RRU Installation

[MVStillwater]

I'm installing the RRU for my 711C setup. The installation manual says that the length of the connecting rod has to be between 13.8" and 21.3". I was hoping to use a pre-existing mounting block that is only 8" from the rudder. I'm curious why this dimension is critical - from a geometry perspective I can't see how it matters, other than ensuring that there is adequate room for the RRU arm to swing. Can anyone shed a light on this?

Thanks

Richard

 

[MVStillwater]

I think I found the answer in a post from a couple of years ago. As I understand it, the longer rod reduces the upward or downward force on the RRU arm if it's not vertically aligned with the arm on the rudder post. If the rod is too short there is a risk the vertical misalignment could cause damage to the RRU as the rudder turns. Does this sound right?

 

[Quitsa]

I think I found the answer in a post from a couple of years ago. As I understand it, the longer rod reduces the upward or downward force on the RRU arm if it's not vertically aligned with the arm on the rudder post. If the rod is too short there is a risk the vertical misalignment could cause damage to the RRU as the rudder turns. Does this sound right?

It makes sense. There may be another consideration, however, which is that the pivoting fitting at the end of the rod would be more like to come in contact with the lever arm. Easy enough to check mocking up the installation.