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“ASKA” developed by National Aerospace Laboratory (NAL) is a quiet, short take-off and landing (QSTOL) research aircraft adopting upper surface blowing (USB) concept as a powered high lift system. To achieving sufficient STOL performance by augmenting stall angle of attack and roll control power, blowing BLC technique was applied to the outboard leading edges and ailerons.Supplied high pressure air to save the BLC piping space,the BLC system which was fit for use of high pressure air was developed. The BLC system, in which BLC air is discharged by a series of discrete jets from small drilled holes (0.8 ∼ 3.0 mm in diameter) arranged in a raw, is one of the unique features of the aircraft. In this paper, the summaries of aerodynamic development of the BLC system are described except for the air piping system.

Forward swept wing (FSW) is known to have excellent performance relative to aft swept wing. The practical application, however, has been limited due to its structural divergence characteristics. The current progress in materials, especially anisotropic composites has opened up new future for FSW. This paper describes design study of FSW for transonic transport looking for high drag divergence performance. Inverse code is applied to FSW aerodynamic design to achieve isobar design concept. The performance is verified by transonic wind tunnel test. The paper also mentions the development of aero-structural integrated design tool, a combination of aerodynamic analysis code and structural analysis code, which is essential to FSW wing development.

Suspension is an important chassis part which is vital to ride comfort [1]. However, it is difficult to achieve our targeted comfortability level in a short time. Therefore, improving efficiency of damper development is our primary challenge. We have launched a project which aims to reduce the workload on developing dampers by introducing analytical approaches to the improvement of ride comfort. To be more specific, we have been putting effort into developing the damping force prediction, the vehicle dynamics prediction and subjective rating prediction. This paper describes subjective rating prediction method which output a subjective rating corresponding to the physical value of the vehicle dynamics with deep learning. As a result of verification using objective data which was not used for learning process, DNN (Deep Neural Network) prediction method could fairly precisely predict subjective rating of the expert driver.

It is necessary to develop a small positive pressure control system for the closed ecology experiment facility (CEEF) to protect against over-differential pressure loading. In the present study, a numerical method was developed to calculate the quantity of state of the closed module, which is fitted with rubber buffers, for the small positive pressure control system. Experiments to examine the pressure change of the closed module were carried out at CEEF. Comparison of calculated and experimental results showed that the present dynamic simulation is suited to estimating the quantity of state of the closed module.

The ASUKA was based upon the airframe of the home produced C-1 tactical transport which was modified into an Upper Surface Blowing (USB) powered high lift STOL aircraft. But the wing configuration was not changed. Therefore, this Experimental Aircraft doesn't always have the optimum configuration of a USB type aircraft. This paper describes the investigations which have been conducted to improve the aerodynamic characteristics of a subsonic jet transport semi-span model with an Upper Surface Blowing Flap system which has been newly designed using the NAL STOL-CAD program. The tests were conducted in the NAL 2- by 2-meter Gust Wind Tunnel and results were obtained for several flap and slat deflections at engine thrust coefficients from 0 to 1.85. As compared with the aerodynamic characteristics of the ASUKA model, we obtained the possibility of reduction of the airframe weight and significant improvement of the aerodynamic characteristics.

The paper describes a high performance Head-Up Display (HUD) guidance system installed on the experimental powered-lift STOL aircraft “Aska”. Since the maiden flight in October, 1985, the HUD system has been used in all the flight tests. The HUD has an accurate flight path symbol generated by inertial velocity from the IRS which is updated by up-linked precision radar position data. The flight path symbol is very useful for precise approach and flare control for Aska which has large ground effects. A synthetic runway is also presented, which is conformal with the real runway, using the position data from the ground tracking radar system. Under Instrument Meteorological conditions (IMC), the pilot can approach and land using the HUD synthetic runway as well as in Visual Meteorological Conditions (VMC). The HUD system proved to be a valuable aid to the pilot for all the Aska flight tests.

