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Old 01-04-2003 | 07:43 AM
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ptarp
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From: Wood River, IL
Default G2 - Prop diameter greatly effecting 3D

I was flying around in the RealFlight G2 simulator with my slightly modified Cap 232 where the only changes was to increase throw on rudder to 45, and elev to 25 for 3D testing. The engine that is "stock" is the OS .91 4s with a 13 inch diameter prop. The 3D was ok, but I thought I would try some different engines and see what I came up with. Being a 6+lb plane, I thought I would get a laugh trying to fly it with an OS 40FP with a 10x6 prop. Much to my surprise the plane was MUCH more "nimble" and responsive to 3d type maneuvers. Although it didn't have enough power to hover, it was much more fun to fly. I couldn't beleive it! At first the only thing that I could think was the reduction in weight(always a factor) tipped the scale making it a much better flier. To test my theory, I reduced the weight of the plane to obtain the same wing loading as with the 40fp and tried the .91 again. Same flying as original weight. Hmm, I thought that maybe the weight needed to come off of the engine, and I reduced the weight of the .91 instead. Still lackluster performance. Then I thought that maybe it was because of the larger diameter of the props the bigger engines used. I had heard that larger diameter props made it easier to torque roll because of the increased amount of prop that would have to be moved, and therefore would desensitize the axes to movement. Anyway, I tried the .91 again(with stock weights), but this time with a 10x12 prop, and WHAMMO, the plane was a super 3D machine! This is contrary to what I have heard that 3D should be done with large diameter/low pitch props. Is this an accurate representation of real life?

Regards,
Philip