PSN-L Email List Message

Subject: STS-1 leaf spring
From: S-T Morrissey sean@...........
Date: Wed, 22 Mar 2000 13:55:51 -0600 (CST)


The only published dimensional info on the STS-1 seems to be in the paper:

Wielandt, E. and G. Streckeisen, "The Leaf-Spring Seismometer: Design and 
Performance", Bull. Seism. Soc. Am., 72, 2349-2367, December 1982

which has a sketch with some dimensions of the elliptic spring 
configuration. The spring, by the way, is firmly clamped at BOTH ends
(to the frame and to the outside end of the boom) with the boom 
inside end pivot under the center of the ellipse. Both ends of the 
two-metal spring have to flex where they are massively clamped under
head-touching-head rows of screws. Rumor has it that adjusting these
screws is a dark art of the assembly process that can take weeks,
and that there is a high rejection percentage (hence the high cost).

The transducers are mounted above the spring and above the pivot with
clear plexiglass fixtures. THey use a proprietary LVDT that accommodates
the rotation about the flexures, which are ~ 6mm Bendix cylinders.
The LVDT coils and the feedback/calibration magnets are mounted to
the frame; fine pigtails connect to the moving coils.

The STS manual gives no dimensions other than overall specs, but does
have some useful photos.  I have some installation photos of the 
sensor with all the shields removed, but not of any focused details.

When I first explored making a VBB vertical in '97, I tried to emulate
a 2x version of the elliptic spring. I quickly realized that the
flexure of the ends of the spring was innately involved, and decided
to mount the spring with isolating flexures instead, and use it strictly
for one-dimensional lift of the boom rather than a bending movement.

I can send you excerpts from the manual; most of it is taken up
with schematics.


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Larry Cochrane <cochrane@..............>