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Externally Sourced Components

To test our evolving design environments and build capabilities, a range of aircraft types have been considered. In all cases, these started with the knowledge that some of the major airframe components have to be externally sourced and that one has therefore to work with what is readily available in appropriate sizes. The following list of such components forms a key starting point for what follows. To maintain low costs, some things simply have to be sourced off the shelf:

  • 1. Engines. Either petrol or glow-plug internal combustion engines ranging from 10 up to 200 cc (cm3) in single-, twin-, three-, and four-cylinder configurations;
  • 2. Electric motors. Usually rare-earth permanent magnet motors with digital speed controllers - which are available in a wide range of sizes;
  • 3. Starters and generators. External or in-built starters, direct drive or coupled via drive belts;
  • 4. Propellers. Pusher and tractor propellers available in wood, nylon, and carbon-fiber- reinforced plastic (CFRP) with between two and six blades;
  • 5. Batteries. NiMH, LiFe, or LiPo aircraft-grade batteries;
  • 6. Receiver/transmitter systems for primary flight control. High end aero-modeler systems from companies such as Futaba (which now support two-way transmission of data including rpm, temperature, and geographical positioning system (GPS) sensors on the aircraft);
  • 7. Autopilots. Many are available, but we use Arduino and SkyCircuits[1] systems (including ground stations and software environments);
  • 8. Servos and actuators. High-quality, high-torque, metal-geared aero-modeler items;
  • 9. Undercarriages and wheels. High-quality aero-modeler items, typically including suspension and sometimes a retract capability.

At larger take-off weights, items such as propellers and undercarriages are more difficult to source, and then it is sometimes necessary to have bespoke items made by specialist suppliers - even so, it is desirable to use companies with sufficient turnover and expertise so that costs can be controlled and quality maintained. Given a ready supply of such items and the intention to build a conventional fixed-wing monoplane, the primary layout choices available to the designer then concern the number and positioning of engines/motors and the choice of fuselage/empennage type.

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