Re: Propellor "reverse thrust"

Date:         29 Aug 97 00:53:42 
From: (ZineGreen)
Organization: AOL
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Yes, a turboprop engine does reverse (though I don;t know of a
reciprocating, i.e. piston engine that does.)  The blades of the propeller
pass through flat pitch (high RPM) to the reverse range, known as
"beta-range" in turboprop-speak, which drives the air forward instead of
backward.  This is accomplished by lifting the power levers over a
mechanical and/or electric lock and bringing them rearward.

As with a pure jet, you can hear the engines reverse on landing.  The
amount of power available in reverse is restricted by torque, temperature
(ITT, TIT, EGT), or RPM (n1 or n2), depending on the engine.