High Ambient Temperature Thermal Analysis of the AH-64D Composite Main Rotor Blade

A thermal analysis was performed to substantiate the appropriate elevated temperature to use in the structural static analysis and testing of main rotor blades. This paper presents thermal analysis and testing results conducted on a prototype composite blade for the Affordable Apache Rotor Program. A thermal finite-element model of the rootend portion of the blade was created to determine blade temperatures for hot-day environmental conditions. The assumptions and general equations used for the thermal model are presented. The thermal finite-element model (FEM) results were validated using test data from a thermal survey performed on a full-scale painted prototype blade. The test details and comparisons between the thermal FEM results to actual test data from the thermal survey are presented. The validated thermal FEM model was then used to predict blade temperatures under other environments. In particular, the thermal FEM was used to establish blade maximum temperatures for a heat-soaked parked aircraft under estimated worst-case ambient conditions. The analysis also evaluated blade temperatures after performing a quick taxi and climb prior to a “2+g” maneuver from an initial heat-soaked ground condition.