Re: md80 vs boeing 727 (noise)

From:         julian@gatwick.sgp.slb.com (Julian Fitzherbert)
Organization: Schlumberger Geco-Prakla
Date:         03 Jun 94 14:13:36 
References:   1
Followups:    1
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In article 1298@ohare.Chicago.COM, tristar500@aol.com (TriStar500) writes:
> In article <airliners.1994.1269@ohare.Chicago.COM>, mbas@argo.unm.edu
> (i am me) writes:
> 
> >what is the difference that causes the 2 powerplants on the md 80 to
> > > >seem to be noiser than the 3 powerplants on the boeing 727???  
> 
> That would be our old friend resonance. There's something about the
> way MD hangs the engines on this airplane that does it. The DC-9 is
> no better, by the way. The MD-80 has an engine sync system that is
> supposed to calm this down by synching N1 or N2 of both engines. I
> understand it's not used much because it actually makes things worse!
> 

I remember that early VC10s used to have some sort of display for the 
flight engineer that monitored engine vibration or noise or something like
that. It was a cathode tube device a bit like those radio magic tuning eye
things. Anyone know what it did - I think it was an engine syncronisation
system ? I don't recall seeing it in later VC10 cockpits.