Some trees, like maples and lindens, have seeds that don’t just drop; they spin. As they twirl through the air, the winged seeds slow their descent and catch the wind, giving them a better shot at traveling farther from the parent tree. It’s nature’s version of an efficient flying machine. Now, researchers in Singapore have taken a page from that natural design book and built something remarkable: a palm-sized flying robot that can hover for 26 minutes using just one motor.
Drones have evolved fast. Not long ago, they were a novelty. Today, they’re used for everything from search-and-rescue missions and environmental surveys to deliveries and warfare. But when Foong Shaohui from the Singapore University of Technology and Design (SUTD) set out to build a new type of drone, he didn’t want it bigger or more powerful. He wanted it smaller, and with much better endurance.
That’s nowhere near as easy as it sounds.
“Achieving flight becomes increasingly inefficient as you scale down. Small drones often have poor endurance because their small propellers generate limited thrust and yet still draw significant power. Our goal was to overcome that constraint,” he added.
Inspired by spinning seeds
The team turned to nature for inspiration. Specifically, they looked at how maple seeds can spin for long periods without any motor or propeller. That led to a breakthrough idea: what if the drone’s entire body became a spinning wing?
Most small drones use four or more rotors. This new design relies on just one. It’s a ingenious physics. As the entire wing spins, it generates lift and helps stabilize the craft. That spinning motion not only simplifies the design but reduces weight, mechanical complexity, and energy loss.
This approach also reduces what engineers call “disc loading,” a big reason why small propellers waste energy. Disk loading of a hovering helicopter is the ratio of its weight to the total main rotor disk area. The less disc loading, the more efficient the flight.
The team modeled their drone after the aerodynamics of spinning seeds, replicating the wing structure and carefully calculating the behavior of the motor and propeller in high airflow conditions. They also fine-tuned the mass distribution and wing geometry using data-driven optimization techniques, tweaking variables like pitch, shape, and center of gravity for maximum efficiency.
And it worked.
In lab tests, their design achieved a power loading of 9.1 grams per watt, outperforming other hovering micro air vehicles in its class. The wing is made of lightweight foam, the spar is carbon fiber, and there’s no complex gearbox or extra moving parts — just a tiny motor and rotor. “It’s a first-of-its-kind achievement,” said Research Fellow Cai Xinyu, who co-led the study.
What Can It Be Used For?
In indoor flight tests with motion-capture guidance, the monocopter managed to hold its position and altitude for a full 26 minutes, all on a single motor, with average power usage of just 3.5 watts. That’s longer than any other comparably sized hovering drone ever built. The entire machine weighs just 32 grams — about the same as a couple of AA batteries.
“The next step is to increase payload capacity and flight time without significantly increasing weight,” said Xinyu. “We’re also looking to explore advanced materials and bio-inspired wing morphologies into the design process.”
While this tech is still young compared to conventional drone systems, the method behind it is what makes it stand out. The researchers came up with a clever bio-inspired idea and then used AI-powered modeling and optimization algorithms to test and refine it. It’s a powerful mix of human insight and machine intelligence.
And the potential applications are already on the table. Because of their efficiency, simplicity, and small size, these monocopters could be ideal for tasks like deploying weather sensors from balloons, doing reconnaissance in disaster zones, or performing environmental surveys in places where larger drones can’t go.
The researchers believe this new approach could make a big impact in the long run.
“With further development, we see this technology playing a key role in a variety of established and emerging applications. The sky is truly the limit.”
