Sonic Ramjet Propulsion

When you play sound on a speaker, you generally expect it to be distributed roughly evenly in the surrounding area to be sensed by listeners’ eardrums. Given sufficient power input, especially as frequencies approach the lower limit of our ability to hear as humans (i.e. single digits in Hz) we can feel, and sometimes even see, the results of this sonic manipulation in the form of vibrations.

The Sonic Ramjet (SR) project takes this sonic energy and controls it via a carefully designed cone structure attached to a small speaker. A simple 40 Hz signal to this speaker produces a standing wave that blows air out of the end of the cone. Multiple SRs have been designed and tested, with two available for download as STLs.

As shown in via a video on the project page, a single SR can generate enough air flow to blow paper towels around. Another implementation uses two SRs on either side of an electronic control assembly to form a strange craft that moves along a table under smartphone control. An STL is available for this Sonic Buggy, and instructions for building either the SR by itself or the SR-based Buggy are available via the project write-up.

It’s a cool concept, and it would be great to see other projects based on this type of sonic setup. As noted o the SR's page, “The tools we have access to today are insane. Don't let your dreams be dreams.” Definitely words to live by if you come up with an exotic, 3D-printable propulsion device!