I was very active in RC in the '80s. Put my stuff in storage due to work demands until I retired last year. Problem: will the old Futaba S26,S28, S38 servos work on the new fm radios? My old radios all AM are not legal. I have several aircraft that have flown for years under the old Am units.
I got a Tower 4 channel unit and refurbed the airplanes (be sure to replace the plastic control links, they get brittle with age). I put J plugs on the servos. I adjusted the controls (I thought). When I flew the first time the trims were a mile off. I bearly got it down so I did a readjustment and flew again. The aileron was nuts. It was so far out of trim that I bearly had time to cut the engine before the crash (totaled the plane).
Lesson learned: The electrical zero center of the servo is not the same as the AM unit. I analyzed the situtation with my pluse meter and found that FM center is about 1.45 ms as compared to 1.20 for the AM unit. Also, I have a feeling that the throw rate is also different. (So even engineers screw up once and a while!!! )
Comments and Suggestions Please.
