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Trimming/bending rear part of canopy side skins

FinnFlyer

Well Known Member
Dayton's log makes it look easy.

I guess I have to admit that I'm compound curve challenged.

I've got the right side skin fitting pretty well from front to a bit rear of cockpit.

As the side skins come from Van's there supposedly is a lot of excess to be trimmed on the rear part (past cockpit).

Steve Sampson's look quite wide at the rear.

How do you determine where they should intersect with the fuselage skin as you move aft of the cockpit?
How far back should I bend them (canopy/fuselage skin bend)?
Seems that bending them will result in a transition near the rear end where the skins will not lay flat.

Obviously I'm worried about trimming off too much.

Finn
 
Hi Brian,

I thought I'd found all RV-4 canopy threads. Must have missed yours.

I started on the left skin. Trimmed a bit too much near rear square tube but think I can still manage 1/4" edge distance there.

I think the answer to my question is: keep it simple and don't trim the lower edge of the rear skin.

I'm using the way suggested in the manual to do the bends. A 1/2" wooden dowel in a 1/2" wide channel made by 3/4x1.5 pieces of wood screwed to my work table. Makes for more gradual bends (more forgiving too).

I drew a line on the fuselage along the lower edge (curve) of the side skin. Then every inch I measured up to the canopy/fuselage skin intersection. However, I discovered that in some areas, due to the gentle bend, the bend line should be a bit lower (shorter distance from line on fuselage to bend line).

If the skin moves as I work my way back bending, I'll have to compensate for that.

I bought a stretcher/shrinker set from Harbor Freight (found out later a bit cheaper on Amazon). I made my cowl cheek extensions in alum, and had a hard time making them follow the slight fuselage curve. Definitely worth $130 if work with metal in three dimensions.

I found a solution to holding the canopy to the frame at the rear. Instead of temporarily pop riveting it on there, I drilled an 1/8" hole in each side of the canopy overhangs I luckily have not yet trimmed off. A piece of safety wire pulls the canopy to the frame there.

https://drive.google.com/open?id=1ldLrkk-ol1stVXrptIsR2sLr4A4e4_lz

Finn
 
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Conves to convave

Brian (and you other metal working wizards out there), what is the secret of going from convex to concave as you bend your way back to the rear tip of the canopy?

Shrink the lower edge?

Or even trim away the lower edge where it meets the fuselage skin? Probably not a good idea because best if skin ends up resting flat on the fuselage skin, to allow for a bit of flex due to temperature changes and canopy lifting a bit in flight.

Finn
 
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