Re: Soft ride mode on B747

From:         d.alan.johnson@larc.nasa.gov (Dave J.)
Organization: NASA Langley Research Center, Hampton, VA  USA
Date:         10 Mar 94 13:07:27 PST
References:   1 2
Next article
View raw article
  or MIME structure

. The captain then announced
>: that the turbulance was unexpected and he has turned on soft ride mode to
>: give us softest ride possible (we were being served lunch then). We were
>: flying B747.

>: Does anyone know what is soft ride mode and how does it work?

Quite a few autopilots have a "soft ride" or turbulence mode associated with 
altitude hold, what this does is it will reduce the loop gain in the 
autopilot control laws to be less agressive in correcting for altitude 
deviation.  In effect the autopilot lets the aircraft altitude deviate, say 
+/- 150 feet rather than +/- 30 feet.  This gives a smoother ride since part 
of the rough ride in turbulence is due to control inputs, not just atmospheric 
energy.

.................................................................
....my opinions, my time, my disclaimer..........................
.................................................................