De Havillands Part 2

In 1941 the new Engine Co started deHavilland’s off on a new pioneering period when they adapted the Whittle design for a turbojet engine. Their first engine was named the Goblin, this was improved to give the Goblin II and later the Goblin III (the engine company often chose names drawn from the supernatural).

With the emergence of the jet engine the Ministry requested the Aircraft Co to undertake the design of a single engine single seat jet fighter. This was to become the DH Vampire, a twin boom aircraft. Design commenced in 1942 and the first flight took place in September 1943. Powered by a Goblin engine it was the first plane to exceed 500mph in level flight and the second jet plane to join the RAF after the Gloster Meteor, but it was just too late to take part in action during the war. Over 3300 Vampires were made, 25% were made under licence, and Vampires served with a number of other air forces. It appeared in several versions including a two seat trainer. Those early deHavilland and Rolls Royce jet engines were very successful by the standards of the day and were well ahead of the rest of the world.

The next development by the engine company was the Ghost, still a centrifugal compressor type, and this was to power deHavilland’s most ambitious project ever, a jet powered liner. This was to be the ‘Comet’, it first flew in July 1949, it was a beautiful aeroplane, much faster, quieter, smoother and flying higher than any other airliner, it was an international sensation. It went into airline service in 1952, but tragically it was a technological step too far. To fly at these high altitudes it was, of course, necessary to have a pressurised cabin - the nature of stress concentrations that could occur in the skin of the pressurised fuselage around the corners of the square windows was not fully understood neither was the phenomenon of metal fatigue. The result was catastrophic failure of the aircraft structure whilst flying at altitude, three aircraft were lost and all on board perished. All Comets were grounded. It took a time for the cause to be fully understood and the aircraft modified, other manufacturers learnt from deHavillands’ misfortune. It was a major blow to the company’s reputation and to the reputation of the UK aircraft industry, the lead that we had over the rest of the world was severely eroded. Modified versions of the Comet went on to be very good aeroplanes, but less commercially successful than the later American designs, the Comet 4 remained in service for thirty years. The Nimrod, which served as a maritime patrol aircraft and as an airborne early warning station, was a development of the Comet and was in service until

The company went on to produce the ‘Venom’ a fighter bomber development of the Vampire fitted with the more powerful Ghost engine, it had improved performance and improved bomb load capability. In keeping with their pioneering spirit they were keen to explore the possibility of supersonic flight. The media had made much of the difficulty that might be experienced in reaching supersonic speeds and had created the concept of the ‘sound barrier’. deHavilland built a plane to explore operating at sonic speeds, it looked rather like a flying wing without the conventional tailpiane and with swept back wings. It was called The Swallow. Sir Geofferey, as he had now become, was married just before he started his company and he had two sons, the first born was named Geofferey and the second, John. Like Sir Geoffery, they both worked as company test pilots. Tragically John was killed in the 1940s when involved in a mid-air collision between two Mosquitos; Geofferey was testing the Swallow at near sonic speed when the aircraft experienced extremely severe buffeting which caused a structural failure, the plane crashed and he too was killed.

A further development of the twin boom design was the DH11O, a bigger and faster twin engine plane potentially capable of attaining supersonic speeds, unfortunately the prototype plane suffered a failure of the outer wing section at sonic speed causing the whole structure to break up whilst demonstrating its capabilities at the Farnborough air show in 1952, one of the engines crashed into the stand and a large number of spectators were killed or injured. It was beginning to seem as though the company was jinxed. In those days there were no computers, not even electronic calculators, calculations were mostly performed using a slide rule, this was sufficiently accurate for most situations —greater accuracy could be obtained by use of tables and methods were developed for more accurately mathematically modelling real situations, but they involved many man hours. In the end it was down to the development engineers and the test pilots to prove the design and produce a successful airworthy plane. Some test pilots were killed taking risks flying planes that were pushing back frontiers, and many became celebrities very much in the public eye.

Other companies had their disasters; the tragedy for deHavillands was that their disasters involved deaths of the public and in such a sensational way. The crash of the 110 was another blow to their reputation. The DH11O was developed into a naval version, the Sea V~xen for operation from aircraft carriers and proved to be a competent aeroplane. The RAF were going to have a suitable land based version but opted for the newer Gloster Javehn.

Meanwhile the Engine Co went on to build the largest and most powerful Jet engine of the time, the Gyron, a new design with an axial compressor. This engine was intended for use in the Hawker P1121, a supersonic attack aircraft, but this became a victim of the massive cuts in defence spending of the time. A smaller version of the Gyron, the Gyron Junior, was also being developed, this was intended for the Blackburn NA39/ Buccaneer and later went into service in this aircraft. (Later versions of the Buccaneer were fitted with the more powerful Rolls Royce Spey.) The Gyron Junior was also planned to be the turbojet half of the mixed power plant SR177, a high performance interceptor fighter using a rocket engine at altitude, another victim of the defence cuts.

Ron Watts (to be continued).