With blueprints produced from disassembled V-2 rockets, the team began producing a working replica of the rocket. This was designated the R-1, and was first tested in October 1947. A total of eleven were launched with five hitting the target. This was similar to the German hit ratio, and demonstrated the unreliability of the V-2. In 1947, Korolev's group began working on more advanced designs, with improvements in range and throw weight. The R-2 doubled the range of the V-2, and was the first design to utilize a separate warhead. This was followed by the R-3, which had a range of , and thus could target England. The Soviets continued to utilize the expertise of the Germans on V-2 technology for some time; but, to preserve secrecy surrounding the ballistic missile program, Gröttrup and his team had no access to classified work of their Russian colleagues on new rocket technology including production and testing facilities. This negatively affected the morale of the German team and limited their technical contributions. The Ministry of Defence decided to dissolve the German team in 1950 and repatriated the German engineers and their families between December 1951 and November 1953.