Uncrewed Systems Technology 043 l Auve Tech Iseauto taxi l Charging focus l Advanced Navigation Hydrus l UGVs insight l MVVS 116 l Windracers ULTRA l CES 2022 show report l ECUs focus I Distant Imagery

70 Start-up and ignition For electric starting in hot as well as cold conditions, a brushless DC motor/ generator weighing 686 g is installed on the front of the crankshaft, in a chamber on the front of the crankcase. As Radim Dundalek, executive director of MVVS UAV engines, explains, “Some customers require the starter, others prefer their own systems, but as standard we deliver the engine with it. It is made, tested and fully validated in-house. “To ensure the generator’s capabilities and functioning are optimised, we collaborate on its design with Fly Henry, a company in the Czech Republic well- known for its many electronic and electric systems it supplies to UAVs, ultralights and light sports aircraft. They provide excellent parts and consultation on quite a few components in our engines.” Fly Henry’s generator systems are designed typically as PMAC systems, using NdFeB magnets, and copper windings insulated for up to 200 C, with six pole-pairs and 14 permanent magnets. Performance-wise, they supply 13-18 V at 1000 rpm, and are tested to operate safely in environments from -40 C to 120 C. “The generator’s maximum power is 1100 W, but we can customise this for a customer depending on their individual weight and power requirements, as different UAVs require different power outputs to run their payloads and other onboard electronics,” Dundalek adds. Ignition systems for the 116 come from two different suppliers: Fly Henry and Falkon Electronic in the Czech Republic. Having a choice here was key to the company’s continued production efforts during the severe supply chain shortages experienced in 2021. “As standard, we install one spark plug in the middle of each cylinder head, but we have experience of designing, testing and supplying engines with dual spark plugs for redundancy and hence reliability without changing the effect on combustion,” Dundalek comments. Both suppliers provide MVVS with capacitive discharge ignition systems, although the standard-issue 116 most often uses an NGK CM-6 spark plug, which comes with a 10 mm thread, as well as a single controller unit housed in a 39 x 16 x 16 mm triple-gasket sealed enclosure using nickel metal electrodes, and weighing 280 g. Charge delivery As mentioned, the 116 engine can be supplied as either a carburetted system or with EFI. Dundalek notes that the carburetted units sell well, even among its UAV clients, despite the reliability and fuel efficiency boosts inherent in EFI. The primary differentiator among customers is cost. April/May 2022 | Unmanned Systems Technology Either a fuel injector or a carburettor will sit beneath the throttle before charge enters the crankcase via a reed valve The 116’s crankcase is CNC-machined from duralumin for flexibility and cost- saving relative to casting Carburettors are simple to operate and easy to maintain, but EFI becomes critical for anyone who wants to fly at altitudes of up to 5000 m