Jason builds a plane

First slat complete!

25/6/2020

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 A really good couple of days in the shop this week.

With the first slat underway, I was time to begin the task of wrapping the top skin over the ribs.  To make this easier, Ron has built a "slat box" as show below.  Made from plywood, it is essentially a reverse or negative pattern of the top surface of the slats.  Green painters tape is added to any contact point to prevent scratching the skins:
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Before getting the slat mounted in the box, I had to tuck the underside into the folded over trailing edge.  It's tight, and I used a thin piece of wood as a slide to get it tucked under.   The resulting pinch of the trailing edge fold is enough to keep everything together for mounting in the box.
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Now it fits in the box and can be strapped down to complete the final wrap over.
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I used a piece of HSS tubing to act as my spreader across the rear of the slat.
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A look inside the each end confirms things are close enough and I can begin drilling the top side rivet holes. 
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To access the top side (which faces down in the box) I tilted the box on it's side:
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Strategically cut access holes in bottom of the slat box line up with the 3 internal ribs so I can get at least 3 rivet holes drilled through the skin into the ribs:
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The fourth hole is to far down inside the box to drill it accurately, but that can wait until everything is out of the box.
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Put the box back upright and added some more blocks.  This allows the force of the straps to transfer down more vertically, tightening everything up and I can begin to drill and cleco the trailing edge down on the underside:
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Take the assembly back out of the box again and finish the top side rivet holes I couldn't access before.  The finger clamp holds down the rear curve of the skin to the double bend flange underneath:
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Layout the rivet line across the top rear.  These will be A4 rivets with 50mm spacing:
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To ensure I had everything locked down where it needs to be, I flipped everything over and drilled out everything to A4 on the underside:
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Back ipright again, drilling the topside rear rivet line, A3, then up to A4 on 50mm spacing.  I also completed the front rivet holes in each of the nose ribs.  Everything is tight and square.
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And it all comes apart again for final debur and priming:
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One of the challenges I'm facing is how to make the inside of the slat structure accessible for the inspector to see my workmanship.  The fold-over design of the skin makes leaving it open like the flaps, elevator etc impossible.  I discussed this with Ron and confirmed with Roger at Zenith that adding a lightening hole on the flap ribs was acceptable here.  I'm not looking to save weight, just want an easy way to see inside.  This viewing can be done with a scope.
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I carefully added some small holes in the centre of the slat ribs using a step drill.  This will allow a camera scope inside.
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I flanged the hole slightly to add strength:
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I scratched off some of the primer doing the holes, but they cleaned up nicely and I re-primed them.
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The new access hole creates a new small problem.  The skin support L now protrudes over the hole:
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the quick solve for this is to trim the L a bit before riveting.  I also trimmed it back a bit on the top of the bend flanges to ensure clearance for the top two rivets.
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Primed the skin and once dry started the re-assembly which goes back together fairly quickly
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With everything drilled out to A4 and clecoed, the slat skin is tight to the ribs and looks good for riveting.  The access hole turned out really nice - there should be lots of room to look inside using a scope.
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Very pleased how this turned out using the steps I came up with worked well, I'll be following the same order when I build the other three.  Again, I'm rather surprised by the size these are, it gives a good impression about the wing dimensions.
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One to the next one, it all starts with alying out the bends.  Thankfully I wrote down the measurements and bend order from the first one - that will make the next three the same.
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Very happy how the first slat turned out considering how complex and tight the bending that is expected of the skin.  It's not a complicated structure, but "fun" to do.

Back in the shop soon to get the rest of the slats done.  I'll be continuing work on the 3D scanning/printing project too, exciting things coming up.  Thanks for reading.
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    Husband, father and 911 dispatcher.  Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be.  First time aircraft builder. Looking to fly my own airplane.

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