Dolphin .40 CG

[belbourn]

Hi,
I have recently purchased a Dolphin 40 ARF Pheonix Models and am having trouble with the CG..........instructions that come with the plane are pictures and nothing much else......I have tried using 30% of the wing for the CG but still seems to be nose heavy .....if anyone has an idea of aprproximate location of the CG it would save me lots of trouble playing around with it

Thanks in advance Bob

[imsofaman]

I usually go from the trailing edge, 2/3 rds to find CG. Tried the diving test yet? Do you know about this?

[belbourn]

no havent heard of a diving test........could u explain
also forgive me but i am not familiar with the abbreviatin rds?

[imsofaman]

Trim your plane so it flies level at half throttle. Then kill the gas, if the model comes down at a steady 45 degree angle, your CG is perfect. If the model dives, arcs upward, and repeats like on the ocean, you are nose heavy. If the plane continually dives wanting to continue almost inverted, you are tail heavy. Seems backwards but that is how to do it. Also a buddy of mine says he goes from the leading edge 25 to 30 percent of the width of the wing to find CG.

[belbourn]

thanks a lot will try it out

[imsofaman]

Something also came to meind......the thrust line of your engine make a big difference when not correct. If the thrust line is too high....lets say at half throttle you trim it so it is flying straight then you increase throttle and it climbs verticle. Try trimming for that higher speed, then drop back to half throttle, if it dives....... the thrust line is pointing twoo high so tilt the egine down using washers under the mounting bolts. And try it again. It happens...

[belbourn]

Thanks for that tip imsofaman thought of that and have already added about 2 degrees of down thrust......unfortunately I wont be able to test it for a few days:( will let u know how it works out