Further Wingbolt-Drilling (June, 13th, 2004)

Today I drilled the 3.2mm pilot holes to intermediate size of 4.8mm. I used a stepdrill for this work. It was a real pain in the A... All this layers of aluminum and steel (deviating from the plans I use chromoly steel for the sparblocks) will stack up to a solid 90mm! The problem now is that only 30mm of my stepdrill is threaded. After this 30mm I have to remove the drill a dozend times after drilling a couple mm to remove the chips. Bus worse is that my small benchtop drillpress has only a 'reach' of 50mm. What now?

The first part of drilling I raised the drillpress for 40mm by placing some particle-bords underneath. These I had to remove successively when I proceeded into deeper regions. All in all a really shitty piece or work.

Coming week I will order a custom precision grinded step-drillbit and a H7 reamer which I will use to open up the holes to final 10mm (also deviating from the plans here I will use M10 high-strength bolts). Yes, I will final-drill the spars NOW. When the wings will be installed to the fuse I will use some purposely milled drillguides for drilling the fuselage wing attach angles.

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It's accomplished! (Wingbolt-Placement) (June, 5th, 2004)

Today I did it! the spars are mated. If I would have only used the pilot holes and trusted in the plans then my craftwork would become a bad match.

So I firstly adjusted both spar ends to equal height. I used a transparent hose filled with water for this. Then I measured the height of the "V" at the center. At three degrees dihadral this should be 173.8mm. At the same time I assured a wingbolt distance of 889.5mm. Changing one of these parameters invalidated the other one, so I spend the whole Saturday morning until everything was in the green. Drilling the pin holes through the blocks and opposite spar was a non-event. The pilot holes I previously drilled according to the plans were about 2mm off center. I decided for new pin holes about 15mm above the old ones.

 

Here's the lefthand spar. Once this root-rib angle (1) is riveted into place, then the spar-endblock (2) never ever can be removed anymore for servicing. If I/you place these bolts (3) the other way in then the block can be removed easily.

I have not yet drilled the boltholes to the intermediate 1/4" because I'm not sure how to proceed from now on. If I'd rivet the spars together and then fit the complete wings I could not remove the chips between the layers when I drilled the holes to final size - not good.

Currently I tend more towards this procedure:

(changes possible at any time without notice ;-))

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Wingbolt-Placement, continued (June, 1st, 2004)

My worries were not unfounded. A second spar test-fit, now with the wing-endblocks mounted, gave a distance of 897mm between the endblock boltholes, when a drillbit was stuck through the center-pilothole. This is 7.5 mm away from my ideal width (see May 30th note below). If I would drill anyway, my bolts would be placed much too close to the inside angle-radius of the wingattach angles - not good.

 

This gap (see arrow) is per the plans. What IF I would ignore the plans (and the pilot holes) and push both spars tightly together - I would regain this precious 7mm - BUT what a can of worms might this open up? Comments highly appreciated.