Unmanned Systems Technology 002 | Scion SA-400 | Commercial UAV Show report | Vision sensors | Danielson Trident I Security and safety systems | MIRA MACE | Additive manufacturing | Marine UUVs

29 In the cockpit of a manned helicopter there is a lever for each of these two functions, Cyclic and Collective. In the SA-400 these levers are optional, along with a centre console that holds the required instruments and switches for a pilot to operate the helicopter manually. The tail rotor is necessary to control the yaw of the craft; it serves as an anti- torque device, counteracting the main rotor’s rotational force, and is also used to control the heading of the helicopter. In a conventional manned helicopter its blade pitch angle is controlled, again mechanically, by the pilot using foot pedals. In the SA-400 all those rotor controls can be operated by servomotors rather than the physical actions of a pilot. Four servomotors grouped on a tray are connected to the mechanical linkages, allowing for easy conversion from manned to unmanned operation. In addition, there is the aforementioned fuel control servo which acts on a closed-loop basis. It is controlled in response to the signal from an rpm sensor on the engine output shaft, so as to keep that shaft running at constant speed. That is the only control over the engine, aside from a solenoid valve to cut the fuel supply in an emergency and an additional electronically operated fuel valve used to provide additional fuel during engine start-up. Jones notes that during flight the onboard autopilot is a key element of control. “It senses how the helicopter moves in space and what its attitude is at any given moment using its internal sensors – accelerometers and gyros. It can detect any movement in any direction at any given time, which allows it to stabilise the helicopter. “If a gust of wind upsets the helicopter then the autopilot will issue commands to bring it back to where it needs to be. But of course, it is one thing if it is hovering at the time; another if it is moving forward. Then there is flying sideways – which is like balancing on a ball!” The SA-400 has an autopilot made by Adaptive Flight, which was established to commercialise technology developed at the Georgia Institute of Technology (‘Georgia Tech’) in Atlanta. The autopilot itself was developed under the leadership of Professor Eric Johnson, the Lockheed Martin Associate Professor of Avionics Integration in the School of Aerospace Engineering. Scion UAS continues to work with Adaptive Flight and with Prof Johnson on development of the autopilot for the SA-400, in particular for the advanced control necessary to land in the unstable environment of a sea-going vessel. “The autopilot is detecting the actual attitude and comparing it with what it should be and keeping that balance,” Jones says. “We have an additional computer on board, which controls the SA-400 itself. This ‘flight controller’ interfaces through the servos and is getting input from the autopilot. So the autopilot tells the flight computer to, say, move right and the flight controller knows how to get that done. It sends appropriate signals to the appropriate servos. “The flight controller isn’t navigating but is, for example, handling functions such as babysitting the engine for temperatures and pressures. In fact, a good example is starting the engine, in which case all those functions are handled by Unmanned Systems Technology | Spring 2015 Having worked together in 2009-10 as subcontractors on an IED Detection UAV project known as the Yellow Jacket, the five founding members decided to form Scion UAS. “We realised that together we had critical-mass capabilities and experience to design and build highly sophisticated autonomous helicopters,” says Scion UAS CEO Steen Mogensen. “Taking advantage of the already established company, Scion Aviation, and its world-class facility in Fort Collins, Colorado, it was decided to locate the new company there.” Scion Aviation is owned by Jim and Betsy Sampson. They are also joint owners of Scion UAS together with long-term Aviation employee, director of operations Scott Lowry, plus Phillip Jones and Steen Mogensen (all five holding an equal share). Jones and Mogensen both joined Scion UAS from autopilot supplier Adaptive Flight, bringing very valuable knowledge of flight control technology – the heart of any unmanned system the company might devise. Jim Sampson is chairman of the board of Scion UAS. He is an engineer specialising in all mechanical aspects of aviation, including the design and production of metallic and advanced composite components. He is also an expert in aircraft engines and is a licensed pilot for fixed-wing and rotorcraft. Betsy Sampson runs the financial side of both Scion Aviation and Scion UAS. Steen Mogensen is the chief executive officer and technical director of Scion UAS, and is an engineer specialising in electronics. Dr Phillip Jones is Scion UAS’ director of flight control and software development, and as such is responsible for all software-related items. Scott Lowry is its director of mechanical engineering, and oversees design using CAD and CAM, the in-house facilities of Scion Aviation. Mogensen remarks that, aside from its internal expertise, Scion UAS is assisted by several subject matter experts in the fields of helicopter design, aircraft structure analysis and aerodynamics. He adds that, until his passing in October 2014, Scion UAS consulted with Ray Prouty, widely acknowledged as one of the pioneers of the modern rotorcraft industry and author of seminal works on helicopter aerodynamics. Scion UAS