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The paper presents a numerical study aimed at converting a commercial lightweight 2-Stroke Indirect Injection (IDI) Diesel aircraft engine to Direct Injection(DI). First, a CFD-1D model of the IDI engine was built and calibrated against experiments at the dynamometer bench. This model is the baseline for the comparison between the IDI and the DI combustion systems. The DI chamber design was supported by extensive 3D-CFD simulations, using a customized version of the KIVA-3V code. Once a satisfactory combustion system was identified, its heat release and wall transfer patterns were entered in the CFD-1D model, and a comparison between the IDI and the DI engine was performed, considering the same Air-Fuel Ratio limit. It was found that the DI combustion system yields several advantages: better take-off performance (higher power output), lower fuel consumption at cruise conditions, improved altitude performance, reduced cooling requirements.

The paper describes a numerical study, supported by experiments, on light aircraft 2-Stroke Direct Injected Diesel engines, typically rated up to 110 kW (corresponding to about 150 imperial HP). The engines must be as light as possible and they are to be directly coupled to the propeller, without reduction drive. The ensuing main design constraints are: i) in-cylinder peak pressure as low as possible (typically, no more than 120 bar); ii) maximum rotational speed limited to 2600 rpm. As far as exhaust emissions are concerned, piston aircraft engines remain unregulated but lack of visible smoke is a customer requirement, so that a value of 1 is assumed as maximum Smoke number. For the reasons clarified in the paper, only three cylinder in line engines are investigated. Reference is made to two types of scavenging and combustion systems, designed by the authors with the assistance of state-of-the-art CFD tools and described in detail in a parallel paper.

The U. S. Coast Guard has recently put into service new 210 ft cutters designed for search and rescue work, law enforcement, oceanographic work, and possible future ASW. This paper outlines the structure and capabilities of the vessel. An important feature of the cutter is its helicopter handling facilities, which have greatly increased the cutter's search and rescue capability by extending the area it can cover. The cutter is the first in Coast Guard service to be powered by a combination diesel engine and gas turbine installation. The combination gives a top speed of 18 knots and a cruising range of 5000 miles.

A colorful series of 150 slides was presented tracing 5 HP to 1200 HP marine gear design evolution beginning in 1906, followed by pre-WWI developments, Liberty Aircraft engine usage and a 1924 to 1972 series of pleasure boat and work boat marine gear photographs. The entire slide presentation is available in 35 m.m. film strip and may be ordered (at cost) from the author, R. C. McRoberts, Twin Disc, Incorporated, Racine, Wisconsin, 53403, U.S.A. For short time usage, a loan film is available. This history of U. S. marine gear development includes information contributed by the Snow-Nabstedt Gear Corp., Capitol Gears, Inc., Paragon Gears, Inc., The Walter Machine Co., Inc., Detroit Diesel Allison Div. of General Motors Corp., Caterpillar Tractor Co., Warner Gear Div. Borg-Warner Corp. and Twin Disc, Incorporated.

The significance and the number of vehicle safety features enabled via connectivity continue to increase. OnStar, with its automatic airbag notification, was one of the first vehicle safety features that demonstrate the enhanced safety benefits of connectivity. Vehicle connectivity benefits have grown to include remote software updates, data analytics to aid with preventative maintenance and even to theft prevention and recovery. All of these services require available and reliable connectivity. However, except for the airbag notification, none have strict latency requirements. For example, software updates can generally be postponed till reliable connectivity is available. Data required for prognostic use cases can be stored and transmitted at a later time. A new set of use cases are emerging that do demand continuous, reliable and low latency connectivity. For example, remote control of autonomous vehicles may be required in unique situations.

The 912 engine is a well known 4-cylinder horizontally opposed 4-stroke liquid-/air-cooled aircraft engine. The 912 family has a strong track record: 40 000 engines sold / 25 000 still in operation / 5 million flight hours annually. 88% of all light aircraft OEMs use Rotax engines. The 912iS is an evolution of the Rotax 912ULS carbureted engine. The “i” stands for electronic fuel injection which has been developed according to flight standards, providing a better fuel efficiency over the current 912ULS of more than 20% and in a range of 38% to 70% compared to other competitive engines in the light sport, ultra-light aircraft and the general aviation industry. BRP engineers have incorporated several technology enhancements. The fully redundant digital Engine Control Unit (ECU) offers a computer based electronic diagnostic system which makes it easier to diagnose and service the engine.

