Dr. Giles worked at the NASA Langley Research Center from 1964 to 1998. His contributions in aeronautics focused on the development of computer aided methods for design and analysis of advanced aircraft structures. The spectrum of computer codes he developed during his career ranged from DAWNS (Design of Aircraft Wing Structures) to ELAPS (Equivalent Laminated Plate Solution). Both the calendar time for model generation and the computer time needed to perform an analysis were reduced by an order of magnitude compared to conventional analysis methods. He applied these codes to the early design of advanced aircraft concepts such as blended wing body and supersonic transport configurations.

His significant contribution to the space program was the development and use of an automated data management/nonlinear stress analysis system that provided rapid structural strength assessment of the insulation tiles before the first flight of the Space Shuttle Orbiter. In a few hours, literally thousands of tiles were analyzed on an individual tile basis. This analysis was used to determine which tiles needed to be strengthened for safe reentry into the earth's atmosphere and contributed significantly to the successful performance of the insulation tiles on the first Shuttle Orbiter flight.