as it was more accurate than the British system. Backup for the British guns was also automatic 40mm batteries. The radar was effective from , the M9 director predicted the target location position based on course, height and speed which combined with the gun, shell and fuse characteristics predicted an impact position, adjusted each gun and fired the shell. In November attacks began from the north-east and additional batteries were deployed along the new azimuths, including the 184th AAA Battalion (United States) brought from Paris. Additional radar units and observers were deployed up to 40 miles from Antwerp to give early warning of V-1 bombs approaching. The introduction of the VT fuse in January 1945 improved the effectiveness of the guns and reduced ammunition consumption. From October 1944 to March 1945, 4,883 V-1s were detected. Of these, only 4.5% fell into the designated protected area. The effectiveness of the anti-aircraft defence meant that only 211 got through the defences; however, those that fell within the area caused damage and loss of life. Japanese developments In 1943, an Argus pulsejet engine was shipped to Japan by German submarine. The Aeronautical Institute of Tokyo Imperial University and the Kawanishi Aircraft Company conducted a joint study of the feasibility of mounting a similar engine on a piloted plane. The resulting design was named ("plum blossom") but bore no more than a superficial resemblance to the Fi 103. never left the design stage but technical drawings and notes suggest that several versions were considered: an air-launched version with the engine under the fuselage, a ground-launched version that could take off without a ramp and a submarine launched version with the engine moved forwards. Post-war After the war, the armed forces of France, the Soviet Union and the United States experimented with the V-1. France After reverse-engineering captured V-1s in 1946, the French began producing copies for use as target drones, starting in 1951. These were called the ARSAERO CT 10 and were smaller than the V-1. The CT 10 could be ground-launched using solid rocket boosters or air-launched from a LeO 45 bomber. More than 400 were produced, some of which were exported to the UK, Sweden, and Italy. Soviet Union The Soviet Union captured V-1s when they overran the Blizna test range in Poland, as well as from the Mittelwerk. The 10Kh was their copy of the V-1, later called Izdeliye 10. Initial