Before committing to the geometry creation (sometimes known as embodiment) stage of design, it is worth going through a checklist to ensure that the detail design result is well founded. At this stage of design, the overall system should have been broken down into logical subsystems for which subteams or individuals have been tasked. Broadly speaking, in the context of a fixed-wing UAV, each subsystem will be composed of the following elements or combinations of them:
• primary structure (in manned aircraft this is defined as “The structure that carries flight, or ground loads, and whose failure would reduce the structural integrity of the airplane or may result in injury or death”);
- • secondary structure (again in manned aviation the same source defines this as “... not primary load carrying members and failure would not reduce the structural integrity of the airframe. Such components do not form an integral part of the airframe, e.g., access panels.”);
- • mechanisms such as hinged control surfaces and actuators;
- • functional electrical, pneumatic, hydraulic, or fuel subsystems or parts such as fuel storage and distribution or electrical power distribution subsystems.
-  http://www.discovery- aviation.com/wp- content/uploads/135A-970-100- 51ir_Stanard_Practices- Structure.pdf.