2024-03-29T00:04:22Z
https://zenodo.org/oai2d
oai:zenodo.org:8279566
2023-08-25T14:26:52Z
user-retalt
user-eu
Marwege, A.
Gülhan, A.
2023-08-19
<p>During the vertical descent and landing of a launcher first stage with the aid of retropropulsion, commonly two main propulsive deceleration maneuvers are performed: the reentry burn in high altitudes at hypersonic to supersonic speeds and the landing burn shortly before touchdown at transonic to subsonic speeds. In the frame of the EU-funded H2020 project Retro Propulsion Assisted Landing Technologies (RETALT), the unsteady aerodynamics of those retropropulsion phases were studied. This paper presents results of experiments performed in the Hypersonic Wind Tunnel Cologne on the hypersonic reentry burn. The exhaust plume was simulated with pressurized air. Proper orthogonal decomposition was performed on high-speed schlieren videos, and spectral analyses of the time histories of the resulting modes were compared to the frequency content found in high- frequency pressure measurements. Dominant frequencies were found in the proper orthogonal decomposition modes for one and for three active engines. In the pressure measurements, dominant frequencies could only be observed for three active engines. The normalized pressure fluctuations are in the range of 0.002–0.012. Additionally, a good scaling of the pressures on the base area and in the wake of the configuration with the total pressure downstream of the bow shock could be confirmed, in the sense that the ratio of the local surface pressure to the total pressure downstream of the bow shock match for varying freestream Mach numbers.</p>
https://doi.org/10.2514/1.A35647
oai:zenodo.org:8279566
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
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JOURNAL OF SPACECRAFT AND ROCKETS, (2023-08-19)
Retro-propulsion
Vertically landing launchers
Re-entry burn
Unsteady Aerodynamics of the Retropropulsion Reentry Burn of Vertically Landing Launchers
info:eu-repo/semantics/article
oai:zenodo.org:6759712
2022-06-28T01:48:37Z
user-retalt
user-eu
Paixão, Sofia
Carvalho, João
Hantz, Christian
2022-06-21
<p>Thermal Protection Systems are key elements of space vehicles to keep the structural integrity of interior parts during the high heat loads reached during atmospheric reentry. Over the years, countless types of TPS were developed, with many different types of materials (since ablative to ceramics), all of them with the same goal: to insulate the vehicle surfaces without compromising aerodynamics or payloads of the final system. Thereby, TPS always should be lightweight, with low thermal conductivity and enough structure to withstand shear forces felt during spatial trajectories.</p>
<p>Amorim Cork Composites (ACC), as one of the leaders of cork industry, has been present in different aerospace projects, where cork performs an important role as thermal protection system. Due to all its attributes of being lightweight, with cellular structure that gives it very low thermal conductivity (around 0,05 W/m·K) and also by the whole possibilities of combining it with other materials, it allows the creation of composites with outstanding properties.</p>
<p>The work performed in the scope of the Retro Propulsion Assisted Landing Technologies (RETALT) project comprised the development of a new TPS, capable of being applied <em>in situ</em>, that fulfills the thermal requirements of the reentry trajectory studied for reusable launchers. The development was focused on a trowelable solution (that could be applied in the form of a paste, with a spatula) and to cure directly in the final structure, at room temperature. The final formulation gathers an epoxy matrix with cork granules and a set of additives that have been resulted from a selection process between different types of resins: phenolic, polymeric polyurethane and epoxy, together with different types of additives: fire retardants, rheological and thermal adjuvants.</p>
<p>During the development, the formulations screening criteria was based on ease of application, followed by the characterization of thermal conductivity and thermal capacity measurements, as well as cone calorimeter tests to mainly observe the quality of the surface in terms of cracks and stiffness.</p>
<p>The selected material formulation was then tested in the L2K facilities at DLR, to evaluate its performance under high thermal loads (up to 600 kW/m2). During all the characterizations, the new material was compared with P50, a cork TPS material commercialized by ACC in the form of sheets.</p>
<p>The present document discloses the development process and results achieved along the project as well as the comparison with a TPS material already commercialized and currently used in spatial missions.</p>
https://doi.org/10.5281/zenodo.6759712
oai:zenodo.org:6759712
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759711
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
TPS
Cork
Trowelable
P50
TPS05
Development of a Trowelable TPS Cork Material for Reusable Launch Vehicles
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:7983827
2023-05-30T14:26:44Z
user-retalt
user-eu
Mariasole Laureti
Sebastian Karl
2023-07-09
<p>In the framework of the Horizon 2020 project RETALT (Retro Propulsion Assisted Landing Technologies),<br>
whose main objective was the investigation of technologies for reusable launch systems, a Single Stage To<br>
Orbit (SSTO) Vertical Take-off Vertical Landing (VTVL) launcher configuration, called RETALT2, was<br>
studied. This paper aims at describing the generation of Aero-Thermal Databases (ATDBs) for surface<br>
heat fluxes as fast-response surrogate models for the aero-thermodynamic heating of the vehicle surface over the entire trajectory, i.e. ascent and re-entry. Representative flow field solutions are discussed in terms of flow field topology and resulting heat patterns on the vehicle surface. Furthermore, the time evolution over the entire flight path of area-averaged heat fluxes on the vehicle nose and base plate are shown and<br>
analysed.</p>
https://doi.org/10.5281/zenodo.7983827
oai:zenodo.org:7983827
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.7983826
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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AEC/CEAS/EUCASS, Aerospace Europe Conference 2023, Lausanne, Switzerland, 9-13 July 2023
Reusable Launch Vehicles
Aerothermal analysis of the RETALT2 vehicle
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:5779163
2021-12-14T13:48:41Z
openaire
user-retalt
user-eu
Starke, P.
Dorbath, C.
2019-07-04
<p>This presentation given at the EUCASS2019 meeting gives an overview of the MT Aerospace Involvement in the RETALT project</p>
https://doi.org/10.5281/zenodo.5779163
oai:zenodo.org:5779163
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.5779162
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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Structures
Landing legs
Design and manufacturing status of advanced structures for reusable launch systems demonstrators with retro propulsion assisted landing technologies (RETALT)
info:eu-repo/semantics/lecture
oai:zenodo.org:6920801
2022-07-28T13:49:02Z
user-retalt
user-eu
Thies, Christoph
2022-07-28
<p>The EU has deemed it crucial to maintain its own independent access to space. To foster the European industry competitiveness, the cost of the European launch systems needs to be reduced and flexibility needs to be improved. The development of reusable launch vehicle (RLV) is currently changing the global market of space transportation systems and is promising immense cost savings. Within this context, MT Aerospace has been investigating the configurations and possible solutions for landing structures at touch-down in the European Funded H2020 project RETALT. This includes the down-selection of previous designs to the current configuration for RETALT1 (Marwege et al. in System definition report, 2022) and the cor- responding architecture of the structural landing leg. A screening of the overall requirements down to driving parameters which have the most significant impact on the structural design is done. Landing events like “nominal” simultaneously four leg touch-down landings and critical single leg manoeuvres are analysed to evaluated safe configurations for landing. These investigations have a major influence on the specification of the launcher.</p>
https://doi.org/10.1007/s12567-022-00456-x
oai:zenodo.org:6920801
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https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
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Creative Commons Attribution 4.0 International
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CEAS Space Journal, (2022-07-28)
Landing leg
Shock loading
Shock absorber
Investigation of the landing dynamics of a reusable launch vehicle and derivation of dimension loading for the landing leg
info:eu-repo/semantics/article
oai:zenodo.org:7064630
2022-09-09T14:27:45Z
user-retalt
user-eu
De Zaiacomo, G.
Medici, G.
Princi, A.
Ghignoni, P.
Botelho, A.
Martinez Arlandis, M.
