Radio Direction and Ranging Radar
Radar was in its infancy at the outbreak of the Second World War, but building on early work by Dr Watson-Watt scientists had given the RAF a rudimentary air surveillance system which when linked to their burgeoning integrated command and control system gave them a distinct advantage in terms of attack warning during the Battle of Britain in 1940. The Germans were also developing radar for air and sea surveillance purposes and in February 1942 a daring combined operation to Bruneval on the French coast permitted Britain to capture vital German radar components. These were examined at the Telecommunications Research Establishment (TRE) which had been moved to Malvern from the Dorset coast at Churchill's instruction to preclude a similar reprisal raid by the Germans. TRE conducted a range of secret electronics work including the development of airborne radar in the form of the H2S airborne ground mapping radar. These early installations were flown out of nearby Defford airfield which subsequently became the installation centre for all early in-service fits.
H2X Radar panel
On the 16th of April 1942 the first Blind Navigation (BN) set, subsequently called H2S (ARI 5119), was flown using a modified 'S' Band 10cm Air Intercept radar scanning in a ground mapping mode. These early radars employed a magnetron secretly developed in Britain, examples of which had been supplied to the United States before they entered the war. By the end of 1942 H2S had been installed in 12 Halifax aircraft of No 38 Squadron and a similar number of Stirling bombers of No 7 Squadron. These aircraft conducted a series of operational trials to prove the equipment using Birmingham and Peterborough as test targets. The programme by now had Churchill's endorsement as part of a range of measures to improve the RAF's navigation and bombing accuracy.
B-17 of the 92nd BG Bombing Blind
By modern standards, the H2S radar image was crude, but when its image was cross referenced to other electronic navigation aids it was possible to determine an aircraft's position at night or when above cloud, common in North-West Europe, to a degree of accuracy which was not possible before. The radar gave a reasonable image of a ten mile or greater radius around the aircraft and it was possible to discern coastlines, large rivers such as the Rhine and major towns and cities.
H2S imagery and map of Schelt Estuary
The first operational mission was made on the night of 30/31 January 1943 in appalling weather conditions and the target was successfully marked by the H2S aircraft for the main force. With the aid of H2S average bombing accuracies of less than ¾ of a mile soon became the norm. In December 1943 the H2S Mk III was introduced to service.
H2S sets were installed in a limited number of B-17's in late 1943 and the first B-24 H2S “Stinky” mission was flown on the 11th of January 1944.
H2S scanner & H2S B-17
Building on the technical information passed to the United States from TRE, the American's developed their own variant of the H2S, the AN/APS-15 or H2X. Deliveries of the H2X “Mickey” set started in late 1943 and by the following year the equipment had become standard in new heavy bombers delivered to the 8th Air Force. In February 1944 B-24 H2X aircraft were ready for operations and in the same month the first production B-17 Gs equipped with H2X had arrived in Britain. By March 1944 sufficient H2X aircraft had entered service and the H2S was withdrawn from 8th Air force use.
Initial HSX fit & H2X B-17
In 1945 the AN/APQ-7 “Eagle” radar started to arrive with the 482nd Bomb Group at Alconbury, but due to problems was not used operationally until April 1945. The problems continued and the 13 sets were withdrawn in the autumn.
H2S imagery and map of Cologne
