Michealvalentinsmith
Well-Known Member
For reasons of portability and the chosen method of folding (ribs accordion to the tips sliding alone the spar) I can't use a rigid D section on my spar.
So I devised this idea where the spar bends to a curve. When I examined the motion of the curved spar in torsion, I found at the upper portion must move forward for the spar to twist (lower backwards) under positive load. So I figured cables from the root TE to the upper surface of the spar would prevent torsion from lifting forces and vice versa for negative load.
A forward cable runs along the LE of the Ribs to control sweep forces and prevents the spar from bending further back under load and resulting relaxation of the anti torsion cables.
In the attached pic I've shown the cables position in heavy red, the lighter red is some other cable positions I've considered but after scale testing don't seem necessary. I intend on using 2 or 3 sets of anti torsion cables only one is shown for clarity.
I'd appreciate any opinions.
So I devised this idea where the spar bends to a curve. When I examined the motion of the curved spar in torsion, I found at the upper portion must move forward for the spar to twist (lower backwards) under positive load. So I figured cables from the root TE to the upper surface of the spar would prevent torsion from lifting forces and vice versa for negative load.
A forward cable runs along the LE of the Ribs to control sweep forces and prevents the spar from bending further back under load and resulting relaxation of the anti torsion cables.
In the attached pic I've shown the cables position in heavy red, the lighter red is some other cable positions I've considered but after scale testing don't seem necessary. I intend on using 2 or 3 sets of anti torsion cables only one is shown for clarity.
I'd appreciate any opinions.
