The 25sep19 load cell tensions from the 3 tiedowns were plotted to check their calibration  (.ps) (.pdf)

• frame 1-3: load cell tensions vs hour of day
• black is load cell 1
• red is load cell 2
  
• top: td12
  
• load cell 1 (black) goes to 0 while ldcell 2  still has tension (12.9  hrs)
• 2nd: td4:
• load cell 1 bottoms out at 6 kips
• 3rd: td 12
• between 11.3 and 13.6 loadcell 1 jumps to 0 and stays there.. after that it jumps back to match loadcell 2
• must be an intermittent bad connection.
• bottom: load cell difference (ldcell1 - ldcell2) vs tension for each td.
• black: td12. decrease at 0-4 kips is because load cell1 has dc offset of -4 kips
• red: td4 load cell 1 is low by 6 kips
• green: td8 dc, gain ok, except for the jump
• The slope of the lines is not to bad so the gain is probably ok.

Summary:

• td	dc offset	gain	comments
  td12	ldcell1 low 4kips	ok
  td4	ldcell1 high 6kips	ok
  td8	ok	ok	jumps

• The problem of the dc offsets  changing has been plaguing the loadcell readings for a long time.