Unmanned Systems Technology 005 | Selex ES Falco UAV | Sense and avoid systems | RCV Engines DF70 | DSEI show report | Fuel cells | CUAV Expo, InterDrone and CUAV Show reports | SLAM

23 Selex ES Falco UAV | Dossier Unmanned Systems Technology | Dec 2015/Jan 2016 normal fuel, although unleaded petrol can be used if the customer desires. Maximum power is 90 bhp at 7000 rpm, and fuel consumption is quoted by the manufacturer as 0.55 lb/bhp/h at 70% cruise. Engine weight is 56.5 kg including the cooling system and a generator. The rotary-type engine is notable for a lack of external vibration but inevitably there is some associated with its operation, in view of which it and its accessories mount to the airframe via anti-vibration mounts. At the front of the engine bay is a structural aluminium bulkhead that carries a sheet steel panel to act as a firewall. Two electric pumps draw fuel from the tank to the engine (two are used for redundancy) and these are mounted on the engine bay side of that firewall. Where the fuel lines pass through the firewall there are non-return and shut-off valves. These valves isolate the engine bay from the fuel tank in the event of fire. The main fuel tank bladder sits inside a carbon fibre box, which in turn is bonded to the fuselage. Engine lubrication is provided by passing oil through it to be burned off in the exhaust on a total loss basis. In view of this a metal tank in the engine bay holds a supply of lubricant, which is fed to the engine by a mechanical pump driven off the rotor shaft. As temperature drops with altitude, so does the viscosity of the oil, and for this reason the tank is heated using hot engine coolant. The radiator for engine cooling is located in a through-duct underneath the engine. This duct extends below the depth of the main fuselage to present an opening to the oncoming air. Having passed through the radiator, the exit is in the direction of the propeller, with the action of its blades helping draw the flow through it. The propeller is driven via a toothed rubber belt, and consequently it is always turning with the rotor shaft. The two drive pulleys are sized to provide a speed reduction, normally arranged to be of the order of 2:1. Typically therefore the crankshaft will run at 6000 rpm with the propeller turning at about 3000 rpm. The propeller is three-blade, with pitch adjustment only possible manually (while stationary). The propeller is a wooden construction with a fibreglass covering and metal reinforcement for the leading edges. The engine management system is part of the electronic control system developed in-house for the entire craft. It is a redundant system, having all sensors and each processor duplicated. The flight management system was specifically designed for the Falco and is produced by Selex ES. The key servo controllers are those operating the ten ailerons/rudders, the engine throttle, the two individual wheel brakes and steering for the centrally located front wheel. For taxiing, the single central nose wheel is steered while the side wheel under each wing can be individually braked as appropriate. The steering and the individual wheel brakes are all controlled by individual servos. The wheel brakes are hydraulic disc brakes, each disc restrained by pads in a single-piston caliper. Thus the landing gear consists of three aluminium legs, each of which is shrouded by a carbon fibre fairing, carrying steel hubs that in turn are fitted with pneumatic tyre-shod aluminium wheels. All three wheels are connected to an individual oleo- pneumatic shock absorber. The wheels under the wings have angled legs that cross each other (forming an ‘X’ when seen in front elevation) within the fuselage. The respective shock absorbers are mounted in the top of each leg beyond the crossover point. The nose wheel is equipped with a mudguard to protect the payload behind from dirt and debris thrown up when taxiing on a semi-prepared airstrip. In addition to the main parachute there is a rear parachute mounted centrally on the tail section. In terms of environmental protection, the fuselage is designed to expel any water ingress. All air cooling ducts are designed such that water will separate from the airflow, falling downwards through drainage channels. The key to the successful operation of the onboard electronics is to keep system temperature under control. This is achieved by forced air cooling of the avionics and payload bays. The Falco is fully equipped with aviation lights, as per a conventional aircraft, including taxiing lights. Some component suppliers to the Falco Engine: UAV Engines Composite components: Compositex Composite components: Riba Composites Recovery system: DBS Avio Para Service Wideband data link: Italiana Ponti Radio Propeller: Hoffmann Propeller Quality control equipment: MDL Renishaw Fuel tank bladder: ATL