RoyJ fired this volley in
m:
Interesting! The electronics and cabling is straight forward but a
few
questions for those of us who don't do this for a living:
-What's a gerb? Suspect it is somewhat equivalent to a shotgun
barrel
but.........
-What's CATO? Suspect the first word is Catastrophic......
-Do you have any more detail on the load cell mounting, especially
how
the over run protection screws mount and work (both the thrust boss
and
the load cell itself)
There are a couple more very fuzzy cell-phone pix at
http://www.pyrobin.com/files/les%20t...2008-04-08.jpg
and
http://www.pyrobin.com/files/les%20t...2008-04-08.jpg
that show how the load cell mounts under the thrust boss.
It's shimmed under the mount end to allow the free end to travel down
under pressure from the load post.
The three crash-stop screws limit the travel of the load cup. But
since the load post is not rigidly attached to the end of the load
cell, the cell may over-travel under its own inertia after a violent
over-thrust. A single large, fine-thread screw in the base, right
under the end of the load cell arm (centered along the axis of the
load post), prevents that inertial overtravel.
A "gerb" is the correct pyrotechnic name for a "fountain". "Gerb" is
derived from the old French word for "Sheaf of wheat", which roughly
describes the pattern of sparks a gerb makes.
Gerbs are a main-line product of all close-proximity pyro
manufacturers. Because fuel variations occur, we sought to
characterize every fuel batch. Measuring thrust and duration with a
fixed weight of fuel at a fixed fuel density and a fixed nozzle size
does that nicely.
CATO means various things depending upon what rocketry guy you ask.
Among them are "CAT(astrophic) O(verpressure)" and "C(atastrophe) A(t)
T(ake)O(ff)".
Basically, it means the device goes BOOM, instead of acting like a
rocket motor. When it does, it really slams the load cell; thus, the
need for protection. Most load cells of this beam type can withstand
only 25-50% overload without permanent deformation.
LLoyd