Re: Unguided orbital insertion (cheap upper stages)

[EMAIL PROTECTED] (Henry Spencer) wrote in message news:<[EMAIL PROTECTED]>...
> A while back, I wrote:
> >...My guess is that the very fast spin of the Juno upper stages
> >was to even out possible performance differences between the solids in
> >each stage. 
> 
> Confirmed.  In fact, they would have liked a still higher spin rate --
> they grumbled about how they couldn't really do precision orbit insertion
> because of dispersion due to motor non-uniformities -- but the motors
> just couldn't take it.

And Henry earlier:
>You need to model possible disturbing
>torques, and decide how much gyroscopic stability you need to handle them. 
>Spin rates for comsats with solid-fuel apogee motors are not high, tens of
>RPM at most. 

So if each stage was a single solid, instead of a cluster of solids, there
would be less disturbing torques.  Also, if we are starting at 90+ km
high then there is less disturbance from air than a lower air launch like
NOTSNIK.  So an orbital launch from an X-prize vehicle could be done
with a more moderate RPM.  Cool.

   -- Vince