Nose hatch latch

With the nose hatch complete, it was time to figure out a latch mechanism. I wanted something easy to open/close (no camlocs or tools required) and something that was "clean" (no wing studs sticking out into the flow).

So I found this push-button release latch from McMaster (part # 2069N18):

Ok great, but how are we going to install this thing?! I needed a bracket that would allow me to bolt the latch mechanism to the nose cross-arm with two bolts. So I made a small bracket out of 1/4" plywood, drilled two holes for t-nuts (location of the bolts was defined by the latch mechanism).

Since the nose slants down a bit, I wanted the latch to be tilted a bit to follow the nose contour. So I made two small wedges (out of extra 1/4" plywood), and used 5-min epoxy to tack the bracket onto the wedges and nose cross-arm.

I then played with the hatch and imagined where the "striker bolt" would be mounted to the inside of the hatch. I figured it would work - so I decided to move forward and glass the mounting bracket in permanently.

Top view... notice how there is a small pocket between the mounting bracket and the nose cross-arm it is being mounted to:

I sanded all surfaces... and filled the pocket shown above with flox. I should note that I inserted cling wrap inside the t-nuts prior so the flox would not get in them.

I then applied a small amount of flox all around the bracket and installed 3 plies BID over the entire thing - overlapping onto the cross-arm about an inch. Then peel plied for a nice transition. Notice the cardboard on the floor to protect any epoxy spills:

After cure, I trimmed everything up and installed the latch with two AN3-5A bolts...

With the latch installed, it was time to figure out a way to install the "striker bolt" onto the inside of the hatch that will lock into the latch mechanism. The latch came with a striker bolt; however, I wanted something that had a longer arm - since it was going to be cantilevered - and I wanted this thing to be BEEFY!  

So I cut a 3" piece of steel rod (3/8" dia):

I then cut a 5" long wood peg (using 1"x1" spruce), and drilled a 2.25" deep hole on one side. This allowed me to insert the 3" rod into it, and have 0.75" sticking out to "strike" into the latch mechanism.

But how can we install this thing onto the inside surface of the hatch so that everything is perfectly aligned?! Ok, see the picture below and let me explain - there is a LOT going on here:

I knew the only way to guarantee that the peg would be installed in the correct location was to prop the peg in place (latched in position), apply flox to it, and then close the hatch onto it. After cure, I could release the latch, and apply BID over it. 

Ok, lets do it! But to guarantee it would cure in the exact position, I needed to install some temporary alignment aids. I used hot glue gun to install "rails" to make sure the 3/8" dia rod was perfectly centered in the latch mechanism: 

I also needed a way to control how far forward/aft the peg would be. You can see from this top view that if the peg is installed too far aft, the striker will hit the mounting bracket. If it's too far forward, the striker will miss the latch completely. So it was important for it to be exactly right.

I measured it 1000 times, and made a mark onto the hatch where the peg needed to go in order for the striker to hit the latch perfectly.

I then held the peg in place, and drilled a small hole through the peg and into the hatch..

This allowed me to stick a toothpick through the peg (on the forward end) and make sure the peg was perfectly aligned (forward and aft) when it came time to bond it with flox:

With the left/right.. and forward/aft taken care of, I now needed something that would gurantee the peg would cure at the perfect "height". If the peg cures too high, the latch won't lock. If it is too low, the hatch won't close down all the way. 

So I tied a piece of string around the striker rod... 

And hung a brick (yes, a 5 lb brick!) to the string. This would make sure to hold the striker as far down as it possibly could while it cures.

You might be thinking this was overkill, but the latch mechanism has an extremely tight tolerance between the place it "clicks" locked and where it bottoms out - so I needed to make sure the striker was going to be all the way down as it cured.

With all the constraints taken care of, it was now time to bond the peg to the hatch! So I sanded all surfaces, painted plain epoxy, and applied flox to the peg...

I then closed the hatch down onto the peg...

...and reached in from the canard opening to press the toothpick into the pre-drilled hole that was in the hatch and press the peg up... notice the brick hanging from the string holding the striker rod down onto the latch... 

I let everything cure and the next day I cut the string and released the latch mechanism. The hatch popped open perfectly!

Notice a small blob of hot glue on the striker rod... I purposely applied it to make sure the striker/peg assembly wouldn't cure too far aft in case the toothpick didn't do its job properly. 

I then opened and closed the hatch multiple times to test it out... it was PERFECT!!! So I removed the hatch from the nose and brought it over to my bench...

I cleaned it up and sanded all mating surfaces getting it ready for glass...

I applied 3 plies BID over the entire peg.. and peel plied for a nice transition...

After cure, I trimmed up the aft face of the peg...

And reinstalled the 3" striker rod...

I then reinstalled the hatch and tested it out again... PERFECT!!

The button release mechanism will be installed on the instrument panel later on. A simple push of a button pops the nose hatch open! Don't worry, it takes a hard push to press the button - so I won't be accidently opening the nose hatch in flight! 

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