野中 聡

In ISAS/JAXA, a fully reusable sounding rocket is proposed as one step for the future full-fledged reusable transportation system. This vehicle aims to be low in cost and to be high frequency of experimental opportunities by its reusability. The enlargement of the flight profile flexibility could acquire the high qualities of the experimental conditions. This vehicle is a fully reusable vertical take-off and vertical landing (VTVL) rocket vehicle. And this has the capability of ballistic flight to the altitude over 120 km and returning to the launch site. In me flight sequence, the vehicle takes off vertically and cuts main engine off about 100 seconds later, and reaches to an altitude about 120 km during the ballistic flight. After that, the vehicle entries into atmosphere and decelerated by aero braking, and vertically lands to the launch place. In landing phase, this vehicle makes a turnover maneuver from a nose-first entry attitude. This makes it possible to achieve the deceleration and soft landing by its main engine thrust. As for the inversion maneuver of the vertical landing vehicle, the aerodynamic turnover maneuver is considered. After turnover maneuver, control torque of a reaction control system (RCS) stabilizes the vehicle in a tail-first attitude before a re-ignition of main engines. To verify the turnover maneuver capability, it is considered to demonstrate the glide tests using the small sized vehicle model. In this demonstration, the technical problems for the turnover maneuver as for the vehicle dynamics and guidance control strategy will be investigated and the guidance and control method will be modified for the practical use to achieve the system requirements. In mis paper, the turnover maneuver control for the nose first entry of the vehicle is numerically simulated and then the guidance strategy for the vehicle is considered. It is important for the guidance that the vehicle attitude could be stabilized after the turnover maneuver. By the given moment torque of the RCS, it is needed for the vehicle to maintain the attitude at 180 degree of angle of attack.

For the prediction of heat transfer coupled with sloshing phenomena in the propellant tanks of reusable launch vehicle, the pressure drop induced by heat transfer and the dynamic motion of liquid in sub-scale vessels were experimentally observed and numerically investigated. The correlation between the pressure drop and liquid motion was confirmed in the experiment. The mechanisms enhancing heat transfer were discussed based on the computation. It was suggested that splash and wavy surface induced by violent motion of liquid cause the pressure drop in the closed vessel. In addition, as the preliminary investigation, non-isothermal sloshing of liquid nitrogen and liquid hydrogen were successfully visualized and pressure drop depending on the gaseous species was discussed. © 2011 by Takehiro Himeno.

The measurement of density distribution over a hemisphere in ballistic range was investigated. The finite fringes were created over a hemispherical model by double-exposure finite fringe holographic interferometry. Holographic interferometry was used for the measurement of density distribution over a 15-mm-nose-radius hemisphere. A pair of paraboloidal mirrors of 300 mm in diameter and 3 m in focal length was used to collimate the object beam. The reference beam was expanded by a plane-concave lens and collimated to illustrate a holographic film. The intersection angle between the object and reference beam was shifted by tilting the collimating lens of reference beam in finite fringe holographic interferometry. The fringe shift could be seen across the bow shock wave. The optical path length through the shock layer was nearly zero immediately behind the shock, and it continuously increased with distance toward downstream.

A fully reusable sounding rocket is proposed in ISAS/JAXA. Vehicle systems and ground / flight operations are conceptually designed for observations of atmospheric phenomena, micro-gravity experiments and so on. The present design of the reusable sounding rocket is summarized. In phase A in the proposed reusable sounding rocket project, technical demonstrations for key technologies to develop the reusable sounding rocket are planed as follows; 1) reusable engine development and repeated engine operation development, 2) reusable insulation development for cryogenic tank, 3) aerodynamic design and flight demonstration for returning flight, 4) fuel/oxidizer management demonstration, 5) landing gear development and 6) health management system construction.

ISAS activities for reusable rocket technology and architecture including flight demonstration by the RVT (Reusable Vehicle Testing) have shown various progresses in technical areas such as frequent-flight propulsion systems, reusable rocket engines, returning flight and vertical landing techniques and demonstrations, composite cryogenic LH2 tank studies, new architectures for reusable and repeated flights with quick turnaround and so on. Following these basic studies of reusable rocket, mission definition and system requirement synthesis of the reusable sounding rocket are completed. In addition to the technical and performance related issues, its operational aspects and requirements for the frequent and repeated flight were given stressed. Throughout the studies, technical readiness to the reusable rocket technique and for the system synthesis for the reusable sounding rocket vehicle are in progress. For the sounding rocket's system definition and requirement analysis, research of the flight demand such as the number-of-flight per year and its frequency by the potential user communities. These requirements are from the needs of the middle to upper atmosphere research, studies from micro-gravity community, engineering community which may use this repeated flight opportunity. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

This paper includes the concept of polymer-lined composite tank, design method, and verification results of prototype tanks. At first the outline of polymer-lined composite tank, their benefits, and overview of fabrication process are shown. This also includes a comparison with the previously developed metal-lined composite tank. Next, the design method based on not only stress and strain but fracture mechanics is shown. Fracture-mechanical evaluation is important to prevent delamination of composite or exfoliation of metal parts. Some example of choice for metal material is also shown. At last the results of the tests for three prototype tanks and other trial tanks are shown. Their failure modes are evaluated and prevent method for each failure is described. As the final result, the third prototype tank passed a proof pressurized test and repeated pressurized tests for MEOP. The test data were fine and any delamination, exfoliation or H2 gas leak was never detected. This concludes the completion of polymer-lined composite liquid hydrogen tank for Reusable Vehicle Test. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

For the prediction of heat transfer coupled with sloshing phenomena in the propellant tanks of reusable launch vehicle, the pressure drop induced by heat transfer and the dynamic motion of liquid in sub-scale vessels were experimentally observed and numerically investigated. The correlation between the pressure drop and liquid motion was confirmed in the experiment. The mechanisms enhancing heat transfer were discussed based on the computation. It was suggested that shear flow and vortices induced by violent motion of liquid was suggested to cause the pressure drop in the closed vessel. In addition, as the preliminary investigation, the heat transfer and phase change between gaseous and liquid phase enhanced by violent sloshing were tried to be simulated. © 2009 by the American Institute of Aeronautics and Astronautics, Inc.

