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Old 6th Apr 2010, 00:19
  #19 (permalink)  
john_tullamarine
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One of the problems not yet mentioned .. and it applies to either prop or jet ... relates to the normal pitching force (ie a vertical force perpendicular to the local airflow direction) associated with the airflow deflection through the prop or nacelle inlet plane.

Problem can be a handful

(a) at high pitch angles (read missed approach especially with poor speed control)

(b) at high thrust settings

(c) for piston to turboprop conversions where the prop is pushed out forward to make the CG aspects a bit easier

when the normal force provides a very destabilising nose up pitching moment.

For the conversions, one sometimes sees the need for a SAS system to keep the stability under some semblance of control .. the expected pull force to keep below the trim speed can end up becoming an unacceptable push force ..

In the field, it probably is a good idea to transition to landing configuration missed approaches (ie lowest speed and potentially highest pitch angle) in a steady, measured manner to facilitate re-trimming .. in particular, without a dramatic slam acceleration of the engines to high thrust settings which can result in the pilot's becoming a one-armed paper hangar ...
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