Repairing tear in Classic Wing...

<Pete S.> wrote in message
news:3gp4qv05sq4v7e50pjfq4tnr58bo8agpbj@4ax.com...
> On Fri, 31 Oct 2003 09:44:17 +0000, Danny Burchett <me@privacy.net>
> wrote:
>
> >Alasdair Allan wrote:
> >
> >> ferret wrote:
> >>> Alasdair Allan wrote:
> >>> > Humph! If it still works, it isn't broken...
> >>>
> >>> CoughHubbleCoughCough...
> >>
> >> Humph! I think its churlish of you to bring _that_ up...
> >>
> >> Al.
> >
> >Please God let it be true, Al was the hubble your fault????
> >
> Now then children, play nicely.
>
> You know that Al didn't do hubble, but he knows a man who F****d up an
> Arianne......
>
> Pete

Wasn't the last one of those that did the "Guy Fawkes" thing down to the
fact that they only tested about 5% of the code on the onboard computers...?

CAS
--
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CAS wrote:
> Wasn't the last one of those that did the "Guy Fawkes" thing down to the
> fact that they only tested about 5% of the code on the onboard computers...?

No, somebody (who shall remain nameless) lifted the gimbal code for the
thrusters from the Ariane 4 thruster code... the Ariane 4 thrusters gimbals
had more travel. The Ariane 5 gimbals went to the end of the travel arm,
and, err, stuck...

Al.

"Alasdair Allan" <aa@ukrecscuba.org.uk> wrote in message
news:bnttb8$15kmhq$1@ID-188041.news.uni-berlin.de...
> CAS wrote:
> > Wasn't the last one of those that did the "Guy Fawkes" thing down to the
> > fact that they only tested about 5% of the code on the onboard
computers...?
>
> No, somebody (who shall remain nameless) lifted the gimbal code for the
> thrusters from the Ariane 4 thruster code... the Ariane 4 thrusters
gimbals
> had more travel. The Ariane 5 gimbals went to the end of the travel arm,
> and, err, stuck...
>
> Al.

Ooops! I'm not in the least bit bothered about who it was, but please,
please tell me more about the hours and days afterwards.... please!

CAS
--
PADI AOW? Get Rescue Training on UKRS Course #1 -
http://divesite.calumscott.me.uk/ukrs/rescue_diver_2004
Temperature @ Stoney? Find it or share it @
http://stoneytemps.calumscott.me.uk/

On Fri, 31 Oct 2003 15:21:39 -0000, "CAS"
<calumscottTAKETHISBITOUT@yahoo.com> wrote:

>"Alasdair Allan" <aa@ukrecscuba.org.uk> wrote in message
>news:bnttb8$15kmhq$1@ID-188041.news.uni-berlin.de...
>> CAS wrote:
>> > Wasn't the last one of those that did the "Guy Fawkes" thing down to the
>> > fact that they only tested about 5% of the code on the onboard
>computers...?
>>
>> No, somebody (who shall remain nameless) lifted the gimbal code for the
>> thrusters from the Ariane 4 thruster code... the Ariane 4 thrusters
>gimbals
>> had more travel. The Ariane 5 gimbals went to the end of the travel arm,
>> and, err, stuck...
>>
>> Al.
>
>Ooops! I'm not in the least bit bothered about who it was, but please,
>please tell me more about the hours and days afterwards.... please!
>
>CAS


There is an excellent report analysing what went wrong and why, it
must be on the web somewhere.

As I remember it. Ariane 4 had a Ring Laser Inertial Navigation Unit
built by some nice people up in Edinburgh. Since it worked so well
someone decided to re use it in Ariane 5, well you should always try
to re use proven systems shouldn't you? Unfortunately no one tested
the system against the Ariane 5 flight profile. Apparently they
couldn't work out how to at a reasonable cost. The vehicle accelerated
sideways harder than 4 (more travel on the thruster gimbals?)
resulting in an overflow of one of the variables. There was no trap to
catch this, since the condition was impossible in Ariane 4, and the
system shut down . All three redundant INUs put out maximum values
for rate and attitude which was the specified action for a failed
unit. The flight control software had a vote on it and tried to fly
using the duff data (gimbals at maximum travel). The vehicle went
unstable and started to break up, range safety terminated the flight
(blew up the rocket).
As far as I know the original manufacturers of the INU had very little
to do with 5 they just supplied some more units when asked.
The witch hunt that followed must have been spectacular.


SimonK