The ancient Indians (from India) had aircraft (Vimanas) and they were controlled by sound.

Why could this Tri-lobed disk not be a sound generator. At a certain RPM it probably produced a melodious sound, possibly even more than one single frequency, to then be utilized to do other productive things such as softening stone, producing anti-gravity or driving a whole army crazy with ultra-sound vibes.

Think about this - I feel that this is probably the best explanation of all.