Canopy Latch, and Windshield.

Well I am finally finished with the canopy. This is one of the last jobs I needed to complete before I start covering her.  On Saturday I was joined by Jay Swindle, Jay is a local Texan and one of my earliest Blog followers. We worked together all Saturday afternoon completing the canopy latch. Since my last blog update, I installed the Engine Primer pump. There is a small fuel port on the reed valve housing that is designed to accept an external primer. This is convenient because of the closed cowling of the engine. I decide to mount the primer on the L/H inboard longeron. To avoid removing any area in the  longeron I decided to mount the Primer on a 3/4" plywood stand off block, that block in turn was bonded to the the longeron with T-88 adhesive.

Fuel primer

The primer bracket was made from .063" 2024-T3 sheet. I bent this part on  a combination sheet metal shear, roller and brake. I bought this tool years ago when the price of steel was low. I paid one dollar a pound for this 350 lb tool.

Multi- Function brake/shear/roller

This is a view of my combination tool. in my plans drawings there is a line on every flat pattern that signifies the center line of the bend. That center line is directly in the middle of the upper radius plate. I usually measure back from one edge and offset that dimension for the width of the "V" groove. A machine square is used to square it to the face of the "V" groove. The flat patterns also account for the stretch that the part will under go when it is formed. I learned this skill by drawing flat patterns by hand on the 747 section 41 fatigue redesign program. I believe I drew over 5000 patterns. After that many, the process kind of sticks with you.

Primer Bracket and Uni Bit

One more word about the Primer bracket, and that is the process of drilling a large diameter hole in thin sheet metal. The best method I have found so far is the Step drill or Uni Bit. At $38 bucks for one bit, its a bit pricy, but well worth the price. As you can see the hole it drilled was very clean.

Canopy Centering clip

I needed 4 of these, canopy centering clips. when the canopy rotates to the closed position, these clips will center the canopy so the latch pin aligns

L/H canopy latch

Here is what I ended up with for the canopy latch. I had a design already drawn, but it was way too complicated and I didn't feel like building it. I wanted something simpler. Jay and I were brainstorming on this and we decided to take a ride to Midway Airport and see how the Germans did it on their sailplanes. What I ended up with is kind of a hybrid between the Schweitzer 1-26 and the Grob 103. There is a fwd and aft detent plate at the front of the latch handle and an adjustable home made eye bolt as the rear latch.

rear canopy latch detail

I took a 1/4" bolt and then made a lug out of 1/8' 4130 steel. I brazed the two together. I purposely made the rear post adjustable vertically to allow for adjustment to the center line of the latch pin. The latch rod by the way is 3/8 hydraulic truck brake line. I cut off a 5/16" bolt and put a 15 degree taper on the end of it. That was then brazed into the latch tube.

Canopy installed

Then it was on to the next big job, final installation of the canopy windshield. I attached the canopy with 200 Avex Countersunk pop rivets. The outside of the canopy was touch countersunk to accept the head of the rivet. The canopy installed very cleanly. There is a protective plastic covering still on the outside of the canopy. I will keep it that way until just before first flight. 

Another view of the canopy

This shows the reason for the yarmulke, the wind shield is flat wrapped with a single curvature. All compound contour is confined to the yarmulke. It also doubles as a sun shield. I'm pretty pleased at the way this came out