Reusable Launch Research Articles

재사용 우주 발사체 개발 동향

최근 우주 기술이 발달함에 따라 전 세계적으로 위성 시장, 특히 소형 위성 시장이 크게 성장하고 있다. 이러한 위성 시장의 성장세 속에서 발사체 시장 역시 성장세를 보이고 있으며 이에 따라 저비용 발사에 대한 수요가 점점 증가하고 있다. 저비용 발사를 위한 방안에는 저비용 추진제를 사용하는 엔진 개발, 제품 생산 및 운송비용 절감 등 다양한 방법이 존재하지만, 발사 비용을 가장 크게 줄이는 방법은 바로 사용한 발사체를 다시 사용하는 것이다. 재사용 발사체의 시작은 유인 우주선으로 유명한 미국의 Space Shuttle이라 할 수 있다. 하지만 Space Shuttle의 경우 재사용이라고 불리기는 하지만 재사용 할 수 있는 부분이 한정되어 있고, 발사 효율이 떨어져 재사용 발사체 임에도 불구하고 상당히 고비용이었다. 최근에는 미국의 SpaceX와 Blue Origin을 중심으로 상업적 목적의 재사용 발사체가 개발 되고 있고 재착륙 시험에 성공하였다. 뿐만 아니라, SpaceX의 경우 이전 재착륙을 성공한 1단 발사체를 정비하여 다시 발사하는데 까지 성공하기도 하였다. 이러한 추세에 따라 유럽, 인도와 같은 국가에서도 현재 재사용 발사체 연구에 심혈을 기울이고 있다. 그리고 Blue Origin을 포함한 미국의 Virgin Galactic, XCOR 등은 민간 유인 우주여행과 같은 재사용 기술을 이용한 상품화도 시도하고 있다. 재사용 기술이 확립되면 세계 발사체 시장의 판도가 바뀔 수 있기에 재사용 기술 동향의 정기적인 확인은 필수적이라 할 수 있다.

Satellite Internet in the Mobile Age

Abstract It could soon be technologically and economically feasible for anyone on Earth to have 2-way access to the global river of data that is modern civilization. Within the next 5 years, new low earth orbit (LEO) satellite constellations providing high-speed broadband may exceed the number of operational satellites currently in orbit. A fundamental question facing the new satellite constellation builders is whether the changes that have occurred in the 2 intervening decades are sufficient to alter the failed results of the 1990s-era constellations. The most likely answer is yes, but this depends on both political actions by governments and the business acumen of firms. Constellations must effectively target the demand segments, coordinate their spectrum usage with each other and the next generation of wireless networks, and avoid rampant orbital debris. As a side benefit, these new LEO constellations may provide a commercial setting for early use of reusable launcher capabilities.

Automatic tuning strategies for model-based diagnosis methods applied to a rocket engine demonstrator

Rocket engines are complex and critical systems mostly relying on simple redlines strategies for monitoring the main functional parameters. This approach is typical on expendable rockets with non-adjustable valves because in case of failure the only possible action is to cut off the engine. Anyway years of experiments on engine firings or subsystem benches show that there is space for an update of the monitoring strategies because this would lead to a reduction of false alarm rates and to an improved exploitation of test hardware. Moreover real-time diagnosis methods will be necessary in case of design of intelligent rocket engine controllers for next generation reusable launchers. The work presented in this paper is part of a demonstration project of new diagnosis tools for rocket engines applied to the cryogenic combustion bench Mascotte. This bench developed by ONERA and CNES is used to analyze combustion and nozzle expansion characteristics of cryogenic fuels such as oxygen and hydrogen or methane. Model-based diagnosis tools have been developed for the combustion chamber and nozzle water cooling circuit. The basis was the setup of simplified expressions for modeling the functional behavior of the water circuit and then the development of predictive strategies such as parameter identification and Kalman filters. Anomalous event detection is obtained via residual analysis based on a CUSUM test. This paper presents the new automatic tuning strategies for the CUSUM threshold setting and the detection results obtained on Mascotte firing data.

