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

71 MVVS 116 NP LC INJ | Dossier “The cost of EFI systems is higher than carburettors,” he says. “The latter are produced by the thousand, they’re simple to operate and easy to maintain, so new adopters of UAVs can more easily afford to buy, install and run them. “But EFI becomes really critical for customers who want not only to use fuel more efficiently but to fly at higher altitudes, up to 5000 m, and we can adjust performance electronically through the software to match any other particulars of EFI users’ operating conditions.” Both charge delivery systems typically sit at about the same location atop the engine. If EFI is selected, a single fuel injector is installed, below and in front of the throttle body inside the inlet manifold leading into the crankcase. The angle of the injector is 90 º to the axis of the intake channel, and it sprays fuel into the path of oncoming air at a pressure of 2 to 2.5 bar. The carburettors are supplied by Walbro, although the systems are adjusted in-house to integrate MVVs’ throttles, flaps and shafts about the Walbro core, with the throttle sized for a 25.4 mm diameter when fully opened. A reed valve sits at the bottom of the air manifold. It is made from carbon fibre that is cut and processed in- house, the shape of the valve having been optimised through r&d aimed at maximising the system’s reliability. Engine block Once in the crankcase, the charge is drawn into the cylinder through a standard Schnuerle porting system. Two transfer ports allow the charge to be forced into the combustion chamber Unmanned Systems Technology | April/May 2022 While the 116 NP LC is MVVS’ flagship product for UAVs, and the wider family of 116 cc twins and 58 cc single- cylinder engines are used in a variety of UAVs, it has also begun offering one of its other designs to the unmanned space: the 190 CN4. This is a naturally aspirated, air- cooled four-cylinder boxer engine that for several years has been the company’s star performer for high- power RC aircraft. Like the 116, it is a modular expansion of one of the company’s previous designs, a 50 cc single-cylinder, with the same cylinders and pistons. Each cylinder has a 40 mm bore and a 38 mm stroke, for a total displacement of 191 cc. “The architecture and materials bear notable similarities to the 116 engine as well,” comments Radim Dundalek, executive director of MVVS UAV engines. “For example, the crankcase is CNC- machined from aluminium alloy, although with more parts and more screws owing to it being a bigger engine. The cylinders and pistons are also aluminium, and the crankshaft is made from multiple pieces of pressed steel alloy.” Both engines also run on 95 octane gasoline, and use a 1:40 premix of Mobil Racing 2T oil in the fuel. Fuel/air management on the 190 CN4 is typically achieved using twin carburettors (HDA189 units from Walbro), although an EFI system is available using many of the same components as the 116. When carburetted, the 190 consumes 5.37 litres/hour at a cruising speed of 4000 rpm, and can fly at altitudes of up to 3000 m; if EFI is selected, consumption drops to 3.94 litres/hour and the flight ceiling is lifted to 5000 m. The TBO is also extended from 300 to 360 hours when switching from carburettors to injection, although checks are recommended more often with EFI (every 80 hours, compared with every 100 for the carburetted version). Overall, the engine weighs 4.42 kg and outputs up to 15.3 kW at a speed of 6500 rpm, with a redline speed of 9000 rpm. “That 15.3 kW does not include any additional power from a generator, but we can include a large direct-drive generator in the propeller washer or a small belt-driven one,” Dundalek adds. The 190 CN4 engine The 190 CN4 is MVVS’ flagship product for competitive model aircraft, and like the 116 it is available with EFI or a carburettor