South African duo win $750,000 in Darpa heavy-lift contest – sUAS News

A South African father-and-son engineering duo have taken second place and a $750,000 (£570,000) cash prize in a prestigious military aviation contest after building a custom-designed drone that lifted nearly four times its own weight.

Mike Bell and his son, Luke Maximo Bell, competing as Team MTech alongside US collaborators, spent months testing and iterating aircraft on a farm in South Africa before travelling to Dayton, Ohio, for the Defense Advanced Research Projects Agency (Darpa) Heavy Lift Challenge.

The competition, which featured a $6.5m (£4.9m) total prize pot, tasked international engineering teams with an objective previously considered near-impossible: building an autonomous drone weighing under 55lb (25kg) capable of carrying four times its own weight over a course of up to five nautical miles (9.3km).

Weighing just 29lb (13kg), the team’s hexacopter aircraft relied on a lightweight triangular carbon-fibre truss frame held together by custom 3D-printed connectors designed in cloud-based computer-aided design software. Flight control and autonomous navigation were managed by a CubePilot Cube Orange+ autopilot running ArduPilot open-source software, while power was supplied by high-energy-density Amprius battery cells capable of storing 390 watt-hours per kilogram, which Luke hand-welded together in an Airbnb during the event.

The team’s path to the podium was marked by relentless setback and repair. Early prototypes crashed into farm ponds during aerodynamic wing tests, while violent motor vibrations repeatedly tore wiring loose from circuit boards during high-power trials.

Upon arriving in Ohio, an initial successful flight carrying a 111lb (50kg) payload — achieving a 3.41:1 payload-to-weight ratio — was disqualified when the aircraft’s autonomous navigation system landed slightly outside a mandatory 10-foot target circle. Undeterred, the team re-flew the course manually, carrying a 119lb (54kg) load to lock in a 3.64:1 ratio and secure second place.

With second place assured, Team MTech made a final bid on the competition’s last day for the historic 4:1 barrier and a potential $2.5m (£1.9m) grand jackpot. Outfitted with custom 3D-printed aluminium heat sinks to prevent motor overheating, the aircraft took off carrying 129lb (58.5kg) — a 4.04:1 payload-to-weight ratio.

The drone flew autonomously for eight and a half minutes over 2.8 nautical miles (5.2km) before a crosswind forced a downstream motor to draw excessive power in turbulent air, overheating its magnets and forcing an emergency landing just short of the finish line.

Despite falling short of the finish line, the team’s performance set a competition record for the heaviest ratio flown over distance. In recognition of their achievement, the aircraft will be placed on permanent display at the National Museum of the US Air Force in Dayton, Ohio.

“We registered late, we crashed a lot, and destroyed multiple drones,” said Mike Bell. “There were moments we genuinely felt it was hopeless. But we placed second, and made the strongest attempt at 4:1. To have our aircraft displayed in the National Air Force Museum — well, that’s something to be pretty proud of”.

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