[Stuart Hugh Arnaud]

Following on alogs 12929 and 12902, an other test was carried out on SR3 giving a bettter understanding of why its first vertical mode was damped. The same V2V tf was taken with the ISI damped, and interestingly enough the Q of this mode gets higher when the ISI is damped, cf attached screenshot.

It appears that the rotational modes of this HAM are also around 1Hz (looking at Rx Ry TF from an ISI measurement taken in May cf attachment), mode that we were certainly exciting when driving the suspension along the vertical axis with the ISI undamped.

At first we were wondering why some previous vertical measurements were showing high Q resonances, but quickly realized that those were taken with the ISI either locked or half locked (from July 15th ISI was locked, from yesterday when doors were off, Matt half locked the ISI to back off the EQ stops).