Thursday, 14 July 2016

C17 progress - it lives!

I originally scrapped the rear fuselage, as the blocking out of foam was not going well.  Too many formers made too many joints in the foam, which used more glue and more shims squaring things up.  I hated it.

So she looked like that a few months ago, and was ready for the bin.

After speaking to Mark Kettle a bit over some PSSA meets, I decided to strip the formers out the middle, and just use 4 longerons (one in each corner) to push a foam "box" up against.  This could then be hot wired and sanded to shape.

Like this :

Then some rough shaping : 

Tail on, in the house!  OK, she's still big then.  Oh, and you can see some more fuselage shaping :

So my worries of the fuselage have pretty much gone away (until I get to the nose section), so I started to work on the wings again.  I was going to use the first panel as a test, but I think it's tidied up quite well and so will use it on the final model :

That's the wing LE and TE being shaped...with a power planer!  They are quite hard 3/4" x 1/2" spruce, so take some work to get right.

This is why I was going to scrap this wing - you can see ripples in the veneer.  This is how the sheets were supplied, and I should have rejected them and got them sent back straight away, but I thought I could get rid of the problems in the press as the veneer went on.  I was wrong.  I have locally re-glued under the bubbles, and am blending it here with lightweight filler.  The spar box and also full-depth ply shear web are now in on this shot too.

So back to to the tail - I re-veneered a part of this in balsa (yes a bit of a mish-mash, but it'll work fine) and set out the servo positions for the rudders.  

I have used some 1/4" square balsa on the edges of the fin for a hinge shroud.  

Will it be finished this year?  Not sure, but I hope it would be ready for the last meet this year.

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