Re: Propellor "reverse thrust"

Date:         11 Sep 97 03:35:32 
From:         Jack Cullen <yoda@daigobah.com>
Organization: WOMR-FM, 92.1MHz - OuterMost community Radio in Provincetown, Cape Cod, MA
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ZineGreen wrote:
> Yes, a turboprop engine does reverse (though I don;t know of a
> reciprocating, i.e. piston engine that does.)

The engine actually has nothing to do with "reverse thrust".
On a "jet" (i.e.: no prop), the "reverse thrust" is accomplished by
re-directing the gas flow using some sort of vent, duct or "clamshell"
door.  (Theoretically, I would guess this could even be accomplished
with a rocket motor!)
On engines driving props -- either turbine or recip -- the "reverse
thrust" is accomplished by changing the propellor blade pitch angle
which alters the amount and direction of "lift" being produced by the
blade through a positive to negative (forward through reverse) range.
Almost every large reciprocating engine -- and quite a few small ones --
has, at one time or another, been fitted with a "reversable" prop.

--
Jack Cullen
West Chatham, Cape Cod, Massachusetts, USA

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