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15 Dr Donough Wilson Dr Donough Wilson is innovation lead at VIVID/ futureVision, which specialises in game- changing thinking for defence, homeland security, and both manned and unmanned aviation innovations. He was first to propose the automatic tracking and satellite download of airliner black box data, technology which is now being adopted. His defence innovations include the automatic cockpit vision system that protects military aircrew from asymmetric high-energy laser attack. As a pilot, he has more than 3000 hours of flying experience in both military and civil environments, and is currently a flying instructor and a flight test examiner. Paul Weighell Paul has been involved with electronics, computer design and programming since 1966. He has worked in the real-time and failsafe data acquisition and automation industry using mainframes, minis, micros and cloud-based hardware on applications as diverse as defence, Siberian gas pipeline control, UK nuclear power, robotics, the Thames Barrier, Formula One and automated financial trading systems. Ian Williams-Wynn Ian has been involved with unmanned and autonomous systems for more than 20 years. He started his career in the military, working with early prototype unmanned systems and exploiting imagery from a range of unmanned systems from global suppliers. He has also been involved in ground-breaking research including novel power and propulsion systems, sensor technologies, communications, avionics and physical platforms. His experience covers a broad spectrum of domains from space, air, maritime and ground, and in both defence and civil applications including, more recently, connected autonomous cars. Unmanned Systems Technology’s consultants Aerospace systems manufacturer Aertec Solutions has successfully conducted a fully automated take-off and landing on a beach with its Tarsis 75 UAV (writes Rory Jackson). The test required modifications to the 74.5 kg UAV’s autopilot software to adapt for the soft, wet and changing nature of the terrain. “We had to compute environmental variables including the side slope of the beach and timings of sea tides for the take-off, and for the landing a few hours later to prevent touching-down in water,” said Rodrigo Valdivieso at Aertec. “We also had to program in adaptations for local wind changes during take-off and approach, which can dramatically throw off fuel calculations. We estimated that an onshore thermal of around 8-12 knots would help during the return leg.” The flight algorithms had to be modified to compensate for the effects on the inertial sensors of the shape and softness of the beach sand during movements on the ground. Other provisions were made to adapt the landing gear wheels to the soft terrain (with a 1-2 mm layer of wet sand sticking around the contact surface after landing), and for the spring mechanism of the landing gear to be adapted to the undulating shape of the beach. Aertec’s engineers wanted to maintain the weight-to-contact surface ratio of the Tarsis 75’s wheels. To collect the data for their optimum radius and width, part of the team went to the beach at different places and times with a device equipped with a set of weighted wheels, to observe how they would sink in the sand, at standstill and while moving. The main gear spring, on the other hand, was ‘softened’ to the point that no undesired rebound could be anticipated. As Valdivieso noted, this part was conceptually easy but took repeated attempts to obtain the exact degree of softness. The UAV’s take-off distance was no longer than that on a paved or pressed airstrip, thanks to an operation settings adaptation called preferential fast lift-off. It did however need a few more metres to land than it would on a runway, owing to the landing corrections made to allow a smooth touchdown amid side-on winds of between 10 and 13 knots. Team hits beach with UAV tests Airborne solutions The UAV’s autopilot software had to be modified to account for the nature of the sandy terrain Unmanned Systems Technology | August/September 2018