Unmanned Systems Technology 008 | Alti Transition UAS | Ground control systems | Xponential 2016 report | Insitu Orbital N20 | UAVs | Solar power | Oceanology International 2016 report

23 R ather than competing with top-tier products such as Insitu’s ScanEagle, Alti’s innovative new Transition UAV is intended to fill a large mid-market gap for long-range VTOL systems for commercial and industrial applications that are easy to operate from any setting and cost less than $100,000, according to the company’s owner, Duran de Villiers. A hybrid in two senses, the Alti Transition is a fixed-wing craft with a petrol engine that drives a pusher propeller, and a battery pack that powers four electric rotors that provide VTOL and hover capabilities. Measuring 2.745 m in wingspan, 1.925 m in length and 0.54 m in height, the aircraft has a maximum take-off weight of 12 kg with a payload of up to 2 kg. Taken together, the wing and tail area amount to about 8700 cm 2 . The UAV can fly at up to 30 m/s (108 kph), faster depending on set-up, and boasts a range of more than 300 km and an endurance of up to six hours. De Villiers says the main challenges in the development of this unusual vehicle were achieving the performance and endurance goals while keeping it small enough to be easy to deploy and operate, commenting that positioning the centre of gravity in relation to the quadcopter rotors has proved “interesting”. Pure VTOL Despite the presence of the pusher propeller, the Alti Transition is a pure VTOL machine. However, it is intended to operate in wing-borne flight as a fixed- wing craft for most of a mission. Following a vertical take-off, the aircraft typically climbs to its transition altitude, which can be fairly low because it does not lose altitude as it moves from hover to forward flight; it then makes a smooth, level acceleration to wing-borne speed before powering down the rotors. It then flies like this for between four and six hours – endurance is still being tested – before transitioning back to hover mode, again with no loss of altitude, for a vertical landing. Take-off and landing processes typically take less than a minute each, de Villiers says. He emphasises that the transition back to hover is very straightforward, without the need for active braking systems such as air brakes, although the company is looking at integrating a parachute for emergencies. To return to the hover, the pusher motor quickly goes to idle and the four electric motors, with their Proportional Integral Derivative (PID) Alti Transition | Dossier to the vertical The lift motors are custom made from aluminium and steel, with ‘oxygen-free’ copper windings for enhanced resistance to short-circuits Unmanned Systems Technology | June/July 2016 Peter Donaldson explains the development process behind this ingenious VTOL fixed-wing hybrid UAV