Issue 45 | Uncrewed Systems Technology Aug/Sept 2022 Tidewie USV Tupan | Performance monitoring | Bayonet 350 | UAVs insight | Xponential 2022 | ULPower UL350i and UL350iHPS | Elroy Air Chaparral | Gimbals | Clogworks Dark Matter

97 Elroy Air Chaparral | In operation He adds that humanitarian users such as AYR would traditionally have used manned helicopters for carrying and landing aid pallets, but the expense of operating rotorcraft coupled with the risk that certain missions pose to pilots and crew make UAVs an appealing option. Fleet maintenance and safety As with its cargo latching mechanism, Elroy Air has developed other test benches in-house for proving the components selected for the Chaparral, particularly with respect to its powertrain. “We built our thrust-test stand a few years ago to fully characterise, burn-in and measure the performance of electric motors, motor controllers and propellers,” Merrill says. “We took design inspiration from a stand NASA had built for similar purposes, and our tool allows us to run propulsors in excess of full mission operating parameters to benchmark rpm, thrusting force, torque, temperature, vibration, electrical current draw and more. “We also have developed a full ‘iron bird’ test bench, encompassing the C1’s powerplant, propulsors and control surface actuators, on a trailer. That enables us to run full mission profiles to characterise and validate performance in advance of flight tests, so we can find and fix problems on the ground before they can happen in the air.” At the time of writing, the iron bird contained the C1’s turboshaft engine and electrical generator, as well as fuel tanks, a battery pack, a power distribution box, four vertical flight motors and several control surface actuators. The system has enabled Elroy Air to run sustained powertrain performance tests to validate full mission power levels. Connected assemblies of the Chaparral’s avionics are also set up in the company’s facility to run hardware-in- the-loop tests in tandem with its in-house simulation environment. Running its flight code and control laws in simulation with avionics operating against the simulated environment and data allows the team to find and eliminate comms bottlenecks or other faults that can crop up when hardware and software operate together. The company anticipates that each vehicle will need perhaps 30 minutes of visual inspection each day, with onboard health monitoring systems expected to spot and flag up most potential issues. “With the redundancy we have designed into the electric motors and power system, any Chaparral suffering a power fault or propulsor failure should always be able to complete its mission and transmit its need for maintenance ahead of landing – unlike traditional helicopters – reducing the urgency, length and regularity of inspections,” Merrill says. “Typically, during take-off and landing, the high power demands of vertical flight mean we’ll have both the engine and battery delivering electrical power, but if the engine ever gives out completely the vehicle can make a safe landing on battery power,” he adds. “We deliberately kept the battery small to optimise aircraft weight, which helps any Chaparral with an engine failure to glide towards its intended landing coordinates and then bring itself down vertically to land.” Future steps The company is working with US government partners on certification, vehicle testing and operational concept development. Merrill cites a previous test flight campaign at the Naval Postgraduate School’s (NPS) test range at Camp Roberts in California as being representative of its productive ongoing partnership with NPS, and adds that the test flights were cleared in a very streamlined manner. Full type certification for the Chaparral is expected to take a few years, given the nature of the process, so in the meantime Elroy Air plans to focus on setting up early commercial operations overseas, in places where civil aviation authorities can quickly approve aircraft for commercial service. “That way, overseas humanitarian and commercial customers will be able to deploy the Chaparral while we’re working through FAA type certification,” Merrill says. “We have strong relationships with prospective customers in Africa, Australia and the Middle East for example, who want to carry packages, cargo and relief supplies using Chaparral systems.” Elroy Air is also preparing for flight tests with the USAF, which are set to begin soon. At the time of writing, the final subsystem integrations and validations of the C1 prototypes were underway. “Envelope expansion with the USAF will occupy the first and second C1 vehicles from now until the middle of next year, then in the back half of 2023 we’ll focus on demonstrating its capabilities with some commercial partnerships,” Merrill adds. A key commercial partner is FedEx Express, which was announced in March. The parcel-logistics giant plans to test and observe how the Chaparral handles middle-mile shipments between its facilities, which could pave the way to larger operational deployments. Other partners are expected to be announced in the next few months. Uncrewed Systems Technology | August/September 2022 Elroy Air Chaparral Hybrid-electric powerplant All-electric propulsion MTOW: 865 kg Payload capacity: 136 kg (nominal) 227 kg (maximum) Length x wingspan: 5.8 x 8 m Maximum altitude: 18,000 ft Maximum airspeed: 125 knots Maximum flight endurance: 8.5 hours Maximum propulsion power output: 250 kW Nominal range: 482 km Specifications