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Future Space Technologies
Published in Mohammad Razani, Commercial Space Technologies and Applications, 2018
By definition a single-stage-to-orbit (SSTO) vehicle reaches orbit from the surface of a body without jettisoning hardware, expending only propellants and fluids. The term often refers to reusable vehicles. Although no Earth-launched SSTO launch vehicles have ever been constructed, it is an interesting technology that has attracted a lot of attention recently. Several research spacecraft have been designed or constructed, including Skylon, the DC-X, the X-33, and the Roton SSTO. One major obstacle in the successful launch to orbit by SSTO is problems with finding the most efficient propulsion system. SSTO has been achieved from the Moon by the Apollo program’s lunar module and several robotic spacecraft of the Soviet Luna program. Having less gravity and almost no atmosphere makes this much easier than from Earth. Figure 4.7 shows the VentureStar which was a proposed SSTO spaceplane, and Figure 4.8 shows VentureStar compared with the space shuttle.
Future Space Technologies
Published in Mohammad Razani, Information, Communication, and Space Technology, 2017
By definition a single-stage-to-orbit (SSTO) vehicle reaches orbit from the surface of a body without jettisoning hardware, expending only propellants and fluids. The term often refers to reusable vehicles. Although no Earth-launched SSTO launch vehicles have ever been constructed, it is an interesting technology that has attracted a lot of attention recently. Several research spacecraft have been designed or constructed, including Skylon, the DC-X, the X-33, and the Roton SSTO. One major obstacle in the successful launch to orbit by SSTO is problems with finding the most efficient propulsion system. SSTO has been achieved from the Moon by the Apollo program’s lunar module and several robotic spacecraft of the Soviet Luna program. Having less gravity and almost no atmosphere makes this much easier than from Earth. Figure 5.7 shows the VentureStar which was a proposed SSTO spaceplane, and Figure 5.8 shows VentureStar compared with the space shuttle.
Defense Information, Communication, and Space Technology
Published in Anna M. Doro-on, Handbook of Systems Engineering and Risk Management in Control Systems, Communication, Space Technology, Missile, Security and Defense Operations, 2023
The attractiveness of a single-stage-to-orbit (SSTO) vehicle that could function like a conventional winged aircraft and thereby eliminate the need for a vertical launch complex is self-evident (Billig 1990). The feasibility of building and operating such a vehicle, however, must be established (Billig 1990). Many formidable challenges must be overcome. In the early phases of a program structured to address these challenges, techniques will be needed to (Billig 1990) (1) expedite the identification of suitable candidate conceptual designs, including the choice of the propulsion system; (2) identify the key technical issues and provide a means for assessing their relative importance; and (3) provide a disciplined procedure to permit a continual assessment of feasibility. The capability of single-stage and multistage rockets can be concisely explained by addressing certain definitions. In general, the overall mass of the rocket stage is the mass of the payload, ML, and usually the smallest value. The mass provides the payload the intended motion, which divided into two quantities; the propellant mass, Mp, and structural mass, Ms. Except when particularly specified, the structural mass is equal to all mass including engine, control and guidance systems, tankage, and supporting structures excluding payload and propellant. The initial mass M0 is expressed as: M0=ML+Mp+Ms
Computational investigation of cooling effectiveness for film cooled dual-bell exhaust nozzle for LO2/LH2 liquid rocket engines
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Martin Raju, Abhilash Suryan, David Šimurda
Single stage to orbit (SSTO) rocket engines can improve the performance with altitude compensation. Therefore, altitude compensating nozzles are of great research interest. Dual bell nozzle (DBN) achieves altitude compensation with its distinct modes of operation at low and high altitudes. There is an area ratio limitation in conventional nozzles for avoiding separation of flow at sea level operation. This constraint leads to under-expanded flow at high altitude operation, and hence non optimized high altitude performance (Horn and Fisher, 1994) . DBN combines a couple of bell nozzles, base nozzle and an extension nozzle, with different geometric area ratios which are attached at a point called inflection. Performance improvement is achieved by the flow phenomena within: flow being attached to walls of base nozzle during the initial phase of operation and to extension nozzle walls at higher altitudes (Cowles et al., 1949).
Control variable parameterisation with penalty approach for hypersonic vehicle reentry optimisation
Published in International Journal of Control, 2019
Ping Liu, Xinggao Liu, Ping Wang, Guodong Li, Long Xiao, Jie Yan, Zhang Ren
Generally, hypersonic vehicle trajectory optimisation can be described as optimal control problems (OCPs) with nonlinear dynamics, nonlinear path constraints and terminal limitations (Dong & Cai, 2017). For instance, the reentry trajectory optimisation for unmanned single-stage-to-orbit (SSTO) vehicle (Pescetelli, Minisci, & Brown, 2013), minimum-fuel ascent of a hypersonic vehicle (Dalle, Torrez, Driscoll, Bolender, & Bowcutt, 2014) and rapid trajectory optimisation for hypersonic missions (Grant & Braun, 2015). To solve these OCPs, direct methods and indirect methods are usually considered. Indirect methods, inspired by the principle of variational calculus, are based on Pontryagin's Maximum Principle to solve OCPs via defining the co-state variables in addition to state variables and solving for a two-point boundary value problem (TPBVP). Alternatively, direct methods transform the OCP into a nonlinear programming (NLP) problem by two strategies: complete parameterisation (CP) and control variable parameterisation (CVP) (Biegler, Cervantes, & Wächter, 2002; Loxton, Lin, Rehbock, & Teo, 2012; Vassiliadis, Canto, & Banga, 1999), then the optimisation results are obtained by solving the NLP problem. Compared with indirect methods, direct methods are less costly and there is no requirement to set up and solve a multipoint boundary value problem associated with Pontryagin's Maximum Principle (Hadiyanto, Esveld, Boom, Van Straten, & Van Boxtel, 2008). Consequently, direct methods are more popular for solving trajectory opitmisation problems in aerospace (Darby, Hager, & Rao, 2011; Palumbo, Morani, & Cicala, 2017; Zhang, Sun, & Duan, 2010). Furthermore, considering that the state trajectories obtained by CVP method are very precise and the dimension of the NLP problem in CP is greater than that in CVP (Liu & Liu, 2017), this paper focuses on CVP method.