Unmanned Systems Technology 009 | Ocean Aero Submaran S10 | Simulation and testing | Farnborough report | 3W-110xi b2 TS HFE FI | USVs | Data storage | Eurosatory/UGS 2016 report

59 running without problem. The engine is unbelievably reliable. UAV customers – both military and commercial – put a great premium on reliability.” Interestingly, recent use of a 3W single- cylinder engine in the Antarctic has proved there is no loss of output and no reduction in TBO as a consequence of the environmental conditions. The package The 110xi is the heart of a turnkey solution from 3W for an entire UAV propulsion system, from fuel pump to propeller and including the damping system for the engine mounting in the craft. New systems can be tested at 3W’s headquarters installed in the craft, which is operated in a test rig with fans to simulate the airflow over it. Schudt remarks, “Our customers require no experience of power unit design and development – this can save them a lot of money.” 3W works closely with the customer on the choice of generator, the cooling airflow and the design of exhaust silencers and propeller. There is also cooperation in terms of the mounting points, which are part of the generator housing. One option is to use a generator mounted away from the crankshaft and belt driven from it, for packaging reasons. 3W is involved in the selection of generator since that has an impact on the engine in terms of considerations such as the inertia and vibration it creates. The propeller must also be carefully matched to the engine in view of the radial forces it generates. There are options of wooden and carbon fibre propellers, each tailored to a given application. Since it is a moulding, the latter is consistent in its manufacturing characteristics, whereas the wooden version needs to be individually tuned. Normally the ECU and the ignition boxes will be in one unit, but that is a customer decision. In the vast majority of cases the engine is supplied with the ECU ready mapped. “It doesn’t make sense for a customer to do their own mapping,” notes Wintrich. “You are more likely to spoil performance than improve it.” The complete propulsion system can be supplied ready to fly, the engine having been run in at the 3W factory. 3W can scale the 110xi up and down in displacement, should a customer require different power characteristics, although the likelihood is that another model from its extensive range will be a more satisfactory solution. It is possible to buy a carburettor-equipped version (using an alternative throttle body) if a customer should so desire. The 110xi equally suits fixed-wing and rotary craft, and 3W has supplied it for use in a series hybrid system, the engine operating a 1.5 kW generator that in turn feeds the battery serving multiple electric motors in an unmanned multi-rotor craft. Schudt emphasises that the 110xi has proved to be extremely robust with a notably long TBO. In addition to light weight, it offers very competitive fuel efficiency, making it an attractive package for UAV developers, he says. He adds, “For military use the quality control has to be very high, and for commercial use the fact that this means the engine keeps on running is good for turnover. “Most airports now have Jet A1 available so commercial users can benefit from running on that heavy fuel, which is a controlled specification fuel so the quality of it is assured wherever in the world it is purchased.” Unmanned Systems Technology | August/September 2016 Preparing a bore of the 110xib2 TS HFE FI We tested one of these engines by running it hard for 240 hours, then disassembled, cleaned and restarted it, and it continued running without problem