In ISAS/JAXA, a fully reusable sounding rocket is proposed as one step for the future full-fledged reusable transportation system. This vehicle aims to be low in cost and to be high frequency of experimental opportunities by its reusability. This vehicle is a fully reusable vertical take-off and vertical landing (VTVL) rocket vehicle. In landing phase, this vehicle makes a turnover maneuver from a nose-first entry attitude. This makes it possible to achieve the deceleration and soft landing by its main engine thrust. In this study, as for the inversion maneuver of the vertical landing vehicle, the aerodynamic turnover maneuver is considered. And the turnover maneuver for the nose first entry of the vehicle is numerically simulated and then the guidance strategy for the vehicle is considered.

The third-generation vehicle RVT#3 equipped with a pressure-fed engine, which had upgraded in terms of durability enhancement and a LH₂ tank of composite material, successfully performed in repeated flight operation tests; and the vehicle reached its maximum flying altitude of 42m in October 2003. The next step for demonstrating entire sequence of full-scale operation is to put a turbopump-fed system into propulsion system. From a result of primary system analysis, we decided to build an expander-cycle engine by diverting a pair of turbopumps, which had built for another research program, to the present study. A combustion chamber with long cylindrical portion adapted to the engine cycle was also newly made. Two captive firing tests have been conducted with two different thrust control methods, following the component tests of combustor and turbopumps separately conducted. A considerable technical issues recognized in the tests were the robustness enhancement of shaft seal design, the adjustment of shaft stiffness, and start-up operation adapted to the specific engine system. Experimental study of GOX/GH₂ RCS thrusters have also been started as a part of a conceptual study of the integration of the propulsion system associated with simplification and reliability improvement of the vehicle system.

A fully reusable sounding rocket is proposed in ISAS/JAXA. Vehicle systems and ground/flight operations are designed for observations of atmospheric phenomena, micro-gravity experiments and so on. In the present design of the reusable sounding rocket, the vehicle carries a 100kg payload up to 120km altitude. The turnaround time for one flight is less than 24 hours (1 day). In the typical ballistic-flight up to 120km, the total flight time is about 600sec. Maximum Mach number is about 4, and the flight condition of Mach number below 1.0 (subsonic speed) is kept for about 70sec over 110km altitude. In this subsonic flight, the observed atmosphere around the vehicle is not affected by the shock wave. This is desirable for the atmospheric observation. Maximum acceleration in the flight is about 4G in ascent and 7G in descent. For the micro-gravity experiments, the flight environments of acceleration less than 10(-3)G, 10(-4)G and 10(-5)G is able to be made for about 180, 150 and 120sec, respectively.

This paper includes everything which is necessary to make a polymer-lined cryogenic composite tank, i.e. concept, design method, manufacturing process, and recent results of tests. They are also the history of development of the tank in our Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS/JAXA). At first the concept and production method of the tank is explained. In the production process it is the key that whole liner is formed at one time by use of heat melt bonding. Next the design method based on fracture mechanics is derived. Here an analytical solution of energy release rate for the bonding structure is formulated by considering difference in strain energies in tension and bending before and after crack growth based on a simplified mathematical model. In addition to this derivation, comparison with numerical results and one design optimization sample are also shown. After that the results of tests for actual tank is shown and current status of the tank is discussed. At last conclusion is shown.

The nonequilibrium flow around the hemispherical bodies are calculated by using the statistical physical-chemical model. The model, based on physical analysis, takes on account the vibration chemistry interaction, and so on. A more detailed description of the freestream nozzle flow in front of the body could also be used to calculate the flow. The computed results are satisfactory in comparison with the experimental data obtained in gun and shock tunnels, thus validating the physical model used in the computations.

A fully reusable rocket vehicle is proposed as a sounding rocket for observations of atmospheric phenomena, micro-gravity experiments and so on. Vehicle systems and ground / flight operations are designed for such science observations. For the development of the reusable rocket, a small test vehicle was built and flight-tested. This Reusable Vehicle Testing (RVT) lessons campaign provide repeated experiences of turnaround operations and vertical take-off and landing flights. In the present design of the reusable sounding rocket, the total length and maximum diameter of the vehicle is about 10m and 3m, respectively. The vehicle is propelled by the propulsion system composed of four liquid hydrogen / liquid oxygen engines. The weight of a payload carried to 120 km altitude is 100kg in the nose-fairing. The instrument for observations can be reused because of the repeated flight. The turnaround time for one flight is less than 24 hours (1 day). In the typical ballistic flight up to 120 km, the flight environments under 10-5G acceleration is able to be made for about 120 sec. The flight Mach number can be subsonic around the summit in the trajectory. These properties of reusable sounding rocket are expected to be useful and effective for many science missions.

For the prediction of sloshing phenomena in the propellant tanks of reusable launch vehicle, the preliminary investigations were conducted in laboratory scale. The dynamic behavior of liquid propellant during the flight of the vehicle was experimentally reproduced with the sub-scale model. The lateral acceleration was provided with a mechanical exciter and the motion of liquid surface in the vessel was recorded with a high-speed camera. The sloshing was also simulated with the originally developed CFD code, called CIP-LSM. The important features of surface deformation and wave breaking were successfully reproduced in the computation.