Required Capability: The earth launch vehicle is required to place payloads in low-earth orbit at high-mass flow rates and minimum cost. Mass flow rates of ^10$ kg per day are required to meet SPS construction schedules. Costs of less than $44/kg to low orbit are required to meet SPS cost objectives. Development Plan: Present engineering efforts should be continued to identify the preferred concept for the SPS earth launch vehicle. Additionally, these studies should consider the requirements of other programs that may use these boosters. Item - HTO-SSTO Vehicle Criticality — Enhance probability of program success Use of an HTO-SSTO vehicle for earth launch should simplify launch operations by reducing the level of launch support required. Also, the vehicle is more versatile because of its aeromaneuvering capabilities, permitting such things as landing at alternate sites. Present Capability: No HTO-SSTO vehicle has flown to date. However, a number of engineering studies have defined their requirements and capabilities. High performance aircraft and the Space Shuttle are the closest hardware technology items in existence. Required Capability; The HTO-SSTO must provide an earth launch capability meeting SPS requirements for mass flow and cost. It should require less launch support and be more versatile than ballistic vehicles. Development Plan: Present studies should be continued to define the preferred approach for SPS. Efforts should be concentrated on better definition of concepts for structures, thermal protection, insulation, and configurations. The ultimate goal should be to keep dry weights down and simplify repair/ refurbishment associated with launch. Item — Air-Breathing Propulsion Criticality — Enhance probability of program success Use of an air-breathing propulsion system on the HTO-SSTO further enhances its viability. The ability to use oxygen in the atmosphere can significantly reduce the propellant requirements and, thus, vehicle mass. Also, aerodynamic flight to the equator with an aerodynamic turn there further enhances the HTO-SSTO performance. Ferrying and flight to an alternate landing site are possible with the air-breathing propulsion system. The most useful propulsion technique is one based on the SWAT series of engines. They are basically a ram jet with a turbofan as a core. At low Mach numbers, the turbofan provides thrust with the ram burner acting as an afterburner. At high Mach numbers, the turbofan is shut down and the ram burner provides thrust. Present Capabilities: Engineering studies have examined the performance and capabilities of this engine concept. The turbofan core is a derivative of today's jet engines. High performance over a wide Mach range is predicted.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==