RE: Extra 260 (SD-models) trim question
Personally I have yet to fly a plane that didnt need thrust correction. For those of you reading this thread for info or to learn its important to understand if you plan on flying any precision IMAC type flying chances are your plane will need thrust correction. This is why there are a number of good step by step trim charts out there.
The reason for this is simple... it is impossible for a designer to know what engine, or what prop you are going to use. It's important to understand that changing props will effect your trim. Find a prop that you like for your plane and then do the trim steps.. I mean you can test CG of course.. but fine tuning should be done once you select a prop. Every prop effects your thrust lines differently.
Trim can be difficult to understand sometimes and sometimes hard to pin point exactly what needs to be changed.. but do a search for a trim chart and follow it step by step.. in the end your plane will fly better and you will be happier with the out come.