Fuselage Design Days 7-9
Nose revisions, tail design, and beam calculations
Design Team revised the nose design to be fail safe at the cost of an additional ≈0.8 pounds. Previously, the force from the nose mounted motor was transferred to the cabin through the top of the hood and the cross web member it was attached to. Though this created a shear force on the cross web member, it was supported by another beam in tension. While we think this would have worked, Design Team decided adding two more beams to make the design fail safe outweighed the additional weight.
Design team also began to lay out the horizontal stabilizer, elevator, and rudder. In the past, we had been hesitant to use bent beams to simplify construction but opted to use them in the tail to eliminate unnecessary gussets and simplify the overall design. Upon sketching the stabilizers and rear control surfaces, we noticed they were proportionally much larger than we expected. Design Team then reviewed all of the major cabin, nose, and tail dimensions and realized they were all a little too small. After a quick meeting with the Physics Team, these dimensions were adjusted to be a bit larger. In addition to changing cabin dimensions, Physics team calculated the strength of the 1”x0.065” 6061 T6 aluminum tubing we had been designing the fuselage around and realized it had a yield strength of 7637lb, almost twice that of the ⅝”x0.035” 4130 steel tubing used in the Legal Eagle which has a yield strength of only 4327lb. Hence, we adjusted the fuselage design to use 1”x0.035” 6061 T6 aluminum beams which has a yield strength of 4244lb and weighs 44% less than the 1”x0.065” 6061 T6 aluminum beams previously used. We hope to eventually simulate the stresses on our fuselage using finite element analysis in Simscale but in the meantime we are taking a more conceptual approach and basing our dimensions off of similar aircraft. Since the Legal Eagle most closely resembles our truss frame, it makes sense for our beams to match the strength of those used in the Legal Eagle. More information regarding our beam strength calculations can be found in our Flight Club Beams Comparisons spreadsheet. Of course, we will also test our fuselage to the recommended loads once it is constructed.
*Editors' note: the thought processes and design choices presented in this article don't necessarily represent those implemented into the final design and are subject to change. Flight Club Aerospace is a group of amateur students with no formal education in any fields of engineering. We present this information for educational purposes only, with the understanding that it is not to be re-created without adequate professional oversight and mentorship. For our latest designs and updates, please see our most recent blog posts.