Originally posted by sledman
PROBLEM: I was breaking in my new Magnum .52 XLS, and anything above 1/3 throttle, and the servos get the jitters, intermittently. What is weird, is if I moved my hand near the front of the airplane while the engine was on (the transmitter was about 5' in front of the plane), it would do it also, like maybe my wedding ring had something to do with it at times. I'm wondering if the throttle linkage, being a metal rod with a Z-bend going through the metal carb arm is vibrating so much that it is causing harmonics. It is a loose fit, and defineately is vibrating when the engine is running. This only happens when the engine is running, and only at 1/3 to 1/2 throttle. The flying wires I have are nylon, and the antenae wire exits the side of the fuse in front of the radio, and is attached to the top of the tail. What should I check, and in what order?
Sledman
There is a "GOLDEN RULE" Never have any metal to metal connections. This includes pull-pull cables, Guy wires, metal push rods that might touch each other and any carbon made parts that might come in contact with any carbon or metal parts. Yes, Carbon fiber should be treated as a metal or metallic surface. Guy wires should have a nylon coating of the wires. Dubro sells there cables this way. The only metal to metal should be treated as a bearing or bushing surface. Similar to your Piston and sleeve; ball bearings and other tight fitting usually designed for movement metal to metal contacts. The guy wire "strap to tensioner" might fall into this category--double check for loosens or possible vibration.
To correct your problem simply put a ball link on the throttle arm. I especially like the heli connectors for this--but be careful the 2-56 rods usually will not work. Get the correct mm size pushrod if you intend to go with the Heli connectors. Loctight the thread on the ball link and over tighten the nut with a good pair of pliers for extra security of it not coming loose while flying.
I have seen many airplanes crash because of the problem you encountered.
Good thing you decided not to fly. You plane would not have made it very far.