Chapter 18 - Section 15

Install Hinges, Cut Out Frame and Install Drip Rail


I fit the top halves of the canopy hinges to the lower halves with 3 layers of duct tape in between (per plan). Then I laid the canopy back on the fuselage and checked for fit. I had un-even spots along the mating surfaces of my canopy and the longerons. In addition, the top of the TB/canopy did not quite line up. What happened


It took me at least a couple of days of sanding and checking to get the canopy to sit reasonably well. The mating surfaces are still not perfect along the full length of the longeron/canopy. The air gap at various spots is about .08" max. Regardless of what I do, I cannot get rid of the gaps between the top hinge and the canopy contact points. I finally called it quits...


Alignment Pins

Instead of 4 alignment pins per plan (one at each corner), I used eight alignment pins. One at each corner per plan plus two (2) more at each side of the cut line - both sides. The reason for the additional alignment pins was to insure the positioning of the forward and aft canopy deck - after they have been sawed through and separated (later). These extra alignment pins were a life saver. You can see my additional alignment pins 5 pictures below.


Attaching Top Hinges to Canopy

My top hinges do not make perfect contact with the under side of my canopy deck - in fact, I have some pretty good gaps at various spots. To remedy the problem, I slopped a line of flox along the center of the top hinge, then lay the canopy on top of it. Then I slipped in the 8 alignment pins and let it cure.









After the flox cured, I removed the hinge pins and turned the canopy over (with the top hinge sides attached). I made more wet flox and packed all the voids under the hinges and the bottom sides of the canopy deck. Next I filled in all the depressions the plan told us to dig out earlier. Then I carefully laid up 2 plies of BID to keep all the flox and hinges in place. It turned out OK.













Installing Hinge Bolts

Since I have the canopy off the fuselage, I decided to install the hinge bolts at this time (instead of later per plan). I marked all the hole locations and drilled all the way through the hard points. Then I flipped the canopy right side up and opened up the bolt holes (with a counter bore) to fit the nuts - making sure I retained at least .25" fiberglass between the bolt heads and nuts.


The challenge on this step was fitting the nuts into the holes as well as holding it in place while tightening. I overcame this challenge by turning down the outside diameter of the nuts (just a hair) and a wrench socket, using my table-top lathe. I only have to trim down a couple bolts to keep them below the canopy deck surfaces.

It is most rewarding to be able to open and close the canopy with the hinges in place...


Cutting the Canopy Deck

The plans' direction is to cut a 1/8" slot with a hand saw at 45o. I expect this to be a difficult cut and that it may be hard for me to keep a smooth cut along the cut line while maintaining the 45o angle. I decided to mark two cut lines 1/8" apart. I will maintain my cut within the two cut lines. Once cut, I take a sander and bring the edges to the cut lines - thus providing the 1/8" separation per plan. 


I decided to use a jig saw instead of a hand saw at the last minute. If you look closely, you can see my double cut lines. Using a jig saw and maintaining the cut inside the two cut lines was much easier than expected. The cut turned out OK. BTW, I removed the canopy off the fuselage before making the cut - didn't think the jig saw blade would be friendly with the instrument panel or longerons.




Glassing the Cut Line Surfaces

I deviated from the plan sequence a bit here. I delayed glassing the drip rail across the cut line. You'll see later on, I actually skipped the balsa and drip rail part and did the lay-up quite a bit differently. 


On the other hand, I did not like to leave the exposed foam at the cut line for long. I decided to jump ahead and glass both surfaces at the same time. I prepared the flox corners and glassed both surfaces with 1 & 2 ply BID layers respectively per plan. I applied peel-ply and a sheet of plastic wrap in between (as shown in picture). Then I put the canopy back on its hinges (remember I jumped ahead and hung the canopy to its hinges first?) as well as all eight alignment pins. If you look closely, you can see the two alignment pins at both sides of the cut line. I highly recommend these extra alignment pins because they do not allow any 'wiggle room' - thus no chance for any slop in alignment. 




Here's a picture of the cut line after cure and sand down, The seam between the canopy and the instrument cover is tight but has no contact. I can slip a .004" shim along the seam with no obstruction, but I will hit a few tight spots with a .008" shim. It's good enough for me!   


You can see the matching edge (i.e. the forward deck) in the 3 pictures below...







Floxing the Side Hinges to the Forward Deck

I decided to jump ahead (Section 16) and flox the upper hinges onto the bottom side of the forward deck. With the 4 alignment pins in place, I prepped the mating surfaces per plan, spread wet flox onto the hinges and forward deck, taped down and let cure. Once cured, I removed the forward deck, flipped it over and packed all voids underneath the hinges with wet flox and let cure. You can see the side hinges and forward hinge (not to plan)  are already in place in the picture below.


Installing the Drip Rail (Not to Plan)

The plan requires us to build a 1/8" spacer on the underside of the canopy deck in preparation for the drip rail. On the other hand, the plan also suggested making the most room under the canopy deck for future instruments. I decided to skip the 1/8" spacer and used packing tape instead. In addition, I extended the drip rail all the way to the aft edge of the canopy deck. 


I followed the plans direction in securing the forward deck with bondo and stir sticks.







Susann helped me to pick up the entire canopy assembly and lay it down carefully on its back. I was surprised how well the stir sticks held the forward deck in place. On the other hand, I may be using too much bondo (again!) and its going to be hell to pay in removing them later on... - I have yet to get a handle on that bondo stuff...As shown, I laid the drip rail all the way to the canopy edge and peel-plied.









Once cured, I separated the forward deck from the canopy frame and trimmed off the rough edges of the drip rail. As shown, my drip rail extends to the edge of the canopy. The real purpose of this extension is to make the instrument panel cover and the forward deck as a single piece (the plan method is two separate pieces). I will discuss my reasoning in Section 16.


If you may recall, the width of my seam (at the cut line) is not much more than .008" and with a tight gap between my extended 'drip rail' and the canopy frame, there is little room for any moisture to come through - and I haven't put in my seal yet...