AS speeds and operational altitudes of modern aircraft continue to increase, it is becoming more and more important that the total drag of the airplane be reduced while the rate of heat dissipation per unit frontal area of radiator be kept as high as possible. The standard method of increasing the temperature difference between cooling medium and coolant has been to use ethylene glycol as a coolant, because its boiling point is much higher than that of water; however, in its pure state glycol has various disadvantages that are not present when a pressure water system is used. This is a sealed system for making use of the physical characteristics of the increase in boiling temperature with pressure. When the radiator receives more heat from the engine than it is dissipating, a small quantity of steam is generated inside the cylinder jackets. The resulting increase in pressure will cause the temperature to rise until a balance is restored between heat rejection and radiator dissipation.

In the summer of 1922 the Buick Company began experimenting with balloon tires. The first tires tested, being four-ply and 32 x 6.20 in. in size, produced a galloping action that was sufficient to prejudice the company's engineers against them, and the tests were discontinued. In addition to the galloping effect, other difficulties encountered included those usually present in steering, the development of wheel shimmying to a serious degree, the lack of proper clearance for external brakes because of the small 20-in. wheels, the excessively rapid wear of the tire tread, and the greater susceptibility to puncture. Leaks because of the pinching of the inner tubes also occurred. When, later, a set of 5.25-in. tires was tried on a smaller car, the galloping was noticeably less; but punctures were more numerous than was the case with high-pressure tires.

Newer automobiles have complex dynamic and stability controls due to regulations, competition, and safety concerns. More systems require testing at the subcomponent level to ensure proper operation in the final vehicle assembly. Many of the stability and navigation features originally designed for aircraft components are now being incorporated into automobiles. Certain types of motion test simulators were originally designed for testing aircraft sensors as: gyroscopes, inertial navigation systems (INS), inertial measurement units (IMU), and attitude heading and reference systems (AHARS) This same type of equipment is now used for automotive testing as: airbag fuse sensors, anti-skid sensors, rollover sensors, vehicle stabilization systems, active suspension sensors, and navigation systems.

BEGINNING with a review of the effects of the almost simultaneous adoption of balloon tires and front-wheel brakes, the authors outline the dynamic conditions of the front-axle system of the conventional car. They show that two types of vibration, otherwise independent of each other, are coupled together by gyroscopic forces when the wheels are rotating. The effect is greatly to lower the frequency, so it can come into synchronism within the speeds at which the car is driven. Shackling the front springs at the front end reduces the error in steering geometry, but cannot always entirely eliminate shimmy and wheel kick. A solution was found by adding a cushioned bracket at the rear end of the left front spring. This introduces damping, because of a phase difference between the gyroscopic forces and the elastic and friction forces, thus eliminating shimmy and at the same time reducing the reaction at the steering-gear to an amount so small that no kick is felt at the steering-wheel rim.

This paper will deal with an emerging technology in the world of design known as Knowledge-Based Design, or KBE. KBE, also known as Rule-Based Design, provides the design engineer with the ability to develop a true virtual prototype of a product prior to committing to manufacturing. A virtual prototype is a combination of the design rules, or product model, and the vehicle geometry. A virtual prototype has all of the geometric characteristics, or attributes, of the product as well as all of the non-geometric attributes such as materials, mass properties, stress and deflection characteristics, etc. KBE allows the development of computer-based tools for the design engineer that extends beyond the capability of current CAD and parametric tools. The early stages of automobile design differs from the traditional method used in aircraft or marine design where there is a well-defined conceptual, or early stage, design phase.

The results of a design study of the application of a simplified aircraft fuel control method to automotive gas turbines is presented. Although the requirements for control of automotive gas turbines impose a degree of complexity exceeding that of fixed geometry aircraft engines, the hydromechanical computing circuit employed in the earlier application is found to be applicable to the automotive requirements. Methods for compensation and/or adjustment for wide range fuel density and inlet temperature variations and for obtaining turbine vane actuation, acceleration optimization, and turbine braking are presented.

