The original idea for a directional sonobuoy was suggested by Dr Alan Butement CBE in 1964.
Alan Butement was born in New Zealand in 1904 and educated at University College London. He made outstanding contributions to Allied defence science during World War II.
As early as 1931, as a 27-year-old, he and PE Pollard were the first to demonstrate in Britain what much later became known as radar: they proved that radio waves that were reflected off a metal sheet could be detected at a distance of 100m. Had their idea been pursued Britain would have had radar much sooner, but the War Office showed no interest in their experiment, and the idea was taken no further. Not until 1935, when Britain realised how vulnerable she was to bomber attack, did Robert (later Sir Robert) Watson-Watt re-invent radar.
Radar receiver beams are relatively broad. Another of Butement's developments was a switched-beam technique to improve radar location of aircraft and ships by about an order of magnitude.
Probably his most important invention was the proximity fuze – in effect, a tiny radar in anti-aircraft shells that detonated when close to an aircraft. It improved the effectiveness of anti-aircraft guns by a factor of about 30 times.
After the war, Butement moved to Australia and became the Chief Scientist and head of what later became DSTO. He continued producing many ideas for new systems.
His many contributions were acknowledged by his appointment as Companion of the British Empire (CBE) in 1959.
In 1967 he joined Plessey Pacific Pty Ltd as their Technical Director. He was co-founder and Foundation Fellow of the Australian Academy of Technological Sciences and Engineering in 1975.
He died in 1990. The HF Radar Building in DSTO Edinburgh, SA, is named after him.
Prof Henry d'Assumpcao AO, then a 30-year-old engineer, developed Butement's basic suggestion further and introduced improvements that made Barra feasible.
Henry d'Assumpcao joined the Weapons Research Establishment (later called DSTO Edinburgh) in 1958 as a young graduate from the University of Adelaide.
Realising that detection and localisation performance improved if more sensors were used, he proposed the use of long arrays towed behind ships. This led to collaboration between Australia and the US Navy who contributed a towed array estimated to be worth $1M (in 1981) for joint experiments and staff exchanges. This work led later to the development, led by Dr Allan Carpenter, of the Australian Kariwara towed array system that is carried in RAN submarines.
d'Assumpcao later took up other positions in DSTO, ending up as the Chief Defence Scientist and the head of DSTO in Canberra.
He retired from the Department of Defence in 1990 and took up a position as research professor in the University of SA, Director of Research Development, and Director and CEO of the Cooperative Research Centre for Sensor Signal and Information Processing. On his retirement in 2000, he was appointed Emeritus Professor. He was Chief Scientific Adviser to the Australian Customs Service until 2004.
He was elected Fellow of the Australian Academy of Technological Sciences and Engineering in 1981, elected Honorary Fellow of the Institution of Engineers Australia in 1993, appointed an Officer in the Order of Australia (AO) in 1992 and awarded the MA Sargent Medal by the IEAust in 2003. The Library at DSTO Edinburgh is named after him.
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