Recupero,C.
Fabrizi, A.
Fernandez, F.
Guidotti, G.
2022-09-18
<p>The capability to partially recover and reuse a launch vehicle is currently the most effective way of reducing the cost of access to space, which is a key endeavour to the commercialization of space. Despite this, it remains a great technical challenge, with only two US companies (SpaceX and Blue Origin) having developed the necessary technology to carry out routinely successful recovery missions, both using retro-propulsive vertical landing as the recovery strategy, and both reporting significant cost savings due to the reusability effort.</p>
<p>In this context, the RETALT (Retro Propulsion Assisted Landing Technologies) project, funded by the EC Horizon 2020 programme under grant agreement No 821890, had the goal of investigating and maturing key technologies to enable reusability in Europe. One of the great technical challenges in this endeavour lies in the capability to define a feasible mission to safely and robustly return the launcher, and to develop a recovery Guidance, Navigation and Control (GNC) system to perform a precision landing in a fast-dynamic environment, with extremely limited fuel margins, and with significant unknown dispersions accumulated during prior phases. In particular, the project aims to increase the Technology Readiness Level (TRL) of the GNC technologies needed for recovery up to 3.</p>
<p>The baseline configuration and the main focus of the project and this paper is RETALT1. The vehicle operates similarly to a typical launcher until separation, after which two scenarios for the first stage recovery are considered: Downrange Landing (DRL) and Return to Launch Site (RTLS). The latter differs in the use of a post-separation flip manoeuvre and boostback burn that modifies the ballistic arc to allow a landing at or near the launch site, while the former foresees a landing at sea on a floating barge. Both scenarios employ a re-entry burn, in order to reduce velocity and dispersions, and an active aerodynamic descent phase enabled by the use of control surfaces. Finally, the first stage recovery mission ends with an engine-powered descent, which slows the vehicle down to a pinpoint and soft vertical landing.</p>
<p>The focus of this paper will be the methodology implemented to assess the feasibility of the recovery mission, identify the mission design envelope for the wide range of launch missions that the system could target, and define a mission solution for representative re-entry conditions, as well as the design, development and test of the GNC solution, that was demonstrated capable of guaranteeing the necessary performance to recover the system.</p>
https://doi.org/10.5281/zenodo.7064630
oai:zenodo.org:7064630
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.7064629
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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IAC, 73rd International Astronautical Congress, Paris, France, 18-22 September,2022
reusable launchers
guidance, navigation, control
flight mechanics
online optimisation
RETALT: Development of Key Flight Dynamics and GNC Technologies for Reusable Launchers
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6597972
2022-09-15T10:21:25Z
openaire_data
user-retalt
user-eu
Marwege, Ansgar
Hantz, Christian
Klevanski, Josef
Gülhan, Ali
Vos, Jan
Charbonnier, Dominique
Karl, Sebastian
2022-05-31
<p>The excel file contains the Aerodynamic Data Base for the RETALT2 configuration. The pdf file contains the necessary information to use this data base</p>
https://doi.org/10.5281/zenodo.6597972
oai:zenodo.org:6597972
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6597971
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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RETALT2 – AERODYNAMIC DATA BASE 2.0
info:eu-repo/semantics/other
oai:zenodo.org:7064613
2022-09-09T14:27:46Z
user-retalt
user-eu
Ghignoni, P.
Botelho, A.
Recupero, C.
Fernandez, V.
Fabrizi, A.
De Zaiacomo, G.
2022-09-11
<p>This paper presents the RETALT recovery mission GNC, with a focus on the GNC solutions for the powered descent and landing phase. RETALT is a European Union Horizon 2020 project with the objective of investigating launch system reusability technologies for different classes of vertical take- off vertical-landing vehicles. Launcher reusability is the most effective way of reducing access to space available, but remains a great technical challenge for the European aerospace industry, which lags largely behind its US counterparts. One of the challenges lies in the recovery GNC strategy and algorithms, in particular those of the powered-landing phase, which must enable a precise landing with low fuel-margins and significant dispersions. To tackle this, state-of-the art algorithms based on hybrid Navigation techniques for state estimation, as well as online convex optimization and successive convexification for the design of the guidance GNC sub-function are explored. The proposed GNC solutions were integrated and tested in a high-fidelity simulator and the performance were preliminary assessed.</p>
https://doi.org/10.5281/zenodo.7064613
oai:zenodo.org:7064613
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.7064612
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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HiSST, HiSST: 2nd International Conference on High-Speed Vehicle Science Technology, 11-5 September 2022
Powered Landing
Recovery
GNC
RETALT: Recovery GNC for the Retro-Propulsive Vertical Landing of an Orbital Launch Vehicle
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:5814915
2022-07-04T11:22:29Z
user-retalt
user-eu
Vos, Jan
Charbonnier, Dominique
Marwege, Ansgar
Guelhan Ali
Laureti, Mariasole
Karl, Sebastian
2022-01-05
<p>In the RETALT (Retro Propulsion Assisted Landing Technologies) project critical technologies for two different vertical landing launcher configurations are investigated. For RETALT1, a Two Stage To Orbit launcher, only the first stage will be recovered using retro propulsion. A large number of wind tunnel experiments have been carried out at DLR in Cologne, while CFD simulations were made by CFS Engineering and DLR in Göttingen. This paper provides a detailed comparison of Wind Tunnel Experiments with CFD calculations in the hypersonic regime, with and without retro propulsion.</p>
https://doi.org/10.2514/6.2022-1308
oai:zenodo.org:5814915
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https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
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Creative Commons Attribution 4.0 International
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Aerodynamic investigations of a Vertical Landing Launcher configuration by means of Computational Fluid Dynamics and Wind Tunnel Tests
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6759561
2022-06-28T01:49:07Z
user-retalt
user-eu
Laureti, Mariasole
Karl, Sebastian
Marwege, Ansgar
Gulhan, Ali
2022-06-21
<p>The RETALT (Retro Propulsion Assisted Landing Technologies) project aims at investigating launch system reusability technologies for two different Vertical Take-off Vertical Landing launcher configurations, namely RETALT1 and RETALT2. This paper describes and summarizes the CFD based aerothermal load predictions, aerothermal database generation and application for the RETALT1 configuration for the complete trajectory. Furthermore, an analysis of representative CFD results is provided with the aim to show typical flow field phenomena and the resulting heating patterns occurring during the retro- propulsion phase. CFD results are then validated by comparison with the wind tunnel experiments carried out at different ground testing facilities in DLR Cologne.</p>
https://doi.org/10.5281/zenodo.6759561
oai:zenodo.org:6759561
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759560
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
Reusable launchers
Computational Fluid Dynamics
Wind Tunnel Experiments
Retro-Propulsion
Aerothermal Loads
Aerothermal Databases and CFD Based Load Predictions
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6759359
2022-06-30T15:51:02Z
user-retalt
user-eu
Marwege, Ansgar
Hantz, Christian
Kirchheck, Daniel
Klevanski, Josef
Vos, Jan
Laureti, Mariasole
Karl, Sebastian
Gulhan,Ali
2022-06-21
<p>The RETALT (RETro propulsion Assisted Landing Technologies) project aims to investigate vertically landing launcher configurations, which decelerate by means of retro propulsion manoeuvres during the descent and final landing phase. One key objective was to understand the complex steady and unsteady flow field and the resulting oscillating pressure loads on the re-entering vehicles.</p>
<p>In the course of the project, extensive wind tunnel test series have been performed in the three aerodynamic wind tunnel facilities at DLR in Cologne. The re-entry burn, with one to three active engines, was rebuilt in the Hypersonic Wind Tunnel Cologne (H2K), the aerodynamic descent phase was analysed in the Trisonic Wind Tunnel Cologne (TMK) and the landing burn was tested in the Vertical Free-jet Facility (VMK). Furthermore, detailed CFD analyses of the various flight phases have been performed by CFSE and DLR with the flow solvers NSMB and TAU.</p>
<p>In this paper the steady and unsteady flow field around the RETALT1 and RETALT2 vehicles in the various flight phases will be compared and the resulting loads will be analysed.<br>
An analytical sizing method for aerodynamic control surfaces for the aerodynamic phase of RETALT1 is validated, for RETALT2 a strong hysteresis was found in the forces and moments in the aerodynamic phase. The plume length in the landing phase of RETALT1 follows a linear analytical approach. The flow field of RETALT1 in the retro propulsion phases during the landing burn and the re-entry burn is highly unsteady which is visible in the variance of the schlieren images and in the high frequency pressure measurements.</p>
https://doi.org/10.5281/zenodo.6759359
oai:zenodo.org:6759359
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759358
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heillbron, Germany, 19-23 June, 2022
Retro Propulsion
Vertical Take-off Vertical Landing
Wind Tunnel Experiments
Retro Propulsion Assisted Landing Technologies
Aerodynamic Phenomena of Retro Propulsion Descent and Landing Configurations
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6797863
2022-07-05T13:48:41Z
user-retalt
user-eu
Gülhan, Ali
Marwege, Ansgar
Vos, Jan
2022-07-05
<p>This paper presents the Editorial to the special issue of the CEAS Space Journal dedicated to the RETALT EU funded project.</p>
https://doi.org/10.1007/s12567-022-00460-1
oai:zenodo.org:6797863
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https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
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Creative Commons Attribution 4.0 International
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CEAS Space Journal, (2022-07-05)
Retro-propulsion
Retro propulsion assisted landing technologies: the RETALT project
info:eu-repo/semantics/article
oai:zenodo.org:5770046
2022-07-05T10:04:13Z
user-retalt
user-eu
Marwege, A.
