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

75 MVVS 116 NP LC INJ | Dossier treated externally through cementation and hardening to enhance its lifespan. “As well as modifying the crankcase to fit different engine bays, there are various customisations we can make to the crankshaft,” he adds. “For instance, with one of our UAV helicopter customers, we’ve extended the shaft to have power take-offs extending from both the front and back of the block for driving more gears, belts and direct systems.” Lubrication Typically, Mobil Racing 2T oil is used in the 116, mixed with the 95 octane fuel in a 1:40 ratio and burned in the process. This is optimal for accommodating MVVS’ large user base of helicopter UAV makers and operators, many of whom might want the engine to be used with the crankshaft oriented vertically. Accommodating a separate wet sump would require some major design and manufacturing changes between crankcases, which would increase production costs and reduce the simplicity and commonality between components that is central to MVVS’ engineering philosophy. And if a dry sump were used, the company notes that adding oil lines (internally drilled and externally connected), pumps and filters would still drive up parts counts, maintenance costs and the system’s overall physical size. That can pose issues for helicopters, as often only limited internal space can be set aside for ancillary engine systems. A premix total-loss oil system is therefore judged as the best method of lubrication. Engine management The 116 is controlled using a Fly Henry engine management system, which includes a main ECU as well as connectors, sensors and further ancillary engine systems. The main hardware unit runs on a DC supply of 11-15 V, and consumes from 0.042 A up to 1.5 A in automatic operations (peak current drain occurring when set to its ‘Fuel Pump Automatic’ mode for altering the fuel delivery pressure). In its enclosure, it weighs 150 g and measures 92 mm long, 72 mm wide and 31.7 mm tall. It is designed for three core functions, the first being the management of the electronic fuel injection system, the biggest and most process-heavy. This takes place primarily through sequence control ranging of up to four injectors; although one is installed as standard, a second could thus be managed if requested for dual redundancy. Injection and throttle mapping can be achieved and controlled through a range of sensor inputs with which the ECU is compatible. As standard, six thermistors are installed – two cylinder head temperature (CHT) sensors (one atop each head), two exhaust gas temperature (EGT) sensors (one per outlet), a water temperature sensor and an outside temperature sensor. The engine also integrates a wideband oxygen sensor, a capacitive fuel level sensor, and a fuel pressure sensor, as well as voltage measurement sensors for the main power supply bus and for the power supply to the throttle servo. “The supplier of the injection system designed the fuel management to resemble how a carburettor is tuned,” Dundalek explains. “Carburettors have two needles – the H-needle and the A-needle – for regulating the passage of fuel into the engine as a mechanical function of air delivery. “The EFI control strategy is based on similar principles, but is carried out electronically. The oxygen, speed Unmanned Systems Technology | April/May 2022 The crankshaft is CNC-machined from steel as multiple parts before being pressed together, while the con rods are made from Certal (aluminium 7022) We don’t want to switch to a design that uses separate cylinders and heads, because then we’d need more screws to bolt the heads on