12 April saw the 75th anniversary of the test run of Sir Frank Whittle’s first experimental jet engine. Here, we find out more about this historic landmark.
Frank Whittle was born in 1907 in Coventry. He attended local schools before winning a scholarship to attend Leamington College. When he was 15 he applied to join the RAF as an aircraft apprentice, but despite passing the written entrance exam with ease, he failed the medical examination. He went on a special diet and exercise regime, applied again, and this time was successful. He reported for duty as a boy apprentice at Cranwell in September 1923. For the next three years he was very unhappy in the atmosphere of strict discipline, but enjoyed his time at school and in the Model Aircraft Society. He was recommended for a cadetship, and began RAF College, Cranwell, as a Flight Cadet. Each Cadet had to write a science thesis every six-month term, and in Whittle’s Fourth Term he wrote Future Developments in Aircraft Design. This farsighted thesis was to fundamentally change Whittle’s life, and the future of aviation. He continued to develop his ideas and in October 1929 was able to update the thesis to include the concept of aircraft propelled by a jet produced by a gas turbine. His proposal made its way to the Air Ministry and Whittle was instructed to present his idea.
The response was discouraging. He was told that the Air Ministry did not view gas turbines positively following a highly unfavourable report a few years previously. Whittle presented his idea to Dr A. A. Griffiths, who was interested in using gas turbines to drive propellers, but Griffiths was not impressed. Whittle soon received a formal letter stating that the Air Ministry considered his idea to be impractical.
His RAF colleague Pat Johnson was a trained Patent Agent, and urged Whittle to take out a patent on his invention, which was filed on 16 January 1930. As the Air Ministry did not put it on the secret list, when Whittle filed his Complete Specification and the patent was granted in October 1932, the invention was published throughout the world. In 1935, when the patent was up for renewal, Whittle had to allow it to lapse when he couldn’t afford the £5 renewal fee, and saw no possibility of his invention being developed.
Following four years of service as an officer, Whittle attended the Officers Engineering Course, passing with Distinction in every subject except mechanical drawing. He asked to be considered to attend the mechanical engineering Tripos at Cambridge University and was allowed, as an exceptional case. He began a two year course in 1934. Despite the intense activity that happened in the last year of his course, he gained a First.
In 1935, Whittle was contacted by RD Williams, a former hut-mate at Cranwell. Williams and his business partner, JCB Tinling, agreed to find financial backers to develop the idea in return for a 25% share each of the commercial rights. Eventually a firm of investment bankers, OT Falk and Partners, agreed to invest in the project and the Four Parties Agreement was drawn up between Whittle, Tinling and Williams jointly, OT Falk and Partners, and the Air Ministry. This formed a company, Power Jets Limited, with Whittle acting as Honorary Chief Engineer and Technical Consultant.
Work began on the experimental engine early in 1936, after Whittle reached an agreement with British Thomson Houston. The first unit was called the Whittle Unit or WU. From the outset lack of money was a major stumbling block. As a result, rather than build and test components separately, they had no option but to build the complete engine. On 12 April, 1937, everything was in place for the first test run, described here by Whittle:
‘For a second or two the speed of the engine increased slowly and then, with a rising shriek like an air-raid siren, the speed began to rise rapidly, and large patches of red heat became visible on the combustion chamber casing. The engine was obviously out of control... I screwed down the control valve immediately, but this had no effect and the speed continued to rise, but fortunately the acceleration ceased at about 8,000 rpm and slowly the revs dropped again. Needless to say, this incident did not do my nervous system any good at all. I have rarely been so frightened!’
From this initial run the engine continued to be developed over the next few years, and it was a version of this design, the W.1 that powered the first British jet aircraft into flight on 15 May 1941.