Concept Study of the ARES Hybrid-OS Launch System

The Affordable Responsive Spacelift (ARES) program is part of a broad initiative by the United States Air Force to improve the responsiveness, flexibility, and affordability of space access capabilities. Based on initial studies, including Analysis of Alternatives (AoA) activities, the Air Force has concluded that the ARES program should pursue development of a hybrid launch system which utilizes a reusable booster and an expendable upper stage. The design philosophy behind this configuration contends that significant cost savings can be achieved compared with an all-expendable approach by reusing two thirds of the hardware mass of the launch system after each flight. In addition, substantial benefits to operational cost and complexity can be realized if the trajectory of the reusable booster is tailored such that a complicated thermal protection system is not required. SpaceWorks Engineering, Inc. (SEI) has supported this effort through a recent design study of an ARES Hybrid Operational System (OS) launch architecture. This study included vehicle performance, life cycle cost, operations, safety, and reliability analysis. Starting with the set of baseline groundrules and assumptions, SEI proceeded to define a feasible upper stage system, design the reusable booster airframe, analyze the main propulsion system for the reusable booster, and determine a means of returning the booster to the launch site after separation from the upper stage. Based on the results of this conceptual design activity, SEI has been able to answer several key questions regarding the feasibility and viability of an ARES Hybrid-OS concept. For instance, the trajectory simulations and aeroheating analysis performed as part of the design closure reveal that it would be possible to forego an extensive thermal protection system on the booster – one of the linchpins of the highly operable ARES approach. SEI’s analysis also explored the potential synergy between low cost commercial small payload launch vehicles and the design requirements for the Hybrid system’s expendable upper stage. In addition, a detailed examination of the ARES Hybrid-OS booster main propulsion elements enabled SEI to refine previously vague design guidelines for development of these liquid locket engines.