Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!ssc-vax!eder
From: eder@ssc-vax.UUCP (Dani Eder)
Newsgroups: sci.space.shuttle
Subject: Re: Orbiter/SRB separation
Summary: how the ET/SRB joint works
Message-ID: <1934@ssc-vax.UUCP>
Date: 17 May 88 17:37:48 GMT
References: <48048@ti-csl.CSNET>, <1869@bigtex.uucp> <4706@hplabsb.UUCP>
Organization: Boeing Aerospace Corp., Seattle WA
Lines: 36

In article <4706@hplabsb.UUCP>, dsmith@hplabsb.UUCP (David Smith) writes:
> True, but since the orbiter is pushing forward on the tank, and not
> vice-versa, might it be feasible to throttle down the SSME's to the
> point that the loads are manageable?
> 

I believe you are misinterpreting what is pushing on whom in the
Shuttle stack.  The majority of the mass of the Shuttle core,
which is the Orbiter plus External Tank, is the oxygen in the ET.
This comprises about 1.4 million pounds of the total 1.8 million
pounds in the core at liftoff.

There is a connection between the forward end of the Solid Rocket
Boosters and the middle of the 'intertank' in the ET.  This is
a ball-and socket joint, with an aft-facing socket on the ET, and
a forward pushing ball on the SRB.  The socket is part of a large
forging which spreads the push from an SRB over the intertank.
The intertank is the corrugated region about one third of the
way back on the ET.  The intertank, in turn, spreads the push
of the SRBs evenly along the rim of the Oxygen tank.  The push
from the SSMEs represents about 15% of the total thrust of the
Shuttle early in the flight.  The push from the SSMEs is transferred
into the skin of the hydrogen tank through the connecting
struts in the aft portion of the Orbiter.

With the present design of the ball and socket joint, there is
no way to separate the SRBs as long as they are firing, they
simply apply too much force (3 million pounds each) to separate
the joint.



-- 
Dani Eder / Boeing / Space Station Program / uw-beaver!ssc-vax!eder
(205)461-2606(w) (205)461-7801(h) 1075 Dockside Drive #905 Huntsville, 
AL 35824  34 40 N latitude 86 40 W longitude +280 ft altitude, Earth