Spare engines

From:         rdd@cactus.org (Robert Dorsett)
Organization: Capital Area Central Texas UNIX Society, Austin, Tx
Date:         02 Apr 93 05:36:09 PST
References:   1 2 3 4 5
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In article <airliners.1993.314@ohareChicago.COM> pete@frosty.rational.com writes:
>The 747 definitely has this feature.  Years and years ago I took a British
>Airways (probably BOAC then) flight from New York to London, which included 
>a fifth engine.  It was located inside of the working engines on the left
>side of the plane.

It's had the capability designed into it, and has been available since 
certification.  The fifth engine is mounted inboard of the #2 engine.  
There are additional knick-knacks, such as a tail plug, and nose inlet 
shield and deflector cone, which are sometimes used.  The engine obviously 
isn't "hooked up" to anything, and doesn't produce any power.

The extra drag throws a lot of performance data out of the window, so
besides the physical installation, the airplane/engine combination has
to be certified.  In addition, due to the different geometry of the
various types of engines, they all have different certification standards.
There isn't just a standard "pod" one can stick an engine in and forget
about.  For example, a CF6 can only be carried if the first stage rotor and 
hydraulic pump are removed; an RB-211 requires that plus the compressor 
splitter fairing, etc.  There are "shielded" configurations, and windmilling
configurations.  Etc.




---
Robert Dorsett
rdd@cactus.org
...cs.utexas.edu!cactus.org!rdd