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Welkin Diary - January 2009

January's first job was sheeting in the nacelles. The undersides were done in 1.5mm balsa and went on reasonably well. Then it was a case of tidying up the fit of the doors and sanding them to a matching profile.

The shot below left shows the door closing wires linked to screw eyes on the opposite side of the nacelle. The loops of sherring elastic just serve to stop the wires from straying too far when the doors are open. As the leg is drawn into the nacelle, it encounters the wires, pulling the doors closed. rotating the screw eyes provides fine adjustment to the tension in the wires. Once the tops of the nacelles were sheeted and the rear blocks added, attention turned to the cowls

The commercial spinners are a bit too pointy so I had to accept that the front of the nacelles wouldn't be exactly to scale. I used this as the excuse to ignore the slight compound curve of the original and just made the cowlings as conical shapes out of 1.5mm balsa. The ply inserts you can see in the picture below left enable the cowl to be fixed by two of the four motor mounting hex bolts.

Next up was the front upper fuselage section which is intended to serve as a removable wing fairing and battery access hatch. A basic framework was built in situ (shown above right). Then the cockpit floors were inserted. As you can see, the rear floor is somewhat higher than the front one in order to clear the wiring and speed controllers. I was a bit worried about how the 1.5mm balsa skins would cope with the changing contours of the fuselage which, like the rear bullet faring, seemed a bit complex. However, as I rolled the sheets into position, it became clear that, complicated though it may look, there are no compound curves and it all went surprisingly well. I was particularly pleased with how the flat top section blended into the sides. This extended flat area is to enable the rear section of the canopy to slide backwards - not a feature that I intend to replicate!

The picture below left shows a number of features of what turns out to be quite a complex hatch cover (you may have to enlarge the picture by clicking on it to see all the details). From the top:

  • Compound curve on front lower section formed from facets of 6mm and 12mm balsa
  • Front locating dowel
  • Front and Rear cockpit floors
  • Alignment posts
  • Underside of flat fuselage top section
  • Steel washer to engage with retention magnet

This last picture shows the magnet let into the rear fuselage to serve as a hatch retainer.

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