387 2) determine magnitude bounds for ex pected variability present in applying I V test data values acquired  in ground test lab- ambient conditions to the on- orbit jitter performance analyses.   The two foremost bodies of data/knowledge available to address these study goals are, chronologically:    1) large body of test data accumulated on a comparably -sized CMG production program at the RWA  supplier under independent engineering and Research & Development  investigations, and   2) 20 IV data sets obtained on delivered RWA flight complement set  (4 flight units, 1 spare).   This study combines a pplicable data available from these 2 key database sources. It also introduces  heretofore unpublished additional relevan t data and insights gained from :    1) early developmental tests performed on the Eng ineering Development Model  RWA (primarily  investigating the effect of different temperature extremes on RWA performance),   2) IV tests performed in support of RWA isolation system program development (primarily concerning  newfound evidence that there seems to be more potentially significant RWA harmonics than previously  investigated), and   3) numerous discussions conducted between LM and the supplier’s technical  personnel conducted over a  two-year timespan ( i.e., primarily concerning the predicted temperature variation effects which are perhaps  the most difficult to quantify/bound).   

Induced -Vibration Variation Based o n RWA Acceptance Test Series Data  

Acceptance test s on four flight RWA units (designated 1001, 1002, 1004, and 1005) and one flight spare  unit ( 1003) were completed by the supplier and resulting data packages were delivered to LMSSC and  reviewed for completeness and correctness (Ref. 1 & 2). Portions of the full acceptance test results (IV test results) have been extracted and compiled. An investi gation was initiated to study and analyze in detail  the  20 full or partial applicable datasets ( out of 24 total ) produced during all flight unit acceptance testing;  four  early, partially unsuccessful IV tests on the first -produced unit (1001) used a different rotor -bearing   assembly, so it was not deemed applicable due to its unique mechanical configuration. It was later restored to the same configuration as the other  flight units after a rework/rebuild, s o only those data sets were  applicable . The investigations focused specifically on: 1) assessing general data trends and consistencies,  2) quantitatively evaluating variability characteristics and factors, and 3) extr acting heretofore unknown  comparative data on additional harmonics. This last effort was important to assess which harmonics had a significant sy stem -level impact on LOS jitter  since it was a challenge  to determine the effect based on  simple first prin ciples. It should be noted that  between each dataset  all RWAs are exposed to varying  environmental/test conditions ( e.g., Random Vibration or Thermal -Vacuum Cycling), so results exhibit  effects from both:  1) variations generated by adverse environmental expos ures that may  alter microstructural conditions particularly in the bearings -lubrication ( i.e., conditions simulating expected launch- toorbit and/or simulated on- orbit operating conditions), and 2) variations due to low -intensity handling and  inherent tes t-to-test random factors (presumed to be significantly smaller than extreme environment  exposures).  It is impossible to determine precisely how much IV dataset -to-dataset variation is due to which  of these specific causes . However, attempts were made to li mit/bound the changes 14.    Investigations  applied the following specific methodology sequence to study/filter  the large amount of I V  data from the 20 data sets comprising over 3700 individual speed- with-magnitude data points  total:  1) Accumulate, basic sort, tabulate, and scrutinize all available -viable data; exclude or interpolate- adjust  highly -anomalous or significantly out -of-family data measurements  (i.e., clear outliers) .  2) Evaluate then document preliminary conclusions; founded upon  prior jitter analyses results .  3) Compute second- order best -fit-curve coefficients for the amount (sometimes variable)  of dataset points  and corresponding frequencies  for each dataset .  4) Select overall compatible criteria for establishing the “final” curve more-direct comparisons.   5) Compute baseline second- order best -fit-curve coefficients and equivalent geometry error values based  on above- chosen criteria/com parisons .  6) Tabulate and graph results; evaluate results and produce consolidated conclusions.   A top -level list of all RWA I V acceptance test dataset s (24) and subsets (20) studied are in Table 12 .  Consolidated  tables of detailed dataset values for local RWA directions and harmonics are in Appendix A.  Computational results of second- order coefficients and root -mean- square (RMS) errors for best -fit-curves ,