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New COZY Canopy Seal System

Date: November, 2007

For a long time, I've been unhappy with the quality of the canopy sealing system, both for air and water leakage.  I got water dripping on my flying hand during rain, and cold air leaking into the cabin in the winter, causing the heat to be less than adequate.  I'd been thinking about how to fix that, and have looked at about a zillion Long-EZ and COZY canopy seals, trying to find something to copy.  I'd seen inflatable seals, glassed lips, and everything in between.  The one that appealed to me the most was a groove with a very soft foam seal in the groove, so I decided to attempt to implement this.

First, I removed the canopy.  The plans have you create a 1" wide lip over the back of the canopy that, if you cut it closely enough, will make a terrific buzz when contacting the top of the turtleback with the engine running.  I removed approximately 1/4" of glass and foam from the top recess of the turtleback (as shown in these pictures), so that the canopy lip glass wouldn't touch anything, and couldn't buzz.  This would also leave enough space for the foam seal to live in, even after being compressed.  I then glassed this area with 2 BID over micro.

Turtleback front lip lowering and glassing with 2 BID

Turtleback front lip lowering and glassing with 2 BID

The next step involved routing a groove in the canopy, approximately 1/4" in from the outer rim. I routed it about 1/2" deep wherever there was just foam under the glass exterior plies, and about 1/8" - 3/16" deep where there were glass or flox pads (the attach points for stuff).  I left the areas where the hinges were attached alone. This groove was pretty much continuous from the rear canopy lip, all the way around.  I shaped the groove so that the foam seal could eventually wrap easily around from the groove to the rear lip, and from the sides to the front.  I also rounded the front and rear corners of the canopy where they meet the longeron/turtleback and longeron/fuselage top, so that instead of having a sharp corner there, I had about a 1" radius.  This would allow the foam to follow the curve without having to stretch much. I undercut the sides of the groove a bit so that I could install flox corners under the layups to the side of the groove.

I then put a 1/8" layer of flox in the groove, as well as the flox corners, and then 2 BID at 45 degrees. You can see the glassed groove in these pictures.

Glassed Groove - flox and 2 BID

Glassed Groove - flox and 2 BID

Glassed Groove - flox and 2 BID

Glassed Groove - flox and 2 BID

Glassed Groove - flox and 2 BID

I prepared the fuselage top so that I could layup up a 3 BID extension over the longerons, which would then allow for a concave micro radius to match the one on the canopy. I prepared the turtleback/longeron areas for a micro radius as well.

When the groove in the canopy had cured, I filled it to within 1/8" of the top with micro, and after cure routed and sanded the micro to get a uniform groove depth of about 3/16". I also created micro radii at all four corners on the fuselage that would allow space for the foam seal.

Glassed and trimmed Turtleback lip

Fuselage Top prepped for 3 BID glass layup

Other side - Fuselage Top

Protective tape over latch recess area

Groove in hinge area

Micro radius at Turtleback/Longeron intersection

Micro Radius on Fuselage Top/longeron intersection

After everything was cured and shaped, I installed a 3/8" wide, 7/16" tall foam seal on the groove area, and a 3/8" wide, 1/4" tall (but VERY soft) foam seal over the hinge area (since there's very little room in between the hinge halves when the canopy is closed.

Foam seal on canopy front radius area

Foam seal on canopy rear radius/lip area

Canopy front radius area near hinge - two types of foam seal

Middle hinge area - two types of foam seal

The two short test flights I performed after this installation seemed to indicate a complete air seal of the canopy. So far, so good. We'll see how it hold up over time, but it seems to work fine with no degradation of the stiffness of the canopy, nor of the working of anything else.  Next, to seal the nose gear cover and get the air vents to seal a bit better.



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