From: Arthur W. Brooks
Sent: Monday, August 20, 2007 3:50 PM
To: Thomas G. Brown
Subject: Update on Stage 3 Screen Traces

Attachments: trace00_path5tom3r12.zip.safe

Tom,

I've updated the laser-on-screen traces as well as the lift point traces using your new coordinate data. The file nomenclature is the same as the last time (see below). 

Since I only have drawings for the right side, I've assumed the lift points will be mirrored but otherwise the same for the left side even thought the attachment to the MCWF will differ. You gave a crane hook height of 285.625 for the right side which means the left will need to be ~30" higher to use the same slings. 

Art


-----Original Message-----
From: Arthur W. Brooks 
Sent: Tuesday, February 27, 2007 9:18 AM
To: Thomas G. Brown
Cc: Michael E. Viola
Subject: RE: Stage 3 geometry

Tom,

I've updated the assembly traces using your new coordinates for the lasers and your revised screen locations.

Attached are some files in an zip file (renamed ...safe) giving the traces of the lasers for assembly from the right (+Y) and the left (-Y). The files ending in 11r are for the right side, those ending in 11l are for the left side. The spreadsheets give the xyz data of the laser traces and plots of them. They also give plots of the "Strap Lengths" on the second worksheet for a fixed hook height. I used a height of 275 for the left side, but reduced it to 255 for the right side to minimize the total variation in length required. The required motion to has dropped slightly to 25.85" inches with this scenario. Unfortunately, you cannot live with one size fits all for the straps. To do that, the stroke would have to increase to >31.1" (ie 36") . This assumes the hook height is fixed during assembly at it's initial height and all vertical adjustment is done with the actuators. 

There are a bunch of ibl files as well. Files labeled trace01 thru trace03 are the laser traces, trace04 is the CG and trace05 thru trace07 are the swivel points. I've looked at these in ProE and the Lasers do track the lines.

I've done a check on the tension of the straps to make sure we are not going into compression. The right side has one sling which drops to only 4% of the load and the left side has one that goes as high as 65%. I've added some columns at the end of the second worksheet that calculates how close to the edges of the triangle formed by the three support points the hook/cg comes (in plan view) which is also an indication of the opposite sling going limp. The right side gets to within 2". If we don't know the CG that accurately, it could force us to move the support points further apart.


Art

-----Original Message-----
From: Thomas G. Brown 
Sent: Thursday, February 15, 2007 2:15 PM
To: Arthur W. Brooks
Subject: Stage 3 geometry

Art - here is some updated Stage 3 geometry.  I'll stop by and chat about this and also drop off a drawing shortly.

Tom