Powerful & Flexible Future Launchers in 2- or 3-stage Configuration

Semi RLV configurations are investigated with reusability of 1st or booster stages arranged in parallel with an expendable upper compartment. The non-symmetrical architecture consists of a winged RLV-stage and attached ELV-part comprising either one or two stages. The rocket propulsion is mostly cryogenic LOX-LH2 with the option of a storable propellant upper stage. The paper summarizes major results of the preliminary technical design process. The overall shape and aerodynamic configuration, the propulsion and feed system, the architecture and structural lay-out of the stages are described and some indicators on the configuration’s launch cost efficiency are provided

Study on future European winged reusable launchers

The realization of reusability for launch vehicles is expected to lower launch costs, subsequently enabling a thriving space industry. Therefore, several high-performance semi-reusable launch vehicle concepts are designed and investigated based on the premise of potential implementation into the Ariane program by using stage and engine parts from future Ariane 6 hardware. These vehicles are imagined as a combination of a winged reusable booster and one to two expendable upper stages for injection into a geostationary transfer orbit (GTO). First stage reusability is achieved by the "In Air Capturing" method proposed by DLR which is currently studied in the H2020 project FALCon. A payload mass of approximately 14 tons into GTO is pursued, consequently surpassing the anticipated payload mass of the Ariane 64. This paper presents the current technical status of the different investigated RLV configurations including geometrical shape, layout, propellant system, propulsion, aerodynamics and structural layout. Additionally, the designs shall be critically analysed regarding their suitability and applicability for a potential implementation into the European launcher roadmap

Full-scale simulations of 'In-Air Capturing' return mode for winged reusable launch vehicles

The recent success of reusable launchers has become a driving force for sustainable launch technologies. An innovative approach proposed by DLR, involves winged rocket stages captured mid air and towed back to the launch site by an aircraft. This recovery concept known as 'In-Air Capturing (IAC)', shows potential for substantial cost reduction, when compared to existing return modes. In the light of the Horizon 2020 project FALCon, full-scale simulations and sub-scale flight testing were carried out for further development of the technology. The paper summarizes the full-scale studies performed within FALCon. The full-scale test cases are introduced and the simulation framework for analysis of trajectories is presented. Then, the IAC maneuver is analyzed through trajectory simulations. Major external disturbances coming from the wake of the aircraft and flexibility of the rope connecting the rocket stage to the aircraft (after capture) are also addressed

Re-entry and Flight Dynamics of a Winged Reusable First Stage

Reusing launch vehicle stages has the potential to reduce launch costs and is hence of high interest in the context of defining the next generation of European launch vehicles. Winged reusable first stages have been a focus of the system launcher analysis group at DLR in the past years. Using wings and other aerodynamic surfaces, the aerodynamic forces during re-entry are used to safely decelerate the vehicle, thus rendering the reignition of any engines and the use of propellants unnecessary. Nevertheless, the design of a winged first rocket stage capable of fulfilling its main objective, accelerating the launch vehicle from ground up to stage separation, while also being able to do an autonomous and controlled atmospheric re-entry offers its challenges. Traversing from hypersonic to subsonic velocities, the vehicle has to be controllable at a vast range of flight conditions. Understanding the flight dynamics behind the re-entry of a winged vehicle in an early design stage is necessary to identify challenges with regards to controlling and actively steering such a high-performance vehicle in order arrive at a feasible and robust design that does not fail to converge in later design iterations. This work focuses on the analysis of the vehicle dynamics using linearized dynamic equations with 6 degrees of freedom. The controllability using aerodynamic surfaces and RCS shall be investigated and, possibly, proven by simulation

RLV-Return Mode “In-Air-Capturing” and Definition of its Development Roadmap

An innovative approach for the return of reusable space transportation vehicles has been proposed: The winged stages are to be caught in the air and towed by subsonic airplanes back to their launch site without any necessity of an own propulsion system. This patented procedure is called in-air-capturing. The project FALCon (Formation flight for in-Air Launcher 1st stage Capturing demonstration) funded by EC in Horizon 2020 is progressing this advanced technology. A dedicated session at the EUCASS 2022 is organized with a total of 6 technical presentations. This paper serves as an introduction into the topic, summarizes system aspects of the launcher performance improvement and explains the structure of the FALCon-project. Main part of the paper is the definition of the next steps for the technical development roadmap. This activity has been organized in cooperation with the European stakeholders from industry, agencies and research organizations. The outcome and results of two dedicated workshops and additional splinter meetings are summarized. The iterated technology development roadmaps considering the recommendations from the splinter meetings are presented

