I have little detailed knowledge of the BN-3; however, I did my first degree in aeronautical engineering at Southampton University circa 1989-1992. I used to sit in long dull propulsion lectures whilst simultaneously it was explained that propellers were old obsolete technology that we didn't need to learn about, whilst I watched trislanders fly past the window every 20 minutes.
I did eventually learn all about propellers, but not there ! I've certainly clarified in my mind that it wasn't me who was missing something.
G