Issue 39 Unmanned Systems Technology August/September 2021 Maritime Robotics Mariner l Simulation tools focus l MRS MR-10 and MR-20 l UAVs insight l HFE International GenPod l Exotec Skypod l Autopilots focus l Aquaai Mazu

65 with port injection at the intake channel. “And for quick health monitoring we’ve installed some LEDs to indicate the ECU’s status – if it’s on, powered and functioning normally or not,” West adds. If Mil-Spec certifications are required, the GenPod will come equipped with a Currawong ECU and fuel pump. “We’ve also worked to optimise the cylinder balancing in the ECU timing,” West says. “With a boxer, when you’re using a single injector at the intake – as Desert Aircraft does – there’s a risk of scavenging imbalance where you’re pulling more fuel into one cylinder than the other.” “With our ECU, we can adjust the injector phasing so that we can inject at exactly the right time to push more fuel earlier in the crank cycle to get the balance of fuel right between the two cylinders. These adjustments are based on a predictive mapping constructed by cycling multiple units of each model of Desert Aircraft engine.” Fuel injection and air intake Ignition is performed using a capacitive discharge ignition system from Desert Aircraft, slightly modified for increased ruggedness. Notably, HFE has added heat-shrink tubing around the metal snakeskins of the wiring harnesses running from the EFI unit to the spark plugs, with clamps to hold the wires still amid vibrations and g -forces. Tests according to standards such as FAR 33 have been carried out to prove the long life and ruggedness of the harnesses and other dynamic systems, given that points of free movement such as these are where most premature failures are likely to occur. The GenPod’s throttle is designed around a customised servo from Volz that has a 2000-hour service life. West adds that this servo is the biggest contributor to the GenPod’s 300-hour TBO (when classifying the TBO not only in terms of core but ancillary engine systems as well). “It’s basically a smaller packaging arrangement of Volz’s DA 15-05-32,” West says. “We asked them to redesign it for how it mounts to the brackets and how it fits inside its packaging, and that made it small enough to fit inside our intake air filter assembly.” Both the servo and the fuel injector are contained within that air filter assembly, which sits at the end of the GenPod’s intake manifold. The fuel line for the injector, as well as the wiring harness for the throttle and sensors, enter that assembly from beneath before emerging upwards into it to connect with their respective systems. A fitting for a manifold air pressure sensor is also installed at the bottom of the air filter, with a tube running from it into the manifold. “We’ve tried to put everything we could inside the air filter, because in the sandy environments where a lot of our engines are used, the throttle bodies, servos and other parts always became jammed Unmanned Systems Technology | August/September 2021 HFE International GenPod | Dossier HFE’s engineers have installed heat-shrink tubing around the EFI wires’ metal snakeskin jackets for increased ruggedness