We conducted various sorts of multiple classification analysis concerning CubeSats primarily developed by universities, based on information published on papers and websites. Single regression analysis led to a future forecast of the numbers of CubeSat launches, and logistic regression analysis predicted accomplishment probability of minimum and full success levels by CubeSats being launched on 2011. Furthermore, we clarified positions of the experienced countries of CubeSat launches, and indicated the direction they should progress for their developments. Thus, we here propose information sharing and collaborative development for beneficial change of CubeSat's success rate.
The space transportation system will need advanced abort systems to secure crew against serious accidents. Here this study deals with the capsule-type space transportation systems with a Launch Abort System (LAS). This system is composed of a conic capsule as a Launch Abort Vehicle (LAV) and a cylindrical rocket as a Service Module (SM), and the capsule is moved away from the rocket by supersonic aerodynamic interactions in an emergency. We propose a method to improve the performance of the LAV by installing fences at the edges of surfaces on the rocket and capsule sides. Their effects were investigated by experimental measurements and numerical simulations. Experimental results show that the fences on the rocket and capsule surfaces increase the aerodynamic thrust force on the capsule by 70% in a certain clearance between the capsule and rocket. Computational results show the detailed flow fields where the centripetal flow near the surface on the rocket side is induced by the fence on the rocket side and the centrifugal flow near the surface on the capsule side is blocked by the fence on the capsule side. These results can confirm favorable effects of the fences on the performance of the LAS.
In this paper, a variable fidelity Kriging model approach is applied to aerodynamic data modeling and uncertainty quantification of 2D airfoil aerodynamic performances. This approach enables to construct an accurate surrogate model efficiently by utilizing high and low fidelity function information simultaneously. The low fidelity functions are defined by utilizing coarser computational meshes in this research. The uncertainty quantification is executed by Monte-Carlo simulation on the surrogate model, which is often referred to as Inexpensive Monte-Carlo simulation approach. The developed uncertainty quantification approach showed comparable accuracy with full non-linear Monte-Carlo simulation results and was executed with much lower computational cost.
Light-weight thin plate structure is expected to play an important role in space development in the near future. Thin film solar array, solar sail, planar antenna, and inflatable structure are the typical examples. We have carried out hyper-velocity impact experiments on thin plate targets using a light gas gun, to study propagation of the impact plasma associated with an interference with electrical parts on the planar plate. Propagation of the luminous cloud and generated plasma were observed by a high-speed video camera and an array of plasma probes, respectively. It was found there existed a high-dense plasma propagating along the surface of the plate at a high-speed more than the projectile velocity. The characteristic behaviors of the plasma propagation were explained by the half-range Maxwellian plasma uniformly ejected from the collision area.
The authors developed a method to produce nonequilibrium plasma by dielectric barrier discharge (DBD) in supersonic flow and investigated the possibility for using it as an ignition enhancement technique in a high speed engine, such as a scramjet engine. The discharge characteristics were investigated by varying applied voltage and the flow Mach number. It was revealed from direct photographs that the discharges got stronger and the volume got larger as flow Mach number increased. Estimated discharge power indicated that nonequilibrium plasma could be generated by considerably small energy in comparison with thermal plasma such as a plasma jet torch, which is a typical thermal plasma. The emissions from several excited molecules and atoms were confirmed by spectroscopic measurement of the plasma. Ignition delay analysis revealed that the effect of ozone (O3) addition to shorten the ignition delay time of mixture is almost equal to those of O or H radicals.
Convective heat transfer characteristics of paramagnetic air induced by magnetic force in a non-gravitational field are scrutinized by two-dimensional numerical computations. In the present research, a shallow cylindrical enclosure filled by paramagnetic air is assumed to be placed inside the bore space of a superconducting magnet. Our numerical results find out that the strength of magnetothermal convection induced by magnetic force in quiescent air under thermal conduction state strongly depends on the relative positions of the enclosure and magnetic center, and the oscillatory magnetothermal convection with regular period and amplitude is generated when the enclosure is placed near the magnetic center. These phenomena can be successfully explained by considering the magnetic susceptibility of paramagnetic substance according to Curie's law. In addition, effect of the magnetic force in a gravitational field is also evaluated by examining magnetothermal convection induced by magnetic force in density stratified air.
This paper reports a wind-tunnel experiment and analysis that have been conducted under the National Experimental Airplane for Supersonic Transports (NEXST-1) project of JAXA. In order to perform the flight experiment, the design of the vehicle was examined from the stand point of aeroelasticity. The aileron buzz as well as flutter was of much concern for its aileron system on the main wing. Therefore, both wind-tunnel test and analysis were carried out by using a semi-span model with fuselage. Although the buzz was not observed in the test, damping responses of the aileron rotation mode were obtained. Critical damping was observed in supersonic flow, that meant a buzz could occur in ``region C'' of Lambourne's classification. Linear unsteady aerodynamic analysis is applicable to this type of buzz and the characteristics of the buzz of the model is discussed.