I am in the process of building a very light weight built up wing. It has a combination of balsa and carbon fiber wing spars, the balsa spars also have sheer webs. The carbon fiber spars only extend 60% of the span, while the sheer web balsa spars are full span. The fuesalage when full loaded with .40os engine, radio, servos, and sheathing, glassed it weighs 52 0z I want the wing it self to finish out at about 10 oz or so.
One thing I am concerned with is, twist or flutter of the wing tips. I was thinking of using truss bracing using 1/8 inch square stock, and alternating it, high low for the span of the wing. I really would like to keep the weight of each wing under 4 oz I am at three now each half of the wing is 32 inches from root to tip and will have a 4 inch middle section over the fuselage. Overall the wing span will be 68 from tip to tip. The wing will be fully sheathed and glassed. As it is now there is a small amount of flex about 1/4 inch when 7 lbs of pull is applied at the tip with the root secured.
But the wing will twist when only 2 lbs of force applied to the LE.
Each wing has 24 X 2.5 inch ailerons ( which extend from the tip in) it has a 10.5 inch cord and the ribs are 12%.
Am I being overly concerned about the twist?