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The relation between the power and the pressure-time history at the exhaust port of a high performance two-stroke engine is explored. Through the use of a variable length expansion chamber with five different tailpipes, the effect on power of stuffing pulse arrival time, magnitude and duration was found. The results from this set of tests are compared with those of two side exit expansion chambers and an inverted tailpipe expansion chamber. Tests were also made to determine how mid-range torque and high speed torque effect of the performance of the motorcycle. An optimum configuration (pipe length and tail pipe length) was found for the 360 Yamaha tested.

The important internal dynamic interactions which ultimately determine the performance of a two-stroke internal combustion engine are identified and then modeled using the bond graph modeling technique. Each of the important dynamic characteristics are developed independently, presenting both the bond graph and mathematical formulation of each of the assumed subsystems. These subsystems are assembled into the final overall system bond graph and governing state space equations are derived. The result of this development is a reasonably straightforward procedure for assembling virtually any size two-stroke ICE with virtually any internal geometry into a cogent, simulatable mathematical formulation. The procedure outlined above is demonstrated for the Yamaha 360 MX motorcycle engine. In addition to presenting results for various internal dynamic interactions (pressure, flow, temperature, etc.), the model is shown to yield excellent predictions for power and torque as a function of RPM.

The sources of diesel engine noise and methods for its abatement are analysed and described. Typically, the overall engine noise is determined by the engine surface noise which, however, can hardly be reduced by more than 5 dB(A) with conventional noise abatement techniques. For reductions of 10 dB(A) or more, it is necessary to attenuate the noise of all external engine parts by a complete encasing of the engine. Various concepts for light weight acoustic engine casings which are closely fitted to the engine without acoustical lining or even integrated into the engine structure and which provide a 15 to 20 dB(A) noise reduction are demonstrated, including one concept for future light weight engines featuring a sound attenuating housing.

The paper divides into two parts. First the investigation of the noise of an unconventional design of two cycle diesel engine, including the results of applying known noise reducing features to it. Then taking one component of that engine, the scavenge blower, and re-designing it from first principles to produce a low noise machine suitable for the low noise engine. The final assembly of engine and blower demonstrated that the noise that has been regarded the characteristic of the two cycle engine is in fact that of the Roots type blower and when eliminated the noise level can be quite low. The present test bed noise level of 97/98 dBA at 1 metre shows promise of this type of engine meeting the legislative requirements of the 1980's.

A new and meaningful test method for evaluating the performance of lubricating oil filters has been developed under the sponsorship of the U.S. Army MERDC. The test procedure is based upon the multi-pass method previously formulated for hydraulic fluid power filters, which has since been accepted on both national and international levels. The multi-pass procedure assesses only the particle separation characteristics of a filter and isolates all other factors which could influence the results. The development effort which resulted in this new lube oil filter test method required an international opinion survey, industrial advisory meetings, and an extensive testing program. Details of the method are given in this paper along with repeatability and discriminatory test results.

An automatic brake has been developed to provide emergency braking and positive position control in hydrostatic drive applications. The brake is automatically applied with the loss of hydraulic pressure to provide the emergency braking function. The brake may be applied at any time by manually dumping the fluid pressure to the brake, to provide the position control function of a parking brake. Because of the convenient mounting of the brake between the hydraulic motor and a gear reducer, the brake may be used in any hydrostatic drive application where position control and/or emergency braking is required.

This paper attempts to put into perspective the noise position of the automotive diesel for the present and the future. It comments on some of the noise measuring techniques and in particular emphasises the importance of knowing the noise characteristics of each design of engine.

Unidirectional fiberglass straps are investigated as a means of providing metal rotor blades with a redundant load path and reduced fatigue crack growth rate. A comparison of crack growth rates for a metal/composite hybrid spar and a conventional metal blade structure are shown. Comparisons of ballistic impact damage for the hybrid spar and the metal spar are presented. Additionally, the results of small-specimen fatigue tests to investigate void propagation at the glass/metal interface are discussed.

In this decade we are witnessing the transition from all metal to all composite helicopter rotor blades. One such helicopter is already in full scale production. A driving factor is structural reliability and guarantee against catastrophic failure. Low crack propagation rate and the nature of failures in composite structures are the characteristics which make this quality product superior to metal structures for rotor blades. The ability to economically tailor blades aerodynamically and dynamically offer important advances in performance, flying qualities, low stress levels, and low vibratory forces.

A three-engine, two-fan arrangement for an advanced vertical and short takeoff and landing (V/STOL) lift/cruise multimission aircraft has many advantages. With three engines, sufficient engine-out thrust is available for safe operation, over the range of multimission emergency landing requirements. The flexibility offered by being able to shut down one engine for loiter and cruise results in a fuel-conserving aircraft. The capability to add the power of the third engine provides a high-speed vehicle when the mission requires. A two-fan system with fans under each wing provides for smooth transition from vertical flight to forward flight and return. Minimum-distance STOL performance is achievable because all of the thrust is available to accelerate the aircraft during the takeoff ground roll and to interact with the wing during climbout.. In shaft-driven systems, clutching horsepower can be drastically reduced or eliminated. Fans can be made interchangeable.

