3D-printed sound-powered jet engines propel micro drones — fliers are completely silent; researchers use ultrasonic frequencies to drive 12,000-RPM silent hovering fliers
A specially shaped 3D-printed resonator can make air shoot out of its nozzle and provide thrust when it hit with the proper frequency. While the prototypes don't deliver practical levels of thrust yet, they show proof that the concept works.
A research team at Switzerland's École Polytechnique Fédérale de Lausanne (EPFL) has created a novel "sound-powered engine" that utilizes 3D-printed cavities with specific shapes to harness sound waves at their resonant frequencies, generating thrust for micro-drones. These tiny flying machines are completely silent, as they operate using ultrasonic frequencies that are inaudible to humans.
The EPFL researchers demonstrated the concept with three practical applications: a boat propelled by three resonators and a pair of microfliers. The first microflier, resembling a rocket, lifts off using three downward-facing cavities, while the second, resembling a helicopter rotor, hovers thanks to three blades each equipped with a backward-pointing resonator.
When these resonators are struck with the correct frequency, they produce thrust enabling the microflier to rotate at over 12,000 rpm, allowing it to hover noiselessly. While the microfliers' maximum altitude is only about 5mm, and the boat is lightweight, the successful demonstration of this technology could pave the way for scaling up the design to power larger micro-drones for various applications.
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