All UAVs carry an avionics fit. This can be as simple as a basic model aircraft receiver, battery, and wiring to control servos. On a long-range, multiply redundant UAV, such as the SPOTTER, quite complex avionics is employed with multiple receivers, autopilots, batteries, generators, and appropriate change over systems to cope with failures. All this avionics equipment must be held firmly inside the UAV, permit access for maintenance and assembly while being lightweight and offering suitable support. Sometimes it is important to use antivibration mountings to insulate devices such as autopilots from engine vibrations. Our preferred approach to housing such systems is via laser-cut plywood base boards, which can be quickly and cheaply designed and cut while being highly customized to the equipment fit being used. Typically, such boards slide into groves in the SLS fuselage or are carried on dedicated antivibration mounts. We find it expedient to enable each board to be readily removable from the aircraft for maintenance - it can be extremely frustrating and time consuming if maintenance in the field has to be carried out through hatches that are inevitably always smaller than one would wish and quite often prevent access with the desired tools (we have found having team members who have very small hands can be most welcome when dealing with some UAVs we have operated, see Figure 4.9). Figure 4.10 shows a typical range of avionics boards designed following this approach.
Figure 4.9 Frustratingly small fuselage access hatch.
Figure 4.10 Typical plywood avionics boards with equipment mounted. Note dual layer system with antivibration mounts in last image.