From: henry@spsystems.net   
      
   In article <137a631.0404081923.7b0d660a@posting.google.com>,   
   Space Cadet  wrote:   
   >> ...Even the Apollo guys   
   >> would have done things differently if they'd had to do it again -- many   
   >> decisions made in haste turned out to be less than ideal.   
   >   
   >Henry, do you have specific examples of somethings the Apollo guys would have   
   >done differently?   
      
   Just off the top of my head...   
      
   The CM heatshield turned out to be grossly overbuilt.  The specs were   
   fixed at a time when they didn't have enough data and they knew it, so   
   they consciously erred on the side of safety.   
      
   A slightly larger-diameter CM would have permitted better reentry L/D --   
   they simply didn't have enough *room* inside to offset the center of mass   
   as much as they'd originally intended.  The CSM size was fixed based on   
   ideas about the diameter of Saturn upper stages which were obsolete almost   
   as soon as the decision was made.  The rounded corner arose likewise, but   
   a sharp corner (like Mercury and Gemini) improves the aerodynamics   
   substantially.   
      
   CSM manufacturing and testing would have been greatly eased by a more   
   Gemini-like design approach, with removable upper-heatshield panels, and   
   equipment accessible from the outside rather than the inside.  Apollo   
   repeated many of Mercury's mistakes because its basic design was fixed   
   before Gemini established that there was a better way.   
      
   The SM engine was sized to lift the CSM off the lunar surface, because the   
   mode decision wasn't final then.  A redesign would have had a smaller   
   engine, or possibly several still-smaller ones (removing the single point   
   of failure).   
      
   Serious consideration would have been given to solar arrays instead of   
   fuel cells.  Solar cells improved dramatically between the time when   
   Apollo's basic design was fixed and the time when it started flying.   
   (Soyuz, designed only a few years after Apollo, is solar-powered.)   
      
   Similarly, serious consideration would have been given to LOX/LH2   
   propulsion for LOI and descent (although storable fuels might have been   
   retained for ascent and return as a precaution).  That's another   
   technology which looked very raw and untrustworthy in 1961 but matured   
   dramatically while Apollo was going from concept to flight.   
      
   More resources would have been invested in making the computer bigger   
   and faster, because software could replace other items of hardware.   
   (Some of this happened during the Block I -> Block II transition, and   
   a redesign would have done more of it.)   
      
   Braking rockets for land touchdown would have been reconsidered.  Some   
   work was done on them for Apollo, early on, and they have advantages.   
      
   A copy of the Skylab toilet would have been fitted.  (There was a plan   
   to test it on Apollo 14, in fact, but Shepard vetoed it.)  The Apollo   
   baggies simply did not work terribly well, resulting in a lot of wasted   
   time and less-than-ideal sanitation, especially when somebody was ill.   
      
   The LM landing gear was another overdesigned piece of gear, thanks to   
   uncertainties about both the lunar surface and the astronauts' ability   
   to fly to a gentle touchdown.   
   --   
   MOST launched 30 June; science observations running     |   Henry Spencer   
   since Oct; first surprises seen; papers pending.        | henry@spsystems.net   
      
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