TM...so what's the difference between a Harvard and a Wirraway? Or just different name? Sounds like the start of a joke, but really a serious question
Very little. Both came from a basic North American design I think. The Wirraway had a slightly more powerful engine which gave it a different sound to the distinctive "howl" of the Harvard or maybe it was the prop that made that Harvard racket. The Wirra also had a nasty wing drop at the stall although later versions had a modification on the leading edge to reduce the severity of the wing drop. The Wirra has a couple of bumps on top of the engine cowl area to accommodate two 0.303 calibre machine guns.