Gülhan, A.
Klevanski, J.
Riehmer, J.
Kirchheck, D.
Karl, S.
Bonetti, D.
Vos, J.
Jevons, M.
Krammer, A.
Carvalho, J.
2019-10-25
<p>The development and operation of Reusable Launch Vehicles (RLV) are currently changing the global market of space transportation. A main game changer in this field are the technologies of retro propulsion assisted landing, which is a concept of decelerating the vehicle during its return to ground by firing its engines against the velocity vector.</p>
<p>To foster a cost-efficient and sustainable global and European launcher market there is not only an urgent need to build up the necessary know-how on state-of-the-art Vertical Take-off Vertical Landing (VTVL) Two Stage To Orbit (TSTO) concepts, but also to go beyond this approach. Historically, many concepts of Reusable Launch Vehicle (RLV) are based on Single Stage To Orbit (SSTO) designs. Therefore, in the EU Horizon 2020 project RETALT (RETro propulsion Assisted Landing Technologies), the VTVL approach is investigated in a twofold manner:</p>
<ul>
<li>
<p>A configuration similar to the SpaceX rocket “Falcon 9” serves as a reference for the state-of-the-art TSTO RLV.</p>
</li>
<li>A configuration similar to the DC-X serves as a reference for a VTVL SSTO.</li>
</ul>
<p>In this way, the concept of vertical landing with retro propulsion is investigated in a more general way and has the potential to be applied to more concepts of future RLV. In the RETALT project research for both reference configurations is performed in the areas of aerodynamics, aerothermodynamics and flight dynamics and GNC, as well as advanced structural parts, materials, health monitoring systems, TPS, mechanisms and advanced propulsion assisted landing systems.<br>
This paper gives an overall overview of the project; the current status of the project will be presented and an outlook of future activities will be given. Furthermore, the configuration layout and landing concept of both configurations will be discussed in more detail.</p>
https://doi.org/10.5281/zenodo.5770046
oai:zenodo.org:5770046
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.5770045
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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Retro-propulsion
Aerodynamics
Aerothermodynamics
Demonstrators
Retro Propulsion Assisted Landing Technologies (RETALT): Current Status and Outlook of the EU Funded Project on Reusable Launch Vehicles
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6759777
2022-06-28T01:48:38Z
user-retalt
user-eu
Krammer, Anett
Nebuloni, Stefano
Lichtenberger, Marc
2022-06-21
<p>Within the framework of the EU Horizon 2020 project RETALT (RETro propulsion Assisted Landing Technologies), mechanisms for the RETALT1 reference launch vehicle configuration are investigated. Almatech has studied the actuation of aerodynamic control surfaces, thrust vector control and landing leg mechanisms.</p>
<p>This paper presents an overview of activities, scaled demonstrator design and test of the landing legs and aerodynamic control surfaces. A scaled functional demonstrator of a single leg is built to verify the leg deployment mechanism function and its kinematics. Another scaled leg demonstrator is constructed and tested in a drop tower to verify the leg shock absorbing function, energy dissipation during touchdown. In addition, functional test of the aerodynamic control surfaces is carried out with a scaled fin demonstrator to verify kinematics of deployment from stowed to nominal position, as well as operation, and axis locking functions.</p>
https://doi.org/10.5281/zenodo.6759777
oai:zenodo.org:6759777
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759776
info:eu-repo/semantics/openAccess
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FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
landing leg
shock absorber
aerodynamic control surfaces
Landing Leg and Aerodynamic Control Surface Mechanisms and Functional Demonstrators for the RETALT1 Launch Vehicle
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6793851
2022-07-04T13:48:35Z
user-retalt
user-eu
Marwege, Ansgar
Kirchheck, Daniel
Klevanski, Josef
Gulhan, Ali
2022-06-30
<p>In the frame of the RETALT (RETro propulsion Assisted Landing Technologies) project, the aerodynamics of reusable launch vehicles reentering the atmosphere and descending and landing with the aid of retro propulsion are studied. In particular, series of wind tunnel tests are performed to assess the aerodynamic properties of such a vehicle in the various flight phases from hypersonic and supersonic re-entry down to subsonic conditions at touch down. This paper discusses the results of wind tunnel tests in the Hypersonic Wind Tunnel Cologne (H2K) at the Supersonic and Hypersonic Flow Technologies Department of the German Aerospace Center (DLR) in Cologne for the hypersonic retro propulsion maneuver during the re-entry burn. Mach numbers of 5.3 and 7.0 were tested with a variation of thrust coefficient, Reynolds number, angle of attack, cold and heated air. A single-engine configuration and a configuration with three active engines were tested. In all tests, the engine exhaust was simulated using ambient temperature or heated air. Dependencies of the flow features of the square root of the thrust coefficient known from literature for the single-engine case can be confirmed and extended to the three-engine configuration. For the single-engine case, the formation of vortex rings was observed, which eventually leads to strong individual vortices and extensive flow field disturbances. The heating of the supply air up to 600 K mitigates con- densation in the retro plume, while the overall flow structures remained unchanged. High thrust coefficients generally lead to vanishing pressure coefficients on the engine bay. The single and the three-engine cases are comparable in this sense. The Mach number and Reynolds number are of subordinate importance for the pressures on the vehicle, while the thrust coefficient is the dominating similarity parameter. Pressure coefficients far downstream of the retro plume are affected less and, therefore, are not negligible at non-zero angles of attack. In this paper, the methodology of the wind tunnel tests and the results obtained are described in detail.</p>
https://doi.org/10.1007/s12567-022-00457-w
oai:zenodo.org:6793851
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https://zenodo.org/communities/eu
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CEAS Space Journal, (2022-06-30)
Wind tunnel tests
Retro propulsion
Vertical descent and landing
Reusable launch vehicle
Hypersonic retro propulsion for reusable launch vehicles tested in the H2K wind tunnel
info:eu-repo/semantics/article
oai:zenodo.org:6783922
2022-07-02T13:49:19Z
user-retalt
user-eu
Marwege, Ansgar
Hantz, Christian
Kirchheck, Daniel
Klevanski, Josef
Vos, Jan
Laureti, Mariasole
Karl, Sebastian
Gulhan,Ali
2022-06-21
<p>The RETALT (RETro propulsion Assisted Landing Technologies) project aims to investigate vertically landing launcher configurations, which decelerate by means of retro propulsion manoeuvres during the descent and final landing phase. One key objective was to understand the complex steady and unsteady flow field and the resulting oscillating pressure loads on the re-entering vehicles.</p>
<p>In the course of the project, extensive wind tunnel test series have been performed in the three aerodynamic wind tunnel facilities at DLR in Cologne. The re-entry burn, with one to three active engines, was rebuilt in the Hypersonic Wind Tunnel Cologne (H2K), the aerodynamic descent phase was analysed in the Trisonic Wind Tunnel Cologne (TMK) and the landing burn was tested in the Vertical Free-jet Facility (VMK). Furthermore, detailed CFD analyses of the various flight phases have been performed by CFSE and DLR with the flow solvers NSMB and TAU.</p>
<p>In this paper the steady and unsteady flow field around the RETALT1 and RETALT2 vehicles in the various flight phases will be compared and the resulting loads will be analysed.<br>
An analytical sizing method for aerodynamic control surfaces for the aerodynamic phase of RETALT1 is validated, for RETALT2 a strong hysteresis was found in the forces and moments in the aerodynamic phase. The plume length in the landing phase of RETALT1 follows a linear analytical approach. The flow field of RETALT1 in the retro propulsion phases during the landing burn and the re-entry burn is highly unsteady which is visible in the variance of the schlieren images and in the high frequency pressure measurements.</p>
https://doi.org/10.5281/zenodo.6783922
oai:zenodo.org:6783922
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759358
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heillbron, Germany, 19-23 June, 2022
Retro Propulsion
Vertical Take-off Vertical Landing
Wind Tunnel Experiments
Retro Propulsion Assisted Landing Technologies
Aerodynamic Phenomena of Retro Propulsion Descent and Landing Configurations
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6783915
2022-07-04T11:18:46Z
user-retalt
user-eu
Marwege, A.
