Unmanned Systems Technology 011 | C-Astral Bramor ppX | IMUs | Autonomous farming | UAV Turbines UTP50R | London Show report | Advanced materials | Las Vegas Expo report

56 Dossier | UAV Turbines UTP50R 50 hp recuperated gas turbine contains a dozen bearings (all ball aside from one roller) – and the shaft bearing compartment share the same oiling system using a pump to scavenge oil from the bearing compartment. That is the only scavenge pick-up; the gearbox is wet sump. The oil pump combines one scavenge and one pressure stage, both of the gerotor type. The oil pump is run off one of the two planet gearshafts, the permanent magnet starter/generator running off the other one. The oil pump runs at a fixed ratio of the rotor shaft speed, and the supply of oil from the pressure stage is split between the engine bearings and the gearbox bearings. The oil pressure is about 200 psi owing to the requirement of the variable propeller, which exploits the same system. The lubrication side runs at about 20 psi. The gearbox provides a reduction from the 106,000 rpm of the output shaft to the 6000 rpm of the propeller, its exact speed set according to customer requirement. The slower the propeller, the more efficient it is, but the slower it turns the bigger it needs to be, so there is a trade- off according to the individual installation. Conventional variable-pitch propellers have an electromechanical operating mechanism, whereas UAV Turbines has developed a fully electronic system which is less complex, reducing cost and weight as well as enhancing reliability. “We have two solenoid valves under the command of the engine management system,” explains Frigerio. “These regulate the oil going in and out of the system, and that eliminates a lot of the complexity in a regular constant-speed, variable-pitch control system. Essentially you are relying on modern computer controls to govern it, rather than having a 1960s electromechanical system.” This approach provides a full-authority integrated propulsion control system, governing both engine speed and propeller pitch as an entire system. December/January 2017 | Unmanned Systems Technology Compressor/turbine castings: Precision Castparts Corp Compressor/turbine: Bogue Machining Housing castings: Uni-Cast/Vaupell Rapid Solutions Housing: Giuliante Machine Tool Shafts: Sirois Tool Gears: Delta Research Bearings: GRW, Barden, Cerobear Seals: JetSeal Threaded components: McMellon Gaskets: in-house Ignition system: in-house Fuel system: in-house Engine management system: in-house Starter/generator windings: Motorsolver Data acquisition: National Instruments Pumps: Parker Oil filter: Pall Air filter: Pall Fluid lines: in-house Wiring loom: in-house Heat exchangers: undisclosed Fuel pump: undisclosed Valves: The Lee Company Suppliers to UAV Turbines include Another view of an engine core instrumented in the UAV Turbines test cell