The IXV experience, from the mission conception to the flight results

The atmospheric re‐entry domain is a cornerstone of a wide range of space applications, ranging from reusable launcher stages developments, robotic planetary exploration, human space flight, to innovative applications such as reusable research platforms for in orbit validation of multiple space applications technologies.The Intermediate experimental Vehicle (IXV) is an advanced demonstrator which has performed in-flight experimentation of atmospheric re-entry enabling systems and technologies aspects, with significant advancements on Europe's previous flight experiences, consolidating Europe's autonomous position in the strategic field of atmospheric re-entry.The IXV mission objectives were the design, development, manufacturing, assembling and on-ground to in-flight verification of an autonomous European lifting and aerodynamically controlled reentry system, integrating critical re-entry technologies at system level. Among such critical technologies of interest, special attention was paid to aerodynamic and aerothermodynamics experimentation, including advanced instrumentation for aerothermodynamics phenomena investigations, thermal protections and hot-structures, guidance, navigation and flight control through combined jets and aerodynamic surfaces (i.e. flaps), in particular focusing on the technologies integration at system level for flight, successfully performed on February 11th, 2015.

Technology demonstration for reusable launchers

Reusable launchers have been studied under CNES contracts for more than 30 years, with early concepts such as STS-2000 or Oriflamme, more recently with very significant efforts devoted to Liquid Fly Back Boosters as with the Bargouzin project led with Tsniimash, TSTO with the Everest concept studied by Airbus-DS as prime contractor or the RFS Reusable First Stage concept of a large first stage associated to a cryotechnic second stage. These investigations, summarized in the first part of the paper, enabled CNES to identify clearly the technology requirements associated to reusability, as well as cost efficiency through detailed non-recurring costs and mission costs analysis. In parallel, CNES set in place development logic for sub-systems and equipment based on demonstrators, hardware test benches enabling maturation of technologies up to a TRL such that an actual development can be decided with limited risk. This philosophy has been applied so far to a large number of cases, such as TPTech and TPX for Hydrogen turbo pump, GGPX as demonstrator of innovative gas generator, HX demonstrator of modern cryotechnic upper stage with a dozen of different objectives (Thermal Protection, 20K Helium storage, measurements …). This virtuous approach, “learn as you test”, is currently applied in the phased approach towards scaled down reusable booster stage, whose possibility to be used as first stage of a microlaunch vehicle is under investigation. The selected technologies allow paving the way towards reusable booster stages for Ariane 6 evolutions or main reusable stage for a further generation of heavy launchers. The paper describes the logic behind this project, together with the demonstration objectives set for the various sub-systems as well as operations.

European company is developing reusable rocket launcher

European company is developing reusable rocket launcher

Preliminary Aerodynamic and Aerothermodynamic Assessment of the VTO Hopper Booster

Within the framework of the Future Launchers Preparatory Program, carried out by the European Space Agency, the VTO-Hopper reusable launcher is investigated. This concept is a winged sub orbital vehicle designed for vertical take-off with an expendable upper stage, able to deliver a payload up to 8 Mg in geostationary transfer orbit. After the staging, the reusable booster will re-enter the Earth's atmosphere, and then perform a downrange landing. In this paper the current design activities are described. The goal has been to define the preliminary booster aerodynamic and aerothermodynamic databases. Therefore, the aerothermal environment that the vehicle will encounter along its lifting reentry has been provided and analyzed. Different design approaches have been addressed. In fact, aerodynamic and aerothermodynamic analyses have been performed by using both engineering and numerical methods. For instance, a 3D Panel Methods code, typical for hypersonics, has been employed; the heat flux distributions have been evaluated by means of improved boundary layer methods. Increasing the order of complexity, a number of detailed 3D CFD analyses have been performed for different flight conditions along the descent trajectory. Results show that the aerodynamics and aerothermodynamics derived from engineering design approach are valid only for preliminary analysis purposes.