Klevanski, J.
Hantz, C.
Kirchheck, D.
Gulhan, A.
Karl, S.
Laureti, M.
De Zaiacomo, G.
Vos, J.B.
Thies, C.
Jevons, M.
Krammer, A.
Lichtenberger, M.
Carvalho, J.
Paixão, S.
2022-06-21
<p>Since SpaceX successfully demonstrated the vertical landing of launcher first stages and made this way of returning them to earth a routine operation with over 100 successful landings after 6 years, the interest in Europe to develop the key technologies for this approach has drastically increased. It not only promises large cost savings, but also reduces space debris and is more environmentally friendly as no debris parts fall back to the earth’ surface.</p>
<p>The first project funded by the EU commission to investigate key technologies for reusable launch vehicles applying retro propulsion is RETALT (RETro propulsion Assisted Landing Technologies) which received a funding of 3 million Euros in the frame of Horizon 2020.</p>
<p>The consortium consists of the German Aerospace Center (DLR), CFS Engineering (CFSE), DEIMOS Space, MT Aerospace, Almatech and Amorim Cork Composites. The key technologies studied in detail are Aerodynamics, Aerothermodynamics, Flight Dynamics and GNC, Structures, Mechanisms, TVC, and TPS. Detailed wind tunnel test series were performed at DLR and were combined with Computational Fluid Dynamics (CFD) studies by DLR and CFSE to generate a sound basis for the understanding of the complex aerodynamic and aerothermodynamic phenomena at play for such configurations. MT Aerospace designed the structure of the aerodynamic control surfaces and landing legs, and closely worked together with Almatech who designed the mechanisms for these applications. Demonstrators were built in a scale of 1/5 of the aerodynamic control surface and the landing leg, and the landing leg was tested in a drop tower. Amorim Cork Composites developed a new cork based TPS material specifically for the application on retro propulsive landing configurations with a focus on an easy applicability of the material. The material was tested in the arc heated facility L2K at DLR.</p>
<p>In this paper a detailed overview of the studied technologies will be given and the interplay between the different disciplines will be highlighted. Design challenges for launcher configurations descending and landing through a deceleration using the engines will be discussed. An outlook for the potential for future research and developments will be given.</p>
<p> </p>
https://doi.org/10.5281/zenodo.6783915
oai:zenodo.org:6783915
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759267
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June 2022
Retro Propulsion Assisted Landing Technologies
Vertical Take-off Vertical Landing
Reusable Launch Vehicle
Key Technologies for Retro Propulsive Vertical Descent and Landing – RETALT – An Overview
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:5779497
2021-12-14T13:48:41Z
user-retalt
user-eu
Botelho, A.
Recupero, C.
Fernandez, V.
Fabrizi, A.
De Zaiacomo, G.
2021-06-25
<p>This paper presents the Guidance, Navigation and Control solution currently in development by DEIMOS Space for RETALT (Retro Propulsion Assisted Landing Technologies), an EU Horizon 2020 project for studying launch system re-usability technology. The general high-level GNC architecture is presented, with a more in- depth discussion on the navigation and landing phase guidance solutions. The navigation solution is based on a Considered Kalman Filter and a sensor suite that includes an INS/GNSS coupled system as baseline. Navigation simulation results are presented, which demonstrate very good performance. The guidance strategy is based on direct optimal control methods via on-board optimization, which is the only available solution able to satisfy the demanding requirements for a booster recovery mission as such. Within this methodology two approaches are identified, namely single convex optimization and successive convexification, for which a trade-off is performed. The former has been preliminarily selected for the RETALT landing guidance due to its lower computational complexity but still high fidelity. High- fidelity simulation results, however, demonstrate that the fidelity achievable with this approach is not sufficient to satisfy the mission requirements, and therefore a more complex solution based on successive convexification is required.</p>
https://doi.org/10.5281/zenodo.5779497
oai:zenodo.org:5779497
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.5779496
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Guidance Navigation Control
RETALT: Development of an Optimal GNC Solution for Recovery of an Orbital Launch Vehicle
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6256435
2022-02-25T01:49:09Z
user-retalt
user-eu
Laureti, Mariasole
Karl, Sebastian
2022-01-04
<p>The assessment of thermal loads occurring on reusable launch vehicles during the entire trajectory is essential for the correct dimensioning of the thermal protection system. Due to the costs and limitations of ground-based testing for large-scale vehicles, these predictions rely intensively on numerical simulations (CFD). The need of aero-thermal databases, as a fast-response surrogate model for the aero-thermodynamic heating, arises from the practical impossibility of performing unsteady CFD analysis over the entire trajectory due to the large disparity of fluid mechanical and structural time scales. The construction of these databases is based on a representative set of CFD simulations which cover, at a minimum, the flight regimes with significant thermal loads. The aim of this paper is to analyse the results of these representative CFD simulations during both the ascent flight and atmospheric entry for the RETALT1 vehicle to show typical flow field phenomena occurring during these phases and the resulting heating patterns.</p>
https://doi.org/10.1007/s12567-021-00413-0
oai:zenodo.org:6256435
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-01-04)
Reusable launch vehicle
Retro-propulsion
Aerothermal loads
CFD
RANS
Aerothermal databases and load predictions for Retro Propulsion-Assisted Launch Vehicles (RETALT)
info:eu-repo/semantics/article
oai:zenodo.org:6007415
2022-02-09T01:49:48Z
user-retalt
user-eu
Gabriele De Zaiacomo
Gonzalo Blanco Arnao
Riccardo Bunt
Davide Bonetti
2022-02-08
<p>In the last decade, the rapid and successful development of reusable launch systems such as SpaceX’ Falcon 9 demonstrated both the operational feasibility of reusable launchers and their economic viability. The objective of recovering a launcher or a launcher’s booster requires to safely return the launch vehicle from orbital or sub-orbital conditions to a soft landing. To increase the reusability, decrease the turnaround time and reduce costs, a precise touchdown on a pre-defined landing site or on a floating barge on the Ocean is preferred to splashdown in the water, due mainly to the highly detrimental effect of the salted water on the launcher components and equipment. The project RETALT (Retro Propulsion Assisted Landing Technologies) was funded by the EU Horizon 2020 program to study and develop critical technologies for launcher recovery based on retro-propulsion. In this context, and based on in-house experience and tools, DEIMOS Space carried out the mission engineering of the RETALT1 vehicle concept to assess the feasibility of a return mission, from a wide range of Main Engine Cut-Off (MECO) conditions, when the stage is separated from the rest of the launch vehicle, in line with the available propellant budget, and while maintaining the peak entry conditions within acceptable limits. Either a DownRange Landing (DRL) on a drone ship at sea or a Return To Launch Site (RTLS) to land in the proximity of the launch pad is performed based on the velocity and distance at MECO from the launch site. For the landing burn, a safe splashdown approach has been implemented to avoid damaging the ground infrastructure in case of anomalies during the flight. Based on the mission feasibility assessment, the needs for the vehicle recovery have been identified, leading to the definition of preliminary mission requirements at the system and subsystem level. Consequently, the consolidation of the return mission design was possible and optimised trajectories have been defined for the DRL and RTLS scenarios.</p>
