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Old 07-18-2009, 07:17 AM
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Default RE: Internal setup for AMA 424 racer

Depending on the plane will determine where things need to go to cg properly. Many of the newer planes fly with a cg around 3" so its pretty common to see 3 servos and a switch just behind the wing, accessed by a hatch.

For throttle, I've always used the sullivan braided cable in the yellow tube (not the flexible). Solder a threaded coupler on the engine side and install a ball link to the throttle and use an ez connector at the servo that the cable goes through. About the middle of the wing, I rough up the yellow tube and CA it to the side of the fuse for support. I've started drilling holes in my backplate mounts where the hole is just large enough for the ball link to go through. If you make a template of the location of this hole, and drill all your backplates and firewalls the same, it will help with interchangability down the road if your swapping motors around.

I place the center of my tank about 1/2"- 1" forward of the CG. I still believe that the force of the plane going forward pushes the fuel to the back end of the tank during flight as it empties. At this spot I do not notice any elevator trim change during the course of the flight, so it must be close.