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,a48e5b99425d742a X-Google-Attributes: gidfac41,public X-Google-Thread: ffc1e,a48e5b99425d742a X-Google-Attributes: gidffc1e,public X-Google-Thread: 1108a1,5da92b52f6784b63 X-Google-Attributes: gid1108a1,public X-Google-Thread: 103376,a48e5b99425d742a X-Google-Attributes: gid103376,public X-Google-Thread: f43e6,a48e5b99425d742a X-Google-Attributes: gidf43e6,public From: Ken Garlington Subject: Re: Papers on the Ariane-5 crash and Design by Contract Date: 1997/03/25 Message-ID: <333831D9.301A@lmtas.lmco.com>#1/1 X-Deja-AN: 228289606 References: <332B5495.167EB0E7@eiffel.com> <858850191snz@nezumi.demon.co.uk> <5gssgv$bei@news.ccit.arizona.edu> <858933630snz@nezumi.demon.co.uk> <5h22cr$c5m$1@news.ccit.arizona.edu> Organization: Lockheed Martin Tactical Aircraft Systems Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.programming.threads,comp.lang.ada Date: 1997-03-25T00:00:00+00:00 List-Id: Frank Manning wrote: > > In article <858933630snz@nezumi.demon.co.uk> Martin@nezumi.demon.co.uk > (Martin Tom Brown) writes: > > > 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. > > OK -- I see your point. A 2-axis accelerometer could measure the > sideways acceleration generated by a non-zero angle of attack. You > could use that information to steer the engines and prevent the > vehicle from flying sideways w/r/t the air mass. Might work. >From experience: An accelerometer/gyro set might be able to back up an IRS sufficiently for flight control use, but not always. It depends upon the airframe stability and other factors. Adding redundant/backup sensors is always a tricky proposition (actually in many respects a hardware analogue to the discussion of using assertions). They add cost/weight/power/cooling, they have to be spec'd/designed/tested, they can introduce faults, and so forth. > > -- Frank Manning -- LMTAS - The Fighter Enterprise - "Our Brand Means Quality" For job listings, other info: http://www.lmtas.com or http://www.lmco.com