A two-engine, three-fan V/STOL airplane was designed to fulfill naval operational missions. Use of interconnected variable pitch fans led to a good balance between the requirements for high thrust and responsive control at low speed, and efficient thrust at cruise speeds. Engine-out requirements, integration of propulsion and aerodynamic controls, and the propulsion installation were the major factors influencing the configuration. An airplane with a multimission capability from both vertical and short takeoff was conceived.

Lift Fan Multimission V/STOL aircraft provide new capabilities which could revolutionize Naval and Marine aviation but the design concept as well as the design philosophy must be carefully selected. Since the propulsion system is the crux of any V/STOL aircraft this is of primary importance followed by secondary design considerations such as fuselage sizing to accommodate the multimission requirements.

The smoke production of aircraft gas turbine engines is currently characterized by the SAE smoke number and, to a lesser extent, the exhaust transmittance. Quantitative relationships are developed between these characterizations and the optical properties of the engine smoke particles for use in subsequent visibility calculations. These optical properties are the particulate mass concentration and the specific projected particle extinction area. The SAE smoke number is both the most common smoke characterization and the one farthest removed from optical properties. The inherent stained filter technique is first treated in general, then specifically in terms of the SAE requirements. A relation between the smoke number and the optical properties is achieved. It is shown that the SAE interpolation procedure is unsuitable at low smoke numbers, and an alternative procedure is suggested.

The rapid and dramatic growth of aviation over the past several decades is a matter of history with which we are all quite familiar. Integral to that growth has been the mushrooming progress in powerplant technology which, by necessity, is the lead factor in the development of aircraft systems. This paper highlights some of the major milestones that have influenced the course of developments in gas turbine powerplants. It traces its origins in work done on turbosuperchargers, with discussion of the stimuli and shifts in requirements that resulted in various types of jet engines leading up to today's high-bypass turbofans. The natural quest to fly higher, faster and further has reached a point of relative maturity in technology so that today's efforts can now be directed more towards improvements in efficiency, reliability and ecological consciousness. The future holds new challenges. It calls for new ways to control the spiraling costs of development and production of powerplants.

This paper presents the results of a design study of a low cost Jet Fuel Starter (JFS). The JFS is a small free turbine turboshaft engine with a peak output of 150 horsepower. The design concentrates on high output per unit volume and weight, and on low cost. A low speed, four stage axial compressor design results in a compact, lightweight starter. Die castings and a radial pin construction for both the static structure and the compressor rotor provide the most significant cost savings over conventional gas turbine fabrication methods. The low speed concentric shaft design (approximately 70 percent of usual design practice) permits a simple two bearing shaft suspension for both rotors. The resulting close coupling of the turbines reduces the number of expensive hot end components to only five parts.

An Aerodynamic Torque Converter (ATC) which operates as a high speed coupling device between a single shaft auxiliary power unit (APU) and the accessory loads has been designed and built, and is in the latter stages of its testing program. The ATC operates at APU speeds and temperatures while maintaining favorable power-to-weight and power-to-volume ratios.

An automatic takeoff and landing system has been developed for remotely piloted vehicles (RPV) operating from prepared runways. This system consists of a scanning beam microwave landing guidance system and a high performance flight control system. Interfaced with the automatic system is a remote operator, who, using a special control station, monitors system performance, evaluates approach quality and may remotely control the vehicle in the event of contingencies. This paper describes briefly the RPV Automatic Takeoff and Landing (Autoland) system development program: the design approach, simulation and flight test results, and conclusions.

By accurately reconstituting accidents whose parameters are well known from multidisciplinary accident investigation, it is possible to associate forces and accelerations values with injuries sustained by occupants involved in in-the-field accidents. In this study, two in-the-field accidents, their reconstruction conducted by using dummies as occupants, and their reconstruction then with human cadavers are analysed. These accidents reconstructions allow to associate and compare accident occupants injuries with acceleration forces, injuries criteria values measured on dummies, and, on the other hand, accelerations, injuries criteria values, injuries sustained by cadavers during the second accident reconstruction.

The head, chest and femurs of three Hybrid II dummies were impacted with a ballistic pendulum at various angles to determine what differences in accelerometer and femur load cell output would result for a constant energy input. Also evaluated were suspicious tension loads in the femur load cell output when the legs were subjected to obvious off-center impacts during crash tests. It was found that the dummy legs can be subjected to very high torsion and bending loads which can have a significant effect on the femur load cell axial load outputs.

Our aim is to show that today's safety standards (FMVSS 208, EC-Proposals) are inadequate in the present state to ensure optimum protection for belted passengers. These standards do not take into account motion sequence during impact. The postulated tolerance limits - HIC, SI, forward displacements etc. - cannot describe the dynamic behaviour adequately. We emphasize the importance of motion sequence to ensure optimum biomechanic conditions, because motion sequence is the necessary prerequisite for any discussion about biomechanical tolerance limits. First results of our current belt-accident investigations indicate that this is an important problem. By applying experience from crash tests and accident investigations, we try to define simple and well-controllable criteria for motion sequence.