Re: Ariane5 FAQ

["Robert I. Eachus" <rieachus@attbi.com>]

Tarjei T. Jensen wrote:
> Robert I. Eachus  wrote:
> 
>>Also the SRI software used the Ariane 4 moments of inertia in its
>>control laws.  The report seems to indicate that there was a 10 Hz
>>ocillation building up due to this.  If it had gone on would that have
>>been sufficient to destroy Ariane 501?  Probably.

> I believe that I saw a program on Discovery in which it was claimed that the
> oscilations would eventually have destroyed the rocket.

As I said, probably.  But if it didn't, the oscillations would result in 
the Ariane 5 not reaching the expected orbit.  Less dramatic, but just 
as fatal for the payload.

And that is why I keep posting on this topic, hoping that everyone will 
"get it."  The actual failure scenario is interesting, but the fact that 
there were two others waiting to happen means that you should look at 
what they all have in commmon:  The missing "scrub" of the SRI 
specifications against the Ariane 5 requirements.  We are talking about 
something that should have taken about a week for three or four people, 
if there were no major discrepancies.  Of course, in this case, the bill 
would have been higher, but a lot less than the bill for the failure.

-- 

                                                        Robert I. Eachus

�In an ally, considerations of house, clan, planet, race are 
insignificant beside two prime questions, which are: 1. Can he shoot? 2. 
Will he aim at your enemy?� -- from the Laiden novels by Sharon Lee and 
Steve Miller.