In May 2025, the German Aerospace Center (DLR) unveiled the RLV C5, a conceptual reusable rocket designed to compete with SpaceX's Starship. the proposal utilizes a winged booster and hydrogen propulsioon to aim for significantly higher orbital delivery efficiency.
A 74% mass-to-orbit efficiency target
The RLV C5 aims to achieve a payload delivery of 74% of its total mass to low Earth orbit (LEO). This target represents a massive leap in performance compared to the current 40% efficiency reported for SpaceX's Starship. By analyzing publicly available telemetry data from SpaceX, the DLR team identified specific performance gaps that their new design seeks to exploit.
This ambitious efficiency goal is the primry driver behind the German Aerospace Center's new conceptual framework. While SpaceX has revolutionized reusability, the DLR suggests that the current Starship architecture leaves significant mass-to-orbit potential on the table.
Replacing methane with liquid hydrogen and oxygen
To reach these efficiency goals, the DLR team proposes using a combination of liquid hydrogen and oxygen as the primary propellant. According to the report, this hydrogen-based approach is argued to be more efficient than the methane and oxygen mixture currently utilized by SpaceX for its Starship launches.
The choice of fuel is a critical component of the RLV C5's theoretical advantage. While methane offers certain logistical benefits for rapid reuse,the DLR's focus on the high energy density of liquid hydrogen is central to their claim of superior orbital performance.
The SpaceLiner's mid-air subsonic aircraft recovery
The recovery method for the RLV C5 differs fundamentally from the high-velocity return and tower-catch mechanism used by SpaceX. Instead, the design features a detachable booster known as the SpaceLiner, which is engineered to glide back toward the launch site.
Rather than attempting a vertical landing on a pad or a catch by a launch tower, the SpaceLiner is intended to be captured mid-air by a subsonic aircraft. This winged approach seeks to simplify the landing process by utilizing aerodynamic glide rather than pure vertical thrust for the final recovery phase.
The RLV C5's preliminary design phase hurdles
Despite the innovation, the RLV C5 remains in a preliminary design phase with significant engineering challenges ahead. As the DLR reported, the project faces strict time constraints and technical complexities that must be resolved before any physical prototype can be constructed.
Several critical questions remain unanswered by the current proposal. the source does not specify the total projected cost of development, nor does it provide a timeline for when the DLR might move from conceptual modeling to actual flight testing. Furthermore, the feasibility of a subsonic aircraft successfully capturing a heavy SpaceLiner booster mid-air remains a highly unverified claim that would require imense aerodynamic precision.
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