<span style="font-size: medium"><span style="font-family: Arial">I'm building a .40 trainer ARF I got from Nitroplanes. I'm going slowly, as Iam not experienced in modeling. Everything is going fairly well so far. Ihave to finish the tail and install the tank and engine. I did a preliminary check of the CG today. It shows it to be about 3/16 " back of the specified location. As Iunderstand it, Iwant the plane to be a LITTLE nose heavy?

I have not mounted the Rx and battery yet and there is room to move it forward behind the tank. Ihaven't drilled the engine mount yet either, and can cheat a little forward with that too if needed.

The instructions included in the kit are next to useless. Idon't recall seeing a firewall to prop dimension. I have been using online manuals for the NexStar and Avistar to get an idea of what the Chinese instructions are trying to show me, and it has helped a lot.

I have an OS .40LA for it. 10 X 5 APC sound right? The only weight given for the kit is ARFweight = 3.3 lbs. I'm guessing it's be abou 5 - 6 lbs when finished.

Any advice is appreciated.</span></span>

I run a MAS(master airscrew) 10x6 with my LA .40 it pulls it nicely. I ran an APC 10x6 and tached out at 11300 RPM tuned for flight. the MAS pulls a little more RPM, I havent tached it yet but you can hear an increase. the plane is a bit faster and can climb out at a slightly steeper rate useing the MAS. a 10x5 prop should work fine.

My LHS only has three-blade MAS props. I may have to get him to order me a two-blade.

I suggest the MAS prop while learning. The MAS props are more tollerant of accidental prop strikes than an APC prop, however an APC prop is more efficient - a 10x5 APC will provide the same performance as a 10x6 MAS.

Have you LHS get you at least 2 props (you will have a spare if you break one).

Thanks for the info Campy. Any suggestion on my CGquestion?

It's way better to adjust CG by moving your battery around than by adding weight. Set it right at the reccomended CG with the nose slightly down when the plane is at that balance point. Then you can fine tune the CG to make the plane float down in landings. A properly balanced trainer will lower its nose gently as airspeed slows. If you see it dropping it's nose hard it's nose heavy, and if the plane seems difficult to control vertically it's tail heavy. A properly balanced plane just flys where you point it and feels stable in the air.