Unmanned Systems Technology 015 | Martin UAV V-Bat | William Sachiti | Sonar Systems | USVs | Desert Aircraft DA150 EFI | SeaCat AUV/ROV | Gimbals

run flight tests, to see what it’s going to do, because the simulation just doesn’t predict what will happen in real flight.” The biggest issue, he says, was finding an autopilot that could control and conduct flight in a full 360° range of movement. While many systems are designed to handle VTOL or conduct horizontal fixed-wing flight, to take off vertically with a vertical attitude and subsequently transition in a forward arc into horizontal flight was consistently found to confuse autopilots’ control algorithms. That meant having to develop a new autopilot in-house from the ground up to handle the V-Bat’s unique launch- and-recovery configuration. Control algorithms The V-Bat can be launched in any open space measuring 20 x 20 ft, such as the helicopter pad or flight deck of a small naval vessel. McAuliffe emphasises, however, that this guidance is for safety purposes – in practical terms, following a ten-minute assembly time, it can be launched without any issues from the crowded front of a boat or a pavement. To take off, the V-Bat generates thrust from its duct section and climbs (typically) to 200 ft at about 500 ft per minute. “Thrust is equal to the weight of the craft in unaccelerated climbing flight, which is what we execute following take-off when we’re ascending towards the transition altitude,” says operations manager Bryon Holbrook. To transition from vertical flight to horizontal flight, it must accelerate to a speed at which the wings can generate enough lift to support its weight (potentially at a high angle-of-attack, as wind speeds of up to 20 knots can be withstood during launch and recovery). The control algorithm takes data inputs from the sensors, which consist of an air data unit for pitot and static pressures, and an inertial navigation system with accelerometers and gyroscopes to measure position, ground speed, airspeed, altitude, orientation (in roll, pitch, and yaw), heading and velocity. From these,