Sliding Canopy - how much plastic aft of rear canopy frame?

IowaRV9Dreamer · #1 05-31-2010, 09:45 AM

I need to do the final trim of my canopy bubble to the canopy frame. The plans show what the dimensions should be between the bubble and frame on the front and sides. I cannot find the dimension on the back.

The closest view I can find of this area is Detail J on DWG 43, but it does not seem to show the plastic bubble.

To be clear, I need to know how far the plastic should overhang the rear round tubes on the canopy frame. Right now it is between 1 and 1.5 inch. I know this will get covered up by the rear skirt.

Thanks for any info!

alpinelakespilot2000 · #2 05-31-2010, 10:31 AM

It really doesn't matter, so long as you have edge distrance. (I think mine extended back ~.75".) The biggest concern is that you remove any "ski-jump" at the rear of the plexi so that the plexi and aft. fuse skin are all on the same "plane." The skirt needs to be able to lay completely flat on both. Hope this helps.

IowaRV9Dreamer · #3 05-31-2010, 10:36 AM

Thanks Steve - I don't think I'll have any edge distance issues (using Sika) so I'll trim it for no ski jump. I think I'll probably end up with 0.5-0.75 inches beyond the aft side of the tube.

Just as soon as it gets hot again for safe canopy work!

Kokemiller · #4 05-31-2010, 11:05 AM

I glued mine as well and had 3/4" overhang. Enough for a good filet of sika. Just make sure there isn't too much that it grabs the skin as it opens.

BJohnson · #5 05-31-2010, 11:06 AM

View G-G section B-2 in the drawing shows 1/2 to 1" aft of the fastener between the aft skirt, plexi, and tube.

Just did this the other day in a 65F shop. Using Vans cutter wheels, the hot plexi hitting my arm was tolerable, but uncomfortable. The trimming creats its own heat. Just support it, or cut off the extra as you go.

I cut mine back close to the 1/2" dimension. Putting the aft skirts on yesterday and today and I think the shorter the overhang the less it can throw off the aft skirt. On areas where the aft bow/plexi was above the line of the line of the upper skin, I sanded a bevel in the plexi not quite up to the fastener line, and polished down to 2000 grit. So far I'm happy with the fit of the skirt in that area, but some massaging of the skirt will still be requried.

IowaRV9Dreamer · #6 05-31-2010, 05:15 PM

Quote:

Originally Posted by BJohnson

View G-G section B-2 in the drawing shows 1/2 to 1" aft of the fastener between the aft skirt, plexi, and tube.

Thanks Brice - I've been staring at this drawing on the wall for so long, I somehow missed it!

I'll split the difference (3/4") for my 1st cut and then see how it looks. I've been looking at all the guys that do fibereglasss rear skirts on the plane and I was thinking I might try that.

Steve · #7 05-31-2010, 05:55 PM

Be sure the top of the center tube is coplanar to the aft bow tube at the weld joint. Grind off some weld bead or add shims as req'd. And you thought you might never get to use that bottle of Vans touch up paint.

IowaRV9Dreamer · #8 05-31-2010, 06:17 PM

Quote:

Originally Posted by Steve

Be sure the top of the center tube is coplanar to the aft bow tube at the weld joint.

Hi Steve - my frame is far from coplanar - in fact I think that one side tube was welded to the center tube quite a bit lower than the other side tube. After my great twist-o-rama, I've got it so that both tubes perfectly follow the shape of the aft fuse. I'm planning on using larger spacers on the right side to make up the difference.

PS - after my great "kink the square tube then reweld" incident, I need to repaint the entire frame anyway. The little tube of touch-up paint aint' gonna do it!

Lars · #9 05-31-2010, 09:26 PM

Dave, having done this twice, my first canopy had the proverbial ski jump. I had to trim the acrylic off just aft of the frame to get rid of it. Would've made a mess of the aft skirt otherwise. Canopy #2 was much flatter- so I left about an inch of overhang, which made it a little easier to get a nice fillet of black slimy stuff.

So the best answer is probably "that depends".

BJohnson · #10 06-01-2010, 12:07 AM

Dave,

I was with you on a fiberglass fairing, until I tried the metal skirts. After two work sessions the skirts fit and are tight on the upper skin and canopy. I have the roll of fiberglass fabric and the gallon+ of west systems to ready to go, but this was much easier with the metal than the wet layup would be (I'm a composites guy by profession). Granted, I have not riveted it yet and it could move during riveting, but so far I'm really happy with it.

I did a few things different from the plans:
> Used three -3 aluminum pull rivets on each side to hold the plexi to the frame while fitting the skirt. When I got to that hole, I drilled them out, and continued on. I might squirt some epoxy in a hole to secure the remnants inside the tube.
> Beveled the aft edge of the plexiglass if a straight edge hit that edge when placed between the canopy aft edge and the upper skin. Beveled enough so that the staghtedge contacted the canopy just aft of the fastener line.
> Trimmed the skirts to the line. Plans suggest cutting them larger. (I was planning on using them for templates for the fg fabric)
> Did not add the 1/16" spacer. By trimming to the line, and the canopy closed, I was able to pull the skin in contact while match drilling the holes. Leaving the skirt long seems like it will just leave a gap after it is trimmed.

Buried in the plans is the most important statement to pull the skirt's lower edge forward when match drilling. This pull rotates the back edge tight against the upper skin. When drilling the final holes to join the aft and side skirts, I grapped a corner of the skirt, extending below the side skirt, with vise grips and pulled hard, while my son drilled the final holes. In the picture you can see the metal triangle bent outwards where I gripped the skirt with a vise grip to pull while drilling.

Either way, give it a try, before reverting back to the fiberglass. You might be suprised.