South African engineer builds pure solar drone
Luke Maximo Bell's solar drone flies with the power that solar cells currently provide. The drone's design is particularly efficient.
(Image: Luke Maximo Bell/Screenshot)
Australian engineer Luke Maximo Bell has built a drone that is powered exclusively by solar energy. To achieve this, however, Bell had to make some optimizations to the drone in terms of weight and efficiency.
Bell built the drone from scratch, which he and his father had already become known for with world-record-breaking high-speed drones. Its basic structure essentially consists of two carbon rods connected crosswise by 3D-printed connectors.
At the ends, Bell attached four T-Motor Antigravity MN4004 300 KV motors. These are lightweight, powerful brushless drone motors that achieve 300 revolutions per applied volt of voltage. The motor uses a single copper wire winding, thus minimizing energy loss, and has a very slim design. Additionally, the motor dissipates heat well and is stable. Overall, the motor is said to provide very good dynamic rotor balance and be capable of rapid acceleration. This allows for stable flight with the NS-18x16 rotors, also from T-Motor and made of carbon fiber. Their low weight means less mass needs to be accelerated, which improves flight efficiency, Bell explains.
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Additionally, the engineer equipped the drone with landing gear below the motors, also 3D-printed, which gives the drone some distance from the ground during takeoff. Bell placed the control electronics in the center of the drone.
Efficient Design
Initially, the Australian conducted a test flight with the drone using a battery. After calibration, the drone flew largely stably. Bell also determined the power required for takeoff and conventional flight operations to calculate the necessary solar cells. According to Bell, the motors generate a lift of 17 g per watt. However, his drone only needs 0.7 g per watt to ascend, which indicates the high efficiency of his design.
Then Bell turned to the actual power source of the system: the solar cells. For this, he used Maxeon Sunpower C60 silicon solar panels with an edge length of 161 mm. They produce approximately 5 watts per cell in full sunlight and are ultra-lightweight—but also very fragile, as he unfortunately discovered multiple times. Bell combined three arrays of 3 × 3 panels each, achieving an output voltage of 24 volts at approximately 97 W. At peak, the power output was even higher under full sunlight.
Dell attached the solar cells to a structure of lightweight carbon rods, which he mounted on the top of the drone. Before that, he had tested with a resistance measurement whether the solar cells would deliver sufficient energy at all.
Bell succeeded in making the drone ascend in full sunlight. He used neither capacitors nor a battery for intermediate buffering of the current.
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The Australian now plans to expand the drone with a buffer battery and autonomous functions. His goal: He wants to set a world record for the longest-flying drone.
(olb)
