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=2.1 required=5.0 tests=BAYES_20,INVALID_MSGID, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 1108a1,5da92b52f6784b63 X-Google-Attributes: gid1108a1,public X-Google-Thread: ffc1e,a48e5b99425d742a X-Google-Attributes: gidffc1e,public X-Google-Thread: f43e6,a48e5b99425d742a X-Google-Attributes: gidf43e6,public X-Google-Thread: fac41,a48e5b99425d742a X-Google-Attributes: gidfac41,public X-Google-Thread: 103376,a48e5b99425d742a X-Google-Attributes: gid103376,public From: Martin@nezumi.demon.co.uk (Martin Tom Brown) Subject: Re: Papers on the Ariane-5 crash and Design by Contract Date: 1997/03/21 Message-ID: <858933630snz@nezumi.demon.co.uk>#1/1 X-Deja-AN: 227468983 References: <332B5495.167EB0E7@eiffel.com> <33308C91.40CC@lmtas.lmco.com> <858850191snz@nezumi.demon.co.uk> <5gssgv$bei@news.ccit.arizona.edu> X-Mail2News-User: Martin@nezumi.demon.co.uk X-Mail2News-Path: nezumi.demon.co.uk Organization: Nezumi Reply-To: Martin@nezumi.demon.co.uk Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.programming.threads,comp.lang.ada Date: 1997-03-21T00:00:00+00:00 List-Id: In article <5gssgv$bei@news.ccit.arizona.edu> frank@bigdog.engr.arizona.edu "Frank Manning" writes: > In article <858850191snz@nezumi.demon.co.uk> Martin@nezumi.demon.co.uk > (Martin Tom Brown) writes: > > > Whilst I am generally in agreement, it isn't usually beyond the > > wit of man to design in a relatively primitive hardware bias on > > servo systems so that they fly top dead centre with no input. > > Or fly round in small circles or whatever the design team decide > > is the least embarassing failure mode. At least that way the rocket > > survives for long enough that humans can decide kill or cure. > > Well, I understand what you're saying, and I agree that generally > this is a good idea. > > In this case, though, I suspect the rocket is statically unstable, > which means the nozzles must be actively steered to keep the > vehicle on course. If the nozzles were locked in the center > position, for example, the vehicle would probably start flying > sideways very quickly. Depending on the speed, it would probably be > torn apart. Essentially what happened to it. I'm sure it is statically unstable like balancing a broomstick on end. My point is that a primitive hardware based accelerometer could have kept the thrust on average parallel to the velocity for quite a lot longer once the main guidance system was wrecked. It wouldn't be injected on the right orbit, but it wouldn't self destruct quite so easily either. Regards, -- Martin Brown __ CIS: 71651,470 Scientific Software Consultancy /^,,)__/