In the development of the world’s first supersonic airliner there were to be many unknowns to be explored, and design calculations to be verified or validated. Once the materials had been selected, it was necessary to carry out an exhaustive programme of laboratory test to reproduce the supersonic flight environment that Concorde would spend her life flying in, both in terms of the thermal cycles that she would be subjected to, and the structural loadings and resistance to fatigue of the articles under test.
An understanding of the thermal demands of the supersonic flight profile could be gained from extensive laboratory testing. The rapid rise in the temperature of materials during acceleration, coupled with prolonged heat-soak in supersonic cruise, followed by rapid cooling under deceleration, could all be reproduced using relatively small articles in the laboratory. Because of the pioneering nature of the project, it was decided to build two test airframes, one for the purpose of static testing, and another for fatigue testing. The use of these test airframes would provide valuable data relating to the ability of the production machines to withstand the rigours of supersonic flight and give confirmation of the calculated in-service life of the complete aircraft.
STATIC TESTING – (French Airframe)
Conducted at – Le Centre d’Essais Aeronautiques de Toulouse (CEAT), Toulouse, France
The principle of static testing is to ensure that the structural integrity of the airframe is such that it can withstand the numerous mechanical, aerodynamic and thermal loads imposed on it during flight. With exception of thermal testing, which was unique to the Concorde project, static testing was, and still is, relatively commonplace in the aeronautics industry, and widely accepted as being valid, and necessary, for all passengers airliners.
Static testing was undertaken at Le Centre d’Essais Aeronautiques de Toulouse (CEAT), Toulouse, and began in during September 1969. Initially, the airframe was subjected to progressively increasing load tests at room ambient temperature. When the structure had been examined and deemed to have passed these test, it was then subjected to a series of test that were repeated alternately between the calculated in-flight temperature and the ambient, thus replicating the supersonic thermal cycle. Testing was achieved using a vast array of equipment. A series of 80 servo-controlled hydraulic jacks applied the sequenced test loads on the airframe, and a total of 35,000 infra-red lamps provided the necessary means to simulate the effects of heat in the supersonic regime. In order to reduce the skin temperature from over 120C to -10C within 15 minutes, thus emulating the flight situation, around 70,000 litres of liquid nitrogen were used. Instrumen-tation recorded and processed data from 8,000 different points every two seconds.
This initial programme reached its successful conclusion in 1972, when the aircraft was cleared for flight at a take-off weight of 385,000 pounds. Further testing resulted in an increase in the take-off weight to 400,000 pounds.
The pictures below shows part of the French static airframe
Below you can see pictures of the remains of the French static airframe at Toulouse, France.