitrary dimension only to then have to do more work when you go to fit the canopy frame.

As I think about this more, you might want to fit the roll bar against the canopy frame and see how they line up and work them both to match widths and to match the particular width of your fuse.
 
Did you remove the shipping brace ??

Jeff, might be too easy but the QB fuse comes shipped with a heavy U shaped brace across the fuse to stablize the "box" while in shipping. Without all of the panel pieces installed, the fuse can be spread a little bit but I think if you cleco the brace back in place, it pulls it together.

Another "in place" holder is the panel substructure. One thing to keep in mind is that if you squeeze the fuse, you could be throwing the panel structure out of wack at the same time. I would suggest that you have all of the panel substructure and the panel blank clecoed in place before you decide that you need to squeeze the fuse. IF they don't fit, you might have a problem, if they do, you probably don't want to squeeze the fuse.

One indicator that the fuse "might" be out of line is to measure the distance between the inside canopy deck at the rear of the canopy rail compared to the front. They should be parallel or very close. ( 1/16 +/-)

Just measured my installed roll bar from inside to inside and it is 39 11/16. It overlaps the canopy deck by about 1/16 on each inside edge. The inside edge of the canopy deck just behind where the roll bar bolts down is 39 13/16 inside to inside. At the same spot, the fuse outside to outside dimension is 42 7/8. This is about 1 inch behind the roll bar and on a 7 not a 9 but they should be the same I think.

What if everything is good but the roll bar is still too narrow? Then let's see how much matters and where. I think the 7/32 spacing (outside edge of the roll bar to outside fuse edge) to the outside for the fuse is critical because of the clearance needed for the windshield so that the sides don't buldge after you glass it in. BUT I don't think that is as critical on the inside dimension as the outside. Meaning, if it is less than 7/32, ( say 3/16) you will have a hard time making a smooth transition on the windshield (it will stick out on the sides). If it is more than 7/32, say 1/4 inch on each side, the windshield sides will just recess more and be almost flush with the outside edge of the fuse. ( Not positive but I think that's the way it would work). I don't think that throws anything else out of wack!

So what I am hearing Jeff say is that his roll bar is too narrow which is much better than too wide. The important thing is that the fuse is the correct dimension so that the panel structure fits well AND that the inside canopy deck edges are parallel front to back so the canopy slide rails will mount properly.

I agree 100% with Vern that whatever you do, cleco everything in place first because all of the dimensions are related. Try not to force anything until you just have to and then as little as possible. If you do "adjust" anything much, try to anticipate where it will catch up with you. Sometimes it matters and sometimes it doesn't.

Hope this helps!
Bill S
 
Not quite true!

BillSchlatterer said:
What if everything is good but the roll bar is still too narrow? Then let's see how much matters and where. I think the 7/32 spacing (outside edge of the roll bar to outside fuse edge) to the outside for the fuse is critical because of the clearance needed for the windshield so that the sides don't buldge after you glass it in. BUT I don't think that is as critical on the inside dimension as the outside. Meaning, if it is less than 7/32, ( say 3/16) you will have a hard time making a smooth transition on the windshield (it will stick out on the sides). If it is more than 7/32, say 1/4 inch on each side, the windshield sides will just recess more and be almost flush with the outside edge of the fuse. ( Not positive but I think that's the way it would work). I don't think that throws anything else out of wack!

Bill S
Click to expand...

BUT BUT BUT ,.... Sorry,...it's not quite true that the roll bar determines the windshield fit on the side. Obvioulsy the front deck panel cover goes around the roll bar on the sides and between the roll bar and the windshield.

This means that if the roll bar is set to close to the sides of the fuse (less than 7/32) it becomes very difficult to pull it (front deck cover) into place. The windshield sides lay up against the front deck cover which tends to make the sides bulge a little. If the roll bar is a little narrow, the front deck cover fits better and is more contured which lets the front deck cover and the windshield fit better.

Sorry to make that so confusing. It is all a bunch of spagetti!

Bill S
7a
 
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