ORIGINAL: Hobbsy
I agree with the 9,000 rpm if the APC is not a wide blade.
Standard prop @ 9000 RPM = 1.522 HP
APC @ 9000 RPM = 1.613
APC W @ 9000 RPM = 1.659
According to this [link=http://personal.osi.hu/fuzesisz/strc_eng/index.htm]STATIC THRUST CALCULATOR[/link]
My FA91S turned a Graupner 13 3/4 X 8 @ 9300 RPM. That calculated to 1.56 HP so it's pretty close, @ least for comparison purposes..