The U.S. Air Force Research Laboratory has launched a new program called the Reusable Booster System (RBS) Pathfinder, which aims to develop a fully reusable first stage booster. The pre-solicitation notice includes this summary of the project:
The Air Force has identified the Reusable Booster System (RBS) concept as a promising approach to meet its future spacelift needs. The RBS consists of an autonomous, reusable, rocket-powered first stage with an expendable upper stage stack. The reusable first stage launches vertically and carries the expendable stack to the staging point. From the staging point, the reusable first stage returns directly to the launch base, landing aircraft-style on a runway.
To return the booster to the launch base, the Government is considering a rocket-back maneuver. The rocket-back maneuver consists of reorienting the vehicle so that it can use its main rocket engines to accelerate the vehicle back towards the launch site. The return to launch site maneuver is completed with an unpowered reentry and gliding flight and landing.
An important goal of the RBS Pathfinder program is to explore the feasibility and design space for the autonomous rocket-back maneuver. To the extent practical, the RBS Pathfinder program should also demonstrate other important technologies, processes and system attributes (TPSAs) that are expected to be included on the operational RBS. These TPSAs include, in roughly priority order:
- Responsive and low-manpower operations
- The use of Liquid Oxygen (LOx) and Kerosene (RP) as main propellants
- Reusable, highly reliable systems with extensive use of Integrated System Health Management (ISHM)
- Aeroconfiguration Traceability to envisioned Reusable Booster System (e.g., high L/D configuration with horizontal landing, main engines encapsulated in nacelles, etc.)
The RBS Pathfinder program is structured with four phases.
- Phase I â€“ Initial Design. This phase consists of trade studies and analysis to mature the RBS Pathfinder system concept and test plan.
- Phase II â€“ Detailed Design and Integrated Propulsion System Test. This phase consists of completing the RBS Pathfinder system design and test plan. Also included in this phase is a ground test of the Pathfinderâ€™s propulsion system. This test should include as much flight or flight-like propulsion system hardware as practical.
- Phase III â€“ Ground Launched Flight Test. This phase consists of the fabrication, assembly, check-out, and delivery of the RBS Pathfinder flight system and operations control center. It also includes support for the ground launched flight tests of the RBS Pathfinder. At least two ground launched tests are expected in Phase III.
- Phase IV â€“ Rocket-back Flight Test. This phase includes support for the rocket-back flight tests of the RBS Pathfinder. At least three rocket-back flight tests are expected in Phase IV.