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68 Dossier | MVVS 116 NP LC INJ the early 2000s as part of a major push to modernise its engines and manufacturing services. For the parts not made in-house, or treated or customised elsewhere, MVVS has largely sought to partner with suppliers in the Czech Republic, to minimise shipping costs, make face-to-face bespoke collaborations as easy as possible, and to foster resilient supply chains and r&d in its local economy. The company says it has now sold hundreds of this 116 cc engine, across Europe, Asia and North America to UAV OEMs including well-established manufacturers such as Sung Woo Engineering in South Korea, Yugoimport in Serbia, and Steadicopter in Israel. Such companies have used both the 116’s fuel-injected version and those using carburettors, including a number of slightly customised versions to fit the chassis and engine bays of different unmanned systems. Operation It has proven particularly popular with integrators and manufacturers of helicopter UAVs, whose operators and technicians appreciate the engine’s relative simplicity, liquid cooling (without the need for downwash air cooling from high airspeeds or rotor rpm), and a lengthy TBO of 360 hours – far higher than that of a typical hobby engine. On top of the TBO, the company recommends internal inspections of the engine every 80 hours, and the use of a 30 in-diameter, 10 in-pitch Mejzlik propeller during fixed-wing operations; Mejzlik is co-located with MVVS. The redline speed of the 116 is given as 9500 rpm, with a minimum speed of 900 rpm, although the actual rpm range for the operating flight envelope runs from 1500 to 7000 rpm. As mentioned, its maximum power output is 8.4 kW, which is achieved at 5900 rpm. The static thrust at this output is 26 kg of force, although that also takes the engine close to its peak specific fuel consumption (SFC): a rate of 4.7 litres/ hour typically accompanies a 6000 rpm crank speed. Below this speed the SFC drops sharply, to 3.15 litres/hour at 5500 rpm, and at a cruising speed of 4100 rpm the 116 consumes 1.26 litres of 95 octane unleaded petrol per hour. April/May 2022 | Unmanned Systems Technology MVVS was founded as the Model Research and Development Center in October 1953, and is currently located in Brno in the Czech Republic. Establishing the state-owned centre was motivated by the wishes of the-then Czechoslovakian government to keep Czechoslovakian aircraft models competitive internationally. To that end, the first head of MVVS was Zdenek Husicka, a well-known aeronautical modeller, theorist and holder of several world speed records for tethered model aeroplanes. The engines and designs from MVVS won Czechoslovak teams several medals and world titles in speed and acrobatic model flying in the 1950s. Production facilities and engine lines expanded in the 1970s and 1980s, and privatisation followed in 1991. After the company was sold, in 2001, a major effort was made to modernise the componentry, treatments and materials of every MVVS engine, including the transfer of all production operations to newly purchased CNC machines. The company also scaled back some outsourcing of core engine components in favour of in-house production with its new machinery, for better quality control. These efforts and the new r&d that came with them culminated in the 2006 release of a new line of 58 cc, single-cylinder gasoline engines that quickly formed the core offering of MVVS’ hobby RC business. Further r&d through the 2000s expanded on these designs to include 116 cc engines (modular two-cylinder versions of its 58 IRS product) as well as 175 cc and four-cylinder 190 cc engines. Following the release of the 58 cc series, the company planned to move into designing professional-grade engines for UAVs. In 2018, it officially announced a cooperation between its engineers and the Czech Technical University in Prague, to test and hence adapt its existing 116 cc engines to exploit critical technologies for commercial UAS operations, such as electronic fuel injection, liquid cooling and high-power starter/alternators. These days, MVVS is working to expand its offerings in the professional UAV space through r&d on its engines’ fuel efficiencies, lifespans and reliabilities, while also continuing to devote resources to its hobby engines. It also plans to expand into high-speed target UAV engines. History of MVVS We have now sold hundreds of this engine to UAV OEMs such as Sung Woo Engineering, Yugoimport and Steadicopter