Capacitance Altimeter

In early 1940, Alan Blumlein and his team at the EMI Central Research Labs began work on the technology behind the Capacitance Altimeter. This device works by measuring the differences in charge between a low-lying aircraft and the charge at Earth’s surface, therefore enabling aircraft and other vehicles to fly at night and in cloudy conditions.

Capacitance Altimeter EMIAT.357 This is a Test Set for a Capacitance Altimeter developed by A D Blumlien. A capacitance altimeter was a non-barometric means of measuring low-level elevation. It was based on the change in capacitance (the ability of an object to hold a charge) between an aircraft and the earth's surface, with the height of the aircraft above the surface. Work began on low-level altimeters in the summer of 1940, with many flight trials carried out in Wellington, Whitley, Halifax, Stirling and Lancaster bombers. Such an instrument allowed 'blind landing'; low-level bombing and torpedo releases; mine laying and parachute dropping. Production: EMI Place: Hayes, England Date: 1940-1943 Photographer: www.thomasbutlerphotographer.com
Capacitance Altimeter – EMIAT.357

In the summer of 1940, the first test flights using this new technology were conducted in Wellington, Whitley, Halifax, Stirling and Lancaster bombers. The development of the Capacitance Altimeter made ‘blind landing’ (landing at night or in foggy/cloudy/rainy conditions) a reality.

During the Second World War, it was used extensively in the armed forces for low-level bombing and torpedo releases, mine laying and parachute dropping. The design and technology developed in this product were significant factors in shortening the length of the Second World War and are still in use today.

Main Image: Capacitance Altimeter catalogue number EMIAT.357 photographed by thomasbutlerphotographer.com