Propulsion vehicle integration for reusable launcher using in-flight oxygen collection

The use of in-flight oxygen collection has shown to significantly improve space launcher performance. The conceptual approach followed by Belgian teams working on oxygen collection has been to try to widening the available design margins in order to reduce the required technological leap and limit the economical risk associated with such a development. The aim of the ESA-funded theoretical and experimental study on an air separation device is to demonstrate the possibility of performing efficient air distillation in a compact rotating column. An integration of the vehicle, propulsion system and separation unit designs is presented. The objective is to optimise the overall vehicle performance while keeping technological difficulty and system complexity at a reasonable level. Reference vehicles are presented within their specific mission profiles with an emphasis on TSTO's. Different layouts of the internal energy and mass flowsheets have been studied and were compared in order to make best use of the refrigeration capacity of the hydrogen fuel running through the propulsion system during the first phase of the flight. In those flowsheets, the separator is considered as a classical distillation tray column. That analysis provides the requirements in terms of heat exchange capacity, compression ratios and number of so-called transfer units needed in the separator. The system is intentionally kept simple to limit complexity, but the analysis is thorough and accurate, including, for example, the effect of the presence of argon. Results for a supersonic carrier are presented. A compact separation unit has been designed in order to reach those requirements. That includes internals, practical building with estimates of pressure drops, separation performance and flow limitation. Main results are given, sizing of the separator bed is provided for a carrier plane showing that such on-board separator is indeed practical.

Project of Ariane 5 LV family advancement by use of reusable fly-back boosters (named “Bargouzine”)

Abstract The paper concerns possible concept variants of a partially reusable Heavy-Lift Launch Vehicle derived from the advanced basic launcher (Ariane-2010) by means of substitution of the EAP Solid Rocket Boosters for a Reusable Starting Stage consisting two Liquid-propellant Reusable Fly-Back Boosters called “Bargouzin”. This paper describes the status of the presently studied RFBB concepts during its three phases. The first project phase was dedicated to feasibility expertise of liquid-rocket reusable fly-back boosters (“Baikal” type) utilization for heavy-lift space launch vehicle. The design features and main conclusions are presented. The second phase has been performed with the purpose of selection of preferable concept among the alternative ones for the future Ariane LV modernization by using RFBB instead of EAP Boosters. The main requirements, logic of work, possible configuration and conclusion are presented. Initial aerodynamic, ballistic, thermoloading, dynamic loading, trade-off and comparison analysis have been performed on these concepts. The third phase consists in performing a more detailed expertise of the chosen LV concept. This part summarizes some of the more detailed results related to flight performance, system mass, thermoprotection system, aspects of technologies, ground complex modification, comparison analyses and conclusion.

EXPERT: An atmospheric re-entry test-bed

In recognition of the importance of an independent European access to the International Space Station (ISS) and in preparation for the future needs of exploration missions, ESA is conducting parallel activities to generate flight data using atmospheric re-entry test-beds and to identify vehicle design solutions for human and cargo transportation vehicles serving the ISS and beyond. The EXPERT (European eXPErimental Re-entry Test-bed) vehicle represents the major on-going development in the first class of activities. Its results may also benefit in due time scientific missions to planets with an atmosphere and future reusable launcher programmes. The objective of EXPERT is to provide a test-bed for the validation of aerothermodynamics models, codes and ground test facilities in a representative flight environment, to improve the understanding of issues related to analysis, testing and extrapolation to flight. The vehicle will be launched on a sub-orbital trajectory using a Volna missile. The EXPERT concept is based on a symmetrical re-entry capsule whose shape is composed of simple geometrical elements. The suborbital trajectory will reach 120 km altitude and a re-entry velocity of 5–6 km / s . The dimensions of the capsule are 1.6 m high and 1.3 m diameter; the overall mass is in the range of 250–350 kg , depending upon the mission parameters and the payload/instrumentation complement. A consistent number of scientific experiments are foreseen on-board, from innovative air data system to shock wave/boundary layer interaction, from sharp hot structures characterisation to natural and induced regime transition. Currently the project is approaching completion of the phase B, with Alenia Spazio leading the industrial team and CIRA coordinating the scientific payload development under ESA contract.

