Wernher was under intense pressure to produce over this period. He had done such a good job promoting the project that his inability to deliver the goods was a serious problem. He and Dornberger had assured Speer and the Army chiefs that the design was ready for production in 1942, but two years later he was still making design changes on the fly. What was "ready" from one perspective ("here is a rocket and it flies as I promised") is different from what is ready for mass production. In 1942 each component had been hand-crafted by specialists. Now he had to produce hundreds of them on an assembly line using slave labor. The design changes were primarily to simplify and fool-proof the production process. He struggled with this all through the summer of 1944, but he was determined to get the first combat launches in the air in September. At the same time he was pushing the envelope, trying to come up with simple modifications of the design that would increase range, and expand their operational range.