Readers letters
Further to Brian Cowell’s valued comments (PE April), as early as 1920 the Aeronautical Research Committee and it Engine Sub-Committee, had considered ‘very fully’ the potential of the gas turbine. But they decided not to recommend any action to the Air Ministry, pointing to the many difficulties remaining to be solved.
Meanwhile, Dr. A. A. Griffiths, who in the 1920s was best known for his theoretical work on stress and failure of metals, proposed a two-stage compressor/two-stage turbine engine – with the second turbine driving the propeller in 1926 while working at the Royal Aircraft Establishment (RAE). He also suggested that blades of compressors and turbines should be treated as aerofoils.
But the thrust of my comments about iconic heroic inventors like Sir Frank Whittle, is best shown by Boxkite to Jet, from the Rolls-Royce Heritage Trust. The author, Douglas Taylor, records the remarkable career of Major Frank Halford who, among other things, designed de Havilland’s 3,000lb thrust Goblin turbojet of 1941 and the 4,400lb thrust Ghost of 1945. He instigated the 15,000lb thrust Gyron in 1950 for supersonic flight. The book also throws light on Whittle’s earlier work.
Taylor quotes (p. 109) the British Under-Secretary of State for Air in 1934 continuing to state: ‘Scientific investigation into the possibilities of jet propulsion has given no indication that this method can be a serious competitor to the airscrew engine combination.’ Someone clearly advised the Under-Secretary for him to make this sweeping statement.
An official letter informed Whittle that successful development of his idea was considered impractical as materials capable of withstanding high stresses and temperatures did not exist. That the Under-Secretary’s unfortunate statement was made four years after Whittle filed his first patent for a ‘gas turbine in combination with jet reaction propulsion’, was possibly responsible for government attitude towards the degree of official support the inventor received in later years.
As I mentioned in my review, Whittle was obliged in 1935 to form Power Jets Ltd. to kick-start his jet engine ideas. No other individual went this far. Indeed, in 1930 it had rankled Whittle that steam turbine maker BTH said that to try out his prototype would cost £60,000, a sum it was not prepared to risk. Only after 1936 did BTH eventually assist Whittle, with Rover entering the scene in 1941.
And when Whittle began to make progress with his engine, Dr. Griffiths was forced to re-evaluate his stance on the use of a jet directly for propulsion.
And it was Whittle’s progress at Power Jets that led directly, in 1937, to the Air Ministry authorising the RAE to start investigating, in conjunction with steam turbine maker Metropolitan-Vickers of Manchester, the RAE’s axial compressor based on Dr. Griffiths’s design. Later, aero engine maker Armstrong-Siddeley joined this work which led to the F2 and F3 axial flow turbine engines flight tested in a meteor. No plans were made to produce the engine in the war.
Dr. Griffiths joined Rolls-Royce in 1939 from the RAE; he remained until 1960. Rolls-Royce, with Dr. Griffiths on board, worked on his ‘contraflow’ idea to develop an engine for the Meteor, thus dropping his original propeller-driving idea in favour of jet propulsion. While at Rolls-Royce, Dr. Griffiths proposed the AJ65 (axial jet, 6500lb thrust) that led to the Avon. Avon development began in 1945, with the first prototypes built in 1947. The first Avon flew from Hucknall on 15 August 1948, nearly 15 years after the Air Ministry stated that the jet could not be a ‘serious competitor to the airscrew engine combination’.
Seven years’ earlier, on 15 May 1941, Whittle’s centrifugal-flow turbo-jet engine made its first flight in the Gloster E28/39! So much for government advice!
Irrespective of the centrifugal/axial compressor issue, Whittle was the man who made the jet engine fly.
John Mortimer, Milton Keynes, Bucks
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