Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!rosevax!ricko
From: ricko@rosevax.Rosemount.COM (Rick O'Brien)
Newsgroups: sci.space.shuttle
Subject: Re: 104% thrust from SSME
Message-ID: <7586@rosevax.Rosemount.COM>
Date: 30 Apr 89 19:49:21 GMT
References: <1460@zaphod.axion.bt.co.uk> <23778@agate.BERKELEY.EDU>
Reply-To: ricko@rosevax.UUCP (Rick O'Brien)
Organization: Rosemount Inc., Eden Prairie, MN
Lines: 45

In article <23778@agate.BERKELEY.EDU> labc-4da@web-1e.berkeley.edu (Bob Heiney) writes:
>In article <1460@zaphod.axion.bt.co.uk> sjeyasin@axion.bt.co.uk writes:
>>Reading the mail there appears to be several schools of thought on this:
>>
[stuff on various theories on thrust levels deleted]
>
>What *is* the rated thrust for the SRBs and the SSMEs?

I design sensors that go on the SSMEs so while I am not an expert on the
engines I have a *little* bit of info on what they do.  As I understand it
the 100% thrust level was the level the engines were first certified to.
In order to go to 104% or higher every component has to go through a 
qualification program of test firings.  The higher thrust levels are not
strictly speaking the result of a new design (although design can be changed
as a result of the testing) but rather the engine went through testing to
certify that it could operate at 104% of the thrust that it was first
certified to.  I had heard that 109% will probably never but used after
Challenger but 104% is used pretty much on all missions.   I repeat, this
is what I have been told by folks at Rocketdyne in casual conversation,
I do not have access to mission data anymore.  

On the performance levels of the SSMEs I have this info:
Type: Liquid Propellant, Pump-Fed, Regeneratively Cooled
Propellants: Liquid Hydrogen/Liquid Oxygen
Dimensions: 168 inches long/96 inches wide
Mixture Ratio (o/f): 6.026:1

Thrust, Pounds       Rated: 100%          104%          109%
  Sea level               375,000       393,000       417,300
  Vacuum                  470,000       488,800       512,300
Pressures,psia
  Hydrogen Pump Discharge   6,140         6,445         7,040
  Oxygen Pump Discharge     7,075         7,380         8,070
  Combustion Pressure       3,006         3,126         3,260

Flowrates,lb/sec(gpm)   
 Total             1,040(20,737)    1,081(21,570)  1,133(22,568)
 Hydrogen            148(15,098)      154(15,710)    161(16,424)
 Oxygen              892( 5,639)      927( 5,860)    972( 6,144)

Power, Horsepower (High Pressure Pumps)
 Hydrogen                  63,200        69,100         77,310
 Oxygen                    21,300        23,600         29,430

 rick o'brien