This paper describes an operational interactive computer graphics system, called Graphic ROCKET, currently being used as a performance analysis aid for the preliminary design and evaluation of aerospace vehicle systems.It provides a means for rapidly specifying and evaluating the performance of a wide range of aerospace vehicle designs and flight plans.The hardware available to the system includes an IBM 360/40 with a 5-microsecond cycle time and 65,536 32-bit words of core storage, with four IBM 2311 disk units for peripheral storage.The interactive graphics terminal includes an IBM 2250 cathode-ray tube display with light pen, keyboard, and function keys. Hardcopy is provided by a SC-4060 graphic output device.pages were designed at the 2250 console and interfaced to the FORTRAN computational routines in a smooth, simple manner via the POGO system. ~ Two display control pages allow the user to specify variables for graphic display and to change displays during the course of the run.The system also includes a simple file management scheme which allows the analyst to store and recall inputs and outputs from his previous runs, or store and recall reference data such as tabular representations of atmospheric, propulsion, and aerodynamic properties.These capabilities have been illustrated in a 15-minute sound film, showing the use of Graphic ROCKET in analyzing an air-launched satellite booster for hurricane photography.Program organization is based on the ROCKET program I, a general-purpose trajectory-analysis program developed in 1961 and maintained and extended since in a batch-processing mode. We modified much of the organization of ROCKET to make it operate more naturally and efficiently in an interactive environment.For example, ROCKET allowed the user a pass at the FORTRAN compiler once during each run. This provided a lot of flexibility but would take too much time for an on-line user, so Graphic ROCKET provides instead lists of options specifiable via the light pen.