tower 4 auxiliary main cable comes loose from the socket.

10aug20

Links:

cable tensions from p50 sagsurvey
Photos of the damage (available to all)
photos of the cable sockets
monitor the platform corners
11aug20: tiedown tensions and telescope position as we moved to hurricane stow position.
13aug20: measure the distance between the auxmain connection points.
 
Notation:




 Intro

  On 10aug20 at 02:35:55 ast the auxiliary main cable from tower 4 (north aux main cable #301) came out of the socket at the tower and fell into the dish.
When the cable fell, the operator stopped the telescope. A few minutes later the operator commanded the telescope to continue tracking. It continued tracking for about 20 minutes.

The plots show the telescope position and tiedown cable tensions when the break occurred (.ps) (.pdf)

SUMMARY:


processing: x101/200810/aux4.pro

Monitor platform corners

The telescope is currently positioned at:

Every two minutes the distomats measure the distance to the corners of the platform.
After each reading, a  plot is generated showing the position of the corners (.ps) (.pdf)
( to the following plot, you may have to refresh the page).

The auxmain4North cable was attached about 60 feet before the corner 12 vertex. It was carrying about 100Kips of vertical load.
When the cable let loose

Note: if you seen horizontal lines in all the traces.. this will be missing data when the computer failed to read the distomats.

Table of when things occurred that may affect the position

date
day on plot
description
200812 13:00
0.5
repositioned distomats so they would hit reflectors on triangle corners. started recording.
200820
14:00
8.6
moved the az,dome,ch (a few tenths of deg) to insert the stow pins
200822
10
tropical storm laura approaches ao.

11aug20: moving the telescope to stow position

    On 11aug20 we moved the dome and azimuth arm from the location after the failure to close to the hurricane stow position.

The plots show the telescope motion and the change in the tiedown cable tensions.
Note that positive azimuth angle increases Clockwise (north to east).

Plot 1:overview of telescope positions (.ps) (.pdf)

Plot 2: 11aug20 showing the telescope motion and td tensions (.ps)     (.pdf)

processing: x101/200917/telescopePos.pro, 200811_poskips.pro


13aug20: measuring the distance between the auxmain connection points

    On 13aug20 felix and I used the tm50 theodolite to measure the distance between the connection points of some of the auxmain cables to verify how long any replacement cable needs to be. This will be an approximate value since the platform is currently not in the standard position  (see monitor positions above)... but the cables are currently spanning the distances we measured.

    The technique was:

The table below contains the results:

  Notes:


processing: x101/survey/200813/

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