Re: Balance and stresses of stack


"Brian Gaff" <Briang1@xxxxxxxxxxxxxxxx> wrote in message
news:73KEe.76160$G8.30517@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> I've been reading that manual I had the link to and one thing is a bit
> vague to me.
>
> They make great store of the fact that the Shuttle is only supported by
the
> tank, and the tank is supported by the SRBs, and the SRBs are bolted down.
> However, where is the centre of gravity when in this configuration, it
> surely must change as the tanking and payload bay vary the weight at
> different times.

Yes, but start with some numbers:

Each SRB weighs 1.3 million lbs.

The ET w/o fuel is about 62,000lbs. With LH2 and O2 on board it's about
1.67 million pounds

But that doesn't really change the com for the ET/SRB portion.

Now the shuttle itself weighs in at about 240,000lbs. Max payload around
50,000bs.

Let's call it an even 300,000lbs to make it easy.

Now, the two SRBs alone weigh in at 2,600,000 lbs or 8 times the mast of the
orbiter.

They're 12' in diameter, so there's a fair amount of wiggle room for the
center of mass to move w/o tipping it over.

So, w/o knowing where the COG of the orbiter is,etc, I can't really answer
your question, but my gut feel is, it doesn't really make much difference.


>
> Presumably, then, if the bold were to give way, the thing would fall over
> on top of an upside down orbiter!
>
> /This prolonged stress, I would have thought, would bend the stack and
> although there is twang at main engine start, I'd have thought the stack
> would crawl in the orbiter direction after the solids fire and the bolts
are
> blown.
>
> Brian
>
> --
> Brian Gaff....Note, this account does not accept Bcc: email.
> graphics are great, but the blind can't hear them
> Email: briang1@xxxxxxxxxxxxxxxx
>
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>
>
>


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