Critical Analyses and Performance Validation of the SKYLON D1 Space Plane

Abstract

DLR-SART has performed a critical analysis of the Reaction Engines Ltd. single-stage-to-orbit (SSTO) re-usable space plane concept, the SKYLON D1 vehicle, and its innovative dual-mode engine, the Synergistic Air Breathing Rocket Engine (SABRE). This analysis focused on the validation of the SKYLON mass budget, system performance and characteristics. A preliminary mass breakdown of the SKYLON D1 vehicle was determined using parametric methods, based on vehicle performance parameters and geometric data provided by REL. The margin philosophy provided by REL was found to be insufficient, and it should be re-iterated. A mass breakdown of the SKYLON Upper Stage (SUS) was also generated using empirical methods based on performance and geometric data provided by REL. Subsystem masses were scaled from the Ariane 6 PPH studies. The ascent trajectory of the SKYLON vehicle was modelled in three parts; the air-breathing ascent, using a comparable turbo/ram engine; the rocket ascent using the SABRE engine; and the SUS flight. It was determined that the SKYLON vehicle with the DLR-SART mass estimates could not achieve orbit, however an optimized trajectory was found for the vehicle using REL mass assumptions. Finally, the performance of the SABRE engine was determined. The conventional rocket-mode performance of the SABRE was found to be highly consistent with REL-provided data, however due to convergence issues related to the control of the innovative pre-cooler used in the air-breathing mode, the full air-breathing cycle could not be modelled. An assessment of the development cost, production cost and launch service cost has been performed using a parametric method and considering different scenarios. Both the SKYLON and SABRE are highly non-conventional, and the need has been highlighted to create analytical models and tools that are compatible with the dual-mode mission profile, space-frame structure and innovative propulsion system for future analyses. It was also seen that the DLR-SART methods for determining sub-system and component masses are based on existing aircraft and launch vehicles and studies, and therefore do not always consider new solutions or technologies. The structure and thermal protection systems are key enabling technologies, not just the propulsion system. New solutions will need to be developed and implemented for these systems.