The Japanese Quiet Short Take Off and Landing experimental aircraft named ASKA was developed and flight tested during 1977 till 1989. The control system hard and software were examined by the functional mock-up with using the actual hardware. The small longitudinal limit cycle was observed in the closed loop test when the Pitch Control Wheel Steering software was on in the mock-up testing. In this paper, first, the method to analyze and to expect the limit cycle based on the describing function was shown. The limit cycle was induced due to the nonlinearities in the automatic control mechanism. The nonlinearities in the hardware were examined to make the model to simulate the system on the computer. The method was shown effective to predict the limit cycle in the mock-up. Second, with using the flight measured dynamics, the limit cycle was concluded as on border line between existing and not, which coincides with the actual flight result.

A series of experiments to evaluate performance of catalysts for CELSS System Wet-oxidation process has been carried out. Data obtained from the experiments show that the noble metal selected for the catalyst gives a good performance in oxidizing Organic Carbon and Organic Nitrogen. The data also show that a catalyst with certain amount of the metal (wt%) shows maximum efficiency in the oxidation; in addition, a catalyst with a different amount of metal gives good performance in producing high quality fertilizer.

System configurations of water recycling for space use have been continued through theoretical and experimental studies. The water recycling system plays a central role in a Closed Ecological Life Support System (CELSS) which offers necessary environment and life styles in closed environment such as space stations, lunar bases, etc.. Membrane technology is a possible candidate for purifying waste water produced by crew use facility, plant cultivation facility, etc. In considerations of the system compactness realizing energy saving, membrane distillation has been revealed to be a suitable purification process. Ground experiments has been performed using membrane filtration processes and membrane distillation process. Thermopervaporation technology with hydrophobic membrane is utilized in the distillation process. The energy saving is achieved by thermal return of condensation energy.

In the first half of the next century, Mankind will expand its sphere of existence to the Moon and space, and they will stand on Mars and study the other planets. Then, humans will inevitably be required to live for long periods, two years or more, in micro-gravity and/or low gravity environments. However, it is well known that such micro or low gravity environments adversely affect human physiology and psychology. The longer the period the greater such effects are and these can result in serious health problems. To improve living conditions in space by generating artificial gravity will be important to solving these problems.

The recovery of important minerals, salt (NaCI) and potassium (K), in a closed system, namely CELSS is discussed. NaCI is needed for humans, but is potentially harmful to plants. Salt is recovered after wet oxidation of urine. Since Na and K have similar chemical and physical properties, their recovery or separation may require sophisticated methods. Na, CI and K ions are separated from other ions by electrodialysis with univalent selective ion-exchange membranes and then NaCI is obtained separately by a crystalization process. Preliminary experiment on crystalization of NaCI-KCl mixed solutions showed a good separation result.

As a CO2 removing and recovering technology, the solid amine utilized as a vacuum desorbing type was developed. The evaluation experiments to measure fundamental characteristics of this material was conducted using the dry air and as the results, the high adsorbing rate, 10 wt% for short period and 7 wt% for long period was obtained and also 7 wt% of adsorbing rate can be expected for the operation of desorption temperature of 80 °C. High accuracy thermobalance device so called thermogravimetric analyzer was utilized to measure adsorption and desorption values of CO2.

The Upper Surface Blowing STOL experimental aircraft ASKA, was developed and flight tested by the National Aerospace Laboratory of Japan. The ASKA operated well on the backside of the drag curve, and because of this flight path control was accomplished with the throttle lever (thrust) during approach and landing. To compensate for the sluggish flight path response caused by the thrust response lag, the flight path control law put in stability and control augmentation system. Flight tests were conducted to evaluate flight path and airspeed response characteristics. This paper describes ASKA's flight path and airspeed response characteristics, as well as construction of the flight path control system.