With the growing complexity and integration of systems as satellites, automobiles, aircrafts, turbines, power controls and traffic controls, as prescribed by SAE-ARP-4754A Standard, the time de-synchronization can cause serious or even catastrophic failures. Time synchronization is a very important aspect to achieve high performance, reliability and determinism in networked control systems. Such systems operate in a real time distributed environment which frequently requires a consistent time view among different devices, levels and granularities. So, to guarantee high performance, reliability and determinism it is required a performance evaluation of time synchronization of the overall system. This time synchronization performance evaluation can be done in different ways, as experiments and/or model and simulation.

Avionics Systems are increasingly used to perform safety-critical functions at high altitudes. But their increasing capacity and concentration of memory and logics leads to more frequent occurrences of single event upsets, especially in high altitudes. In this work we discuss the effects and mitigation of single event upsets on avionics systems to help in developing future requirements. To do that we initially present the concepts of radiation environment of the atmosphere, radiation induced errors, single event upsets, etc. Then, we discuss some of their effects on avionic systems and ways of mitigation. Finally, we discuss provisions to demand the adoption of such mitigation measures, and their sufficiency. This will help in developing future requirements to accomplish the objectives of a safe operation of civil transportation aircraft.

The performance and flight characteristics of an aircraft are markedly affected by the aerodynamic design, which can be done making use of various tools such as wind tunnel tests and computer simulations. Despite the fact that wind tunnel testing permits great trustworthiness of results, they are still slow and costly procedures. On the other hand, computational methods allow for faster and lower budget analysis. For the conception and the initial phase of an aircraft design, where it is necessary to evaluate a great variety of wings and lifting surfaces configurations, it is desirable to have a method able to determine the main aerodynamic characteristics, such as drag and lift, quickly. In more advanced phases of the design the interest is in obtaining results which shows a more detailed flow around the aircraft.

The simple forced vortex pump design presented in this paper has demonstrated usefulness in satisfying the requirements of propulsion systems for aircraft and rocket motors. A simplified theory of design is expanded, and theoretical and actual performance curves along with sketches and photographs of this type of pump are presented. This pump, with its small size, light weight, high operating speed, and simplicity of design, establishes itself as a centrifugal type pump in a range of flows and pressures normally considered to be the domain of larger, heavier, more costly, and complex positive displacement pumps.

A method is outlined for calculation of aircraft whose configurations vary in a systematic manner, so that the aircraft which is best configured to meet the necessary requirements may be found rapidly. The approach is sufficiently general that it may be used for many different types of vehicles. Through the use of general tabular inputs, a large degree of versatility is available in the calculation process whereby an IBM machine may be used with one basic program which will accept inputs from a variety of different vehicle types. In this manner, improvements in materials or constructional state-of-the-art can be affected without costly and time-consuming reprogramming.

The growing usage of Unmanned Aerial Vehicles (UAVs) for aerial surveillance and reconnaissance in military applications calls for lightweight, reliable powerplants that burn heavy distillate fuels. While mass-produced engines exist that provide adequate power-to-weight ratio in the low power class needed for UAVs, they all use a spark-ignited combustion system that requires high octane fuels. Southwest Research Institute (SwRI) has embarked upon an internal research effort to design and demonstrate an engine that will meet the requirements of high power density, power output compatible with small unmanned aircraft, heavy-fuel combustion, reliable, durable construction, and producible design. This effort has culminated in the successful construction and operation of a demonstrator engine.

The heavily loaded thrust bearing in aircraft turbines must be 100% reliable, which requires a different philosophy from that on which catalog ratings are based, namely, 10% of failures. Principal problems are: 1) to raise the minimum life of bearings regardless of the wide spread between minimum and maximum, and 2) to raise the permissible operating temperature. Metallurgical improvements offer the best possibilities for gain in 1 and 2 above. Other factors such as geometry, finish, and dimensional accuracy are helpful in category 1 but do not promise large gains.

The reliability of airborne equipment is related to the thoroughness of the environmental test program. The importance of being able to rationalize the environmental tests in terms of the actual flight environment is stressed. Present environmental vibration test procedures, which are based for the most part on flight data obtained in propeller driven aircraft, are reviewed. It is shown that such procedures cannot be applied to turbojet aircraft. An environmental test procedure is proposed which utilizes the latest type laboratory shaker and control equipment to provide a vibration and noise analogue of an aircraft. The penalties of “over-testing” are pointed out. In conclusion, an environmental test specification is compared to an insurance policy, and it is urged that its implications be fully understood.