many years later, with possible “new start” costs. A more sequential approach of delivering, perhaps, one vehicle per year would result in higher unit costs but would offer a much better opportunity for incremental improvements and continued production, as launch rates or other requirements dictate.
NASA conducted 135 space shuttle flights over 30 years, an average of 4.5 per year, with a fleet of 3 to 4 orbiters. Because of modifications and refurbishments, the “mission ready” fleet probably averaged fewer than three vehicles. While on average the orbiters flew a little more than once a year, the real use was probably more like two flights per year when the vehicle was operationally ready.
The RBS is intended to be much more reusable than the orbiters—perhaps 10 times more so. With an anticipated launch rate of about 10 per year, it seems like a vehicle fleet of four reusable flight sets, with each vehicle able to be flown from either launch base, would be sufficient to meet anticipated needs, continue operations after loss of a vehicle, and surge, if required. An open production line to replace any losses (and perhaps perform depot-level maintenance) would sustain the industrial base while providing a robust operational capability.
The committee believes that the initial RBS fleet size of eight vehicles (four at each coast) is too many. Based on the rationale presented in the preceding paragraph, an initial fleet size of four (three at CCAFS and one at VAFB) is likely sufficient, and this can be re-analyzed as the program moves toward production. This retained production capability and reduced initial fleet size is intended as an example approach that would help reduce the initial investment while maintaining program strength and flexibility.
18.104.22.168 Payload Capability
Developing a single launch vehicle to meet the full spectrum of payload delivery requirements has always been an unachievable goal. Families of vehicle elements have been fielded to meet a wide spread of requirements, but systems that are optimized for medium-class payloads are almost always far oversized for small payloads and require substantial change to meet the heaviest requirements. For example, Delta IV Heavy services a small, albeit extremely important, niche requirement. An Atlas V Heavy would need to be fielded to satisfy the same requirement with that family.
Although the Air Force may be required to meet the full spectrum of launch, the committee believes that burden should not be applied to the RBS. Specifically, the committee believes that the RBS would best be designed to meet the current EELV medium-lift requirement and not sized to accommodate the heavy-lift requirement. It is recommended that in constructing a phased development plan that the issues associated with the need for the RBS to satisfy the heavy-lift requirement be resolved prior to initiation of the development.
22.214.171.124 Commercial Use
A launch system that is as efficient as the RBS is intended to be very attractive to those wishing to provide access to space for commercial payloads. The Delta II, Atlas II, Titan III, and EELV systems did this through joint operations with the Air Force, with varying degrees of success. In most cases, government launches were conducted by contractor teams with government oversight, and commercial launches were conducted by contractor teams and contractor oversight. The potential commercial use of RBS could be addressed by the Air Force as it develops its operational concepts since, in the case of the RBS, the vehicles may be owned by the government, regardless of who does the hands-on operations.
The program described to the committee seems to presume a single contractor in each phase of the program: flyback demonstration (Pathfinder), engine development, RBS demonstrator, Y-vehicle prototypes, and production. The committee interprets this to mean that the contractor that does the engine development would continue into demonstration and production, and the RBD contractor would also build the Y-vehicles and the eventual production vehicles. While this is probably the lowest initial cost approach if all goes well, that benefit is achieved at the expense of both competition and alternative paths to mitigate risk. If RBS is successful, it will be the primary