Hrs: 8.5

Thickness wing spars

The construction manual calls for making spacers before riveting the side skins to make sure the wings will fit later. However my wing spars are thicker than expected and don’t fit in the carry through.
The wing spars at the root are still in the jigs, to be sure they are clamped together I torqued 4 of the 8 AN6 bolts to 26 Nm (the value in the construction manual for the wing bolts):

According to the construction manual the spacer should be 23.3 mm thick:

However my spars are thicker. Depending where to measure the thickness varies from 23.7 to 24.5 mm:

The reason why my spars are thicker than the specs is due to the same issue Sling 2 builder Adam had: Main wing spar Issue 4 – interference between spar caps and spar core fold radii

Feeler-gauges from 0.05 mm up to 0.20 mm fit in the gaps on both the top and bottom side of the wing spars:

Since my wings are ready it’s quite difficult disassembling the spar root and chamfering the edges to allow a tight fit.

To investigate if the ticker spar would fit into the carry through I made 2 spacers; 23.9 mm for the top and 24.5 mm for the bottom. At the bottom there is sufficient play to insert the wider spacer but not on the top.
With a M8 stud, some wooden and steel washers and 2 nuts I made a “spreader”, with little force it was possible to widen the gap and insert the 23.9 mm spacer.

I sent an e-mail to Sling Aircraft to see what is best to do now…

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