Tipup canopy skin fitting

I need to continue the quest to get a nice fit on the tipup canopy skin and have a few problem areas and need to know what you guys have done with these areas. Please offer your thoughts on the best way to deal with these spots:



I took seaming pliers to the front lower corners and bent the edge in toward the fuse on the last 1/4" or so at the bottom. You can see that in the pic. Even with this, there is still an gap and you can see right thru there from the inside.

Brian,

No particular fixes from me - I've been having the catching problem in the center of the TU. I have finally decided that the gap has to be more than one would think - I'm ending up with at least 1/16". Along the sides, I think seeing through that gap is a fact of life until you put some weatherstrip along there - from your photo, the fit looks reasonable to me. I also ended up tweaking the bend just a little by hand to make the canopy fit the fuse. Presuming your plexi is not yet glued in place, this can be done by placing the part upside down on a sandbag and "springing" it a bit. The sandbag keeps it from bending sharply in one place.

cheers,
greg

Make sure the gap is wide enough to handle the paint that you apply if not it will chip out and make a horrible mess. About another 10 thou.

I had to trim the center so it wouldn't catch, and even then once riveted it still caught and dinged the center a little. It still needs a little work prior to final painting. For the outboard leading edges, I ended up shimming the forward skin. Once that was riveted, I found that I could have used a little more shim. You'll probably find that once you think it's fitting great, it's all going to change a little when it gets riveted for the final time.

Just to clarify... The gap that I concider necessary is the gap between the front skin and the canopy skin in the horizontal but the one I am trying to remove is the air scoop effect of the canopy skin in the corners being higher than the front skin.

That and trying to get the sides to fit the fuse correctly from the front corners (too far outboard) to the splice plate with the side rails (too far inboard).

I will continue to bend the side rail splice plate area out to meet the sides of the fuse and several have told me that the front corners will fit better once the skin is riveted to the frame.

Check out Dan Checkoway's site, in the Nov 30,2003 area. There, he describes the problem he was having and the fix, with pictures even.

Sounds like / looks like what you are describing...

Hey Brian,

It seems there's no way around some of these issues no matter how much reading and forethought you do. I spent a ton of time making sure things were right on the money when I drilled my hinges and the result is pretty much exactly like yours. The hinges turned out perfect but I seem to have some downward pressure in the middle of the tip up skin and the front sides along the subpanels have the slight air scoop you speak of. I have not started on the side and rear portion of the frames but see the same problems coming.

I was nervous about riveting the front canopy frame splice plate so I didn't before drilling the hinges. I noticed that it was down slightly in the middle and have corrected that. Not sure why it ends up low in the middle but it definately shouldn't be in my opinion. I've looked at a lot other peoples pictures and many seem low. I'm sure this causes the center to catch on the front skin. Still nervous, I have the splice plate temporarily riveted with 6 or so AN426-AD3's. I'll commit to the 4's when I see how some of this shakes out.

As for the slight air scoops along the outboard sub panels, that is definately caused by the flanges on the subpanels not following the curve. I really noticed that when I left the canopy frame and skin on, and took the front skin off. Shimming seems to be the answer here since one would be hardpressed to follow that amount of curve with a fluted, more than perpendicular flange. I'm sure many just fill it later when doing body work too.

Not sure what one could do differently at this point in the build. Duct tape, tie down straps, etc get the canopy right where it needs to be when you drill it but when you take all that off....

Here you are! Welcome to the club!

One other thing to consider as you are fitting the front of the canopy skin to the forward fuse skin is the affect of the hydralic lifts. You can get your canopy opening and closing with just the right amount of clearance w/o the lifts in place, put the lifts in place, and the clearance will disappear or be reduced. The lifts put a forward pressure on the canopy frame as it comes down and changes the fit slightly. It could ruin your whole day. Don't ask me how I know.

Cheers,

db

I will be installing the jack bolts/brackets like several others to help prevent this problem.

Shim away

Brian,

I too had some issues. Made up some shims and achieved an acceptable fit. Haven't riveted the forward skin on yet but all looks good for now.

I posted my shimming technique some time ago. Search on "shim or shimming" the forward skin and you should find the post.

what's your opinion?

I'm at the same stage as Brian but my problem is slightly different.

Overall, I'm happy with the fit of the tip up and along the line of the skins, the 0.32 spacer gap is constant. I appear to be lucky as there is very little shimming needed. However, where the WD716 meets the fuse, there is a discrepancy. On the port side, there is a gap of 3/16ths (it doesn't sit down) whilst on the opposite side it sits down firmly. If I adjust to make both sides meet the fuse, the 0.32 gap changes to almost 0 along the left side!






