Canopy latch

Canopy latches

I remember the first time I read the plans and came across page 18-10; I thought "Holy crap, I know none of this makes sense now, but someday it will!" Well, that "someday" finally came!

I should start out by saying I had to modify a few things due to the fact that my canopy bubble is wider than standard Long-EZ's. This caused my canopy frame to be a narrower and taller rail. That in turn gave me less area to mount my C7 and C8 brackets. More on this later.

Before I could begin, I had to make sure that the top of my longerons were 100% level. Back when I did the bottom of the canopy (link here), I had added flox to the top of the longerons so that the rollover structure would be flush with the longerons. At the time, I didn't spend too much time leveling them since I wanted to move on, but I had no choice now and get this done.

I purchased a rail (typically used for dropped ceilings, these are super cheap at any local hardware store and are the flatest/straightest rails I found at the store!)

Placing it on top of the longerons, I could see a little bit of light shining through...

I put duct tape on the rail so it wouldn't stick to the flox I was about to place it on...

Prepped the surfaces by sanding them, plopped flox on top of the longeron....

And pressed the rail on top of it...

After cure, the rail popped right off, and the longerons were 100% level!

Super happy with the results! 

I repeated this for all longeron surfaces...

No light shining through now!

And everything is perfectly flush with the rollover assembly...

With the longerons level, I now focused on marking where the C1-L and C2-L hooks needed to be installed. I couldn't follow the dimensions stated in the plans since I distributed my hardpoints different than the plans to avoid the attachment points of my rollover structure. 

Since the hard points were already glassed inside my canopy frame, I didn't have too much wiggle room. I marked the hard point edges onto the longerons... and marked the mid-point. The tricky part here is that the latch point (the AN525-10R10 screw) is offset from the pivot point of C1 and C2-L, so I had to measure the offset and marked that as the pivot point. 

Red arrows = limits of the canopy hard point (where the C7 & C8 need to be installed)

Yellow arrow = mid-point of the hard point

Blue arrow = the pivot point of C1 & C2 (location of where I need to drill through the longeron)

I then measured 0.6" from the top of the longeron...

With the three locations marked... measured and checked 100 times... it was time to drill!!!

Rather than use an AN3-13A bolt micro'd from the outside (as the plans indicate to do), I decided to use t-nuts (similar to the way I installed my rollover structure). Here's the process... after drilling the through hole, I used a dremel to clean out the foam and micro...

I milled off foam slightly larger diameter than the t-nut...

I then used an AN3 bolt to tighten the t-nut into the longeron... 

I removed the AN3 bolt, and replaced it with an AN525 screw, 2 large area washers and a 5/16" OD (5/32" long) spacer. 

The idea behind the spacer is to allow me to tighten the screw against the spacer, and still allow the C1 and C2 hooks to pivot freely.

This of course meant I had to open up the #12 hole up to allow the spacer to fit...

Taaaa-daaaaa!!! C1-L installed...

The middle C2-L hook installed....

And the aft C2-L hook installed....

It was now time to make the remaining pieces (C4, C6, C3, etc..)

Since the location of my hooks were different than the plans, I had to measure the lengths for my connecting rods (C6). I needed a way to hold the hooks in place as if though they were latched, so I taped a card to the top... 

This held them in place to allow me to make my measurements...

With measurements in hand, I was able to cut my C6 tubes to length and install the 1/4-20 threads on the ends...

I was about to cut the tube when I remembered that the mark is the pivot point, not the cut mark! So I had to account for the extra length...

I then cut everything up to size and installed C3 on the end. I later realized that the rivet should have been installed 90 degrees with respect to the through hole - but as long as the rivet does not interfere with the C1/C2 hooks, it should be fine!

I then installed the push rods and test them out...

I had to drill through the top left shoulder of the pilot seat to allow the pushrod through...

I then had an "oh crap" moment... I noticed that there wasn't much room between the bottom of the longeron and the pushrod... and would actually touch when the latch was in the open position - not allowing for maximum "open" travel... what happened?! Why?! 

After searching through notes, banging my head on my desk a few times... I finally realized what was going on! I remembered that back in Chapter 5 when I installed my stiffener, I had installed a 0.5" high stiffener instead of 0.4" (also ran into this very same issue back when I did the fuselage cutouts!). That with the addition of a bit of flox that I added to level the top of the longerons with my rollover assembly meant that there was more "meat" on my longerons. Since I had kept the C1 and C2 hooks per plans, there was less clearance for them to move!

 

I knew what had to be done - redo C1 and C2 with more clearance!! And here it is... I simply copied the "hook" part, and extended the bottom (where it attaches to the pushrod).

With C1 and C2 pivoting perfectly, it was now time to focus on C7 and C8... (by now, you would think that I would be smart enough to not make all three without testing one out first...)

