Unmanned Systems Technology 017 | AAC HAMR UAV | Autopilots | Airborne surveillance | Primoco 500 two-stroke | Faro ScanBot UGV | Transponders | Intergeo, CUAV Expo and CUAV Show reports

67 to take appropriate action in terms of how it controls the engine. In any case, the autopilot itself is programmed to react to excessive temperature readings. Initially the Primoco 500 is equipped with a carburettor rather than fuel injection in view of simplicity, ease of operation and price, Smat explains. He adds that port fuel injection is to be offered as a future option; Motordesign and VM Motor both have experience of the technology. The carburettor is a Walbro 27, and is a 1.0 in version, with one used for each pair of opposing cylinders, the two items being connected by a throttle control rod (running in ball bearings), which in turn is operated by a servo motor under the command of the autopilot. Autopilot- controlled servos also operate the Walbro 27 chokes. The autopilot is supplied by Spanish company UAV Navigation. To keep the craft free of electromagnetic interference from the engine’s ignition, the spark plugs are platinum-iridium with a suppression resistor, while the plug leads are automotive grade with appropriate interference suppression, Smat reports. In the UAV airframe the air filters directly feeding the two carburettors are fed from an intake manifold that is headed by an initial intake pre-filter. Smat explains that the concept here is that debris such as dirt or insects will be caught by the first filter, with any remaining fine powder attaching to the respective individual carburettor filter. Performance The 500’s operating speed is governed according to the size of the directly driven propeller, to avoid the blade tip speed reaching close to the speed of sound limitation. Considering the One 150 propeller, its parameters and design are in line with engine characteristics. The ECU is programmed to cut sparks at 6500 rpm, then to cut ignition completely at 7000 rpm to protect the engine from over-revving. Normal cruising speed is then in the range of 4000-5000 rpm. Take-off engine speed will be about 5500 rpm, the exact figure depending on take-off weight and ambient conditions. The power curve is being developed to ensure it is as flat as possible across the range of take-off/maximum load crankshaft speed requirements. The use of an additional (fifth) rear transfer port has been found to improve engine performance in this respect. While the target TBO is 500 hours the crankshaft bearings are expected to last longer than that, depending on customer handling and the operational environment. The One 150 has a 55 litre fuel tank that when full accounts for about 43 kg. The vehicle itself adds up to a further 77 kg, leaving 40 kg for payload within the nominated maximum take-off weight (MTOW) of 150 kg. The MTOW of the aircraft with this engine can however be up to 250 kg, when used on other platforms. At the time of writing, the actual performance figures had yet to be verified, as the development stage was just getting underway. It was clear though that the 500 has been extremely well thought out for its specific application as a UAV power plant and that it is based on well-proven technology exploited by highly experienced engine engineers. It is without doubt a fascinating newcomer to the world of UAV propulsion. Unmanned Systems Technology | December/January 2018 Primoco’s UAV (One 100 and One 150 alike) has a wingspan of 4.85 m, a length of 3.65 m and a height of 1.25 m. It requires only 300 m to take off and land, which it does automatically, controlled by its UAV Navigation autopilot. It can exploit GPS, Glonass, Galileo and Beidou satellite navigation systems, and carries a Mode S transponder to assist air traffic control. Communication with the ground control station is via radio data link in the 900 MHz to 5 GHz spectrum and Iridium (H2 2017) satellite comms. As a standard payload, the UAV carries camera(s) and/or a Lidar sensor. Camera options include daylight and infrared, multi-spectral and hyperspectral. This allows continuous high-resolution monitoring for an endurance of eight hours or more, with a real-time long-range data link. The Primoco UAV The Primoco UAV has a pusher power unit configuration