Overview
It was decided to try and obtain a better match between the faring and the wing tip by mounting attachment strips to the side of the rib instead of using the 0.5mm [0.020"] aluminium strips fitted to the elevator stab.
To do this four [4] strips were laser cut in 1.0 mm marine grade aluminum by Laser Wizard using a DXF file provided by the builder.
Installation
The profiles were first folded into a right angle to allow installation, next they were offered up to the end rib and trimmed to fit and then alodined.
Starting at the front a 1.0 mm angle was used as a spacer between the top side of the skin and angle. Supporting the spacer while using a finger to determine the correct location for the angle a hole was drilled and cleco fitted. This operation was repeated for the length of the angle.
When the aft rib was reached the limitation of the arrangement was encountered as this builder managed to hit a number of factory holes or just no metal. To compensate for this a sheet cover was fabricated and riveted to the face of the rib.
While not perfect, it is a solution.
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| Angle strips ready for installation |
One the starboard a couple of the holes were slotted using a 3 mm OD file to adjust the position while the port side went smoother - practice is of some advantage here.
Next the factory tip was offered up to check the fit and once satisfied the location for the fixings was marked from the rivet line using the same techniques used for the rudder / elevator stab.
With the top side fixed using 3/32'' clecos, time to look at the underside. Here there was a distinct gap due to the rib and skin fit. There was a blog on the "Cat in the Hat" , this was for the efforts to align the faring at the top of the rudder fin, here the builder tried to sand the tip into alignment and ended up with that hat from that famous cat.
It was decided this time to add material so the tip was remove and a strip of fiberglass added. This was manufactured using two layers of 8 oz cloth and epoxy. It was placed between two boards covered with packing tape then brick added to the top board. this produces a ultra thin strip of fiberglass tape. This was cut into a strip 25 mm wide and fixed to the inside face of the tip using 5 mm epoxy.
The edge on the tip was chamfered along the fiberglass tape using a Dremel and sanding drum, then Plasti-Bond was applied and allowed to harden.
The tip was offered up again and the profile obtained with multiple sands / refit / sand - get the picture it's called time..!
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| The dark edge is the filler and the text - the instructions of what to do when removed many times |
Once satisfied with the profile the mounting holes were drilled as per the top side.
All holes were drilled 3/16'' and fitted with M3 rivet nuts pressed into the hole to engage the spline. All holes in the fiberglass were enlarged to 4 mm od using a tapered grinding stone fitted to the Dremel motor tool. Finally the tip was refitted and secured with M3 x 12 S/S flanged button head screws.
Next it was noted that the aileron fouled the tip with the solution begin to notch the edge to align with the aileron edge.
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| Foul with aileron |
Comments
It is critical that the skins are in a line not staggered, the lower skin on the underside had to be removed and trimmed to rectify this issue.
The angles worked well BUT if doing again it would be developed over a accurate drawing of the end ribs to ensure ease of assembly and accurate layout.
Overall not hard once you get a good assembly procedure.
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| Always another job |
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