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

Evolution of the SpaceLiner towards a Reusable TSTO-Launcher

Since a couple of years the DLR launcher systems analysis division is investigating a visionary and extremely fast passenger transportation concept based on rocket propulsion. The fully reusable concept consists of two vertically launched winged stages in parallel arrangement. The space transportation role of the SpaceLiner concept as a TSTO-launcher is now, for the first time, addressed in technical detail. Different mission options to LEO and beyond are traded and necessary modifications of the passenger stage to an unmanned cargo-carrier are investigated and described in this paper. Meanwhile, technical progress of the SpaceLiner ultra-high-speed passenger transport is ongoing at Phase A conceptual design level. Iterative sizings of all major subcomponents in nominal and off-nominal flight conditions have been performed. Potential intercontinental flight routes, taking into account range-safety and sonic boom constraints as well as good reachability from major business centers, are evaluated and flight guidance schemes are established. Alternative passenger cabin and rescue capsule options with innovative morphing shapes were also investigated. The operational and business concept of the SpaceLiner is under definition. The project is on a structured development path and as one key initial step the Mission Requirements Review has been successfully concluded

Towards the next step: SpaceLiner 8 pre-definition

The SpaceLiner fully reusable launcher and ultra-high-speed rocket-propelled passenger transport is in conceptual design phase. The ongoing concept evolution is addressing system aspects of the next configuration release 8. The winged, reusable upper stage, almost untouched since 2016 is moving now in focus of promising redesign options described in this paper. The SpaceLiner cabin integration is an important aspect to be addressed as well as the feasibility of performing multiple missions compliant with noise and sonic-boom constraints. The systematic assessment of different critical separation cases revealed that the aerodynamic unstable design of the capsule is not acceptable and needs to be redesigned for SpaceLiner 8. Further, the nose section of a future SLC should include part of the separation motors and thus help improving stability of the emergency-case separation maneuvers

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

Mission Design and Sensitivity Analysis for In-Air Capturing of a Winged Reusable Launch Vehicle

The cost of access to space has always been a major obstacle for space exploration. With the growing commercial success of Reusable Launch Vehicles (RLVs) however, low cost and more frequent launches become achievable. The innovative ‘In-Air Capturing (IAC)’ mode proposed by DLR, involves capturing of a winged launcher stage mid-air using an aircraft and towing it back to the launch site. By using the aircraft for propulsion, the RLV stage no longer requires its own propulsion system for descent, thereby reducing the overall launch mass and cost. A typical recovery profile of IAC starts when the winged first stage separates from the launch vehicle. During IAC, the RLV and the towing aircraft must come into proximity of each other at around 10 km altitude to attempt an unpowered formation flight. However, uncertainties can lead to non-ideal conditions for the capturing attempt. The RLV could deviate from its nominal trajectory due to variations in separation conditions. The towing aircraft itself can correct for some errors in the trajectory and improve chances of capture. But non-ideal conditions at the beginning of the formation flight can make it challenging to maintain longer formation time, and reduce the probability of successful capture. Thus, the following paper will evaluate the effect of RLV separation conditions on the success rate of IAC

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

ReFEx: Reusability Flight Experiment – Trajectory Design

The DLR project ReFEx aims at flying a trajectory representative for aerodynamically controlled stages. Further objectives are demonstrating maneuverability capabilities and ensuring safety. The ReFEx trajectory is oriented towards flight paths of operational and conceptual winged reentry vehicles represented in a Mach-Altitude map. Reentry trajectories are designed based on iterative solution of three degrees of freedom equations of motion. To analyze the mission performance under perturbed conditions, they are integrated in a six degrees of freedom, closed loop simulation environment. After the experimental phase and prior to touchdown a reduction of impact energy through a flare maneuver is foreseen

Systematic Assessment of SpaceLiner Passenger Cabin Emergency Separation Using Multi-Body Simulations

The SpaceLiner ultra-high-speed rocket-propelled passenger transport is in Phase A conceptual design. The ongoing concept evolution is addressing system aspects of the next configuration release 8. The space transportation role of the SpaceLiner concept as a TSTO-launcher is further refined and suitable precursor steps with expendable upper stages are investigated. In the central part of the paper, the separation of the passenger cabin and rescue capsule and its subsystems is systematically investigated for relevant emergency conditions. The separation process is studied taking into account multi-body dynamics of the up to 3 vehicles. A critical assessment of the baseline procedure and potential improvements of components design and sequences are discussed

FUTURE EUROPEAN REUSABLE BOOSTER STAGES: EVALUATION OF VTHL AND VTVL RETURN METHODS

Reusability of launch systems will strongly impact the launch service market if certain characteristics, such as sufficient reliability and low refurbishment costs, can be achieved. The German Aerospace Center (DLR) is performing a systematic investigation of return methods for a reusable booster stage of a future European launch vehicle. This launcher shall be able to transport 7 t to a geostationary transfer orbit (GTO), launching from the European spaceport in Kourou. The final goal is the determination of the impact of the different return methods on a technical, operational and economical level and the assessment of their relevance for a future European launch system. Compared to previous work presented at the IAC 2017 [3], this paper includes winged vertical take-off and horizontal landing (VTHL) as well as non-winged vertical take-off and vertical landing (VTVL) configurations. The preliminary results of a first design phase employing structural indexes derived from existing stages were used to narrow down the field of potential designs, especially with regard to the rocket staging. The selected launchers were modelled in more detail, including the preliminary design of major subsystems such as propulsion, aerodynamics, structure, propellant management and the thermal protection system. The comparison of different potential propellants is made across the different return options in order to assess the suitability of the various possible combinations. The fuels investigated within this paper in combination with liquid oxygen are kerosene, liquid hydrogen and methane. Two different engine cycles, namely gas-generator and staged combustion, and their impact on the launcher systems are also evaluated

ReFEx: Reusability Flight Experiment - Flight Safety Analysis

The German Aerospace Center project ReFEx aims to demonstrate autonomous GNC capabilities for aerodynamically controlled RLVs, its launch is scheduled for 2024 in Australia. This paper covers the flight safety analysis required by the Australian Space Agency (ASA). Monte Carlo campaigns results are used to assert that the flight termination system is capable of destabilizing the vehicle, to define impact probabilities for different ground areas, which are then use to calculate the risk of human injury for offnominal trajectories of the reentry segment. The results show that the requirements of the ASA are fulfilled with margin