At 08:42 AM 11/6/97 -0500, you wrote:
>I'm sure its usefull to have solid fuel rockets on the side tanks of the
>shuttle but what is more interesting is how it is possible to reuse them. I
>think that they are not made of solid fule for the purpose of reuse since I
>would imagine that they will be damaged after ejection and dropping several
>miles back to earth?

They are actually reused dozens of times.  The case is machined aluminum
with steel fittings on each end.  The case (segment) goes to Utah where they
cast the fuel in place.  It's a rubbery material, sort of like a pencil
eraser.  It has a whole down the middle.  The fueled segments are sent to
KSC where they get inspected.  The SRB is built up my mating segments end to
end.  Several hundred steel pins go through holes where the ends of the case
nest.  A steel band is placed around the joint to hold the pins in place.
Several segments are pinned together to produce an SRB.

The shuttle is stacked on the SRBs, and wheeled to the pad.  When ignition
time approaches, a mechanical stop is rotated out of the way, which allows a
charge to propagate through a cord to a small rocket engine that is aimed
down the whole through the center of the SRB.  It takes about 400 ms for the
pressure to build up to the point that the SRBs start producing thrust.

After the SRB's seperate, an altimiter in the frustrum monitors the pressure
to figure out how high it is.  When low enough, the nose cap is blown off,
which deploys a pilot chute.  The pilot chute dose not slow down the SRB
much, but it does aerodynamicaly stabilize flight path.  (Bottom end first)

After a while longer, the drouge shoot is deployed.  This starts the process
of slowing the SRB.  Since the airspeed at drouge deployment is so high, the
drouge shoot is reefed.  It has two pyro based timers that cut the two
reefing lines in order, about a minute apart.  If I remember correctly, the
air speed has dropped to about 400 MPH now.

When it gets lower, the whole frustrum is blown off the front, which deploys
the three main chutes.  They slow the bird to about 60 - 100 MPH for water
impact. It will bob there with the top of the SRB just barely sticking out
of the water.  The recovery vessles deploy a dive team.  They install a plug
in the aft end where the fire used to come out.  They then pump the water
out, and it flops over and floats like a log.  They tow it back to shore,
clean it off and ship it back to Utah for more fuel.

Wynn Rostek
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