Thin wall aluminum tubing is surprisingly resistant to torsion. The largest diameter you can fit, glued along the entire length of the false trailing edge of the flap will help. Insert it into a groove. Drill a hole to insert & glue a ball link. I did this very thing with my design ... my avatar Su-27.
Some arrow shafts are aluminum tubes sheathed with a thin layer of CF tow on the OD. Super stiff, resistant to twisting ... and light. I bought some exclusively for torque tube applications (hiding linkages in fuselage, etc). Archery ranges sometimes have these kinds of broken arrow shafts in the garbage. Usually only the head breaks off, leaving lots of good stuff for RC use.
Originally Posted by PeterVRC
I am still not happy with the 'visualisation/thought' over the LEF's with a Carbon Fibre strip face, or made from a balsa block. Neither way seems truly 'twist free' enough - versus the fact that the outer regions are getting smaller quite fast, so 'twist' beyond about the 2/3 point is not likely anyway. But I want something assured to remain rigid... to at least "6.3 on the twistigidy scale".
I am more leaning towards 2.5mm plywood LEF face, because that will glue 'properly' to the foam and thus make a very rigid 'ply' structure of the two. But.... all 2.5mm sheets I ever get are bowed anyway! And that is enough 'inbuilt force' to distort the LEF - unless jigged in some manner to assure it 'wins' over the ply's bow while the glue dries.
So... a dilemna over what to do for it still.....
I could make totally new ones from beech, or pine..... LOL
Or.... use a CF LEF face strip, then with the whole LEF glassed (GF sheet and WBPU) to get assured rigidity.
I aim to do it over this weekend, so whatever I come up with as 'acceptable' tomorrow will be it..... (I wonder how much Pine would weigh......??? A bit of a nuisance to work with! Especially a reasonably complex shape in total.)