Structural Subsystem
Structural sub team is responsible for the design of the aircraft in cooperation with Αerodynamics Design (aka Aerodynamics) sub team. Structural sub team’s job though does not end there, they are responsible of the materials that are going to be used in an aircraft, the fabrication methods, the assembly and the overall construction of the aircraft.
In 2020, Structural began the design of Aether the new UAV of Aeronautics which consists of the following individual steps. First step that the sub team must do takes part during the conceptual design of the aircraft. The sub team calculates in approximation the overall mass of the aircraft with the payload (Wo) and the empty weight (We) mass fraction (We/Wo). Those two approximations are playing a crucial part of the following design. The Aerodynamics Design sub team continues the conceptual design by calculating the basic dimensions of the air-vehicle, such us the main wing, fuselage and tail of the aircraft. Second step of Structural’s role in the design procedure is to calculate a better approximation of the empty weight (We) and for the first time an approximation of the centre of gravity (CG). Following there is a cooperation (feedback loop) between Structural and Aerodynamics Design in order to recalculate the basic dimensions, mass and CG of the aircraft so they fit best our mission. Note that all the above are calculated with tools in the form of MATLAB code that has been written by Structural team members.
Continuing the conceptual design, Structural had to design the fuselage of Anemone at first as a «back of a napkin sketch» and then in CAD (SolidWorks). Anemone is the first aircraft of Aeronautics that is not going to have a tubular fuselage, in particular the shape of the fuselage is «produced» by airfoils in order to not affect the distribution of lift under the main wing. Structural was then assigned to design the landing gear in terms of type, dimensions and materials. Next step of the design, and the last step of conceptual design, falls into the responsibilities of Structural, the sub team sketches in CAD the whole aircraft in no detail using the optimized dimensions found in previous steps of the design to get a glance at the overall geometry of the aircraft.
The sub team has to move on into the process of studying and choosing the materials that are going to be used in the fabrication of every individual part of Anemone. The aircraft will be constructed mainly with composite materials, in example the main wing is disassembled into three main parts the outer surface which is going to be fabricated from carbon fiber woven sheets and resin, the two carbon fiber tubular spars that will receive the stresses of the wing and the spar supporters that are specially cut out of XPS foam. Besides the material studies that are being conducted, the sub team also conducts a research for different fabrication methods. Structural targets to find the best fabrication methods in terms of cost, durability, precision and construction time. The materials and fabrication methods affect the performance and the durability of an aircraft in a major way, consequently the sub team conducts a study throughout certain bibliography on the subject: Behavior of anisotropic materials and their stress performance into different directions. Simultaneously, Structural is obligated to complete the detailed CAD design of Anemone in order to approximate with great accuracy its mass (We) and its CG. The last responsibility of the sub team is the supervision of construction which takes place after the aircraft’s design has finished. Note that all sub teams of Aeronautics project involve into the construction of the aircraft.
