Unmanned Systems Technology 027 l Hummingbird XRP l Gimbals l UAVs insight l AUVSI report part 2 l O’Neill Power Systems NorEaster l Kratos Defense ATMA l Performance Monitoring l Kongsberg Maritime Sounder

30 changes, and many times had to toss them out and start over,” he says. By the time he had decided to build the Hummingbird XRP, Adam Works had switched to a different, cheaper and more flexible way of making moulds. This involves CNC-machining a hard, high- density compressed material to create a master ‘positive’ mould from which carbon fibre ‘negative’ moulds can be made that are used to make the final parts. The company now uses pre-preg carbon fibre cloth instead of manually applying resin to fibre. “This is very efficient and cost-effective, and these moulds are good for more than 100 final parts before they need replacing,” Bishop says. “Also, when we go to full-scale production and are building a vehicle every two days or so, we will need multiple moulds. We can produce as many moulds as we need for basically the same cost as producing the final aircraft parts, or a little more because the moulds have thicker cross-sections for more rigidity.” This process is also flexible enough to allow them to incorporate changes quickly and relatively inexpensively. “The few changes we made to the structure at the very end were simply done in the master high-density material moulds, and then we created the production moulds as needed,” he says. “Adam Works produces the entire Hummingbird airframe – all the carbon fibre, landing gear, arm joints, upper and lower duct and the main girdle. “The girdle is our main structural element. It goes around the middle of the aircraft and on it we attach the landing gear, external fans, hard points and other optional accessories. It is a U-shaped channel that also houses the cabling, control lines and fuel lines so that they are all hidden and protected.” The Hummingbird also makes extensive use of 3D printing for parts including mounts and enclosures for electronics and even secondary structure. Reference Technologies’ partner here is iFuzion in Denver. Materials used include several types of plastic, some infused with carbon fibre reinforcement, and metals including aluminium, stainless steel and titanium. The covers for the electric motors that drive the rotors in the centre duct, for example, are 3D-printed. “They fit perfectly, like they came out of a plastic injection moulding machine,” Bishop says. One of the most important 3D-printed metal parts is the autopilot enclosure that fits inside the upper front electronics bay. Although Bishop wouldn’t reveal what the material is, he says the enclosure’s purpose is to hold the autopilot securely in the bay and act as a Faraday cage to protect it from deliberate RF interference. August/September 2019 | Unmanned Systems Technology Dossier | Hummingbird XRP The final composite structural parts are made using carbon fibre ‘negative’ moulds taken from CNC-machined material masters, such as this for the central duct (Courtesy of Reference Technologies) Vehicle electronics in one of the bays include an ignition module for the engine in the lower right-hand portion of the bay (Courtesy of Reference Technologies)