Ok I got some info.
He repleyed and said this.
He felt he was not as accurate as possible, and after a short communica decided this.
Mount the base plate SOLIDLY at vertical, 90°, strut parallel to floor.
Measure out along the strut 85 cm, including mounting plate.
Take a measure to the floor, note.
Add 5 kilos, 5 liters h2o,as close to your 85 cm mark as possible, centered on mark.
Take measure to that 85 cm mark, note difference.
For twist, torsion, mark axis, center at fuse connection, of strut, measure back towards tail 30 cm, mark, measure to floor, note.
Add same weight again centered on mark, measure, note difference.
I am now just thinking how to do this with tuttle box systems? Maybe strap board to wall?
I hope to do this with my 3 home made foils and post results but Have MANY other things to do.
Does anyone have a better idea