The above posts are all correct. BUT... It is humbly submitted that the missing part of the analysis so far is the ergonomics, meaning the hand movement necessary to generate a given control deflection. Clearly, a 3 incher will give more angular bellcrank deflection for a given hand movement than a four incher. This excess bellcrank rotation generates two undesirable effects, the first being that over rotation. Once the bellcrank is past 20 or 30 degrees, the effective moment arm of the bellcrank gets noticeably shorter. The shorter the arm, the more force is required, and the less tolerant the whole system is to minor corrections. Which leads to the major difficulty with 3 inchers, the controls are too quick. Think of it in terms of control deflection per length of leadout travel, not per the angular rotation of the bellcrank. Most of us have experience with some plane which had ultra quick controls. Try one again sometime, and see how difficult it is to fly accurately with quick controls. The slower controls make the whole setup easier to fly accurately. So most of the poster so far haven't thought of it in terms of flyability, e.g. the comfort of the pilot.
Topic: 4" Bellcranks, are they necessary in Classics?? (Read 10929 times)