Monday, 12 October 2015

Glass Slipper (3)

Come a long way since the last post:

 I completed planking the upper half of the shell and in the main I am very happy with it..

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Lots of pins

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Now that the rear planks have been trimmed, it looks somewhat better than the photo from a couple of days ago. Sanding at the stage involved just removing the 'edges' - it will be sanded down more thoroughly before it gets covered

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And the front former (behind the canopy) after it has been trimmed and rough sanded. A little ragged on the LHS (of the pic) but acceptable

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Now I can get it off the jig I can examine the inner surface. I am pleased with that - generally quite tidy. I took the fus (on the jig) down to our club night on Tuesday night (at the pub!). I was asked how I do the edge joins. I have done quite a bit of planking in the past. Obviously, when working around a curve, you need to bevel the edges to the planks to fit against each other. I think that the mistake is try and bevel both edges. Use a stripper to cut parallel strips - on this the main planks are 1/4 x 1/8 - cut with a stripper. I then place the plank vertical and trim a bevel using a razor plane. All done by eye - after a while it gets easy to judge the correct angle to hold the plane. The other side is left square. If you try and bevel both edges, you will simply end up chasing yourself round in circles. I have also stopped trying to cut tapered planks for the same reason. Just taper the edges where you need to fit them. It all gets covered up in the end so no-one will notice

This morning - after another bad nights sleeps and hence early start in the workshop, I removed the fuselage from the jig. Now in hindsight, it would have been much more sensible to have done the bottom first - there is more of it, however, by removing the middle jig supports, I have got it in the jig, cut the lower slot for the lower backbone and fitted it - this one is laminated from 2 off 1/8 sq spruce

Now being left to dry..
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Planking has started on the lower fuselage, its quite tricky around the bend by the fin post but apart from that is mainly more of the same..

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One thing I nearly forgot to do was fit the pushrod tubes for the rudder and elevator. It would have been very entertaining trying to fit them after the planking had finished

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At the rear

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and at the front..

Note both these photos are actually upside down 0 hope they don't upset your sensibilities and/or OCD

I have progressing the planking slowly

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Just working down one side, adding one plank at a time and letting it dry. The pins are pushed through from one plank to the next making sure the line of the fuselage is maintained

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A couple of days later.. This is as far as I can go. I need to get the other side this far - the next big job will be to fit the wing joining tube which sits in this slot


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which will be opened up at both sides when it is fully supported by the planks.
Also need to add the rudder push rod

One area that I am bothered about, I don't think the fin is large enough and may redraw with the fin about 50mm taller. Not a show stopper at the moment though

Getting very near the end.

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The idea is to get the wing joiner tube fitted, so plank down until you get to the slot in F4

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Carefully remove the edge pieces with a Razor saw.. The former should be self supporting now.

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Cut a length of the phenolic tube about 30mm too long and adjust the gap for a snug fit with the tube centrally between the upper and lower former halves

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When happy, liberally apply a large dollop of slow setting epoxy.
Use the full length of the joining tube, centralised cross the fuselage and then triangulate to the fin post, ensuring that the distance is the same for both halves.

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Then leave it to harden. Tomorrow evening, I'll carefully remove the joiner, then complete the planking. There are two thick (10mm) balsa end ribs capped with 1/16" ply that will provide the structural strength to the wing to fuselage junction

Fin and Tailplane next