https://doi.org/10.1007/s12567-021-00415-y
oai:zenodo.org:6007415
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-02-08)
Launcher
GNC
Optimal guidance
Hybrid navigation
Optimum control
Reusability
Mission engineering for the RETALT VTVL launcher
info:eu-repo/semantics/article
oai:zenodo.org:7027372
2022-08-28T02:26:25Z
user-retalt
user-eu
Becker, Laura
2022-08-27
<p>This internship report, written in German, discusses the design and building of a 1:5 scale model of a landing leg used for the RETALT project.</p>
https://doi.org/10.5281/zenodo.7027372
oai:zenodo.org:7027372
deu
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.7027371
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Landing leg, CAD, Design
Konstruktion und Fertigung eines Landebeins für das RETALT Projekt
info:eu-repo/semantics/report
oai:zenodo.org:6256294
2022-02-25T01:49:09Z
user-retalt
user-eu
Paixão, Sofia
Peixoto, Cláudia
Reinas, Marta
Carvalho, João
2022-01-08
<p>The present document discusses the development of a new trowelable Thermal Protection System (TPS), able of being mixed, applied and cured directly onto the vehicle structure, with the aim to fulfill the requirements of the thermal properties for the re-usable launch vehicle studied in the Retro Propulsion Landing Technology (RETALT) project. During the development of this TPS, several formula optimizations were made to improve or eliminate cracks in the char surface, increase char stiffness, rheological adjustments, and adhesion improvement to different substrates. The most promising material developed is<br>
composed by cork and epoxy resin, together with a set of rheological and thermal resistance additives, that makes it possible to be applied with a spatula, while at the same time it is able to withstand the demanding environmental conditions during atmospheric reentry. In terms of thermal properties, the developed material has a higher thermal conductivity than the current P50 TPS commercialized by Amorim Cork Composites (ACC), but it has a better behavior when exposed to flame conditions.<br>
It is expected that the absence of cracks improves its structure and resistance to demanding conditions. The development work included a detailed study of the composition and processes required for the development of a TPS material, which were evaluated by several types of flame characterization tests and thermal properties analysis.</p>
https://doi.org/10.1007/s12567-021-00417-w
oai:zenodo.org:6256294
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-01-08)
TPS
Cork
Char
Trowelable
P50
RETALT_TPS design and manufacturing
info:eu-repo/semantics/article
oai:zenodo.org:6592386
2022-05-30T13:50:41Z
user-retalt
user-eu
Laureti, M.
Karl, S.
Marwege, A.
Gülhan, A.
2022-06-21
<p>The RETALT (Retro Propulsion Assisted Landing Technologies) project aims at investigating launch system reusability technologies for two different Vertical Take-off Vertical Landing launcher configurations, namely RETALT1 and RETALT2.<br>
This paper describes and summarizes the CFD based aerothermal load predictions, aerothermal database generation and application for the RETALT1 configuration for the complete trajectory. Furthermore, an analysis of representative CFD results is provided with the aim to show typical flow field phenomena and the resulting heating patterns occurring during the retropropulsion phase. CFD results are then validated by comparison with the wind tunnel experiments carried out at different ground testing facilities in DLR Cologne.</p>
https://doi.org/10.5281/zenodo.6592386
oai:zenodo.org:6592386
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6592385
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
AEROTHERMAL DATABASES AND CFD BASED LOAD PREDICTIONS
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:7027367
2022-08-28T02:26:39Z
openaire_data
user-retalt
user-eu
Marwege, Ansgar
Hantz, Christian
Klevanski, Josef
Gülhan, Ali
Vos, Jan
Charbonnier, Dominique
Karl, Sebastian
2022-05-31
<p>The excel file contains the Aerodynamic Data Base for the RETALT1 configuration. The pdf file contains the necessary information to use this data base</p>
https://doi.org/10.5281/zenodo.7027367
oai:zenodo.org:7027367
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6597912
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
RETALT1 – AERODYNAMIC DATA BASE 2.0
info:eu-repo/semantics/other
oai:zenodo.org:6597913
2022-08-27T09:34:42Z
openaire_data
user-retalt
user-eu
Marwege, Ansgar
Hantz, Christian
Klevanski, Josef
Gülhan, Ali
Vos, Jan
Charbonnier, Dominique
Karl, Sebastian
2022-05-31
<p>The excel file contains the Aerodynamic Data Base for the RETALT1 configuration. The pdf file contains the necessary information to use this data base</p>
https://doi.org/10.5281/zenodo.6597913
oai:zenodo.org:6597913
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6597912
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
RETALT1 – AERODYNAMIC DATA BASE 2.0
info:eu-repo/semantics/other
oai:zenodo.org:7027362
2022-08-28T02:26:39Z
openaire_data
user-retalt
user-eu
Marwege, Ansgar
Hantz, Christian
Klevanski, Josef
Gülhan, Ali
Vos, Jan
Charbonnier, Dominique
Karl, Sebastian
2022-05-31
<p>The excel file contains the Aerodynamic Data Base for the RETALT1 configuration. The pdf file contains the necessary information to use this data base</p>
https://doi.org/10.5281/zenodo.7027362
oai:zenodo.org:7027362
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6597912
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
RETALT1 – AERODYNAMIC DATA BASE 2.0
info:eu-repo/semantics/other
oai:zenodo.org:6759659
2022-06-28T01:48:38Z
user-retalt
user-eu
Martinez, Marc
Ghignoni, Pietro
Botelho, Afonso
Recupero, Cristina
Fabrizi, Andrea
Fernandez, Vincente
De Zaiacomo, Gabriele
2022-06-21
<p>This paper presents the GNC concept solution developed for the recovery and landing of Vertical Take-off Vertical Landing (VTVL) launch vehicles in the context of RETALT (RETro-propulsion Assisted Landing Technologies), a European Union Horizon 2020 project with the objective of investigating and developing launch system reusability technologies based on the use of retro-propulsion. The project aims to increase the Technology Readiness Level (TRL) of the recovery technologies up to 5 for structures and mechanisms, Thermal Protection Systems (TPS), Aerodynamics and Aero-thermodynamics, and up to TRL 3 for GNC. One of the great technical challenges related to the reusability of launchers is the recovery Guidance, Navigation and Control (GNC) system, of which DEIMOS Space is in charge for RETALT. In particular, the design of the powered- descent and landing GNC offers a difficult challenge, since it must allow the system to perform a precision landing in a fast- dynamic environment, with extremely limited fuel margins, and with significant unknown dispersions accumulated during prior phases. To tackle this, state-of-the art algorithms based on hybrid Navigation techniques for state estimation, as well as online convex optimization and successive convexification for the design of the guidance GNC sub- function are explored. The Control algorithm operates in distinct modes dependent on the GNC phase and available GNC actuators, and it is based on modern robust control methods in order to provide analytical guarantees over the control performance in the presence of uncertainties and unmodelled dynamics. The proposed GNC solutions were integrated and tested in a high-fidelity simulator and the performance were preliminary assessed, demonstrating the capability to successfully steer the vehicle to the desired landing site.</p>
