Quote Originally Posted by avidflyer View Post
Fourth paragraph says that best performance is at or below 700 fps or 475 mph. At 3150 rpm, your prop tip speed is 628 mph. I think our Jabirus are in need of a gearbox to be most efficient. Nobody wants the extra weight or complexity though. JImChuk
That also says at cruise - so if you're cruising at 3150 it's high. If you cruise at 2400 or so you're pretty close! I'm not a Jabiru guy so FWIW!

Greg