RETALT: review of technologies and overview of design changes

Ansgar, Marwege,; Gülhan, Ali; Klevanski, Josef; Hantz, Christian; Karl, Sebastian; Laureti, Mariasole; Zaiacomo, Gabriele De; Vos, Jan B.; Jevons, M.; Christoph, Thies,; Krammer, Anett; Lichtenberger, Marc; Carvalho, João Paulo; S., Paixão,

doi:10.1007/s12567-022-00458-9

Cited by 11 publications

(6 citation statements)

References 13 publications

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“…After the Main Engine Cut Off (MECO), the first stage returns either to the launch site (RTLS) or lands downrange on a seagoing platform (DRL). Further details on the RETALT1 configuration can be found in [10].…”

Section: Al "Retro Propulsion Assisted Landing Technologiesmentioning

confidence: 99%

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Hypersonic retro propulsion for reusable launch vehicles tested in the H2K wind tunnel

Ansgar¹,

Kirchheck²,

Klevanski³

et al. 2022

CEAS Space J

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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 condensation 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.

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Section: Al "Retro Propulsion Assisted Landing Technologiesmentioning

confidence: 99%

“…The pressures in plane 1, which are the sensors that are positioned the farthest downstream along the cylindrical body, are close to ambient pressure. In [14], it was shown, that (10)…”

Section: Single-engine Casementioning

confidence: 99%

Hypersonic retro propulsion for reusable launch vehicles tested in the H2K wind tunnel

Ansgar¹,

Kirchheck²,

Klevanski³

et al. 2022

CEAS Space J

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“…Reusable Launch Vehicles (RLVs) have become instrumental to meeting the increasing launch demands at a reduced cost. Most of the RLVs currently in service, focus on the recovery of the rst stage via Downrange Landing (DRL) or Return To Launch Site (RTLS) [1]. These launcher stages rely on descent propellant for slowing down and landing vertically.…”

Section: Introductionmentioning

confidence: 99%

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

Singh

Sippel

Stappert

2023

J. Phys.: Conf. Ser.

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

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“…The successful retro-propulsive landing of the first stage of the Falcon 9 heavy lift launcher in 2015 and the successive application of this method in its operations, resulted in that vertical landing with the aid of retro propulsion can be considered to be state-of-the art in the USA. This created large interest in Europe, which resulted in the RETALT (Retro Propulsion Assisted Landing Technologies) project which was funded by the European Union in the frame of the Horizon 2020 framework program under the grant agreement No 821890, to study key technologies identified for retropropulsive descent and landing (Marwege et al 2022a, Marwege et al 2019). One of the main goals of the project was to create a foundation for the understanding of the complex unsteady aerodynamics for such vehicles during the descent and landing approach.…”

Section: Introductionmentioning

confidence: 99%

“…After the purely aerodynamic phase, the landing burn is performed to decelerate the vehicle down to nearly zero velocity for touch down (Botelho et al 2022). The characteristics of the RETALT1 vehicle are described in (Marwege et al 2022a, Marwege et al 2019 and are summarized in Table 1, the outline is shown in Fig. 2.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic Characteristics of the Retro Propulsion Landing Burn of Vertically Landing Launchers

Marwege,

Gülhan

2023

Preprint

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In the frame of the European funded H2020 project RETALT (Retro Propulsion Assisted Landing Technologies) the unsteady aerodynamics of vertically descending and landing launchers have been investigated. In this paper experimental data of the landing burn tested in the Vertical Free-Jet Facility Cologne (VMK) at DLR in Cologne is presented. The landing burn was simulated with a cold gas jet of pressurized air opposing the wind tunnel free stream. Tests with several jet conditions were compared to results without active jet. Proper Orthogonal Decomposition of Schlieren recordings and spectral analyses of their time histories are performed and are compared to frequencies in pressure measurements. Dominant frequencies were found, which are strongest at Mach 0.8. Especially a Strouhal number of 0.2 was found to be most dominant. The intensity of the dominant frequencies, can be lowered if the engine is active. The normalized root mean square pressure fluctuations are between 0.1 and 0.3 during the landing maneuver. Additionally, the steady flow features scale well with the ambient pressure ratio and the momentum flux ratio.

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RETALT: review of technologies and overview of design changes

Cited by 11 publications

References 13 publications

Hypersonic retro propulsion for reusable launch vehicles tested in the H2K wind tunnel

Hypersonic retro propulsion for reusable launch vehicles tested in the H2K wind tunnel

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

Aerodynamic Characteristics of the Retro Propulsion Landing Burn of Vertically Landing Launchers

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