Re: DC-10-30 (and -10's ??) #2 Thrust reverse useage

From:         lchiluku@ucsd.edu (Chilukuri)
Organization: Univ of California at San Diego
Date:         08 Feb 96 03:21:06 
References:   1 2
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In article <airliners.1996.58@ohare.Chicago.COM>, slacker@arlut.utexas.edu
says...

>Speculation: the high-placement of the #2 engine on the DC-10 means that
>reversing it tends to lift the nose-wheel?
>

The cascade boxes on the tail engine reverser are usually selected to obtain
a net vertically upward load, and a corresponding nose down pitching moment.

This means that the lower cascade boxes have less forward turning (usually
about 15 degrees) and are termed as flow spoilers. The cascade boxex on the
upper half of the reverser turn the flow forward by as much as 45 degrees.

>727s landing with ONLY #2 reversed. In addition, airlines that power-back
their
>727's from the gate (American and TWA, for example) do so using only #2 in
>reverse thrust. (since the reverse blast from #2 is directed to the sides
>rather than upward and downward, it doesn't kick up debris from the ramp).
>

Besides FOD, reingestion of the reverser plume into the engine, and
crossingestion between engines is an issue. Typically, self-reingestion on
wing mounted cascade reversers will occur at less than 30 knots aircraft
speed. These concerns do not apply to the tail engine because of the height.