Cooling fan question...

Once had an aftermarket fan that wasn't off-set, and at certain engine speeds it sounded like a small aircraft.
Something to do with harmonics.
My previous ranger and my Frontier both have plastic blade clutch fans, and they have equal spacing between them all, so no offset. Can’t say they’re noticeably louder than the Jeep due to their Fan blade design, really all 3 vehicles sound like hurricanes. Maybe if the trucks had metal blade fans, they’d be louder than than the Jeep though? No idea. Really doesn’t matter to me, if I can hear it, I know it’s cooling :ROFLMAO:
 
It was actually a common swap on TJs to switch to an 11 blade Ford Explorer fan and HD fan clutch. Now that makes some noise. Also moves a ridiculous amount of air.