dbonner
New Member
Hello, I'm designing a 6m span wing for a 120 kilo takeoff weight. I'm designing to 6G positive 3G negative. Sketches are on electric car project (don't mind the name of the link, you can click through to the aircraft project). It's a high wing, strut braced halfway out, but the struts work only in tension, so the highest spar cap stresses are at the wing root in the 3G negative condition. The wing is in two halves that join above the pilot's head. At the wing root the idea is for the top & bottom spar caps from left & right to attach to each other at the root so that the spar cap tension & compression is fed directly from one side to the other. The spar caps are square rods 60mm2 (10 mm wide by 6 mm thick). I am thinking of making small 4130 steel fitments to do this. The 4130 piece would be gloves enveloping the carbon on all sides, screwed together on top of glue (screws to either side, not piercing the carbon). The steel fitment would then attach to the other fitment opposite, and also to the fuselage.
As is typical in these cases I am not taking shear into account for a first estimate, since it tends to be so much lower than tension/compression in a spar cap.
Does anyone know how to calculate the minimum safe length of a steel glove around a carbon spar cap so that it can transmit the full force in tension or compression of the carbon rod? ALL the carbon fibers will be interrupted at the root, so that we are talking about all of the stress getting dispersed to the surface of the rod by shear into the steel glove fitment. Can I just use the figure for shear strength of the resin matrix, over the entire contact surface, with some appropriate safety factor?
With thanks in advance, David Bonner
As is typical in these cases I am not taking shear into account for a first estimate, since it tends to be so much lower than tension/compression in a spar cap.
Does anyone know how to calculate the minimum safe length of a steel glove around a carbon spar cap so that it can transmit the full force in tension or compression of the carbon rod? ALL the carbon fibers will be interrupted at the root, so that we are talking about all of the stress getting dispersed to the surface of the rod by shear into the steel glove fitment. Can I just use the figure for shear strength of the resin matrix, over the entire contact surface, with some appropriate safety factor?
With thanks in advance, David Bonner
