I was once curious about if in a line of propellors, having the propellors rotating in the same direction (line wheels on a shared belt) or counter rotating (li

I was once curious about if in a line of propellors, having the propellors rotating in the same direction (line wheels on a shared belt) or counter rotating (like interlocking gears) would produce any difference in thrust. I made a rig to test this https://www.youtube.com/watch?v=SJ7BVa8Ol1I https://www.youtube.com/watch?v=SJ7BVa8Ol1I. Unfortunately it seems I didn't upload the strain gauge measurements, but I remember the net difference was negligible.