Progress Summary of H2020-project FALCon

The innovative approach “in-air-capturing” for the efficient return of reusable space transportation vehicles has been refined in the EC-funded H2020-project FALCon. Following the basic idea, winged stages are to be caught in the air and towed by subsonic airplanes back to their launch site without any necessity of an own propulsion system. The project FALCon (Formation flight for in-Air Launcher 1st stage Capturing demonstration) funded by EC in Horizon 2020 and running from 2019 until 2022 has achieved significant progress. The project finished after 45 months in November 2022. The paper provides a retrospective progress summary. The successful establishment of significantly refined simulation models and the definition of the development roadmap for the next steps in technology maturation are presented. Further, lessons learned from the complex authorization process of the UAVs to be used in the lab-scale flight demonstrations are discussed. Finally, an outlook on the intended follow-up activities is given, including an estimate of the relatively modest investments required

In-Air-Capturing Development Roadmap (Update)

Any RLV degrades the launcher’s performance compared to an ELV due to additional stage inert mass. The major impact on additional RLV mass stems from the need to bring the used stages fully intact back to the launch site. This task is a fundamental challenge of all RLV compared to ELV. Several different technical approaches have been proposed in the past for the return of RLV. Four different return modes are most relevant: RTLS: autonomous rocket-powered return flight (similar to some Falcon 9 missions that return to Cape Canaveral), DRL: down-range landing; in case of Kourou-missions only possible on a sea-going platform (“barge”) which subsequently brings the stage back to the launch site, LFBB: autonomous airbreathing-powered return flight at subsonic speed, IAC: capturing in flight of the winged unpowered stage with an aircraft and subsequent towing back for an autonomous landing in gliding flight. The technical development roadmap of "in-air-capturing" is described and synergies to other applications are identified. The report serves as input for the discussions in the 2nd Development Roadmap workshop

Ultra-Fast Passenger Transport Options Enabled by Reusable Launch Vehicles

The latest architecture of the SpaceLiner 7 configuration is described including major geometrical and mass data. Some elements of the next iteration step, the SpaceLiner 8, are highlighted, having its focus on most recent analyses, partially not previously published. A passenger rescue capsule is intended to be used in case of extreme emergencies. The design of the cabin and the ejection system is refined in a systems engineering approach to obtain a feasible and viable solution. Multibody simulations of the emergency capsule separation are performed in a wide range of flight conditions and technical challenges are identified. The adaptation of the large unmanned booster stage, currently under way might include a new wing lay-out capable of swiveling-out in the lower speed regime. Advantages and technical challenges of this approach are addressed in the paper. Simulated 6DOF ascent trajectories analyze behavior of the Thrust Vector Control system in case of wind and gusts interacting with the winged configuration in nominal and off-nominal conditions

Concept 4: A Reusable Heavy-Lift Winged Launch Vehicle using the In-Air-Capturing Method

Reusability is expected to significantly lower launch costs if refurbishment and recovery costs can be kept low. To analyze and understand the impact of reusability on launch systems, the DLR is conducting studies of reusable space transportation configurations. In this context, a range of promising semi-reusable launch vehicles with a winged reusable first stage and either one or two expendable upper stages for an injection into a geostationary transfer orbit (GTO) were designed and investigated. Different engine and propellant combinations, using either LOX-LH2 or LOX-LCH4, were studied in order to identify potentials and drawbacks of each combination. The winged first stage is recovered by the 'In-Air-Capturing' method which is currently studied in the framework of the Horizon 2020 funded project FALCon. A special focus is put onto the aerodynamic behavior of the winged stages. Since the stage performs a mostly aerodynamically controlled re-entry, transitioning from supersonic velocity of Mach 6-9 down to subsonic velocity, the vehicle has to be controllable throughout a vast range of different aerodynamic states. Therefore, a reference stage from the system analysis is selected and subjected to an investigation of dynamic behavior, controllability and stability along a reference trajectory. The insights from this analysis shall be used to re-evaluate the system design and determine implications on a system level