Green Satin, also known as ARI 5851, was a Doppler radar system developed by the Royal Air Force as an air navigation aid. The system provided direct measures of the drift speed and direction, and thereby allowed accurate calculation of the winds aloft. These values were then fed into the Navigation and Bombing System.
It was originally specified in 1949 as OR.3015 for the English Electric Canberra bomber. The first examples arrived in 1953,[1] and it was soon fitted operationally. It was subsequently used on the V bomber fleet. It remained in use on the V-bombers until the Avro Vulcans 1969 when it was replaced by the Decca 73. Handley Page Victors may have used it until they left service in 1993.
The name comes from an era when the Ministry of Supply used random combinations of colours and code words to prevent their code names being too literal. A version known as Blue Silk with lower top-speed limits was used in some marks of Canberra and Royal Navy aircraft.