https://doi.org/10.5281/zenodo.6759659
oai:zenodo.org:6759659
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759658
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
GNC
Hybrid Navigation
Successive convexification
Optimum GNC Solutions for the Recovery and Vertical Landing of an Orbital Launch Vehicle
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6759589
2022-06-28T01:48:36Z
user-retalt
user-eu
De Zaiacomo, Gabriele
Medici, Giovanni
Princi, Alessandro
2022-06-21
<p>In the last decade, the number of space-based applications increased dramatically. To cover such a demanding market, launch technologies adapted and new launch solutions were developed, to increase the efficiency and the cost effectiveness of the access to space. In particular, reusability became the focus of multiple activities devoted to the design and analysis of current and future launchers solutions. Worldwide, Space X was able to make the reusability of first stages look like a routine operation with more than 50 successful landings and recoveries, and reuse up to 6 times. ULA and Blue Origin are developing their next generation launchers to be partially reusable, and also China is testing technologies to achieve reusability for micro-launchers. In Europe, several initiatives have been started in the last years to analyse and test critical technologies and system that will enable reusability. The RETro-propulsion Assisted Landing Technologies (RETALT) project is an H2020 activity, funded by the European Union and coordinated by DLR, aiming at developing key technologies to enable the recovery of vertical take-off vertical landing launchers making use of retro-propulsion, in the field of aerodynamic and aerothermodynamics, flight dynamics and GNC, and structures and mechanisms. In this context, mission engineering is a critical process of the design-for-reusability chain, and it is a discipline of excellence of DEIMOS Space. In this paper, the mission engineering process developed and applied to RETALT is presented, as well as the results obtained.</p>
https://doi.org/10.5281/zenodo.6759589
oai:zenodo.org:6759589
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759588
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
atmospheric entry
launchers reusability
flight mechanics
supersonic retro-propulsion
Mission Engineering for the Recovery and Vertical Landing of an Orbital Launch Vehicle
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6759766
2022-06-28T01:48:39Z
user-retalt
user-eu
Thies, Christoph
2022-06-21
<p>The RETALT project, funded by the European Horizon 2020 program, has the objective to study critical technologies for Vertical Take-off Vertical Landing (VTVL) Reusable Launch Vehicles (RLVs) applying retro propulsion, combined with aerodynamic control surfaces and landing gear components. Two reference launch vehicle configurations are defined:</p>
<p>RETALT1, which is a Two Stage To Orbit (TSTO) RLV similar to the SpaceX rocket ”Falcon 9” and RETALT2, which is a Single Stage To Orbit (SSTO) RLV similar to the DC-X vehicle.</p>
<p>This paper describes a scaled drop test procedure for a scaled landing leg 1:5 (LL) of the reusable launcher configuration RETALT1 and summarizes the recorded data of the performed short time dynamic impact test.</p>
<p>The performed drop test simulates a dynamic shock loading (landing manoeuvre) on the 1:5 scaled landing structure to proof the strength resistance of the frames during landing. Additionally, the functionality of the kinematic system and the resistance and damping behaviour of the absorber is tested. The test results are used to correlate the mathematical strength and kinetic models for future works and provide an upscale methodology to the 1:1 launcher configuration for the landing gear.</p>
<p>The drop test consists of a large mass, which is mounted on a drop tower to store high potential energy, which is then transformed into kinetic energy after the release of the mass. After touching the foot pad of the LL, the impact energy leads to high forces in the landing leg and absorber. To withstand the applied kinetic energy, the compression and tension forces in the lightweight carbon fibre reinforced polymer (CFRP) LL were simulated via FEM. The applied kinetic energy quantity matches the optimal efficiency range of the non-linear damper system.</p>
<p>During the drop test the landing gear is equipped with high sampling accelerometers, strain gauges and an optical measurement system for the detection of the deformation and strains at critical positions such as interfaces, hinges, rivets and highly stressed CFRP components.</p>
<p>Furthermore, a short description of the control fins is represented in this paper, which were built by MT- Aerospace (MTA) and used for the development of kinematic mechanisms by MTA’s partner Almatech.</p>
<p> </p>
https://doi.org/10.5281/zenodo.6759766
oai:zenodo.org:6759766
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759765
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
Reusable launch vehicle
Landing Leg
Impact loads
Drop test experiment
Control fins
Drop Test Description and Evaluation of a Landing Leg for a Re-usable Future Launche Vehicle
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6256370
2022-02-25T01:49:09Z
user-retalt
user-eu
Krammer, Anett
Blecha, Luc
Lichtenberger, Marc
2022-01-13
<p>To foster the competitiveness of the European industry in the global launcher market, the need arose to build up the necessary know-how on state-of-the-art vertical take-off vertical landing (VTVL) concepts and corresponding technologies. In the EU Horizon 2020 project RETALT (RETro propulsion Assisted Landing Technologies), the VTVL approach applying retro propulsion is investigated for two-stage-to-orbit (TSTO) and single-stage-to-orbit (SSTO) reusable launch vehicles, these configurations are named RETALT1 and RETALT2. In the project framework investigation of both reference configurations is performed in several areas: aerodynamics, aerothermodynamics, flight dynamics and guidance, navigation, and control (GNC), as well as thermal protection and structures and mechanisms. Focusing on solutions for the RETALT1 launch vehicle, Almatech contributes with the design of mechanisms to actuate the aerodynamic controls surfaces, retain and deploy the landing legs and provide means to dissipate energy during touch-down. Demonstrators of these mechanism are also built during the project. In addition to the above activities, Almatech proposes thrust vectoring solutions. This paper presents an overview of these activities and results obtained so far.</p>
https://doi.org/10.1007/s12567-021-00421-0
oai:zenodo.org:6256370
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-01-13)
Mechanisms
Aerodynamic control surfaces
Landing leg
Thrust vector control
Shock absorber
Fin actuation, thrust vector control and landing leg mechanisms design for the RETALT VTVL launcher
info:eu-repo/semantics/article
oai:zenodo.org:5779174
2021-12-14T13:48:40Z
openaire
user-retalt
user-eu
Bonetti, D.
De Zaiacomo, G.
Blanco Arnao, G.
Medici, G.
2020-10-29
<p>This presentation gives an overview of the DEIMOS involvement in the RETALT project, with emphasis on the GNC concept and Mission analysis</p>
https://doi.org/10.5281/zenodo.5779174
oai:zenodo.org:5779174
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.5779173
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Guidance Navigation Control
Mission
DEIMOS' R&D on Reusable Launchers' Technologies
info:eu-repo/semantics/lecture
oai:zenodo.org:6759268
2022-07-04T11:18:45Z
user-retalt
user-eu
Marwege, A.
Klevanski, J.
Hantz, C.
Kirchheck, D.
Gulhan, A.