Overview of some optimal control methods adapted to expendable and reusable launch vehicle trajectories

Launcher trajectory optimization is a complex task, especially when considering the specific problems arising in the study of reusable launch vehicles. Part of the difficulty comes from the different characteristics of the trajectory arcs which make up the vehicle's mission (constraints and controls may not be the same). Another difficulty is the necessity, in some cases, of a global optimization between ascent and re-entry phases (branching optimisation). Finally, optimization tools devoted to this task should be polyvalent and robust, as the studies of reusable launch vehicles usually cover many different concepts, and also many different trajectory cases (such as abort scenarios). The purpose of this paper is to present different approaches used in France by CNES and ONERA to solve optimal control problems in the context of launcher trajectory optimization. These approaches, which are powerful implementations of classical optimization methods, were designed to cover the needs for both expendable and reusable launchers trajectory calculation. The first optimization tool presented is OPTAX, which uses an indirect shooting method. The second and third tools presented are CNES's ORAGE and ONERA's FLOP/OLGA, which use two different variants of the gradient method. The paper describes the equations and methodology behind these tools, and also presents their advantages and drawbacks.

Ceramic Matrix Composites Life Cycle Testing Under Reusable Launcher Environmental Conditions

This article focuses on the thermal protection system (TPS) and hot structures based on carbon fiber‐reinforced SiC (C/SiC) material, which protects the high thermal‐loaded areas and control surfaces of a reusable launch vehicle (RLV). The goal of the test program is the evaluation of the lifetime of different types of TPS under reusability aspects for RLV application, reflecting the re‐entry environments together with the effect of impacts from low‐speed impact, rain erosion, and hail core impact. The test results of the C/SiC samples with the self‐healing oxidation protection system showed very promising results concerning reusability and lifetime.

Technologies for thermal protection systems applied on re-usable launcher

The development of any future reusable launch vehicle (RLV) shall aim at a significant reduction of the payload transportation costs. One of the most expensive systems for any RLV is the thermal protection system (TPS), which protects the vehicle from the high thermal loads during re-entry. EADS ST is developing and qualifying TPS components and technologies for a wide range of applications and temperatures. As a part of the German National technology research programme ASTRA, these technologies were used for a TPS pre-design of the suborbital Hopper (Fig. 1) as a reference RLV system. On the basis of aerothermal re-entry loads determined by computational fluid dynamics methods, temperatures and heat loads during re-entry were determined for the entire vehicle. According to those findings, one or more possible TPS concepts were then pre-selected for the various vehicle areas according to the maximum temperatures. After the final selection (using trade-offs when necessary), a conservative estimate for expected TPS mass was established.

Future European launcher plans

The paper reports about the conclusions of a strategic reflection conducted within ESA in the field of reusable transportation strategy and it describes in particular the current lines of action for the development of future reusable launcher technologies. On-going relevant programmes are discussed and the plans for future complementary activities are given. Special emphasis is given to in-flight demonstration through the development of test beds and experimental vehicles. Possible benefits deriving from international co-operation in this field are discussed.

Space Hotels: Civil Engineering’s New Frontier

This paper reviews the prospects for the development of commercial hotels in space; it shows that it is increasingly accepted that this could become a lively new field of business within little more than a decade. The key enabler is the availability of low-cost access to space through the operation of reusable passenger-carrying launch vehicles, the development of which requires investment equal to no more than a few months worth of existing space budgets. When this becomes available, competition will lead to rapid development of progressively more exotic facilities in orbit as companies exploit the unique environment of space to provide guests with ever more popular services. Discussed are some of the civil engineering topics that will arise as orbital accommodation grows from assemblies of prefabricated modules to large structures assembled in orbit, including rotating structures offering “artificial gravity,” and eventually to buildings on the lunar surface.

Future launchers strategy : the ariane 2010 initiative

With the new cryogenic upper stage ESC, the European heavy launcher Ariane 5+ is perfectly suited to the space market envisioned for the coming decade: flexible to cope with any payload and commercially attractive despite a fierce competition. Current Arianespace projections for the following years 2010–2020 indicate two major trends: • satellites may still become larger and may require very different final orbits; today's market largely dominated by GEO may well evolve, influenced by LEO operations such as those linked to ISS or by constellations, • to remain competitive, the launch cost has to be reduced. The future generation of the European heavy launcher has therefore to focus on an ever increased flexibility with a drastic cost reduction. Two strategies are possible to achieve this double goal: • reusable launchers, either partially or totally, may ease the access to space, limiting costly expendable stages; the assessment of their technical feasibility and financial viability is undergoing in Europe under the Future Launchers Technology Program (FLTP), • expendable launchers, derived from the future Ariane 5+. This second way started by CNES at the end of year 1999 is called the “Ariane 2010 initiative”. The main objectives are simultaneously an increase of 25% in performance and a reduction of 30% in launch cost wrt Ariane 5+. To achieve these very ambitious goals, numerous major modifications are studied: • technical improvements : ◦ modifications of the Solid Rocket Boosters may consist in filament winding casing, increased loading, simplified casting, improved grain, simplified Thrust Vector Control, … ◦ evolution of the Vulcain engine leading to higher efficiency despite a simplified design, flow separation controlled nozzle extension, propellant management of the two cryogenic stages, ◦ simplified electrical system, ◦ increased standardization, for instance on flanged interfaces and manufacturing processes, • operational improvements such as launch cycle simplification and standardization of the coupled analyses, • organizational improvements such as a redistribution of responsibilities for the developments. All these modifications will of course not be implemented together; the aim is to have a coherent catalogue of improvements in order to enable future choices depending on effective requirements. These basic elements will also be considered for the development of other launchers, in the small or medium size range.