My questions are;

1). Would you leave the WD716 as it is in the knowledge that the pressure from the struts will bring it into position?
2). Is a 0.32 spacer gap big enough bearing in mind the paint has to go on?
3). Once I am happy with the set up and am ready to drill the hinges, which is the best way of doing it? I would like to do it with everything in place so that the gap does not change, is it just a matter of getting on your back inside the fuse and working from there? Any suggestions will be appreciated.
4). Should I shim before drilling the hinges?


Martin

I would put the side rails on and then put the required 1/8" spacer under each end of them. That will raise that low side up. Looks like your canopy skin is overlaping the fuse on the right side. If so, it is suppose to sit right on top of the canopy deck even with the side skin.

Martin,

As has been noted before, likely everything will shift around as you continue to put parts together. I agree with Brian that it is probably worth putting the side rails on and clamping them in place on the deck before drilling the hinges.

I drilled the hinges by removing the clecos on one side, lifting the front deck skin, and drilling through the block into the hinge with a 6-inch drill (that would be 15 cm for you....). A longer drill would have been useful. It is also useful to have someone eyeball your drill to make sure you keep it straight during this procedure. I would also suggest either 1) using an unibit to at least start enlarging the hinge hole for the bushing, rather than using a 3/8-inch twist drill (which tends to wallow out the hole) or 2) using a steel template to keep your twist drill from wandering. (You can guess how I came about this knowledge...) If you do the latter (what I did on my second canopy frame), it is a simple matter of drilling a 3/8 hole in a piece of steel (I used 3/16 thick stock). Put the bearing in your steel hole and then use a drill to align the 1/4 hinge hole (that you just drilled) with the hole in the bearing. Use a couple of strong clamps (vise grips work well) to clamp the steel in place on the hinge, remove the drill and bushing, and then enlarge the hole in the hinge using your 3/8 twist drill.

Hope this helps.

greg

Brian and Greg, thanks for the tip on the tip up. Initially I set it up with the rails in place but removed them before I got to the final position, I'll replace them and reset it to see how it comes in.


Martin

I should have went with a slider! Help on the tipup canopy!

This week I have been painting and final riveting the canopy frame together.





I painted the deck above the instrument panel with flat paint.



Installed this edge gripping 3/8 OD bulb seal to the sides of the canopy side rails per Dan Checkoway but I the size and number recommended by him does not work well. He recommended one (mcmaster #1120A712) with a 1/32 grip width with the gripper tit on the same side as the bulb. That did not fit very well so I trashed it and purchased one (mcmaster # 1120A111) with a 1/16 grip width and with the gripper tit on the opposite side of the bulb. This fits like a dream....



But with the seal in place along with the struts and the jam bolts to prevent the canopy from being pushed forward, and without the rear latches in place, I have a gap all along the front side and side rails and the bubble is 1/4" above the roll bar at the back top center. I can push this down with some effort so maybe the seal will relax and once the latches are on, it might pull down in the rear but the front sides really concern me. Their is some major gaps here and the corners are way higher than the front skin!

I have no idea how to fix this because the center of the canopy skin is as low as it can go, the curves of the canopy frame do not match the curves of the front skin and the sides are too high. There is allot of flex in this frame allowing the side fronts to come up.
Keep in mind that before riveting the side skirts were sitting nicely on the longerons/canopy decks and the front sides had a gap of about 1/16". Now everything has gone to pot.





The front corners of the canopy skin stick up at least a 1/8" above the front skin at the 10 & 2 o'clock positions. There is no way that that little seal that goes on the seal support is going to touch the canopy skin at those positions inside. I am thinking that this thing is going to leak air and water like a sieve!

I have heard of people that glass some sort of extentions to the canopy skin/skirts to cover these gaps. Any pics or details out there?

I had a heck of a time getting that skin to fit. I got a hint from Vans one day when I was in their lobby buying parts for something else I was doing and noticed a particular poster on the wall of a 6 or 7 with a tip-up. In the photo I could see that there was a definite crease in the skin down the side that made skin fit the frame perhaps a little better. Taking the hint I went back to the shop and began experimenting with my experimental.

canopy gap

Oh the gap at the bottom of the canopy. That's probably because the sub pannel isn't nailed down to it's final position. A warning I gave in another post covered this but some choose to disregard, OH WELL . So if the struts are installed and there's any movement allowed in the subpanel area that gap is going to happen. I spent about a week trying to figure out what happened on mine and just happened to finally notice a small amount of change in the position of parts between open canopy and closed canopy. That little discovery lead me to a final solution. Not going to be much help with what I did though since I can't quite remember what I did. It only took me three or four days to fix it though.

I have the stop bolts installed that the canopy frame bumps into to prevent the struts from pushing the hole mess forward. These do prevent that issue but they don't do much to prevent the front sides/corners from flexing upward from the hinge points and creating this gap. Matter of fact, I think they make it worse.

I think I will detach the struts, install the rear latch fingers, and cleco on the front top skin, reset the gap at the rear of the side skirts to the aft top skin side wings, then do the glass on the front to ensure that the load is even between the hinges and the jam bolts. Like you say, without the top skin on, the subpanel is worthless and can move at will.