Karl, S.
\Laureti, M.
De Zaiacomo, G.
Vos, J.B.
Thies, C.
Jevons, M.
Krammer, A.
Lichtenberger, M.
Carvalho, J.
Paixão, S.
2022-06-21
<p>Since SpaceX successfully demonstrated the vertical landing of launcher first stages and made this way of returning them to earth a routine operation with over 100 successful landings after 6 years, the interest in Europe to develop the key technologies for this approach has drastically increased. It not only promises large cost savings, but also reduces space debris and is more environmentally friendly as no debris parts fall back to the earth’ surface.</p>
<p>The first project funded by the EU commission to investigate key technologies for reusable launch vehicles applying retro propulsion is RETALT (RETro propulsion Assisted Landing Technologies) which received a funding of 3 million Euros in the frame of Horizon 2020.</p>
<p>The consortium consists of the German Aerospace Center (DLR), CFS Engineering (CFSE), DEIMOS Space, MT Aerospace, Almatech and Amorim Cork Composites. The key technologies studied in detail are Aerodynamics, Aerothermodynamics, Flight Dynamics and GNC, Structures, Mechanisms, TVC, and TPS. Detailed wind tunnel test series were performed at DLR and were combined with Computational Fluid Dynamics (CFD) studies by DLR and CFSE to generate a sound basis for the understanding of the complex aerodynamic and aerothermodynamic phenomena at play for such configurations. MT Aerospace designed the structure of the aerodynamic control surfaces and landing legs, and closely worked together with Almatech who designed the mechanisms for these applications. Demonstrators were built in a scale of 1/5 of the aerodynamic control surface and the landing leg, and the landing leg was tested in a drop tower. Amorim Cork Composites developed a new cork based TPS material specifically for the application on retro propulsive landing configurations with a focus on an easy applicability of the material. The material was tested in the arc heated facility L2K at DLR.</p>
<p>In this paper a detailed overview of the studied technologies will be given and the interplay between the different disciplines will be highlighted. Design challenges for launcher configurations descending and landing through a deceleration using the engines will be discussed. An outlook for the potential for future research and developments will be given.</p>
<p> </p>
https://doi.org/10.5281/zenodo.6759268
oai:zenodo.org:6759268
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759267
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June 2022
Retro Propulsion Assisted Landing Technologies
Vertical Take-off Vertical Landing
Reusable Launch Vehicle
Key Technologies for Retro Propulsive Vertical Descent and Landing – RETALT – An Overview
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:5770094
2021-12-09T13:48:50Z
user-retalt
user-eu
Starke, P.
Dorbath,. C.
Zell, D.
2019-10-25
<p>To foster the competitiveness of the European industry on the global launcher market there is not only an urgent need of building up the necessary know-how on state-of-the-art Vertical Take-Off Vertical Landing (VTVL) Two Stage To Orbit (TSTO) concepts, but also to go beyond this approach. Historically, many concepts of Reusable Launch Vehicle (RLV) are based on Single Stage To Orbit (SSTO) designs, e.g. the VentureStar, the DC-X and the Russian CORONA. In the EU Horizon 2020 project RETALT (RETro propulsion Assisted Landing Technologies) the VTVL approach is also investigated for SSTO RLV. In this way, the concept of vertical landing with retro propulsion is investigated in a more general way and has the potential to be applied to more concepts of future RLV.</p>
<p>The vertical landing of an RLV applying retro propulsion is a complex multidisciplinary task. The investigation for both reference configurations will be performed in the areas of aerodynamics, aerothermodynamics and flight dynamics and GNC as well as advanced structural parts and materials, health monitoring systems and advanced propulsion assisted landing systems.</p>
<p>The focus of the contribution of MT Aerospace lies on design and manufacturing of hardware for aerodynamic and aerothermal experiments as well as demonstrators of structures and mechanisms of aerodynamic control surfaces and landing structures. Therefore, TRL 5 will be reached during the project.</p>
<p>This paper presents an outlook on the upcoming activities.</p>
https://doi.org/10.5281/zenodo.5770094
oai:zenodo.org:5770094
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.5770093
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
reusable launcher
structures
landing leg
control surface
Design and Manufacturing Status of Advanced Structures for Reusable Launch Systems Demonstrators with Retro Propulsion Assisted Landing Technologies (RETALT)
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6400895
2022-03-31T13:49:26Z
user-retalt
user-eu
Charbonnier, Dominique
Vos, Jan
Marwege, Ansgar
Hantz, Christian
2022-03-25
<p>The European project RETALT (Retro Propulsion Assisted Landing Technologies), funded by the Horizon 2020 frame- work program (Grant agreement No 821890), has as main objective to investigate critical technologies for the assisted descent and landing of re-usable first stages. Among these technologies, one can find aerodynamics, aerothermodynamics, flight dynamics, guidance navigation and control (GNC), Structures, mechanisms, thrust vector control (TVC) and thermal protection systems (TPS). The present paper focuses in particularly on the aerodynamics technology applied to a vertical landing launcher configuration, called RETALT1, including retro-propulsion. During the landing phase of the first stage of the launcher, the main devices for control and trim of the vehicle (besides the retro-propulsion) are the aerodynamic control surfaces (ACS). Three types of aerodynamic control surfaces are investigated by means of numerical computations, using the NSMB (Navier Stokes Multi Block) CFD code. The control surfaces considered are the deployable interstage segments (also named petals), grid fins and planar fins. Aerodynamic coefficients as well as forces acting on the control surfaces are extracted from the CFD computations to assess the efficiency of each type of devices and to populate the Aerodynamic Database (AEDB) for flight dynamic analysis.</p>
https://doi.org/10.1007/s12567-022-00431-6
oai:zenodo.org:6400895
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-03-25)
Aerodynamics
CFD
Control surface
Reusable launcher
Vertical landing
Computational fluid dynamics investigations of aerodynamic control surfaces of a vertical landing configuration
info:eu-repo/semantics/article
oai:zenodo.org:6221061
2022-07-05T10:03:55Z
user-retalt
user-eu
Ansgar Marwege
Christian Hantz
Daniel Kirchheck
Josef Klevanski
Ali Gülhan
Dominique Charbonnier
Jan Vos
2022-02-22
<p>In the RETALT (RETro propulsion Assisted Landing Technologies) project vertical landing launcher configurations are investigated. In the aerodynamic phase of retro propulsion assisted descent and landing, the main devices for control and trim of the vehicle are the aerodynamic control surfaces. In this paper, experimental data of a novel concept where the inter-stage is divided in four segments which are used as aerodynamic control surface during the aerodynamic descent of the first stage is presented. The results are compared to theoretical results obtained using a simplified modelling of supersonic and hypersonic flow fields. The interstage segments show to be very effective in creating drag for aerodynamic deceleration in the atmosphere. A large deflection of the interstage segments can lead to largely unsteady flows. The deflection of only one interstage segment does not yield statically stable configurations.</p>
https://doi.org/10.1007/s12567-022-00425-4
oai:zenodo.org:6221061
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-02-22)
Wind tunnel tests
Aerodynamic control surfaces
Retro propulsion
Vertical landing
Interstage
Wind tunnel experiments of interstage segments used for aerodynamic control of retro‐propulsion assisted landing vehicles
info:eu-repo/semantics/article
oai:zenodo.org:6759736
2022-06-28T01:48:38Z
user-retalt
user-eu
Hantz, Christian
Marwege, Ansar
Paixao, Sofia
Celotti, Luca
Wiśniewska, Maria
2022-06-21
