Technical development was difficult. The J-10 represented a far higher level of complexity than earlier generations of Chinese aircraft. About 60% of the aircraft required new technology and parts, instead of - according to Chengdu - the usual 30% for new aircraft; the high proportion reflected both requirements and limited domestic capability. Development and modernization of China's aviation industry occurred alongside the J-10; the program was an early Chinese user of digital design, modelling, and testing including computer-aided design (CAD) and computational fluid dynamics. The J-10 was the first Chinese aircraft to make major use of computer-aided design (CAD) for its structural design, allowing the detailed design to be completed in 1994. The hydraulics system was tested with physical models because of limited digital modelling capabilities.