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

Hirth Engines The best solution for UAV applications 35 HF 35 series High performance, Lightweight and Fuel Efficient 60 HP Heavy Fuel 4201 42 series Perfectly matched Power and endurance 2-stroke Best performance for unmanned aerial vehicles (UAV) Ultimate control in extreme conditions More information: www.hirthengines.com Over 90 years in aviation UAV Navigation cutting edge autopilots for professionals Field proven reliability Navigation in GNSS denied environments Certified hardware DO-178C oriented software development Outstanding technical support Over 60,000 flying hours since 2004 www.uavnavigation.com Numerous satisfied tier 1 and professional customers worldwide MRS KittyHawk MR-10 and RavenHawk MR-20 | Digest Power distribution Such was MRS’ need for a fully integrated, streamlined powertrain that the company has designed and produced its own power distribution board. The concept arose early in its development roadmap, and the first versions were completed in mid-2020, MRS having found that it was easier to build its own than find COTS products suitable for UAVs. It is a circular module that serves as a bus board. It features a wide range of inputs as well as Teflon insulation parts to ensure safe connections to however many e-motors, ESCs, payloads or other systems MRS would want to install on one of its vehicles. “We’ve gone from prototypes that featured upwards of 100 solder points to this power distribution system that effectively requires none,” Nickell explains. “Any solder point is a potential point of failure, so it was critical for the long-term safety and reliability of our aircraft to see how close we could really get to zero soldering.” The initial versions of the power board were developed specifically for the KittyHawk and its 24 V bus, but the same design is fully transferable to the 48 V RavenHawk as well as the (currently unspecified) voltage to be used on the Dauntless. The board’s design consists largely of a pair of ring-shaped connector assemblies, with set screws used axially to secure the radially held connector inputs. “Our early prototype aircraft pulled enough power to melt a number of solder points on the initial power boards, which broke connections between subsystems,” says MRS co-founder Michael Dowell. “With this new arrangement though, if one of our end-users pulls too much power and causes excess heat build-up, they’re far more likely to weld their male and female connectors together than break them apart and risk cutting off, say, a battery pack or ESC. For end-users it makes for a much simpler plug-and-play I/O set-up for their electronics – they don’t need to worry about soldering at all when they want to install a new subsystem.” Flight systems While a few different data links can be used depending on mission requirements, MRS has found the Herelink system from Hex/ProfiCNC to be particularly effective across many of its flight tests and demonstrations, and anticipates using this system most often in the future. “That currently works over LTE to handle command telemetry, HD video from payloads and an FPV camera we’ve installed on the front, as well as other data,” says Dowell. At the centre of all the avionics and data is a Cube Orange autopilot from Hex/ ProfiCNC, with the open-source nature of the product enabling quick modifications or reconfigurations based on the