I finally got my hands on a 20" 5-blade box fan after so long since I started collecting vintage fans. The grilles on this fan are a little darker than on my Ambassador 4-blade. It may have been used in a window. The noise you hear is not from the motor but from the front grille. The motor, I don't believe, is a Westinghouse motor like inside my Ambassador. I'm a fan of 4-, 5, & 6-blade propellers. Thanks for watching!