Canopy Frame - Part 1

The canopy frame is hinged on the starboard side as per the prototype Tucano using two factory supplied hinge sets and a monster one piece frame measuring 2.3 x 0.6 meters.

The initial trial fit showed that it lined up with the cockpit profile leaving only one larger question - Where to start?

Overlap

After careful consideration of the plans and aircraft it was decided to fit the hinges as a starting point. 

The lower hinge's were riveted to the longeron previously allowing the frame to be positioned onto the air-frame and taped into it final position. As the frame is fairly flexible two main points used to align and position the canopy frame. The V at the junction of the top longeron's and the overlap  around the baggage compartment.

Canopy frame alignment

Note: The use of the alignment point's on both sides is critical as the canopy frame has to be removed and taped back many time's in the process and this allowed the frame to be re-positioned correctly each time.

With the canopy frame in it assigned position the position on the cutout for the hinge was marked to accept the full hinge plus a margin for adjustment. These were cut out and dressed back to the top side of the canopy frame using a single cut medium bastard file.

Cutout for hinge

The hinges were trial fitted to the frame and two differences were noted - the front hinge was at 90 degrees with the rear at least 100 degrees. with this in mind the hinges were pinned together and the frame fitted and taped into position. This indicated that packers were required to allowing the hinge flange to be fixed to the frame side while maintaining alignment. 

Two spacers were manufactured with the front begin 3 mm thick and the rear 6 mm thick. Next the packers were fitted and clamped and a test swing undertaken which indicated that all appeared to work. 

It was decided to fix the front hinge to the side with the base hard on the underside of the frame - remember the angle this will reveal itself later.

First correction

With the frame in it final position it was noted that to fit the rear hinge flush with the base the frame the flange would have to be corrected. This was undertaken with a lot of heat and  clamps, 3 mm stainless is tough stuff.

Correcting the correction

The corrected angle was fitted with the frame removed and this was were the rub revealed  itself - the frame base is not at 90 degrees more like 100 and the fit was worse, back to the bench to correct the flange back to where it was. 

The gap

Front Hinge Installation
A check pf the front hinge also revealed a massive gap as the original opening was only just to clear the top side of the hinge and once fully dressed to match the rear was the gap revealed.

The solution chosen was to grind an aluminium tapered wedge 5 mm thick x 22 long and fit it with a film of epoxy metal at the mating face and rivet with 4 mm x 12 pop's.

Wedge

Note: Modifying the angle would have lowered the canopy base and the hinge pin just fitted and it was not considered an option.

Front Hinge - Assembled

Rear Hinge Installation
With the angle set and the canopy frame reinstalled and aligned the hinge was fitted to the frame. With the hinge in its correct position the pivot point did not align and a base packer is not a option so again the hinge was removed, heated and bent. This required a number of operations but it was finally positioned to the builder satisfaction then assembled.

Note: The pin was installed at all times to maintain alignment and the final adjustments were to ensure that the pin can be inserted with a minimum of force.

Rear Hinge Assembled
Note offset to align pivot point