The object of this research effort was the investigation, through analytical studies and experimental testing, of several blade-to-disk attachment concepts and airfoil shell-to-strut attachment concepts to determine the optimum concept for use on future small, high-temperature turbine rotors. Appropriate technical personnel of the U.S. Army Aviation Materiel Laboratories have reviewed this report and concur with the conclusions contained herein.The findings and recommendations outlined herein will be taken into consideration in the planning of future axial turbine programs. Task ABSTRACTThis report describes the analytical, experimental, and developmental efforts that were conducted to design, fabricate, test, and evaluate turbine-rotor blade to rotor disk (blade/disk) attachment methods for an air-cooled turbine rotor in a small gas turbine engine. This investigation was launched because the combination of factors that are necessary to satisfy the design requirements of a small cooled gas turbine has made it increasingly difficult to utilize conventional blade attachment means. Specifically, the program was directed toward achieving a suitable attachment method for an axial turbine with an inlet temperature of 2400 0 F, an airflow rate of 4.0 lb/sec, a tip speed of 1500 ft/sec, and matched to a compressor having a 10:1 pressure ratio.Detailed aerothermodynamic design activities were conducted to determine a turbine design that would provide optimum specific fuel consumption (SFC) and specific horsepower (sp hp), The design included an optimization study to obtain the best compromise of turbine efficiency, cooling geometry, blade and disk stress effects, and fabrication considerations.Detailed mechanical design activities were conducted in parallel with fabrication technology development efforts to establish the materials, designs, joining methods, and fabrication techniques necessary to determine feasible means of blade/ disk attachment. Results of these activities showed that diffusion-bonding, brazing, and electron-beam-welding blade/ disk attachment methods possess the greatest potential for application in the subject turbine design.A secondary purpose of the mechanical design and fabrication development activities was to study the feasibility of developing the strut-supported sheet metal blade (shell/strut attachment) that was revealed by the aerodynamic optimization study to be the most effective blade cooling configuration. Full evaluation of the shell/strut attachment was beyond the scope of this program; however, it was determined that both diffusion-bonding and cast-bonding concepts of joining could be considered as feasible methods to develop for the purpose of shell/strut attachment.A final fabrication and test activity was conducted to complete evaluations of the three blade/disk attachment methods. Final specimens were designed, fabricated, inspected, and subjected to tensile,stress-rupture, and low-cycle fatigue testing at 1200 0 F.iii Evaluation of the final specimen test results revealed that (...