Unmanned Systems Technology 001 | UAV Factory Penguin C | Real-time operating systems | Hirth S1218 two-stroke twin | Base stations | ASV C-Enduro | Composites | Datacomms

24 floor are triggered by the onboard control system, and the downward-facing forward antenna is retracted to avoid it being damaged on landing. At the same time, the control system releases the parachute bay roof (it is likewise connected by a Dyneema cable), and the parachute is ejected by a powerful spring; a complex linkage allows this spring to be released by a small servo. Popiks notes that it is important that the spring puts no load on the servo until it is to be operated, and then that it should not break the servo. “That made designing the linkage a surprisingly complex task!” he says. Amazingly, given the size of its compartment (the roof of which measures 15 cm x 15 cm), the parachute is a full 10 sq m. It is made from the thinnest available grade of ‘ripstop’ nylon, a fabric that is reinforced against tearing. It is folded so that it resembles a pillow, then compressed so that it fits into a bag small enough for the parachute compartment. That compression involves a full 24 hours within a high-pressure tool. The way the parachute is folded, and its complex attachment lines arranged, ensure a carefully controlled opening once it has been released. The parachute automatically disconnects on touchdown to prevent wind dragging the aircraft. It can be replaced in the field in less than five minutes. The Penguin C is intended to be used primarily with a gyro-stabilised gimbal- mounted camera (which might be still and/or video, normal or infrared or of another type according to application); however, customer-specified alternatives can be supplied. The Penguin C has its centre of gravity location optimised for maximum efficiency in flight, so if an alternative payload is fitted then ballast is normally used to re-optimise the centre of gravity’s position. Currently the Penguins, like other UAVs, do not have collision avoidance, as a 100%-dependable system has yet to be developed for the 3D world of airspace. A Penguin is normally operated using signals from a ground station via an antenna. The two-way data link between ground station and the aircraft, which sends command instructions and receives video and telemetry data, operates at up to 12 Mbit/s. UAV Factory offers a tracking antenna system so that a more powerful directional rather than omnidirectional antenna can be used. This incorporates a pan-and-tilt mechanism operated by an actuator, which in turn is controlled by a system in communication with the UAV. Whereas an omnidirectional antenna tends to be effective over about 10 km, the directional antenna can maintain the two-way data link up to 100 km. One method of controlling the aircraft is to use the feed transmitted back from the onboard video camera to ‘see’ where it is and react accordingly in real time, sending out control signals in response to the view. Normally, however, the craft is flown between defined waypoints (points in airspace plotted on a three-axis basis) and guided by its autopilot system. Waypoints are transmitted to the aircraft, and the autopilot will guide it from one to the next. The autopilot is Cloud Cap Technology’s Piccolo model. Typically the waypoints are defined with no specified time of arrival. The autopilot sets an appropriate cruising speed according to predefined parameters, primarily as a function of ambient temperature, height above sea level, weight of the payload and a fuel consumption target. The speed and position of the Penguin C in flight is controlled by servomotors operating the throttle and ailerons, wing flaps and ruddervators, and these in turn are operated in accordance with command signals from the autopilot. Penguin C has the capability to be controlled remotely over the internet. In this case the remote base station – which might be anywhere in the world with internet connection – has the ability to receive real-time flight data together with video. The autopilot also controls landing. The parachute release spring and its bay cover are both controlled by ‘on or The Penguin C is intended to be used primarily with a gimbal- mounted still and/or video camera For take-off and to reduce drag at other times when it isn’t required, the payload can be retracted into Penguin C’s fuselage November 2014 | Unmanned Systems Technology