After WWII it was the dawn of a world of new technology, but one innovation was devised in 1929 that saw the light of day in the 1950s. Frank Whittle, an office of the Royal Air Force, proposed powering an airplane with a gas turbine engine. It took eleven years for his idea to reach fruition with Britain's first jet fighter the Gloster Meteor. But, it was in 1952 that the de Havilland Comet would make history as the world's first commercial jetliner.
The Comet has the ability to fly at speeds of up to 490 miles per hour while the fastest propeller planes could only go 315. The cabin was pressurized and the plane could fly above storms rather than through them. The new jetliner was a hit and soon everyone was aware that Great Britain would lead the world in commercial jetliners. American Aviation Magazine said:
"Whether we like it or not, the British are giving the U.S. a drubbing in jet transport."
Then on October 26th 1952 a Comet failed to get airborne and crashed on takeoff. No one had major injuries, but the plane was a loss. The blame was placed on pilot error. That March another Comet crashed on takeoff becoming the first time anyone had died in a jetliner incident. Once again pilot error was blamed. But on January 10th 1954 it was clear that pilot error was not a factor when a Comet crashed into the Mediterranean. The pilot was in the process or radioing "Did you get my ..." then it cut off. Fishermen saw the pieces of the plane falling into the sea.
Immediately all the Comets were grounded and a massive investigation was launched. Unfortunately the wreckage was 500 feet below the water so that the investigation was not complete when 50 recommendations were made to correct the problem, which had not been determined. The Comet was cleared to fly again, until April 8th 1954 when another Comet went down in the ocean. By that time more wreckage had been recovered from the first water crash and there were some odd findings. The tail stabilizer had blue marking on it. Analysis determined that they were from the seats hitting the stabilizer at high speeds. Just what had happened? The Ministry of Civil Aviation came up with a novel method of finding out.
They constructed a massive water tank and put the fuselage of a Comet into it. The wings were connected to hydraulics to provide vibrations similar to what would be felt at high altitude cruising. Then the tank was filled with water to a pressure that would match the 33,000 feet cruising altitude of the Comet. After the testing was complete they opened the tank and were shocked at what they found. There was a split in the fuselage starting from an escape hatch that stretched eight feet. Eight months later when more wreckage was pulled from the sea of the second crash a similar fracture was found. The real problem was metal fatigue. The cause was the square windows. A round window distributes the pressure, but a square one puts too much stress on single points at the corners. To make matters worse the rivets were punch driven stressing the metal more, and the windows had been designed to be glued and riveted, but they were just riveted. Every Comet was declared unsafe to fly. It would take four years for the Comet to be redesigned with oval windows and thicker metal skin. By that time the Boeing 707 had been released with the ability to carry twice as many passengers twice the distance. The Comet would remain a major contender in the commercial jet liner market, but would never fully recover from the loss of market share.
The blame for the failure to detect the problems before the plane took flight fell to he testers. They had tested the fuselage in a stationary pressurized room without any of the other stresses the plane would encounter during use. If the plane had been properly tested the disaster could have been averted. In the United States the U.S. Civil Aeronautics
Administration which was the
predecessor to the FAA was not comfortable with the square windows and refused to grant it an
air-worthiness
certificate. Without the certificate the Comet never flew in the U.S. with square windows. One good thing that came out of this disaster was the development of the modern "Black Box" data recorder. The disaster inspired Australian engineer Dr. David Warren to create a device that would record the instruments and the cockpit voices.
-Professor Walter