Chapter 18: Canopy Hinges


(a.k.a, those *@%^&*!! hinges.)

In my humblest opinion, one of the greatest compromises in building this plane is installing the hinges to be functional without being cosmetically challenged.  Leave no doubt about it, because we are installing the hinges in a straight line over a curved distance (longeron and canopy), some parts of the hinges are going to stick out somewhere.  So the compromise is to install the hinges in such a way as to be able to fully open the canopy (functional), but at the same time, minimize the amount of hinge that has to be exposed (cosmetic challenge).   What most builders do is install the hinges as best they can, then hide them as best they can with micro during the contouring and finishing process.  Walk down any EZ flight line and you'll see the good, the bad, and the uglies.  I guess it's just the nature of the geometric beast. 

 

Step 6: Installing Hinges on the Longerons

 

I originally installed my hinges in Chapter 8 (I think it was Chapter 8) just like everyone else.  But by the time I got to Chapter 18, I realized the hinges were positioned too far outboard.  So I reset the hinges using the following procedure.

I started over by putting my strake table top between a few saw horses.  I cut the hinges to length, and using one side of the plywood sheet as the "straight-line" reference, I temporarily secured the hinges in line with one another at the distances shown in the plans.  I then placed the canopy on top of the table and moved it around over the hinges until I got the best compromise between hinges hidden, hinges not hidden.  Warning!  It is real tempting to hide the hinges by placing the hinges completely under the canopy deck.  You can certainly do that, but you won't be able to open the canopy very much because of binding -- the starboard edge of the canopy deck will rotate downward and impact into the top longeron.  So, it's a cosmetic compromise.  Once I settled on a position, I lifted the canopy slightly, mixed a few dabs of 5-minute glue, and temporarily bonded the canopy onto the hinges.  Why 5-minute glue?  It allows you to do the fit-checks without drilling any holes.  If the hinge positions are not correct, it's easy to remove the hinges and start over.  

 

 

After cure, I released the hinges from the table and trial-fitted the canopy/hinges to the fuselage.  When I was satisfied that I got the best cosmetic compromise possible, I again lifted the canopy and put a few dabs of 5-minute glue on the longeron at the hinge locations.  After cure, I pulled the hinge pins, lifted the canopy off the fuselage, drilled the hinges, and installed the screws.

 

How do I feel about these hinges?  I think my buddy Clark Canedy sums it up best in the humorous (as in "to laugh") parody of David Letterman's Top 10 reasons for Cozy canopy hinges.  If I EVER do this again, I'd seriously, seriously, seriously consider going with a forward hinged canopy.  That's how much I despise this canopy hinge approach.

 

Top Ten Things You Say to People to Explain Why the Hinges Look That Way

 

10.  They won't look better because Nat, Vance, Jack, Alex, and Dennis can't solve it.

9.  They stick out that far to add flight stability like a second canard.

8.  They stick out that far to make room for the explosive bolts to jettison the canopy in an emergency.

7.  They give the appearance of another step so people think you can enter the plane from BOTH sides.

6.  You need something in the slip stream in flight that whistles so people think you are jet-powered when you fly by.

5.  It's an engineer's joke.  They laugh at non-engineers trying to install straight hinges on a curved surface.

4.  After carving the perfect nose and deck, the hinge process is there to remind you that you are not that great of a builder.

3.  The hinges look that way so people will constantly ask you, "What are those?"

2.  If your hidden RST marker beacon antenna fails you can always wire directly to the hinges as an alternate.

1.  There is a solution but Nat will consider it an aerobatic upgrade requiring ALL flight maneuvers to be removed from the manual.

 


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