Development and application of a prototype KBE system is presented, details of the development tools and platforms, system flow chart, hybrid knowledge representation, and integrated system framework are illustrated. All design tasks of a missile seeker are integrated into a single computer-aided environment with a clear guidance to design processes from the user interface. Development and application of a prototype KBE system is presented, details of the development tools and platforms, system flow chart, hybrid knowledge representation, and integrated system framework are illustrated. All design tasks of a missile seeker are integrated into a single computer-aided environment with a clear guidance to design processes from the user interface.