Tuesday 13 October 2015

Canopy Frame - Part 3

The canopy now freely hinged but the port side sill requires pins to fix its final location when closed. Factory supplied aluminium 12 mm pins are installed for this purpose and require the frame to be positioned to achieve it final alignment. 

Pin Installation
The canopy was now taped using the reference line at the port side as mention previously in Part 1. At this point it was decided to add a 1 mm packer under the rear spreader to allow the overlap to close smoothly and allow the location pin to be installed.


Positioning Pin
The underside of the canopy has three [3] holes drilled to position the locating pins. It was decided to enlarge the hole using a step drill to 9/16'' to locate the pin on there taper with the canopy closed and locked in it final position requiring more tape.

When ready the tape on which the pin was resting was marked at 3 places and the canopy opened. With the pin located on the center of the circle the canopy is closed.



Locating pin center
The pin was checked and when satisfied the center was located by using a square from the side of the fuselage to mark the outer edges of the circle the a ruler use to locate the center and this was repeated on the other axis using the circle edge.  

The center was marked with a automatic center punch then enlarged in two steps to suit the M4 rivet nuts supplied. As they cannot be expanded fully due to the thickness of the metal, Loctite 308 Black Max Super Glue was applied liberally to both faces before expansion.

A M4 x 50 screw was installed and cut to 30 mm long for installation. Next the hole for this pin was enlarged to 12 mm OD and finally the pin was installed. 

The canopy was swung and the installation verified. 

This operation was repeated at the front then the center using the same procedure.

Pin Adjustment
On this installation the canopy swings slightly forward off it's correct location, it was decided to pack the pins into three [3] steps. The front one is the highest with the second and third on 3 mm steps.

The canopy is thrown over and rests on the pilots [front] pin. A slight reward pressure and the pins all cascade into location. 

Canopy Frame
The final task was to sand to lower edge of the canopy frame into alignment. With the canopy closed and taped shut a 2 mm strip of metal was used to mark points along the canopy edge using the top side of the longeron as the reference.


Scribing sanding line
The Port edge was flipped over and a steel straight edge was used to create a line of best fit, then with a dab of caution a line was scribed using the Ofla knife into the canopy coating.

A single cut bastard file was now used to file to the line and the whole lot finished with 180 grit aluminium open cut paper on a sanding stick. 

The canopy was closed and a series of 2 mm packer placed under the edge and final adjustments noted and sanded as required.

This operation was repeated on the hinge side but required the canopy to be removed to undertake the work.


It works.........!

Comment
It is hopped that once the canopy proper is installed a lot of the flexibility should disappear , time will tell. Once the canopy is in place the builder will re-visit the engagement with the front pin but is in no doubt that it will be nearly 100% when finished.

The next job is fitting the perspex molding and that will require some solid drinking time to approach ...!

Was this a good way to approach the exercise - hell I don't know but the builder got there and there were no book of rules to say I am wrong - yet.


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