Servo push rod types
 

I have sullivan Gold'n' Rods installed in a plane and had the trims neutral with neutral control surface deflection (rudder and elevator).

Yesterday was a warmer day than recent days have been and when I took off the plane climbed steeply. It took almost all of the available downtrim to maintain level flight, the rudder trim also had to be significantly adjusted.

I have put this down to the expansion of the push rod inner with the higher ambient temperature.

I propose to remove the yellow inner rod and replace it with a length of threaded metal rod inside the red sleeve.

Will this remedy the problem?

Daily temperature diference morning to afternoon can be quite significant at times and I expect this will be an ongoing issue.

RE: Servo push rod types
 

I never liked the red golden rods ,thought they were too flexable .Used to build them into the wings & make a curve with them . I have never had trouble with the blue colored ones,much stiffer . I think you may have had a bending problem from the heat . Metal rods might help but they may expand also . Good luck , MAX H.

RE: Servo push rod types
 

I only use them on engine controls. Never on a flying surface. They get 2-56 or 4-40 steel rod in tube. If I buy a swapmeet plane that uses nyrods on a flying surface, I replace it with steel rod.
Edwin

RE: Servo push rod types
 

It is humidity as well as heat that causes changes in nylon rods. You can solve the problem with Sullivan carbon-filled pushrods- they are absolutely stable. If you want to use metal pushrods don't install a thick,heavy threaded rod, but use a smaller diameter music wire rod with soldered connectors at the ends. The plastic outer tube will provide the rigidity.

RE: Servo push rod types
 

Great thanks that what I thought. I will get some 4 40 rods tomorrow