Ok Guys,

I'm currently running a phoneix extra 330s w/ST 90 12x9 prop on it. I live in denver(alt 5500) and am curious as to why props for 3d manuves are the 4-6 pitch variety. Is it to purely keep the RPM's up? How much different would my plane handle if I went from a 12x9 to a 13x4 or 13x5?

Thoughts?

On a ST90 were I live (2,000 ASL) a APC15x4W is pretty good. A 14x6 would be my second choice.

David

Wider props will give more pulling power and less speed. Steeper pitched props deliver alot of speed, but not as much power. A 14X4W would offer you alot of pullong power witout alot of speed. Most 3D maneuvers are performed at or near stall speed, and use the ailerons, elevator and rudder more as thrust deflectors. It would be much easier to govern slower speeds with a smaller pitched, wider prop. Things like HA Knife Edges, hovers and harriers would be hard to control with a steeper pitched prop. (I didn't say they were impossible). I had an edge 540 when I was in Colorado Springs (Ft. Carson). At first I was running a 14X8 with an OS 1.08 FSR. I thought that because of the altitude I would need a steep prop. I tried a 16X4W and it was a totally different plane. A 15X6 Zinger was my second choice.

aka static thrust