[SvingenB]

The HS is mounted in the rig, everything is measured up, and I can start drilling holes. The manual say start at the intersection of HS-408/rear spar and go up and out in each direction from there. This is a bit vague, should I go up the HS-408 and the HS-407 and then out? or up and out at the same time? Should both sides (up/down) be done simultaneously? hmmmm

 

[SvingenB]

Looks like nobody wants to answer this for some reason or another What I did was to clamp both leading edges at the ends, use three wooden clamps + some additional clamping, start at the intersection HS-407-402-408 and spread out from there in all directions alternating the top and bottom side to prevent real (or imaginary ) tensions that could possibly warp the skin. In hindsight, the skin is probably? so stiff that as long as it is clamped on good, no warping, pillowing or stretching will happen no matter how the sequence of drilling is.

 

[Mark Bolton]

Looking at the pictures in the log you appear to have done it right. The sence of what you are trying to achieve is that the slack in the skin is worked out toward the trailing edges and not trapped in the interface between the inner structure and the skin. In the empenage this effect isnt really going to be apreciable as you point out since the skin is so robust and the room for slack is negligable.

The principle is the same as following the tightening sequence in torquing down the head bolts in a six cylinder motor.

I remember how tentative one is in the early stages when unfamiliar with aircraft construction.

You will really notice the effect of starting in a central spot and working the lack out toward the edges when it comes to the leading edge of the wings. It is actually a very satisfying task.

Regards

Mark