Brian, what gap did you end up with between the canopy skin and the forward skin? And/or did you shim the area between the hinges up in order the eliminate the skin interference?

I'm working on my frame and skin alignment now and have it fairly tight. ~.020" and it definitely hangs up in the center. Unable to open the tip-up with the skin attached.


My sides look good.....for now. But I'm sure that will change as I build on.

Brian,

I have not finalized my gap yet but it will be much wider than 0.020". I will also have a slight roll up in the center and roll down on the sides. I will not finalize the gap until the front subpanel structure is solid by riveting the top skin on the front deck. That is the only way to lock it down 100%. Now I keep a piece of sheet metal under the canopy skin overlapping the front deck to prevent it from catching while I am working in around and on the plane.

By the way, mine looked just like yours until I got further along. It is hard to tell which way this whole mess is going to move on you until you actually finish it up.

Jack Bolts / Laminated Shims

Brian-

I am about 4-6 weeks behind you on the canopy work, and am experiencing exactly the same problems (surprise!) I drilled the goosenecks yesterday with a 12" bit, then enlarged on the drill press and installed the bushings. I then had to trim the center seal support way down to allow the frame to open without the skin on, and when I installed the skin, I can't get it open more than 2-3 degrees. I will install a shim below the front of the canopy skin to allow it to at least open temporarily as suggested.

For the "air scoops" created by the fwd skin being too low, I will use laminated shim stock, McMaster #9574K69. Anybody else ever use this peelable shim stock for this purpose? Seems like it should work well. It's also available in stainless and brass.

Brian, you mentioned jack bolts / brackets a couple of times. I can't find reference to this in the archives. Can you explain this and maybe post a photo?

One other trick I have up my sleeve is that I machined solid Oilite (similar to brass but oil filled) cylindrical plugs which press into the gooseneck holes in place of the bushing, and can be drilled off-center to allow final repositioning and fitting / fine adjustment. I figure I can easily move my holes .035 in any direction if necessary without weld-filling the gooseneck holes (again) - I bought this project from another builder and he had these holes drilled out of position, which is why I made the plugs but even that wasn't enough, requiring the weld repair and re-drill completed yesterday).

Oh, this canopy is going to be so much fun...

Fat canopy frame.

I've been struggling with my canopy frame for some time with all the same problems as most of the posters.
1/ I have just drilled the bubble to the frame, and now the side rails are pulled out about 1/8'' by the plexi. Anybody have a slick way of fixing this?
Now the side rails are riveted to the front part it's a bit big to put in the vise.
2/ Second problem I'm working on is how to dimple shims.
The WD 725 will obviously be machine countersunk. The skin will be dimpled.
What works best for the shims? I have two layers of shim in the middle and both options seem to present problems. If I dimple them I will have three layers of dimples nested together. Does that work?

Should be able to stack as many dimples as (reasonably) necessary.

greg

Here is a post from a while back....

Brantel said:

Here is a pic that someone donated:

Here is step by step directions donated by Bob Collins:

http://home.comcast.net/~rvnewsletter/articles/2008/frame_brace/

This works better than great but I did see a little lifting of the side skirts in the front but I think that will go away once I put the front top skin on perm. Right now these are taking the full load of the struts when closed because the sub panel and the hinge area is flimsy without that top skin.

Click to expand...

Noah said:

Brian, you mentioned jack bolts / brackets a couple of times. I can't find reference to this in the archives. Can you explain this and maybe post a photo?...

Click to expand...

I'm working on the tip up canopy frame. I found fluting the WD716 help me eliminate the air scoop effect. Instructions say to flute the flanges until 90 degrees. Before I started to flute the WD-716, I had both top skin cleco'd, and the canopy hinges drilled and pin.


1) I marked with a sharpie the high area (scoops)

2) Uncleco/remove the C-771 forward top-skin (access pins)

3) Remove the hinge pins

4) Transfer air scoop sharpie marks on C-702 tipup canopy to WD-716 canopy frame to help locate fluting locations.

5) Remove C-702 from C-716

6) start fluting the flange as needed.

7) I start with 1 small flute and cleco everything together to check progress.

I repeated this process 4 times before I got it perfect (sides, top, and clearence between the two top skins). I bet I logged 12 hours getting it right)

As you flute the flanges on the WD-716 (outer flanges), it tightens the radius (which lowers/eliminates the air scoop effect), and pulls the canopy frame sides inward (which eliminates the gap between the WD-716 and the F721A).

I started with:

a) two 1/4" air scoops on top, each side.

b) both sides stuck out an 1/8",

c) Both sides 1/8" above the F-721A

d) Gap between F-771 forward top skins and C-702 tipup foward was/is 1/8".


Hope this helps