Canopy side skirt clearance

[sparkcrafter]

I’m just finishing the installation of the canopy side skirts on my RV-12is in preparation for doing the canopy front fiberglass work. When closed, the tolerances of the side skirt gap seem within tolerances, but when closing the canopy it can shift enough that the forward bottom corner of the aluminum side skirt catches on the fuselage deck. Does this problem go away once the front fiberglass is in place to help solidify the canopy structure or do I need to modify the side skirt clearances now before doing the fiberglass work? Also, is there anything I should be doing to protect the fuselage paint from being rubbed off by the side skirts?

Thanks!

 

[N8DAV8R]

For the first part of your question, I don't recall and interference problem that was resolved by doing the fiberglass work. It's hard to say for sure without taking a look at exactly what you mean but it just doesn't sound right to me. You can push things out a little bit with additional washers on the pivot bolts.

I don't want to say that it's a 'problem area', but the canopy on the -12 is delicate. The structure is subjected to some flex while closing, even when you are being careful to keep things straight. If it's close enough that you have the skirts rubbing on the fuselage sides you are at risk of some interference issues when you are using it like an actual airplane. Based on what you have described here I would encourage you to look for ways to get a little more clearance.

 

[Rrhsch]

With what you are describing, you may get away with just more pivot bolt washers. If the washers don’t work and you have already mounted the canopy skirts to the plexiglass and frame, it is too late to bend and adjust the frame for a proper fit. You well need to install your canopy pivot bolts and washers and make shims for the frame to push the skirts and plexiglass out enough to clear the fuselage with gap specified on Vans plans. It may take several different thickness of shims to achieve the proper gap around the fuselage. The frame should be able to open and close without wanting to rub and naturally rest with equal clearance on both sides. This must be done prior to fiberglass work. The Fiberglass will give rigidity to the canopy frame and not much can be done to change the clearances when the fiberglass is installed and sets.
The skirt clearance disappears with paint. Make sure you have enough of a gap for your needs.

 

[Rv-12David]

The canopy assembly becomes more ridgid when you add the fibreglass faring. The shifting you’re experiencing will be much less. I had a bit of what you speak one but now it’s complete it closes much better with very little side to side flexing.

 

[ravenstar]

I think I'm having a similar problem to the OP at an earlier stage: I'm at the step of "adjusting" the canopy frame so that there's a 1/32" overhang on each side of the fuselage. There's so much flex in the frame that I'm having trouble telling where it naturally wants to sit on the fuselage. I can move it about an inch either way with nothing more than a light touch of a finger, and repeatedly opening and closing it isn't informative. I *think* it most naturally sits flush on the port side and overhangs slightly more on the starboard side, but it's at the whim of how evenly I can push both sides of the frame. It seems like any bending of the square tubing frame as the KAI suggests would require so much force as potentially to make more of a problem than it solves. Should I be obsessed with getting the overlap perfectly even on both sides at this point or will ensuring that it's properly centered when I drill and attach the canopy be sufficient? Other measurements like the front-bow/instrument bay distance are within 1/32", so I really don't want to do anything drastic.

 

[Rv-12David]

I ended up getting my frame in the ball park then moved on. Eventually you’ll have the canopy on with Clecos and you can see where you’re at. I had thought that the fit was off but when all was cleco’d together it fit quite well.

 

[ravenstar]

I ended up getting my frame in the ball park then moved on. Eventually you’ll have the canopy on with Clecos and you can see where you’re at. I had thought that the fit was off but when all was cleco’d together it fit quite well.

Terrific, thank you, and thanks for the photo. I've been debating waiting on the baggage compartment skins until I'm ready to attach the tail cone, but that means waiting for the engine kit which is months away. Looks like you have made good progress without attaching the tail cone. Do you have any advice for following that path? I thought I might cleco the cone in place to position the skins and window so I could drill everything and move forward on the canopy while I await the remaining kit.

 

[Rv-12David]

Ravenstar- That’s exactly the way I went. Cleco on the tailcone. Cleco the baggage compartment skins. Fit and drill the rear window. Build the main canopy and fibreglass faring. Then take it all apart and install the wiring when the avionics kit arrives. Removing the tailcone for the Avionics and fuel pump installation was some of the best advice I’ve received here.
Sounds like you have the right idea.

 

[sparkcrafter]

Do most people stick with the recommended 1/32” gap between the side skirt and the side of the fuselage, or did you end up increasing this distance slightly to avoid potential issues with the skirts rubbing the sides of the fuselage?

Anyone have pictures of this gap looking up from below?

I’m just trying to determine how exact it needs to be along the entire edge and what size of gap to aim for. For example, would a 1/16” gap look bad or cause issues?

For those that used shims, do you have any pictures?

 

[ravenstar]

@Rv-12David, thank you, that'll give me something I can work on while I wait for my engine.

@sparkcrafter, I haven't assembled my canopy yet obviously, but I did cut a 1/32" spacer from scrap to check the overhang of the canopy frame, and found that my frame leaves just a little more than 1/32" (but less than 1/16"). Given how much effort it would be to bend the frame and how unlikely it would be that I bend it evenly, I'm leaving it alone. My thinking is that it's more important that the skirt doesn't bind on the fuselage when closing the canopy, so a little extra gap won't matter. The canopy is sealed by the frame compressing a seal strip against the fuselage, so the small variation in the gap won't affect the seal. I'm sure others who have completed this step will have better advice, but if you haven't already made a spacer there's a piece left over from separating the F-1202D-L/R that's the right thickness. Try holding it under the frame and overlay the skirt and see what you think. 1/32" looks like plenty of clearance to me.