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The Structures and Materials Research Center of the National Aerospace Laboratory of Japan (NAL) conducted a vertical drop test of a fuselage section from a NAMC YS-11 transport airplane in December2001. This test program is a part of research activities in NAL on the structural crashworthiness of transport aircraft. In addition a cooperative research related to this test program was carried out between NAL and Kawasaki Heavy Industries, Ltd.(KHI). The main objective of this program is to develop optimal numerical models for crash simulation of aircraft fuselage and to obtain background data by drop tests of small-scale structural models and a full-scale fuselage section. Prior to the drop test of a full-scale fuselage structure, a trial numerical simulation on the crash behavior of a small-scale sub-floor structure was conducted by NAL using the explicit, nonlinear dynamic analysis code, LS-DYNA3D.

Motorcycle engines are operated at an extremely broad range of revolutions, from 1000 min-1 to 10000 min-1 or more. Ideally, the natural frequency of each part should never match the engine excitation frequency at any point over that entire range of revolution speeds, but practically, there are times when resonance cannot be avoided because the range is so broad, and therefore the vibration amplitude at resonance must be kept low. For this reason, it is important to grasp not only the resonance frequency but also the vibration amplitude at that point. This may be achieved by two methods, measurement and analysis. The direct measurement of vibration is generally difficult because the motorcycle muffler system has a complex shape and in addition it gets very high temperature when the engine is operating. For this reason, with the aim of being able to predict muffler vibration at the design stage, we carried out a vibration test and FEM (finite element method) analysis.

The authors developed an air-to-air surveillance system that acquires mutual position and informs the position to the pilot. This system transmits position information obtained by GPS via TDMA (Time Division Multiple Access) datalink. Position information received from other aircraft is shown on a display. If proximity condition exists, voice alert is activated. This system can be used as an support system for collision avoidance. This paper describes the outline of the system and flight test result. Two prototype systems were installed on two helicopters. The third system was installed on a ground vehicle. Flight tests were performed using these three systems.

This paper describes the predicted results of acoustic transmission loss (T.L.) for a motorcycle muffler. First, the T.L. of a prototype muffler with one expansion chamber was obtained by measuring sound levels at the inlet and outlet ports of the muffler by speaker test. T.L. was then calculated by using a three-dimensional Finite-Element Method (FEM) for acoustic fields in the muffler. There was good coincidence between the calculated T.L. and experimentally observed data. Second, T.L. of the prototype muffler while attached to a motorcycle engine was measured. On this step, however, a similarly calculated T.L. using FEM to consider the effect of exhaust gas temperature in the muffler showed differences from the measured one. It was estimated that muffler body vibration sounds may affect the result. A dynamic analysis of the structure was carried out using FEM to obtain the eigen modes of the muffler body.

With an increasing number of vehicles, the reduction of traffic noise emissions becomes a greater social requirement. On the other hand, as users' tastes for motorcycles have diversified, it becomes important to develop and supply products to meet customers' requests within a short period. Therefore, it is a key factor to efficiently develop motorcycles which conform to the noise regulations. This paper describes concrete examples of currently utilized noise-source proving methods and noise reduction methods for motorcycles.

A waterjet propulsor has come to be used more popularly for high speed watercrafts such as personal watercrafts. The most difficult problem for designing the waterjet system is that a tradeoff is required to properly determine the best parameters for the waterjet pump and subsequently the best overall propulsion system. This paper presents the design method and performance improvement of the waterjet propulsor used for personal watercrafts. The authors have clarified the performance of the individual component in the waterjet propulsor and improved the component efficiency empirically, and established the method to estimate the thrust and power characteristics of the propulsor on board from the component test results and other design parameters, which enables the optimization of the waterjet system.

Though most street-use motorcycles are now equipped with 4-stroke engines, off-road motorcycles, especially moto-cross racers, still mainly use 2-stroke engines because of their high power and light weight. 2-stroke engines for moto-cross racers require the engine characteristics of high power and excellent throttle response on a wide range of engine speeds. These characteristics immediately require an effective exhaust device to improve output performance at the middle-speed range while maintaining high power at the high-speed range. The latest 2-stroke engines maintain such performance by using an exhaust device, and also by the application of extensively improved basic elements such as the scavenging passage arrangement, exhaust timing and passage shape, etc. This paper briefly summarizes continuous efforts for the improvement of our exhaust-system device from its beginning until the present.

The impact of inlet unstart phenomena on supersonic transport (SST) was investigated by wind tunnel testing. Inlet unstart condition was simulated by controlling the captured mass flow by the inlet. Unsteady pressures on the lower surface of wing and unsteady forces of the wind tunnel model were measured. Unsteady pressure measurement was carried out to detect shock wave motion. Unsteady force measurement by using both internal balance and accelerometers was to estimate axial/angular acceleration of airframe when inlet unstart was occurred. The pressure measurement data revealed that shock location fluctuated with dominant frequency although the controlled mass flow was steady. And it was analytically shown that the dominant frequency is corresponding to the first order frequency of organ pipe resonance.

The quality of exhaust sound has become one of the important factors in the motorcycle market. Therefore both an efficient sound quality evaluation method and technology to achieve ideal sound quality have become necessary. Sound qualify evaluation has generally been performed by trial and error through repeated modification of exhaust silencer construction until desired quality was obtained. But it usually took painstaking work and long hours. In order to solve such problems, we established an objective auditory evaluation method. We also applied Principal component analysis to analize the result of the “Semantic Differential Method (SD method)” so as to determine the affecting elements. Through this analysis system, “powerful sound” caused by relatively higher content of the low frequency range and “crispy sound” caused by a cyclic sound pattern were determined to be desirable sounds for “American type” motorcycles.

