Re: Propellor "reverse thrust"

Date:         05 Sep 97 17:27:23 
From: (C. Marin Faure)
Organization: Northwest Nexus Inc.
References:   1 2
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> In article <airliners.1997.1846@ohare.Chicago.COM>, wrote:
> >On the subject of reverse thrust, I took a flight on a Manx Airlines
> >Shorts 330 a few years back. When the plane landed, a big roar went up
> >and the plane slowed dramatically. Do prop planes such as this deploy
> >reverse thrust by somehow altering the pitch of the propellor blades to
> >the extent they "blow" air forward?

Yes, the blades twist from forward pitch through flat or zero pitch to
reverse pitch.  So while the propeller continues to revolve in the same
direction, the blades have pivoted or twisted on their hubs to move air
forward.  Piston airplanes cannot be run too long in reverse pitch as the
cylinders don't get the cooling airflow they need, but I don't believe
there is any limit to the time a turboprop can be run in reverse pitch.

C. Marin Faure
  author, Flying A Floatplane