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Tip-Up canopy latch force

Draker

Well Known Member
How much force should it require to close and latch the tipper? Mine seems to require quite a bit of force, to the point where I am seriously worried about the aft stress I'm putting on the bulkhead behind the seat (where the latching mechanism is attached). You can barely see it, but that bulkhead bows aft a bit when the canopy closes! The long tube that connects the latches on the two sides also bows a bit when the canopy is closed. It is actually normal to have to gorilla-arm that thing closed, or should it easily snug closed?

The latch moves freely until the last 1/4" of canopy travel, where it is compressing a thin strip of weatherstripping I installed along the canopy edge where it contacts the deck. I might try ditching the weatherstripping and see if that helps.

I'm using the JDAir flush latch, but that shouldn't matter because the pushrod mechanism that actuates the latch is the same.
 
I added some weatherstripping this winter and have to pull down on the handle to get it tight enough for the latch to fasten easily at first. Now that it is warming up, it is not as difficult. Maybe the weatherstripping is finding it's shape and compresses better. I do fasten the latch when it is in the hangar and maybe being compressed most of the time helps.
 
Ryan,

The answer is somewhere between “enough” and “not much.”. When closed, the latch tangs should engage with the canopy latch “finger” roller bearings and have enough force to hold them in place. You shouldn’t see deflection along that torque tube during opening/closing.

Reshaping the hump in the tang is probably the easiest fix, or resetting the canopy fingers…
 
How much force should it require to close and latch the tipper? Mine seems to require quite a bit of force, to the point where I am seriously worried about the aft stress I'm putting on the bulkhead behind the seat (where the latching mechanism is attached). You can barely see it, but that bulkhead bows aft a bit when the canopy closes! The long tube that connects the latches on the two sides also bows a bit when the canopy is closed. It is actually normal to have to gorilla-arm that thing closed, or should it easily snug closed?

The latch moves freely until the last 1/4" of canopy travel, where it is compressing a thin strip of weatherstripping I installed along the canopy edge where it contacts the deck. I might try ditching the weatherstripping and see if that helps.

I'm using the JDAir flush latch, but that shouldn't matter because the pushrod mechanism that actuates the latch is the same.

Not needed as long as you canopy skin laps over fuselage skin.

Inside latch should work with almost no effort in order for the outside latch to work.
 
The open/close force could be low.

I removed all the high compression force weather striping. There is a reason that Vans uses the teardrop style.

The latch tube will deform and not latch completely if it force is too high, then the latch is on the wrong side of the slope.

If it is tight you are just waiting for the day temps change and you can not get the latch open. That scared me. Get serious about lowering the force before that happens.

In the solution process, I added some rubber bump stops under the aft ends of the rails and tailored (sanded) them to latch force. The plexiglass, side rails etc all are basically held into a fixed gap, if any. I did not want to allow the plexiglass to carry latch loads and it seemed to rattle if not tight. I use the teardrop under the front, and on side rails aft of the connection to the canopy frame. Forward of the frame-to-rail connection a compressed foam seal is used.

I do still have a leak on the under the left side rail. It is ~.030" too high. ( a warning for builders). I need something to fill that space ( thicker adhesive? suggestions welcome)

BTW - I tested the pressure capability of that tear drop and it can handle dynamic pressures over 250ktas. It is a good seal, and low compression force per foot.
 
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