Performance Evaluation of Airframe-Integrated Aerospike Propulsion Systems in Off-Design Flight Conditions

Abstract

The thrust performance of airframe-integrated linear aerospike propulsion systems for high-speed aircraft operated under off-design in-flight conditions was evaluated, based on performance prediction models established for linear aerospike nozzles by accounting for the freestream effect. The airframe configuration, equipped with a boattail appearing to the right upstream of the primary cell nozzle exit, enabled the freestream effect to be used for increasing the spike surface pressure. Performances of each thrust component were predicted by using the physics-based models established in separately performed studies. First, a parametric study was conducted on a rocket primary thruster with various design parameters. Then, an advanced concept with an airbreathing primary propulsion system was evaluated for its feasibility by comparing its thrust performance with that of a conventional rocket primary thruster. The benefit of the aerospike nozzle integrated into the airframe was also evaluated by comparing its thrust to a configuration without the aerospike nozzle. Results showed that the employment of the aerospike nozzle offered improved performance from takeoff to cruise phases. The advanced concept using the bypass airbreathing system for the primary thruster followed by the aerospike configuration exhibited further improvement in thrust by compensating for the boattail drag.