The National Aerospace Laboratory (NAL) has been conducting basic research on the future landing navigation system of airplanes and a proposed future unmanned reentry space vehicle, using NAL research airplane Dornier Do-228 in which a Collins NAVCORE- I GPS C/A receiver was installed. A ground-to-air data link system was developed in order to realize the real time DGPS operation which improves accuracy. In this paper, experimental evaluation test results of not only GPS stand-alone operation but also DGPS operation are discussed. Since the navigation algorithm in the NAVCORE- I receiver could not be modified, this paper mainly discusses the difference of the two operations. In fixed point ground tests, ground and onboard GPS receivers were connected to the same antenna in order to avoid common errors, and both receivers output positions were compared with a reference map position. In the flight tests, approach/landing flights were conducted.

A new flight reference display for powered-lift STOL aircraft was proposed and evaluated in actual flight environment. The display was developed to provide a simple monitoring system of STOL safety margins with good handling characteristics in place of a speed indicator. Using this display, pilots repeated simulated approaches of the experimental jet STOL “ASKA” using the VSRA as an in-flight simulator. In the evaluation, emphasis was placed on agreement between the display and the motion cues experienced by the pilot. Pilot comments and flight data confirmed satisfactory control characteristics and safety margin presentation of the display.

The viscous effect on the high-speed impulsive (HSI) noise for a helicopter rotor has been investigated by using a combined method of computational fluid dynamics (CFD) techniques with the extended Kirchhoff's equation. The pressure distributions around a rotor blade are obtained by Euler and Navier-Stokes equations to capture a precise shock behavior. The Kirchhoff's equation extended to a moving surface is applied to calculate the acoustic pressures at the observer point. In this calculation, the pressures and pressure gradients on the Kirchhoff surface, in which all the acoustic sources are enclosed, are obtained by using CFD techniques. In order to estimate the effect of the viscosity on the acoustic pressures, two types of turbulence model in Navier-Stokes calculations are used. One is Baldwin-Lomax model and the other is Coakley's q - ω model.

Hybrid laminar flow control (HLFC) is one of the most practically promising aircraft drag reduction technologies. We have investigated both numerically and experimentally aerodynamic characteristics of HLFC airfoil and wing at high subsonic, high Reynolds number conditions. In this paper we report the result of a wind tunnel test on drag characteristics of two-dimensional HLFC airfoils with porous and slot suction approach under some adverse factors against laminar flow, and a numerical analysis of the wind tunnel data, which is based on the boundary layer calculation with new transition prediction method allowed for the adverse factors and the Squire-Young drag formula.

The closed ecology experiment facility (CEEF) has a small positive pressure control system consisting of rubber buffers and a mechanical subsystem. In the present study, effects of small temperature disturbances caused by changes of surrounding conditions on the pressure control system are investigated experimentally and in numerical simulations. Though solar radiation causes a pressure disturbance in the facility, choosing the proper diameter of ducts which connect the rubber buffers to the modules, the rubber buffers can follow fluctuations of low frequency, like daily atmospheric fluctuations and pressure changes caused by temperature control of the facility’s air conditioners, and can cut off those of high frequency due to changes of environmental conditions.

The flight area of drones and other unmanned aerial vehicles (UAVs) had been highly restricted but has been relaxing, including flights beyond the scope of sight. Deregulation without aircraft-reliability improvement increases the risk of accidents. However, demanding high reliability for all aircraft leads to an increase in the price of the aircraft. Therefore, if airspace restrictions are relaxed for more reliable aircraft, the cost of higher reliability and its benefits can be balanced. This will improve efficiency and optimize cost-effectiveness. The purpose of this proposal is to balance the cost of aircraft-reliability improvement (which allows flight to continue in the event of a failure) and its advantages. Specifically, the author proposes rules that apply more relaxed airspace restrictions to UAVs with higher FCLs (Flight Continuity Possibility Levels) and stricter airspace restrictions to those with lower FCLs.