Building an aerodynamic model of a vertical landing reusable launcher based on CFD and wind tunnel experiments in SALTO and CFD4SALTO
Marwege, Ansgar; Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR); Klevanski, Josef; Zhai, Junnai; Gülhan, Ali; CFS Engineering (Switzerland); Vos, Jan
- Publisher
- Zenodo
- Language
- en
Abstract
Since the Falcon 9 first stage successfully landed the first time in 2015, the perception of reusability of launchers has drastically changed. While it was formerly considered a costly, complex and unprofitable solution, it is now seen as indispensable for the cost effective and environmentally friendly space transport. In this context, the SALTO (reusable Strategic Space Launcher Technologies & Operations) project, funded by the European Union in the frame of the Horizon Europe programme, is supporting the ESA Themis programme in which a demonstrator for a vertically landing launcher first stage is built. A first version for this demonstrator is propelled by one Prometheus engine with about 120 t thrust and performs simple trajectories. This version is called T1H, where the H stands for the “Hop Test” to be performed. A later version, called the Themis 3 or T3, shall have 3 engines and perform more complex flight trajectories. In SALTO the Hop Test of T1H is performed and technologies for the T3 vehicle are matured. In the ESA FLPP project CFD4SALTO, CFD computations for the generation of the aerodynamic databases of the T3 vehicle are performed and the extrapolation of wind tunnel experiments to flight are investigated. The task of the DLR in SALTO is, among others, the aerodynamic design of the T3 vehicle. This paper summarizes how the aerodynamic model of the T3 vehicle is set up. First the strategy for the aerodynamic modelling is described. Then, the various flight configurations are defined. Consequently, the strategies and mathematical formulations are elaborated which are applied to reduce the large amount of necessary data points. Afterwards, low-fidelity computations (generated in SALTO) and high-fidelity computations (generated in CFD4SALTO) are compared to show to which extent simplified modelling approaches can be used for the sizing and aerodynamic design, but to also highlight their limitations. Lastly, the paper discusses first wind tunnel experiments performed in the Trisonic Wind Tunnel Cologne (TMK) for the assessment of the aerodynamic performance of the configuration and for the verification of the modelling approaches. Index Terms— Reusable Launch Vehicle, Retro-Propulsion, Wind Tunnel Tests, CFD, Aerodynamics, SALTO.
Full text
BUILDING AN AERODYNAMIC MODEL OF A VERTICAL LANDING REUSABLE LAUNCHER BASED ON CFD AND WIND TUNNEL EXPERIMENTS IN SALTO AND CFD4SALTO FAR 2025 19.05.2025 Ansgar Marwege, Josef Klevanski, Junnai Zhai, Ali Gülhan Institute of Aerodynamics and Flow Technology Supersonic and Hypersonic Technologies German Aerospace Center (DLR e.V.) Jan Vos CFS Engineering
SALTO •SALTO - reusable Strategic Space Launcher Technologies & Operations •funded by the European Union in the frame of the Horizon Europe programme •supports the ESA Themis programme •T1H hop tests •Technology maturation for T3 and future launcher configurations 2
SALTO 3
CFD4SALTO •Partners: DLR, CFS Engineering •Carried out under a programme of and funded by the European Space Agency (ESA) – through the Future Launchers Preparatory Programme (FLPP) •High fidelity CFD computations and AEDB generation for SALTO •Support the design of the wind tunnel models used in the SALTO project •Extrapolate wind tunnel results to flight conditions 4
SALTO 5 Hop Test demonstrator with one Prometheus® Demonstrator to be flown in the frame of SALTO. T1H Reference configurations for future launchers with vertical take-off vertical landing. 5 Prometheus® and 9 Prometheus® engines. Future Launcher Configurations MECO Flip over LANDING BURN AERODYNAMIC PHASE REENTRY BURN 2nd stage to orbit MECO Flip over LANDING BURN AERODYNAMIC PHASE REENTRY BURN Reference configuration for future demonstrator version with three Prometheus® engines with more complex trajectory including all flight phases of vertical descent and landing with retro-propulsion T3 High TRL Medium TRL Low TRL
T3 mission profile 6 Hop Test demonstrator with one Prometheus® Demonstrator to be flown in the frame of SALTO. T1H Reference configurations for future launchers with vertical take-off vertical landing. 5 Prometheus® and 9 Prometheus® engines. Future Launcher Configurations MEC O Flip over LANDING BURN AERODYNAMIC PHASE REENTRY BURN 2nd stage to orbit MECO Flip over LANDING BURN AERODYNAMIC PHASE REENTRY BURN Reference configuration for future demonstrator version with three Prometheus® engines with more complex trajectory including all flight phases of vertical descent and landing with retro-propulsion T3
T3 vehicle •3 Prometheus engines (approx. 120 t thrust) •Approx. 80 km altitude •Diameter 3.5 m •Length approx. 29 m 7
Overview •Modelling strategy •Configurations •Coordinate system •AEDB construction •Comparison of low and high-fidelity CFD 8
Aerodynamic modelling strategy 9 Low Fidelity CFD High Fidelity CFD Wind Tunnel Tests Test design Validation Uncertainties Computation Definition Aeroshape update Aerothermal CFD Grid Fin CFD Unsteady CFD Full configuration CFD Aeroshape
17 Rotation strategy mirroring strategy Superposition of wind tunnel data (UFN)
18 Rotation strategy mirroring strategy Superposition of wind tunnel data (UFN)
Comparison of low-fidelity and high-fidelity CFD (UF2) 19 DLR (low-fidelity) CFSE (high-fidelity) [0,0,0,0] [20,20,20,20] [-20,-20,-20,-20] ! "!!!! #!!!! $!!!! %!!!! &!!!! '!!!! (!!!! )!!!! *!!!! ! " # $ % !"#$#%&'()*+ ,-./(0%*1'2()3+ 𝑞$=23255 𝑃𝑎 𝑞$=38340 𝑃𝑎 𝑞$=203𝑃𝑎 𝑞$=13624𝑃𝑎
Comparison of low-fidelity and high-fidelity CFD 20 Complete change in behavior Sudden jump in coefficient
Summary and outlook •Definitions of flight configurations, reference frames and free stream angles •Superposition of grid fin deflections •Rotation strategy •Mirroring strategy – imposes quarter symmetry •Validation with wind tunnel data shows good agreement for both strategies •Comparison of low-fidelity and high-fidelity CFD •Good agreement in complete Mach regime •Deviation in higher altitudes •Identification of changes in flow field 21 Summary Outlook •Second loop of AEDB with Aeroshape 2.0 •Further evaluation of test data of forces and moments •Cold gas experiments in TMK •Hot gas experiments in HPTF (and VMK)
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