Two research combustors were designed and tested, one of which was representative of low pressure-ratio, regenerative gas turbine cycles and the other representative of high pressure-ratio, nonregenerative cycles. The design goal was to achieve emission levels not exceeding one-half of the Federal 1975/76 emission standards. The over-all aim was to develop design guidelines on the basis of detailed experimental data. Extensive modifications were made to conventional combustor configurations, but direct use was made of existing combustor design technology. Full-scale models were tested over wide ranges of operating conditions representative of typical driving cycles. Cold-flow tests were made to measure aerodynamic performance and detailed combustion tests were made to measure emission, combustion, and thermal performance.