Reusable Launch System Research Articles

Comparative analysis of European vertical landing reusable first stage concepts

AbstractReusable launch systems have the potential to significantly impact the space launch service market if both a high reliability and low refurbishment costs can be achieved. This study delves into the Vertical Takeoff and Vertical Landing (VTVL) methodology, as currently employed by SpaceX, and forms a segment of the ENTRAIN study by DLR. This broader study encompasses an examination of both Vertical Takeoff Horizontal Landing (VTHL) and VTVL reusable first stages, exploring their performance across high-level design parameters. This manuscript’s primary objective is to assess the quantitative impact of high-level design factors on launch vehicle performance, particularly in relation to the development of a future European reusable launch system featuring a VTVL first stage. For a two-stage vehicle with a payload performance of 7.5t into GTO, the effect of varying propellant combinations, staging velocities and engine cycles are assessed. The study encompasses an iterative, multidisciplinary analysis and sizing process for ten different configurations. Each design iteration not only entails a structural design analysis but also includes optimization of the ascent and descent trajectories. Finally, the developed vehicle concepts are compared to derive quantitative insights into the trade-offs associated with key design choices.

Feasible options for point-to-point passenger transport with rocket propelled reusable launch vehicles

For the first time in spaceflight history the flight of a fully reusable launch system with rocket propulsion appears possible within the next couple of years. Apart from the implications for the orbital launch market, a fully reusable system could also enable an entirely new class of commercial point-to-point transport on Earth. Rocket propelled point-to-point systems promise the ability to transport passengers or cargo to any suitable landing site on Earth with extremely short travel times (typically less than 90 min). In this study the primary focus is on DLR-SART's SpaceLiner 7 vehicle concept with an initial comparison to Starship, currently being developed by SpaceX.The trajectories are identified using multi-objective optimization with evolutionary algorithms. These allow the identification of a solution space with regard to multiple objectives, in this case minimal overflight of populated areas and minimal peak heat flux, while still respecting other constraints (e.g. structural loads). The population disturbance is computed by using a global population density database and integrating the number of people along the flight track. Ideally, the solution space consists of a pareto-front which correlates to the most optimal solutions possible for all objectives.The mission analysis identifies various feasible trajectories around the world. Primarily, these routes are going along less populated areas such as the oceans and the polar regions. Especially the latter enable large longitudinal changes during the flight and consequently connecting distant places on Earth. The critical routes are large longitudinal crossings around the equator where land masses must be overflown. These shall be reconsidered and/or improved in the future.Comparing SpaceLiner to Starship, it is found that the mission profiles vary significantly. While SpaceLiner uses its high lift-to-drag ratio in the higher atmosphere to manoeuvre around large land masses, Starship can only follow the direct route. In contrast, Starship flies higher into space and thereby might avoid having large population disturbances on ground. Only the re-entry and landing are critical as it does not have significant cross range capability. As a design option for the next iteration of the SpaceLiner development, SpaceLiner 8, it is planned to assess the possibility of using a smaller wing to follow a similar coast through space like Starship and have a steep re-entry at the end of the flight instead of a prolonged glide.

Mission design for point-to-point passenger transport with reusable launch vehicles

With the progress of SpaceX’s Starship system, a fully reusable launch system appears possible in the near future. With this technological advance, a new class of transport missions could become economically feasible: Rocket-propelled transport of passengers and cargo at near-orbital speeds from one point on the Earth to another. This mission type is investigated for two reference vehicles: Starship from SpaceX and the SpaceLiner concept, developed by DLR-SART. For both vehicles, the properties during reentry are assessed and the impact on the descent trajectory is investigated, including parametric studies with regard to the effect of launch heading and crossrange capability. While the SpaceLiner upper stage relies on its high hypersonic L/D to cover the majority of the distance in quasi-stationary flight within the atmosphere, the Starship relies mostly on a ballistic flight path at higher altitudes. The flight within the upper layers of the atmosphere allows the SpaceLiner to change its heading mid-flight through banking maneuvers and thus efficiently curve around populated areas. However, this prolonged flight at high velocities within the upper atmosphere does necessitate active cooling of the leading edges. An exemplary mission from Shanghai to California is optimized for both reference vehicles, with the optimization target being minimal peak heat loads. Due to the Starship’s reliance on the ballistic portion of its flight to cover range, the peak heat flux is substantially higher on westward missions, compared to the eastward return flight.

Numerical simulation of gas flow in nozzle channels with a central body

The development of a reusable launch system is one of the most promising directions in the development of cosmonautics. World rocket companies are striving to create a space vehicle with improved tactical and technical characteristics. The main task is to ensure the most efficient flight mode of the reusable spacecraft from the point of view of the full load of the injection system. Since the main costs are spent on transporting the fuel of the rocket and its own design, the developers strive to fully load such a system not only when sending into orbit, but also when returning back. The implementation of the idea of a reusable spacecraft entails large energy losses, which suggests the idea of creating a single-stage reusable launch system.

A phased approach to orbital public access

The most significant problem with the creation of any viable space passenger business is the “investment trap”; that is the large size and long duration of the initial investment needed to acquire the infrastructure required by the business (launch vehicles, etc.) mean the commercial operations can never generate sufficient revenues, fast enough, to repay the investment and make a profit. This problem is greatly exacerbated by the need to achieve demonstrated levels of safety suitable for public use. The only strategy to overcome the investment trap is to exploit an existing infrastructure developed for the general space business. To illustrate this, a feasibility study of a Personnel Module for the Skylon reusable launch system is outlined. This Personnel Module has two versions, an Initial Configuration suitable for support of the ISS and a Final Configuration with passenger seat prices and levels of safety suitable for support of post-ISS space stations with public access as their main activity.

