If this is what you are talking about, I did it this way. The stick boots that I ordered from Classic Aero covers the exit and tape.
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I later installed a 9 pin plug to make the stick removable. I ran the wire out of the bottom on the pilot stick as it was not removable and I didn't want to jeopardize the strength of the stick.
Blain, I can get a picture if you want it, but here is what I have done and why.
Background: There are two forces on the stick. Elevator, and aileron. Both of these can act on the stick above the bolted pivot joint. This means any hole there can be in a stressed area due to some combination of the two.
Below the bolted pivot, only the aileron forces act on the stick, the load always go side to side. This means there is a "neutral axis" where a hole can be placed with confidence.
The hole should be small, and only what is needed for the wire bundle, maybe a snake skin sheath, maybe 5/16?
The hole should be carefully deburred and basically polished around the perimeter.
Hole Location:
If the hole is put in the lower part of the stick, drilled along the axis of the aircraft, (perpendicular to the aileron rods), and just above the lower weldment, then it is in the neutral axis and in the lowest bending moment portion of the stick. To keep flexure of the wires to a minimum, and keep wires from moving around in the hole, tape the bundle back to the stick so it tracks back up to the bolted elevator pivot point and then loop to fuse so in full motion the wire moves the least.
firesuit on - YMMV
PS - the principles work for the 8 as well, but I don't know if the geometry allows this like the 7.
With the -8, the forces acting below the pivot are the elevator only (fore/aft). To your point, a hole in the side of the stick would be of minimal impact there. (But then again, I would worry more about the stick failing in fore/aft loading, just due to the higher fore/aft stick loading, versus lateral, in an RV).Below the bolted pivot, only the aileron forces act on the stick, the load always go side to side. This means there is a "neutral axis" where a hole can be placed with confidence...
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I drilled the stick just under the grip and ran the wire down the front of the stick.
Can't see the wire. As stated in other posts, the further from the pivot point the better.
Would you Tig that, Dan?
Questioned Vans and got a response. Too late for me, I had already made my decision. But as a conclusion to this thread I thought I would pass it on.
Copy of email;
Sorry for the delayed response, I finally got word back on this from the engineers. They will
allow a 1/4 inch hole (no larger, smaller is preferred) on the forward side of the stick just
above the cross tube. I have take pictures of what we have on our RV-8, this hole is 3 3/4 up
form the bottom of the stick. See attached picture.
Sterling
BTW, I put a 1/4" hole on the aft side about the same height as suggested. Will probably plate it per Dan H. diagram. Seems that there would be less tensle stress on the aft side but I'm no engineer......and they probably wouldn't endorse a bent stick either.