Saving Lives in War
With the outbreak of World War II, EMI shifted its focus to military innovation. In 1941, Alan Dower Blumlein and an EMI team were seconded to the Government and worked for the Telecommunications Research Establishment (TRE). Their task was to develop an air-to-ground radar system that allowed bombers to “see” the terrain below through clouds, adverse weather and in darkness, displaying cities, rivers, and coastlines on a cathode-ray tube. The new top-secret radar system was given the name H2S.
Alan Dower Blumlein was a key technical architect in developing H2S. Working at the (TRE), he applied his expertise in high-frequency electronics, signal processing, and system design to the radar’s transmitter, receiver, and display systems.
H2S was the first radar system to utilise a high-power cavity magnetron in an airborne setup. It operated at centimetric wavelengths (around 10 cm), which enabled it to resolve much finer details than earlier radar systems that operated at longer wavelengths. This centimetric wavelength allowed the H2S system to depict features such as rivers and coastlines, and to navigate effectively in darkness.
June 7, 1942, was a beautiful summer’s day. H2S development was in the final stages, and at RAF Defford, a RAF Handley Page Halifax bomber was prepped and ready for a test flight of the H2S system. Alan was not supposed to be on the plane, but when a seat became available, he seized the opportunity to go on the test flight. He must have been excited yet somewhat apprehensive about observing the performance of the radar system that he and his team had hurriedly produced using cutting-edge technology, including a magnetron microwave system. Shortly into the flight, an engine caught fire, and despite the pilot’s best efforts to make an emergency landing, the plane crashed into a hill in Ross-on-Wye. All 11 on board were killed. Following the crash, recovering the magnetron system was as crucial as retrieving the bodies.
Due to the project’s classified nature, Alan Dower Blumlein’s death was kept secret. Despite the loss, Churchill ordered 200 H2S sets to be built immediately, ensuring that Alan’s invention went on save thousands of Allied lives and played a vital role in the strategic bombing campaign.
The H2S project was so vital to the war effort and so secret that we may never fully understand all the details of the crash…