<p>Within the RETALT project, multiple Thermal Protection System (TPS) materials have been tested, using DLR ́s arc heated facility L2K in Cologne, Germany. The high enthalpy flow was used to simulate the aerothermal heating during reentry of the 1st stage of the RETALT 1 launcher.</p>
<p>In total, 21 samples of five materials in stagnation point configuration have been tested, having two ablative cork materials and three high temperature ceramics. The cork materials by Amorim Cork Composites featured an existing material (P50) and a newly developed, trowelable cork based TPS. The ceramics were provided in cooperation with the LightCoce project.</p>
<p>The samples were exposed to cold wall heat fluxes in the range of 200 to 800 kW/m2. In addition to tests with only one heat exposure, some samples were tested 3 times at the same cold wall heat flux and same total test time, named cycle tests. Those cycle tests are intended to yield more information on a possible reuse of the materials. Surface recession and mass change is measured.</p>
https://doi.org/10.5281/zenodo.6759736
oai:zenodo.org:6759736
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759735
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
TPS
Cork
reusable launch vehicle
ablator
LightCoce
Thermal Characterization of Cork and Ceramics-Based TPS in DLRS Arc-heated Wind Tunnel L2K
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6205683
2022-02-23T13:53:41Z
user-retalt
user-eu
Afonso Botelho
Marc Martinez
Cristina Recupero
Andrea Fabrizi
Gabriele De Zaiacomo
2022-02-21
<p>Launcher reusability is the most effective way of reducing access to space costs, but remains a great technical challenge for the European aerospace industry. One of the challenges lies in the recovery GNC strategy and algorithms, in particular those of the powered-landing phase, which must enable a precise landing with low fuel margins and significant dispersions. While state-of-the-art solutions for Navigation and control problems can be applied, namely, hybrid Navigation techniques and robust control, for the powered descent guidance problem novel techniques are required to enable on-board optimization, that is necessary to achieve the landing accuracy required to recover the first stage of a launcher. This paper presents the GNC solution currently in development by DEIMOS Space for RETALT (Retro Propulsion Assisted Landing Technologies), an EU Horizon 2020 funded project for studying launch system re-usability technologies for different classes of vertical take- off vertical-landing vehicles. At first, the architecture of the GNC solution identified for the return mission of the launcher is presented. Then, the paper focuses on the landing phase guidance solution, whose performance is critical to enable the recovery and, therefore, the reusability of the launcher making use of retro-propulsion. The guidance strategy is based on direct optimal control methods via on-board optimization, which is necessary to satisfy the pinpoint landing requirement in a high uncertain dynamic system, such as a booster recovery mission. Online convex optimization and successive convexi- fication are explored for the design of the guidance function. The proposed guidance solution was integrated and tested in a high-fidelity simulator and the performance was preliminary assessed. The guidance assessment allowed selecting the best algorithms to be further consolidated and integrated in an end-to-end GNC solution for the return mission.</p>
https://doi.org/10.1007/s12567-022-00423-6
oai:zenodo.org:6205683
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-02-21)
Launcher
GNC
Optimal guidance
Successive convexification
Reusability
Design of the landing guidance for the retro-propulsive vertical landing of a reusable rocket stage
info:eu-repo/semantics/article
oai:zenodo.org:6759393
2022-06-28T01:48:36Z
user-retalt
user-eu
Vos, Jan
Charbonnier, Dominique
Marwege, Ansgar
Hantz, Christian
Gulhan, Ali
2022-06-21
<p>In the frame of the RETALT project a large number of CFD simulations and Wind Tunnel experiments were made for both the RETALT1 and RETALT2 configurations to better understand the physics and mechanisms of retro-propulsion at supersonic flow conditions. For RETALT1, it was found in both CFD and Wind Tunnel experiments that the flow structure (bow shock stand-off distance, location of the Mach disk) varies linearly with (cT ), with cT the thrust coeffi- cient. However, other flow features, as for example the ratio of nozzle exit pressure with the post-stagnation pressure, show a linear dependence on the cT . For RETALT2 a hys- teresis effect was observed in the Wind Tunnel experiments when varying the incidence angle, and a similar behavior was found in the CFD calculations.</p>
https://doi.org/10.5281/zenodo.6759393
oai:zenodo.org:6759393
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6759392
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
FAR, 2nd International Conference on Flight Vehicles, Aerothermodynamics and Re-entry Missions and Engineering, Heilbronn, Germany, 19-23 June, 2022
Reusable launchers
Wind Tunnel Experiments
Computational Fluid Dynamics
CFD Simulations and Wind Tunnel Experiments for Re-usable Launch Vehicles
info:eu-repo/semantics/conferencePaper
oai:zenodo.org:6794034
2022-07-04T13:48:35Z
user-retalt
user-eu
Marwege, Ansgar
Gülhan, Ali
Klevanski, Josef
Hantz, Christian
Karl, Sebastian
Laureti, Mariasole
De Zaiacomo, Gabriele
Vos, Jan
Jevons, Matthew
Thies, Christoph
Krammer, Anett
Lichtenberger, Marc
Carvalho, João
Paixão, Sofia
2022-06-30
<p>RETALT (RETro propulsion Assisted Landing Technologies) is a project funded in the frame of the European Union Hori- zon 2020 program, that is studying critical key technologies for the vertical landing of launcher configurations with the aid of retro propulsion. In particular Aerodynamics, Aerothermodynamics, Flight Dynamics and Guidance Navigation and Control (GNC), Structures, Mechanisms, Thrust Vector Control and Thermal Protection Systems are investigated in detail in the project. This paper provides an overview of the technological achievements in these different technological areas, with emphasis on the interaction between them. Design changes made to the RETALT1 configuration are laid out in detail. The novel approach of using interstage segments as aerodynamic control surfaces proved to be challenging from the aerodynam- ics, flight dynamics, mechanical and structural points of view. For this reason, planar fins were introduced as aerodynamic control surfaces in the new base line configuration for RETALT1. The paper concludes with a summary of future steps to be made in the RETALT project to reach the targeted Technology Readiness Level (TRL) of the different key technologies.</p>
https://doi.org/10.1007/s12567-022-00458-9
oai:zenodo.org:6794034
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
CEAS Space Journal, (2022-06-30)
Retro propulsio
Vertical take-off vertical landing technologies
RETALT: review of technologies and overview of design changes
info:eu-repo/semantics/article
oai:zenodo.org:7081540
2022-09-15T14:26:29Z
openaire_data
user-retalt
user-eu
Marwege, Ansgar
Hantz, Christian
Klevanski, Josef
Gülhan, Ali
Vos, Jan
Charbonnier, Dominique
Karl, Sebastian
2022-08-26
<p>The excel file contains the Aerodynamic Data Base for the RETALT2 configuration. The pdf file contains the necessary information to use this data base. The CFD Excel sheet contains the results of CFD simulations for different conditions and control surface deflections</p>
https://doi.org/10.5281/zenodo.7081540
oai:zenodo.org:7081540
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.6597971
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
RETALT2 – AERODYNAMIC DATA BASE 2.0
info:eu-repo/semantics/other
oai:zenodo.org:5770145
2021-12-14T11:12:24Z
openaire
user-retalt
user-eu
Gülhan, A.
Marwege, A.
Klevanski, J.
Karl, S.
Bonetti, D.
Vos, J.
Jevons, M.
Krammer, A.
Carvalho, J.
2019-11-11
<p>The presentation gives an overview of the EU funded H2020 project RETALT (RETro propulsion Assisted Landing Technologies).</p>
https://doi.org/10.5281/zenodo.5770145
oai:zenodo.org:5770145
Zenodo
https://zenodo.org/communities/retalt
https://zenodo.org/communities/eu
https://doi.org/10.5281/zenodo.5770144
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
retro-propulsion
Aerodynamics
Aerothermodynamics
Structures and Mechanisms
Guidance, Navigation, Control
RETALT - RETro propulsion Assisted Landing Technologies
info:eu-repo/semantics/lecture