[DARPA is an important American military research organisation. Jan]

The drone that South African father-and-son Luke and Mike Bell built to win $750,000 (R12.2 million) in the Defence Advanced Research Projects Agency (DARPA) Lift Challenge cost roughly R1.2 million.

This is according to Luke Bell, who shared a breakdown of the build and travel costs with MyBroadband. He noted that approximately R600,000 in parts were provided by sponsors.

“It was actually very expensive, to be honest! In total, it was about R400,000 for all the R&D and travel costs. There was about an additional R600,000 in parts provided by sponsors,” he said.

“All in all, when the drone crashes and goes up in flames, as it did, that’s about a R200,000 fire just in parts.”

This brings the total cost of the drone to approximately R1.2 million, and it went on to win the team R12.2 million.

Bell also highlighted that, while DARPA runs the competition, it doesn’t own any of the intellectual property. He said DARPA holds competitions like this to motivate builders and further innovation.

“They are doing a round 2 in 2028, which they have made over two times more difficult. We will be entering that as well!” he added.

Luke Bell and his dad, Mike, built their drone and participated in the DARPA Lift Challenge as Team MTech, placing second and securing the substantial prize money.

The contest challenges participants to design and build ultra-efficient unmanned aircraft capable of carrying heavy payloads. The organisers set strict conditions.

The participating drones may weigh up to 25kg, including all their components and power sources, and must complete a 5-nautical-mile circuit in less than 30 minutes.

Aside from the monetary investment, the Bells invested months of their time designing and testing their aircraft in preparation for the competition.

Mike handled the frame engineering aspects of the build and mechanical fixes, while Luke took control of systems, electronics, design, and tuning.

Just shy of winning R31 million

The Bells’ drone took the form of a hexacopter, which has 6 rotors, and its frame was built from lightweight triangular carbon fibre, connected with custom 3D-printed connectors.

Mike was responsible for the truss frame, which he designed using structural engineering principles and truss systems to create a strong, lightweight structure capable of carrying heavy payloads.

It was designed using computer-aided design software, and Mike also carried out running repairs and structural fixes during initial load-testing failures.

Luke explained that the team used OnShape to strengthen the frame arms, modify the hubs, and design custom component mounts after the base design was completed.

On his end, he was responsible for the thrust rig and sensors, which he designed and built from wood, a strain gauge, thermistors, and an RPM logger to test several motor–propeller pairings.

After nailing down the best combination, Luke installed the motors and Hargrave ESCs on the frame before wiring it all together and configuring settings in ArduPilot.

He also hand-built the power source with high-capacity battery packs, a K-Weld spot-welding system, and 3D-printed cell holders.

The team improved the system over 140 tuning flights, during which they tested propeller efficiency and various autonomous flight paths.

The Bells’ first autonomous run was unsuccessful as the drone landed outside of the demarcated 10-foot landing circle.

However, during a second attempt in which the drone was flown manually, it carried a 54kg payload, giving it a 3.64:1 payload-to-weight ratio, and securing second place.

Team MTech had another go on the last day of the competition, during which they tried to succeed with a 4:1 weight-to-payload ratio.

It took off with a payload of 58.5kg, putting it slightly above the target ratio, and flew 2.8 nautical miles before encountering problems.

A crosswind led to one of the aircraft’s downstream motors drawing excessive power, which overheated its magnets and forced an emergency landing short of the finish line.

Had it succeeded in its final attempt, the team would have secured the grand prize of $1.9 million (R31 million).

Source: https://mybroadband.co.za/news/gadgets/668596-south-african-father-son-drone-team-turn-r1-2-million-into-r12-million.html