While it is theoretically possible to create an aircraft propelled by sound waves, there are several challenges and limitations that make it currently impractical.
One concept that has been explored is called the "acoustic levitation" or "sonic boom propulsion." The idea is to use intense sound waves or shockwaves generated by speakers or other devices to propel an object forward. By creating a series of rapid and controlled shockwaves, it would be possible to generate a net forward force on the aircraft.
However, there are several challenges with this approach. First, the energy required to generate and maintain the intense sound waves necessary for propulsion would be enormous, making it impractical in terms of efficiency and power consumption. Additionally, generating such intense sound waves would likely create significant noise pollution, making it unsuitable for practical use in populated areas.
Furthermore, even if we were able to overcome the energy and noise challenges, there are other limitations to consider. Sound waves are relatively slow compared to other forms of propulsion, such as jet engines or rockets. The speed and efficiency of sound-based propulsion systems would be significantly lower, limiting their practical applications for aircraft that need to travel at high speeds.
Currently, there are no viable sound-based propulsion systems that can replace conventional engines for aircraft propulsion. However, research and exploration of alternative propulsion technologies are ongoing, so it's always possible that new breakthroughs may occur in the future.