Date: 29 Aug 97 08:10:43 From: email@example.com (michael piersdorff) Organization: The Communications Research Centre References: 1 2 Followups: 1 2 3
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Marc Schaeffer <firstname.lastname@example.org> wrote: >Trond Olav Berg wrote: >> Was it a safe plane? >No, there were 20 crashes with Comets. De Havilland underestimated the >forces and stress at high altitude and speed. However there were no >references at that time so the constructor can't (fully) be blamed. Also >calculators and computers were not existing .. After solving the >structural problems the Comet4 was pretty safe, meaning that most >incidents could not directly be blamed on design defects. My understanding of the problem was that most of the in-flight breakups were explosive decompressions of the fuselage resulting from fatigue failure. Successive pressurisation/depressurisation cycles (takeoff and landing, respectively) in combination with flight loads caused cracks at the corners of the square windows used in the early models. Any strength of materials textbook will show that a square-ish corner is a tremendous stress raiser in a tension stress situation, as a pressurised fuselage most certainly is. The solution, of course, was to go to the more or less oval windows one sees today. The second jetliner to fly was the AVRO Canada C-102 Jetliner. It was ready to have been first, but Empire still counted for something in those days, and it would not do for one of The Colonies to beat Britain in the honours for first flight. The C-102's first flight was therefore delayed until the Comet had groaned off the ground. Only one C-102 was built, despite strong interest from Canadian and US commercial airlines, because the then-Liberal Canadian government wanted to concentrate AVRO's efforts on production of the CF-100 fighter, and the design of its successor (the CF-105). It was the time of the Korean war, remember, and our high powered thinkers were more concerned about National Security (the Red Menace) than they were concerned about commercial gain for the shareholders of A.V.Roe. In 1959 their successors (Diefenbaker's Conservatives) abandoned National Security, too, and delivered the coup de grace to the already weakened AVRO by killing the Arrow.