Canopy II

8/19/2011

The canopy is now ready for final fitting. As you can guess, it took a while to get there^%$#^%!

One day, I decided to put the canopy on top of the plane to see what it looked like, and before I knew it, I started cutting off all the surplus. I used an angle grinder with a 1/16 metal cutting blade. I then needed some hoop frames for the canopy.

The hoops are 1/2 x 0.035 4130, the wind shield hoop being 3/8 tube, bent over a $4.99 bending jig. A piece did break from it, just like I KNEW it would. So I fashioned something out of steel for it to mount to. From then on, it worked well. I made formers out of 3/4 MDF. Achieving the profile of the rear former was easy - match the turtle deck (or rather, a little under), the front hoop and front wind shield hoop were more of a challenge, since I needed to copy the bubble profile. I ended up shaping a 1/4 steel rod as a former on the outside of the bubble, then subtracting the dia' of the 1/4 rod, canopy and hoop tube, then plotted out on the MDF the profile required.

The canopy hoops were welded in place. The wind shield hoop is bolted on. Now, I was ready for the BIG cut....where I had to separate the front wind shield from the main bubble. Amazingly, it went without a hitch; I started a cut at the bottom of both sides, then finished at the top, ensuring that EVERYWHERE was supported. I now have a front wind shield that's ready for major trimming at the front, and a rear bubble that's just about ready for fine trimming and gluing to the frame. Yes, I am gluing it. After reading up on the RV guys having great success with marine type adhesives, I will be using something called Sikaflex, this one seems to have the longest track record on an RV canopy (700 hours on one RV). So, hopefully all that worry of drilling plexiglass and the nightmare cracks that can follow has been eliminated.... touch wood. The canopy frame and front hoop are ready for powder coating.

Emergency Release Mechanism

Initially, the canopy design did not have a quick release system, one needed to hope that when opening during egress, two joints would fail due to extreme battering of the wind. I was concerned that if the canopy didn't tear off the plane, it would beat the crap out of me. I looked at the Firebolt release system, and decided that was too busy a deal. So, I came up with a cable release approach; with one pull, two safety pins are released, then two primary pins are retracted releasing things. The jettison sequence is:

- pull a pin at right shoulder

-pull a red handle at forward/right of instrument panel

-release the regular locking pins, push on the bubble and duck.

I know there are quicker release systems, but at least I now have a cleaner escape, and won't get battered on the way out.

The red nylon handle was custom made: I ordered a red cat leash off Ebay, you could have your catss name custom embroidered on the leash, purchase options; Color: Red, Pets Name: EMERGENCY RELEASE. :0) I will of course be trimming the leash, radically. I have yet to work out exactly how to connect the handle to the cable....

The cable came from a $4.79 pack of bicycle cables and housings from Walmart. I will use the housings, but will replace the mockup cables with aircraft cable. Terminal cable ends will be crimped nipples and the safety pins silver bearing soldered. There was one final piece to the whole canopy puzzle that I finally found: I wanted some sort of taxi opening position for the canopy. I managed to achieve this with the most simplest of ideas and without adding complexity - utilizing the existing opening mechanism by adding a small bushing extension to one of the locking bolt bushings; retract the main locking pin, lift the canopy an inch or so, insert the pin back into the second bushing. Voila. This gives me a two inch crack at the rear of the canopy...enough for a nice prop blast to find its way in the cockpit.

I am ready to powder coat the fuselage!!!!!! I mean, REALLY ready. I spent all last Saturday plugging every relevant hole I could find, with scrap steel tubes and safety wire. The fuselage should have gone for blasting and coating this week, but the vendor called with an oven problem and were waiting for a part to repair it. We should be good for next week. Fingers crossed.