A Concept of Vertical Takeoff Two-Stage-to-Orbit Reusable Launch Vehicle with an Integral-Rocket-Ramjet Booster

AbstractReusable launch vehicles (RLV) currently envisioned incorporate a wide variety of propulsion types. Various propulsion devices have been designed, or are being designed. The Integral-Rocket-Ramjet (IRR) propulsion mainly applies to a tactical missile boost system and few have mentioned this system in RLV design. According to the technological ability of Taiwan and a feasibility study, it shows that the present reusable launch system can exploit the potential benefit of IRR propulsion for the RLV system. A conceptual study of an unmanned two-stage-to-orbit (TSTO) launch vehicle is designed in this paper. The first stage of the vehicle is reusable with IRR engines. The second stage is expendable and rocket powered. The assumed mission is designed to insert a 100kg payload into a low earth circular orbit at various inclination angles. The calculations are made for the case where the TSTO system is used in Taiwan. The fundamentals of launch vehicle design are examined using simplified two-stage performance equations. Launch vehicle design is optimized when the performance and programmatic drivers are balanced. There is an acceptable set of launch and landing sites on islands off the coast of Taiwan.

RLV Hopper: Consolidated system concept

The Hopper, a concept for a reusable launch system was developed and found attractive in the frame of FESTIP, ESA's Furure European Space Transportation Initiation Programme Later, in the national German ASTRA programme this concept was adapted to newly emerged requirement and subjected to a detailed design loop. Taking off horizontally and staging at high sub-orbital velocity, the Hopper needs a rail-guided launch sled, downrange landing, re-transportation back to the launch site, and one, but only one upper stage. Horizontal take-off is used to improve safety and to reduce thrust requirement, and number, mass, and cost of main engines, and also problems with vehicle centering. Transportang of the cargo (e.g.) payload and expendable upper stage) in the RLV results in only one aerodynamically affected flight configuration. Staging at high sub-orbital velocity above the sensible atmosphere enables the use of only one standardised upper stage for all missions. Using a cryogenic upper stage the Hopper system is nearly optimally staged for the dimensioning GTO mission. The paper describes the consolidated unmaanned RLV concept and highlights areas of special interest, evolution potential, and further steps.

3316 再使用型 CAMUI ハイブリッドロケットの打上げ・回収試験

To develop a reusable launch system, development study of jet-impinging hybrid rocket has been made. To prove a reliability and safety of a launch-recover system with jet-impinging hybrid rocket motor, a ballistic launch test of CAMUI (Cascaded Multistage Impinging-jet)-02 was performed on a January 13,2003 at TAIKI Hokkaido. The CAMUI-02 went up stably and reached about 500m in altitude. the rocket was recovered safely by parachute. These results prove reliability and safety of the launch-recover system with CAMUI hybrid rocket.

Development costs of reusable launch vehicles

The paper deals first with the definition and understanding of “Development Costs” in general. Usually there is large difference between initial “development cost guesses”, “Proposal Cost Estimations” and the final “Cost-to-Completion”. The reasons for the usual development cost increases during development are discussed. The second part discusses the range of historic launch systems' development costs under “Business-as-Usual” (BaU) - Conditions and potential cost reductions for future developments of RLVs, as well as the comparison to commercial, industrial development cost. Part three covers the potential reduction of development cost by application of “Cost Engineering Principles”. An example of the large potential cost range (between 6 and 17 Billion USD) for the development of the same winged rocket-propelled SSTO launch vehicle concept is presented. Finally the tremendous development cost differences are shown which exist for the different potential Reusable Launch System Options which are under discussion. There remains an unresolved problem between the primary goals of the national space agencies with emphasis on new technology development/national prestige and the commercial market requirement of a simple low-cost RLV-System.

Editorial

The Hopper, a concept for a reusable launch system was developed and found attractive in the frame of FESTIP, ESA's Furure European Space Transportation Initiation Programme Later, in the national German ASTRA programme this concept was adapted to newly emerged requirement and subjected to a detailed design loop. Taking off horizontally and staging at high sub-orbital velocity, the Hopper needs a rail-guided launch sled, downrange landing, re-transportation back to the launch site, and one, but only one upper stage. Horizontal take-off is used to improve safety and to reduce thrust requirement, and number, mass, and cost of main engines, and also problems with vehicle centering. Transportang of the cargo (e.g.) payload and expendable upper stage) in the RLV results in only one aerodynamically affected flight configuration. Staging at high sub-orbital velocity above the sensible atmosphere enables the use of only one standardised upper stage for all missions. Using a cryogenic upper stage the Hopper system is nearly optimally staged for the dimensioning GTO mission. The paper describes the consolidated unmaanned RLV concept and highlights areas of special interest, evolution potential, and further steps.

Cost analysis for single-stage (SSTO) reusable ballistic launch vehicles

The ballistic SSTO Vehicle seems to be the prime candidate for a future reusable launch system for medium-size cargo due to its inherent technical and operational simplicity by limiting the number of stages to just one, and by using conventional rocket propulsion. Based on the MBB vehicle studies from 1969/70 and 1986 (BETA II) and taking into account requirements of the recent SDIO-Contract (“Delta Clipper”) a cost and cost driver analysis is presented using the TRANSCOST Model. First, the potential development cost for ballistic SSTO vehicles in the range of 200 to 1000 tons propellant mass are presented and the main influencal parameters - including the so-called “non-technical” factors - are discussed. The results are compared with actual total development cost of other launch systems. Then the potential ground and flight operations cost are discussed, based on the proposed “Standardized Launch Cost Definition (SLC, Level I, Level II Cost). In this case especially the impact of annual launch frequency on the cost per launch is shown, and the expected specific transportation cost compared with the present values of expendable launchers. A substantial cost reduction is to be expected, even under non-optimistic assumptions.