🚀 go-pugleaf

In article <1992Nov12.130538.28783@slcs.slb.com> brydon@dsn.SINet.slb.com writes:
>Philip R. Forrest (Forrest@eng.au) writes:
>>Here's a good trivium...How can ANY engine develop more than 100% of rated 
>>power output ?? (i.e. 104% ?)
>
>I'm an electrical engineer, not a rocket scientist, but if principles of
>electrical generators apply to rockets...
>
>Electrical generators in hydro stations routinely run at 110% (or whatever) of
>rated capacity during peak loads.  In one respect, the rating is a somewhat
>'soft' ceiling and the actual load can be exceeded for 'short' periods of
>time.  The term 'short' for large generators can be measured in days.  The
>rating assumes steady state operation (which it isn't) and is mostly thermal
>in nature.  It takes a long time to heat up one of those suckers, and 'burn
>out' would have to be pretty drastic over a long period of time.
>
>Same thing with circuit breakers.  While a 35 amp breaker is designed to trip
>at about 35 amps steady-state operation, it is also designed to pass much
>larger currents (ie. about 200 amps) in surges for short periods of time to
>allow for things like motors to start up.  A motor will routinely generate
>this kind of load when you turn it on.
>
>Is this applicable to shuttle engines?  Do I get a gold star?

The 100 percent rating for SSMEs was determined during initial testing.
Since then, the engines have been improved.  They could change the rated
thrust, or use 104 (or even 109) percent.  NASA chose the latter.
.
++rich
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   rich kolker       rkolker@nuchat.sccsi.com
                          It's been a long, long time
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