From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fac41,e01bd86884246855 X-Google-Attributes: gidfac41,public X-Google-Thread: 103376,fb1663c3ca80b502 X-Google-Attributes: gid103376,public From: "Robert I. Eachus" Subject: Re: Interresting thread in comp.lang.eiffel Date: 2000/07/23 Message-ID: <397A5CB4.AF5F6B8A@earthlink.net>#1/1 X-Deja-AN: 649648724 Content-Transfer-Encoding: 7bit References: <8ipvnj$inc$1@wanadoo.fr> <8j67p8$afd$1@nnrp1.deja.com> <395886DA.CCE008D2@deepthought.com.au> <3958B07B.18A5BB8C@acm.com> <395A0ECA.940560D1@acm.com> <8jd4bb$na7$1@toralf.uib.no> <8jfabb$1d8$1@nnrp1.deja.com> <8jt4i0$18ec7$1@ID-9852.news.cis.dfn.de> <8k5a31$1p61t$1@ID-9852.news.cis.dfn.de> <3966D7B0.5D6475E4@earthlink.net> <396CA5AD.EE955F7A@earthlink.net> X-Accept-Language: en,pdf Content-Type: text/plain; charset=us-ascii X-Complaints-To: abuse@earthlink.net X-Trace: newsread2.prod.itd.earthlink.net 964320396 63.24.55.184 (Sat, 22 Jul 2000 19:46:36 PDT) Organization: The MITRE Corporation MIME-Version: 1.0 NNTP-Posting-Date: Sat, 22 Jul 2000 19:46:36 PDT Newsgroups: comp.lang.ada,comp.lang.eiffel Date: 2000-07-23T00:00:00+00:00 List-Id: (I'm replying directly because it has been a few days, and this is getting pretty far from Ada and or Eiffel. But feel free to quote elsewhere... Ken Garlington wrote: > > "Robert I. Eachus" wrote in message > news:396CA5AD.EE955F7A@earthlink.net... > > As I remember it, there was planned to be a relationship as part of the full-up > > simulation of the flight control system. When the decision was made not > > to use the SRIs in the simulation, that part of the contract was cut back or > > cancelled. I think they still had the SRI hardware supplier on contract, but not the > > software developers. > Actually, I posted the AW&ST articles on my website. They indicate that > Sextant was a full partner in Ariane 5, and in fact that the Ariane 4 SRI > was *not* used "as is". See First, there is a bit of confusion above. If the software developers in England had been involved in the SIMULATION contract, they could have, and probably would have noticed the problem. But they were not on contract for the Ariane 5, they were contracted to develop a new IRS for the Ariane 4! This game playing was AFAIK the idea of CNES. The IRS was upgraded for Ariane 5, but--and here the game playing begins. It was decided to use the "new" IRS in the Ariane 4. To keep the cost overruns on the Ariane 5 down, the development costs were moved to the Ariane 4. So far, no problem. But then, and I'll quote the report on this: "It is even more important to note it was jointly agreed [by CNES and its contractors] not to include Ariane 5 trajectory data in the IRS' requirements and specifications." There is the disaster in one sentence. The new IRS for the Ariane 5, was designed for, and only for, the Ariane 4. And since EASAMS Ltd. was a major contractor on the Ariane 4, but a sub to Aerospatiale on the Ariane 5, they were not directly involved in the decision not to get the Ariane 5 data, and according to my sources, the decision was directly due to the unwillingness by the French to release the data to a British firm--even though most of the work was done in Germany. (I heard the later after two German beers. So while some of this is very well documented, I can't vouch for that. I can vouch for the fact that EASAMS never got the Ariane 5 specs. Not they were told not to use them, but they were not permitted to see them.) And I also know, and it is very well recorded, that the issue of horizontal position post launch was NOT decided by the programmers. They objected, and it went to a multi-contractor review where it was decided not to protect it. But this was at an ARIANE 4 meeting, not an Ariane 5 meeting, because the development of the new IRS was officially part of the Ariane 4 project. I'm sorry to keep harping on this, but system engineering and system integration is what MITRE does, and at MITRE I worked on several multi-national projects. I was in a position to gather some of this information first-hand, but MITRE as such put a lot of effort into figuring out where the failure occurred, even before the official report came out. We wanted to make sure that we didn't repeat the same errors, and I was able to use the Ariane 5 as an object lesson on one project. By the way, I am now, as of last week, on long term disability. :-( I'm better than I was in January, but I still haven't been into the office since then. Hopefully, I'll get to finish some books and article while they are trying to figure out just what is wrong. > The gains changed abruptly when the aircraft transitioned from > takeoff-and-landing to up-and-away mode. This produced a sudden transient, > triggering the start of the PIO. The transition now occurs more gradually. That fixes the primary cause, but not the actual failure mode. Does the stick now have tactile feedback? Or has the rate limit on the stabilator been changed? (Yes, avoiding sudden non-pilot-induced control inputs is a very good thing. But tactile feedback, such as stick shakers for stall warnings have the great advantage of focusing the pilot on where the action is needed. -- RIE