Re: What is "synchronizing" propellers and why was it done?

Date:         21 Dec 97 02:32:39 
From: (Gerard Foley)
Organization: The Greater Columbus FreeNet
References:   1 2
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Bob Mann ( wrote:
: Multi-engine equipment used electrical or mechanical propeller synchronizers,
: phasers and in some cases, combined synchro-phasers, to reduce the frequency
: and magnitude of vibrations associated with "beating" of propellers that were
: out of speed and phase (angular/rotational) synchronization.  Reduced
: vibration contributed to lower cabin noise and lower vibration/cycle fatigue.

   It didn't take four engines to make the beating of out of synch engines
unpleasant in the cabin.  Most crews did their best to make the period
of the beat long in DC2 and DC3.