The problem I ran into is that if I use 0.45" wide extrusion (as indicated in the plans), I would drill into my canopy bubble (since my canopy bubble is wider than standard Long-EZ's). So I came up with a workaround... rather than use 0.45", I went with a much wider lip...

This way, I have plenty of room to bolt C7 and C8 brackets on. (the top of the bracket will rest on the longeron when the canopy is closed).

I used hot glue gun to temporarily bond them on and test it out before drilling anything...

 

Good thing I did... because something wasn't sitting right. I noticed that the hook wasn't "hooking" into C7 and C8 properly. After much head-scratching, I noticed it was because the hooks I made were just a hair oversized, and the 0.6" dimension in the plans didn't allow enough clearance. So rather than shave off some of the hook (and potentially weaken it), I decided to remake C7 and C8 (yep, for a second time now) with 0.65" clearance. This worked like a charm!

Here I am testing the new C7 and C8 brackets... worked great!

With everything working right, it was time to bond them on permanently. I predrilled them with pilot holes (to make it easier to drill through the canopy frame later)...

I put tape on the outside to prevent flox from passing through and bonding itself to the longeron side...

I then taped each bracket in position, with C1 and C2 latched in...

I also taped off all around the brackets to keep flox from spilling down to the longeron..

And masked off the hooks, pushrods, etc... didn't want ANY flox on them!

I then prepped the mating surfaces by sanding them and cleaning them...

It was time to mix epoxy! I started by painting all the mating surfaced with plain epoxy...

Canopy side too...

I then put flox on top of the brackets...

And very gently closed the canopy down...

Making sure everything was sitting right... 

The next day, I reached in from F28 bulkhead and with a little jiggle popped the canopy open... the only thing that was keeping the canopy closed was the tape that was protecting the longerons from flox...

I cleaned all the tape off and very carefully tested the canopy latches...

With everything working great, it was time to drill through the canopy hardpoints!

Made it through the other side!

Since I was using wider extrusions for my C7 and C8, I did not like the idea of tapping into it and screwing them on from the top. Instead, I decided to countersink from the bottom and install them with a washer and nut (similar to the way the canopy hinges are installed on the other side). So I took my countersink tool and went to town...

I placed duct tape on the canopy to prevent dust and debris from scratching it...

Using a dremel I milled away some of the hardpoint to make room for the washer and nut...

Taaaa-daaaa! Brackets installed!! I ended up using MS24694-S64 (for C7) and -70 for C8... 

The rest of the gap between the canopy and longeron will get filled during finishing. This will also allow me to install a proper rain/weather seal.

With the latches complete, I focused my attention to the lock plate (C9). Since my canopy has rounded corners, I had to place my C1 handle further aft than per plans. This meant I couldn't build a standard C9 bracket since it would sit too far away from the instrument panel. I had to come up with a workaround. My solution was to use an off the shelf draw latch that would hold the C1 handle in its locked position. Let me show you...

The draw latch was purchased from McMaster - draw latch. 

I had to make a plate so that I could adjust the draw latch forward/aft to provide the right amount of tension on the C1 handle.

Here's the rough trim...

I then cut a slit using the multitool...

Slowly and patiently, I then used a metal file to open up the slit...

And a little bit more...

Taaaaaa-daaaaa!!!! Plate complete!

I used NAS1097AD5-4 rivets to attach the draw latch to the plate...

This gave a flush back which will allow me to slide the latch forward and aft...

But how will I mount the plate to the fuselage wall? Excellent question! 

The draw latch needed to be 1" offset from the fuselage wall (for it to be flush with the C1 handle). So I made a nutplate using 1/4" birch plywood... and a 0.75" thick standoff. I installed t-nuts to the nutplate... and drilled out room for the bolts to go through the standoff...

Time to glass the standoff in place! But first, I made sure to put cling wrap into the t-nuts to keep epoxy from getting inside. Also, notice the small hole I made near the center... I'll explain later...

I marked where the standoff needed to be installed and removed the C1 handle (so that I wouldn't get epoxy all over it while glass the standoff in place)... I then used 5-min to tack the standoff into position...

I then painted all mating surfaces with plain epoxy and floxed the nutplate over the standoff.. using a toothpick through the hole I made earlier to keep it from sliding off. I then glassed 2 plies of BID at 45 over everything and peel plied the edges for a nice transition... 

The next day, I cleaned everything up... I opened up the t-nut threads and removed the cling wrap. 

I then temporarily install the draw latch and marked where to install the latch clip onto C1 handle...

With everything installed, it was the moment of truth!!!! Here I am lowering the canopy...

C1 is pushed forward as the canopy closes, latching onto the C7 and C8 brackets... 

The draw latch is then placed over the clip on the C1 handle and locked until it clicks...

The draw latch has a safety clip to keep it from opening on its own...

And there you have it!!! The canopy latch is FINALLY complete!!!!