fuel-delivery system to discern whether the fuel has frozen or a filter has clogged. Additionally, a MAP sensor is integrated as standard, along with sensors for manifold air temperature and humidity. Onward and upward Having validated the RW1 engines in dynamometer tests, cycling them in environmental pressure and refrigeration chambers, as well as vibration tables, while scanning them with high-speed and infrared cameras to study for mechanical and thermal performance, UAVHE is now looking towards production numbers. It anticipates scaling back manufacturing of its piston engines in favour of its rotaries. “In terms of new products, we’ve done a few projects in jet engines and have learned what it takes to make ECUs, fuel injectors and so on for those, so we’re hoping to show some hybrid turbojet designs by 2025,” Bogdanov says. “We’re also planning to diversify into making helicopter transmission parts, from swashplates to rotor heads. It will need some skilled specialists, but in most cases the overall helicopter powertrain loses a lot of its quality if it uses an engine, a transmission and a rotor from three different manufacturers without a common telemetry, common design approaches and so on.” UAVHE is also investigating the use of sustainable aviation fuels (SAF). Neste in Finland has provided some samples for testing, while Repsol in Spain has produced a bio-kerosene formula that Bogdanov cites as producing “great” performance in his company’s engines. Meanwhile, at UAVHE’s manufacturing plant, raw materials and finished components are being closely tracked along production lines, with QR codes for exhaustive traceability and quality control logging. Its production machines include 5-axis and 9-axis CNC milling machines from DMG MORI, with additional CNC metal cutters from Haas and other companies, as well as laser etching machines for the surface texturing of iron sleeves to improve oil distribution across some components. “Haas’ machines come with a control system they’ve made in-house, so operating them is quick and intuitive. Their control hardware advances slowly, but their software gets optimised and hot-fixed very quickly,” Bogdanov says. “Bigger brands often use something like a Siemens Fanuc control system, which is well-made but problems get fixed really slowly. With Haas, by contrast, I once asked them to add some M-code to extract some data. They did so, and through that my machines now send me notifications based on entirely custom data triggers. “I’ve been working around CNC manufacturing for the last 20 years, and the progress I’ve seen over the last five to six years has been amazing. I know there’s endless buzz about additive manufacturing, but multi-axis CNC machines can now be used to mill really complex shapes with more precision than ever. I honestly feel like we’re in a golden age of CNC production in which hardware simply isn’t a limiting factor anymore.” 79 Uncrewed Systems Technology | April/May 2024 RW1-79 Wankel rotary hybrid Range extender Single rotor, charge- and oil-cooled Electric supercharger Two-stage fuel injection Forced air-cooled housing Weight: 5.2 kW Dimensions: 162 x 177 x 193 mm Effective displacement: 79 cc Power: 22 hp Maximum generator output: 11 kW Fuels: JP1, JPA, wide range of automotive and aviation gas SFC: 240-260 g/kWh Maximum continuous speed: 13,000 rpm Oil: API TC TBO: 690 hours tested, 1000 hours expected RW1-300 Wankel rotary hybrid Gearbox with centrifugal clutch Single-rotor, charge- and oil-cooled Electric supercharger Two-stage fuel injection Liquid-cooled housing Weight: 17.7 kg Dimensions: 330 x 280 x 280 mm Effective displacement: 298 cc Power: 62 hp Maximum generator output: 11 kW Fuels: JP1, JPA, wide range of automotive and aviation gas SFC: 250-260 g/kWh Maximum continuous speed: 9500 rpm Oil: API TC TBO: 690 hours tested, 1000 hours expected Some key suppliers: Spark plug ceramic insulators: NGK Electrical components: Amphenol CAD software: Ansys CAD software: Matlab CAD software: Solidworks CNC machines: DMG MORI CNC machines: Haas CNC machines: Starrag Bumotec Specifications
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