Unmanned Systems Technology 004 | Delair-Tech DT18 | Autopilots | Rotron RT600 | Unmanned surface vehicles | AMRC | Motion control | Batteries

23 Delair-Tech DT18 | Dossier than 10% of the fuselage, wing and vee- tail composite structure is anything other than glass-reinforced. The lithium-polymer battery is housed in the wing structure, which has some wooden longitudinal spars. De Lagarde notes that given the composite construction of the wing, these spars are not fundamental to reinforcing the structure. The wing flaps articulate cleverly using special areas of the composite skin as hinges, while the servos operating them are mostly inside the wing to minimise their aerodynamic impact. The vee-tail is V-shaped when seen in front elevation, and when seen in side elevation its central longitudinal axis runs along the top of the fuselage, to which it has front and rear connections. The rear connection is hinged. This means that if the front connection is broken, the oncoming air will cause the entire tail to rotate upwards and rearwards around the hinge. There is a provision within the onboard control system to break the front connection given certain stacked failure conditions. The consequent backwards flip of the vee-tail will create a deep stall that will send the craft into a descent, hopefully reaching the ground without damage to itself or its surroundings. The snout of the fuselage is open, with the propeller-motor assembly providing closure. On the face of it, there is no specific cooling for the motor or the other electronics inside the fuselage. However, there is a very small opening in the propeller nose cap that ducts air through it, into the fuselage where it passes onward through an aperture in the nose bulkhead. This could arguably be considered an air cooling system, although there Unmanned Systems Technology | Autumn 2015 The vee-tail is made in one piece and is attached to the fuselage at a point on the front of its longitudinal axis and another on the rear. The rear is a pivoted joint, which in forward flight allows the tail to flip backwards if not secured at the front. The front connection is a screw fixing that can be deliberately broken by a patented mechanism in the event of the control system triggering an immediate emergency landing. Rigidly mounted into the fuselage, the motor is of the brushless dc type run by an electronic speed controller. The propeller is directly connected to an extension of the motor’s rotor shaft, and it has two flexible blades that are each hinged to one end of a rotating metal arm, a hole in the centre of which fits over a cone formed in that driveshaft. A nut on the front of the shaft squeezes the arm back against the cone, thus providing a grip that transfers drive from shaft to blades. The propeller has a nose cap ahead of the arm, concealing it for aerodynamic reasons. Key component suppliers Propeller: Aeronaut Motor: Axi Speed controller: in-house Battery: in-house (with multiple suppliers for the cells) Battery charger: Graupner Pitot tube: in-house GPS: in-house (with Ublox chip) Voltage regulator: in-house Autopilot: in-house Antenna: in-house Image sensor: IDS Other sensors: Thermoteknix  Data acquisition: in-house Electronics boards: in-house Wiring: in-house Wind tunnel testing of the DT18 prototype The only airframe sealing is via O-rings; there is no seal between the payload bay section and the fuselage, and overall the craft is splash-resistant