I’m trying to figure out the amount of torque required for my elevator servo (single, in a pull-pull system). I’m doing an electric Impact and trying to save as much weight as I can. I’m considering either the DS8411SA or the DS9411SA. Not sure if the 82 oz/in of the 9411 will be enough for both elevators? Savings of .7oz (every little bit helps) times 2 aileron and one elevator servo makes it worth while.

There used to be a site on the net that showed a way to calculate the required torque, however I can’t find it.

Any first hand experience or good theories welcome!

Wayne Powell

Hi Wayne

I have been using a 90 oz servo (Futaba 9252) driving both elevators, works great. The deflections are so low that it doesnt take that much jam to run the elevators.

Way back in '99 at the Worlds in Florida I noticed that CPLR was running a 50 oz servo to drive both elevators (Futaba 9102). If anything the elevators on new designs are smaller than in '99.

Good to see you, Wayne!!!! Hope things are well....
You won't have ANY problem with 90 oz. I've run 8231's on dual-elevator pull-pull setups on the EMC2 in FAI... lots of large hard pulls at that time, never a problem. You're good, believe me (and others).....if you were saying maybe 70oz, well....