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: 103376,be534a508ac1bb3b,start X-Google-Attributes: gid103376,public From: Ken Garlington Subject: Ariane V update Date: 1996/06/12 Message-ID: <31BEA439.14BA@lmtas.lmco.com>#1/1 X-Deja-AN: 159792825 content-type: text/plain; charset=us-ascii organization: Lockheed Martin Tactical Aircraft Systems mime-version: 1.0 newsgroups: comp.lang.ada x-mailer: Mozilla 2.02 (Macintosh; I; 68K) Date: 1996-06-12T00:00:00+00:00 List-Id: Aviation Week and Space Technology has an article on the Ariane V failure. It quotes Jean-Michel Desobeau, director of engineering at Arianespace as saying: "The on-board computer received or self-generated bad attitude information. It thought the vehicle was at the wrong attitude, commanded the SRB nozzles to compensate, and they executed it." Other items: o The flight is called a "qualification" flight, which sounds to me like it was part of the test program and not really a "production" flight. o Although the telemetry data from the inertial units showed no failures, the output path to telemetry from the IMUs is different than the one to the on-board computers, so "there is a chance the computers were receiving different information than the telemetry." o The on-board computers are dual-redundant (which amazed me; I would have expected triplex at least). The June 12, 1995 edition of AW&ST apparently had an article on some problems encountered with the development of the fail-operational [!] fault detection algorithms between the two computers, requiring extra manpower to solve. o "The computers are more powerful than the single [non-redundant!] one in the Ariane 4, but they use the same general logic." o The on-board computers have a "common sense" algorithms to fault isolate between the two inertial units. [In my experience, these algorithms are not easy to do right.] -- LMTAS - "Our Brand Means Quality"