A Temperature and Humidity Control (THC) assembly an essential system in order to provide comfortable environment for crew members in Japanese Experiment Module (JEM). Development of an engineering model (EM) and a proto model (PM) of JEM THC assembly started from March 1991 and completed on March 1995 successfully. In this development phase, it is called JEM EM phase, qualification test of THC was conducted to verify the THC design. This paper presents JEM THC design and an outline of the assembly model development.

An Oxygen Generation System (OGS) is an indispensable system for a long manned space mission. A Solid Polymer Water Electrolysis System (SPWES) has been developing by Kawasaki Heavy Industries, Ltd. for a future space mission since 1985. The authors have been studying the SPWES of a new solid polymer electrolyte with simplified cell structure. We presented the initial study results until 1993 at the former International Conference on Environmental Systems (ICES) shown in REFERENCE. The study was focused on the development of a SPWE cell at ambient pressure. This paper describes a follow-on study results related to development activity of a pressure cell module especially.

As a result of our researches into reduction of exhaust emissions for small utility two-stroke engines which are widely used for handheld equipment such as a brush cutter and a hedge trimmer, we here discuss how much exhaust emissions can be reduced with only minor modifications of an engine. For the purpose of reducing emissions, we evaluated the effects of exhaust timing retard and of enleanment of carburetor mixture on mass emissions using the existing 25cc two-stroke engine, which emits high levels of HC and CO, and substantially low levels of NOx. We attained great reduction of HC and CO. The power output, however, dropped and both the plug seat and the exhaust gas temperatures rose, which would detract the practicability of the engine. But we solved the problems by modifying the combustion chamber and the exhaust port shape, keeping the emissions reduced as mentioned above.

The engine noise accounts for a relatively large percentage among the noises generated by a motorcycle. Among the parts of the engine, the cover is important in design as well as a source of the engine noise, being at the end of the vibration transfer path. This paper clarifies that the natural frequency of the cover with a flat surface clearly affects its vibration and noise radiation and that its vibration depends on this surface, by investigation of the effect of surface shape of the cover on its vibration and noise radiation and by a modal analysis of its vibration characteristics. In addition, we confirmed that the calculated value of the radiated noise from the cover agrees well with the measured value.

In the closed environments, removal of trace contaminants generated from persons, animals, and plants is important function to keep the environment below the allowable level. We conducted the fundamental tests in order to confirm design of TCCA (Trace Contaminants Control Assembly) for Closed Ecology Experiment Facilities (CEEF), and obtained the following results; 1) The palladium-on-alumina catalyst is suitable for CO, CH4, C2H4 conversion at temperature lower than 400°C. 2) The alkali impregnated AC (activated charcoal) is effective for NO2, SO2 removal and prevents catalyst poisoning from SO2. 3) The active-desorbing conducted by hot air blow-throw an AC is effective for C2H5OH, CH2Cl2 desorbing. We discuss the fundamental test and design conditions for TCCA.

In the closed environments such as manned space station, it is necessary to remove contaminant gas to keep a suitable environment. Removal of gaseous contaminants generated from crew, animals, and plants is important function to keep the environment below the allowable level in the Closed Ecology Experiment Facilities (abbreviated as CEEF). CEEF consist of three modules for habitat, animal and plant, the supporting facilities for each module and a plant cultivation facility. CEEF are scheduled to be constructed from 1994 in Aomori Prefecture, northern part of Japan. For designing Trace Contaminant Control Assembly (TCCA) for CEEF, the following six (6) trace contaminants have been selected as major contaminant gas in CEEF; Ammonia (NH3) Methane (CH4) Ethylene (C2H4) Carbon Monoxide (CO) Nitrogen Dioxide (NO2) Sulfur Dioxide (SO2) Ethylene is well-known as an aggressive contaminant to plant growth and maturity.

This paper describes results of the thermal-hydraulic performance experiment system (THYPES) of the two-phase flow loop thermal control system using the test rocket which can maintain a gravity level of 10-4G for about six minutes. Feasibility study of this system had been conducted for loading into a experiment module of test rocket TR-IA No. 3. In 1991, engineering model of the experiment system was designed and manufactured in order to investigate its function, performance, and endurance against launching conditions. In 1992, flight model of the experiment system was designed and manufactured. The following tests were conducted so as to ensure the capability and compatibility of THYPES; functional test, performance test, environmental test, and interface tests between the experiment system and rocket avionics section. The experiment was performed on September 17, 1993 and the results are evolved.

Regenerative processes for the air revitalization system of spacecraft atmosphere are essential for realization of long-term manned space missions. These processes include Oxygen (O2) Generation System (OGS) through water electrolysis. The authors have been studying O2 generation system of a new Solid Polymer Water Electrolyte (SPWE) with simplified cell structure since 1985. The initial study results until 1991 were presented in the 21st and the former International Conference on Environmental Systems shown in REFERENCE. This paper describes a follow-on study activity to OGS which focuses on the improvement of cell endurance performance and resource.

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.

“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.

A new 0.9-liter 4-valve-per-cylinder liquid cooled engine was developed for 1984 model motorcycles. This new engine was optimized from the standpoint of performance, durability, and weight efficiency. Semi-Flat slide carburetors, high compression ratio, relatively short stroke and large valves were employed. This engine was upgraded every other year with changes in displacement. Induction system, exhaust system, and valve train. This paper describes, from the viewpoint of the designer, the evolution of the 4-valve liquid-cooled engine from the 1984 to 1988 models. In that evolutionary process we employed: (1) semi-down draft carburetors with smooth air ducts, (2) a computer-aided intake and exhaust port design and manufacturing system. (3) individual rocker arms. (4) a cool air intake system. (5) lightweight pistons. (6) angle -controlled tightening of connecting rod bolts.