Aeronautical scientist who pioneered research into jet engine noise reduction
Born: 16 November, 1919, in Isleworth, Middlesex.
Died: 20 September, 2015, aged 95.
Dubbed by his contemporaries as “the father of aeroacoustics”, Professor Geoffrey Lilley was a leader in this field over seven decades, pioneering research in a number of areas such as jet engine noise reduction, sonic boom and even human-powered flight and went on to become an innovator in engineering education.
As a professional engineer he worked with industry and government research laboratories on project-orientated research with commercial and military aircraft and space applications, and worked alongside industrial partners including British Aerospace, Rolls-Royce, Lockheed, Boeing, the US Airforce and Nasa. He was instrumental in persuading politicians on both sides of the Atlantic that Concorde’s noise levels were acceptable; failure to do so would have resulted in the Anglo-French plane being scrapped.
The importance of aeroacoustics - a subject vital to the reduction of noise in jet engines - for the aerospace industry cannot be underestimated. Research in this field has become increasingly important over the decades and, with public concern about excessive aircraft noise emissions, regulations have been adopted near heavily populated urban centres.
In terms of traveller comfort, environmental perception and industry expansion, it was vital and Lilley was at the forefront of a number of significant developments, receiving six patents for his noise reduction technology.
Born in Isleworth, Middlesex, in 1919, Geoffrey Michael Lilley was the youngest of four children to Micholl Morland Dessau, a wealthy American rubber magnate and inventor, who predicted the use of rubber roads in the future; he lost his vast fortune following the 1929 Wall Street Crash and the ensuing Depression of the 1930s and subsequently abandoned his family. Lilley was Geoffrey’s mother’s maiden name.
In 1934, aged 15, Lilley left Isleworth Grammar School and joined the RAF, although his dreams of training to be a pilot were thwarted after failing the eye test. Consequently, he resigned in 1936 and embarked upon a general engineering apprenticeship with Kodak. Soon after, he demonstrated his practical flair with his design and installation of a sophisticated air conditioning system, complete with specialised ducting, air filtration and a refrigeration plant, which enabled the company to store and process the RAF’s vast library of high quality reconnaissance film acquired during the Second World War.
Upon leaving Kodak in 1940, he joined Vickers-Armstrong engineering and aircraft factory at Weybridge and Vickers Supermarine in Southampton, where he worked on numerous aircraft and high-speed bomb projects. He worked briefly with Sir Barnes Wallace, inventor of the “bouncing bomb”, which was used during Operation Chastise, RAF 617 squadron’s attack on four German dams, subsequently publicised as the “Dam Busters”. Lilley worked at Vickers throughout the war, while also serving in the Home Guard in London. He also attended evening class to complete a BSc, with first-class honours, before obtaining an MSc from Imperial College London in 1945.
Post-war, he began designing commercial wind tunnels for research into subsonic and supersonic air speeds at Vickers. His wind tunnel is still in use at British Aerospace Systems.
In 1946, deciding upon an academic career, Lilley became one of the founders of the College of Aeronautics at the RAF base in Cranfield, Bedfordshire (now Cranfield University). Throughout the 1950s and 1960s, he and his colleagues worked in the development of many aspects of aircraft research and design, which led to considerable growth and diversification into other technologies and into manufacturing and management, which helped establish it as a centre of excellence. He was appointed Professor of Experimental Fluid Mechanics in 1961.
In 1948 Lilley began his research, with Robert Westley and Alec Young, into jet-engine noise reduction. Their designs for noise-reduction nozzles fitted to the rear of jet engines were installed on all commercial civilian jet aircraft from 1959-1970 making them acceptable from the perspective a noise impact.
During the 1950s, he was part of a team that developed the first definitive study of the “supersonic bang”, the pattern of shock waves around an aircraft flying at supersonic speeds. From 1955 he was a member of the UK Government’s Supersonic Transport Aircraft Committee, established by Anthony Eden’s Conservative government. This led to the design of Concorde. Later, Lilley headed the technical team charged with persuading New York’s Port Authority that the new supersonic aircraft could meet the US’s strict noise restrictions.
The Americans had cancelled Concorde’s rival supersonic transport programme, the Boeing 2707, in 1971, and observers believed the US government had encouraged opposition to Concorde as it lacked competition. In 1976 shortly after its launch, Congress banned Concorde landings, citing public concern over sonic booms preventing launch on the coveted North Atlantic routes.
In spite of complaints about noise, the noise report noted that Air Force One, at the time a Boeing VC-137, was louder than Concorde at subsonic speeds and during take-off and landing. Lilley and his team then countered US technical objections line-by-line and successfully persuaded the Americans to withdraw their ban. Concorde remained operational until its withdrawal in 2003.
In 1963 Lilley was appointed Professor of Aerodynamics and Astronautics at Southampton University. During his tenure, he retained his earlier connection with the Royal Aircraft Establishment at Farnborough, which resulted in him securing, the much sought after, large RJ Mitchell wind tunnel, since used extensively by Formula 1 teams to test racing car aerodynamics as well as by students and academics.
One of his more unusual areas of interest concerned how owls flew so silently and the possibilities of noiseless flight for military and civilian jets. In later years, he used the owl as the basis for successful research into how to reduce noise pollution caused by planes approaching airports.
In his free time, he enjoyed playing cricket and walking, and was a founder member and life president of Southampton University’s Light Opera Society.
Self-taught in French and German, Lilley, a self-deprecating man, was known as a great raconteur, often turning the joke on himself. He did not tolerate pompous fools gladly but would enthusiastically encourage talented students to think unconventionally without ridicule.
Lilley received many awards including an OBE in 1981 for services to government, the Gold Medal of the Royal Aeronautical Society and the Aeroacoustic Medal of the American Institute of Aeronautics and Astronautics in 1983. An honorary doctorate was received from Southampton University in 2004.
He married Lesley “Peggy” Wheeler, a primary school teacher, in 1948, six months after they met . She died in 1996 and he is survived by their son and two daughters.