🚀 go-pugleaf

9Wanting to refresh my somewhat rusty remembrance of things rocket,
I picked up "Rocket Propulsion Elements" by George Sutton
(1986, 5th ed, John Wiley and sons).
Therein I found the following interesting numbers:
 
Space Shuttle Main Engine	Saturn J-2 Upper Stage
 
Thrust (at alt): 470,000 lbs	230,000 lbs
Specific Imp (alt)   455 sec        426 sec
Dry Weight:         6335 lbs       3454 lbs 
Thrust/Weight:	      74             67
Mixture Ratio:	       6	      5.5
 
Now, I have been led to believe that the SSME is a large
advance over previous engines. The above seems to imply
that with a little work the 6 J-2s could have powered
the shuttle quite nicely.  Perhaps a 6:1 mixture would have
given it the same Isp as SSME - the J-2 thrust and thrust/weight
would have then been 246,000 lbs and 71.5.
 
Also:
 
       Space Shuttle SRB         Saturn F-1 First Stage
 
Thrust(at alt):	 2,372,000	 1,748,000 
Specific Imp:   266 (average)	  265 (grnd) - 305 (alt)   
 
Now, the F-1 does not replace an SRB one for one, but its
no too far off.  Given its good record maybe the F-1 could
have been rerated to 135% throttle to equal the SRB.
 
Hence the question in the title of my post:  What was NASA
thinking about?  Apparently the Saturn engines could have
been used to build the shuttle vehicle.  Why weren't they?
 
A shuttle with 5 or 6 J-2s using 2 uprated F-1s in the recoverable
boosters would have taken advantage of a history of literally
dozens of successful flight firings.  Plus there would
have been a much wider range of abort modes.
 
Happy new year.  Let's hope for more rational future design.
 
-- 
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu