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My forward hinged 320/360 canopy, which hinges from the longeron,
would not require the additional bid.  This is because the hinge
pulls on the canopy sides rather than the canopy middle.  I was
once told that the canopy creates about 250 pounds of lift at cruise.
I don't know this for a fact however.  Perhaps someone who forgot
to latch their canopy closed for takeoff could comment.

The forward longeron hinged canopy does require some planning especially
if you have a header tank to work around.  I've got a crude CAD drawing
of the geometry if anybody is interested and can read my DXF files.

The Al alloy that I used was 2024 T3 quite a bit stronger than the
6061 T4 or T6 you mentioned. 6061 would work good though and has better
corrosion resistance.  2024 should be anodized or alodined and painted
unless you get the Alclad grade.

I do know that the mid sides of the canopy will bow out about 1 inch
in relation to the longeron if you don't plan a keeper to prevent this.
The clear view of the ground between the longeron and the canopy
on my fist test flight was a bit distracting.  Most of you will have
a keeper as a part of your canopy seal system so don't have to worry.

Jim
Lancari Network News