Karl
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Re:OK 4 stroke. what prop & why? - 2007/01/02 23:33
Rob,
First off, you'll need to determine what kind of flying your going to do.
It had been suggested to me that for the 3D flying that I believe you are pursing as well, that a longer length, lower pitch wide prop would be preferable on my 70 OS FS.
With this engine, I tried the APC 14x4w which the OS will spin up to about 8750RPM. As you have seen, the UltraStick with the OS 70FS on it has pretty much unlimited vertical and I sure that if I ever develop the talent to be able to do more than a half rotation of a torque roll, the engine/prop combination would hang the plane there as long as I needed it to. One thing about the 14x4w props, when you chop the power, you need to have some airspeed or air space because they almost act like an airbrake. Fortunatly the 4strokes have the transition to get the plane moving again if you run out of either.
On the other hand, If you are looking to go for mach 3 passes of the field, I would recommend the 12x8, 13x8. This will give you the higher airspeed.
I have most of the props that you mentioned, 12x4, 12.75x3.75, 12x6, 12x7, 12x8, 13x4w, 14x4w that you can try out to see what the differences are.
Hope this helps.
Karl
Post edited by: Miller2149, at: 2007/01/02 23:35
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Not that it ever happened to me.