Numerically robust 3-D finite element Reynolds Averaged Navier-Stokes solver for the study of turbulent supersonic external flows

A 3-D finite element Reynolds Averaged Navier-Stokes solver for supersonic flows is presented and described. The solver has been developed to target industrial aerodynamics applications in the field of reusable launcher design and, therefore, specific emphasis has been put on maximizing numerical robustness. To achieve this goal, the turbulence model can be chosen beforehand between two options: a k-ε formulation or a combined algebraic/ k-ε scheme that gets the best characteristics out of both formulations. In addition, to ensure quick convergence in the early stages of the time-marching procedure, a theoretical analysis is performed to gather and implement into the algorithm the limiting behavior of k and ε wherever turbulent production is dominant. Results of the validation campaign are presented, a practical application case is shown, and finally, conclusions are drawn.

Seals research to boost rocket engines into the 21st century

The move towards reusable launcher vehicles, coupled with the need for increased payload in rocket powered space vehicles is driving rocket engine development to produce smaller and more durable turbopumps, operating at higher speeds and pressures. Seals in these future turbopumps, which supply high pressure liquid oxygen and hydrogen to the combustion nozzle, will be required to operate under more stringent conditions, whilst wearing less. This enormous design challenge, requiring improvements in seal materials and new seal design strategies, is the subject of a current consortium project using BHR Group's sealing expertise.

RAMS approach for reusable launch vehicle advanced studies

The emerging of reusable single stage to orbit concept as credible launchers in the turn of the century is changing some technical and technological approaches in the way of doing future launcher advanced studies. Among others (such as operations through the “aircraft-like operations” concept), the RAMS approach (reliability, availability, maintainability and safety) has to be implemented from the very beginning of a concept study, especially for the SSTOs ones in order to meet the “able” requirements (affordable, reusable, reliable, available and operable). Beyond the “traditional” considerations applied to expendable launchers and/or man rated space transportation systems, the RAMS involvement in reusable launcher advanced studies and concept trade-offs must allow to perform the best balance between costs, performance and related risks. For instance, in the framework of SSTOs key technologies identification studies performed at Aerospatiale, the RAMS have been involved from the beginning of the preliminary design task. This approach has shown that the assessment of the main propulsion failure risks and associated probabilities of occurrence have strongly affected the vehicle design within the mission management and technical aspects such as main propulsion specifications, ascent trajectory shaping and landing phase scenario (VTOVL configuration). This paper intends to describe this RAMS approach and addresses how it has been applied on trade-off on VTOVL concept.

Efficiency analysis of reusable aerospace launchers

An efficiency analysis of basic types of reusable aerospace launchers is made. The criteria used are the ratio of payload mass to launch mass of the vehicle as well as the ratio of mechanical energy acquired by the payload to fuel chemical energy. The second criterion correlates well with payload launch cost as it is followed from estimates performed. It is shown that two-stage aerospace planes with a high stage-separation speed ( M = 12–12.5), which incorporate novel technologies based on using aerothermodynamic properties of hypersonic flow, are several times more effective than other known reusable launchers. In addition, such vehicles may ensure qualitatively higher flexibility of the space transportation system permitting offset launches to be performed with flight ranges of 3000–6500 km. Single-stage aerospace planes of the comparable technological level cannot be created at all.