Search Results

An outer loop guidance architecture was designed to control autonomous aerial refueling mission from the trail aircraft side. The design utilized bank, yaw rate, velocity and climb rate commands implemented using a previously developed adaptive trajectory concept. The concept was based on position error feedback that was used to control trail aircraft overshoot and tracking about the lead aircraft refueling point. To demonstrate this application, an open loop linear trail aircraft model at a given flight condition was selected. Inner loop control laws were designed using Linear Quadratic Regulator feedback controller and Balanced Deviation theory. The outer loop guidance architecture was then added to implement the application. The performance of the system was then evaluated for a selected position error, and disturbance.

In the future, it will be possible to manufacture very small, robust machines, which may be attached to the surface of a wing allowing the classic boundary condition of “no-slip” to be altered at will. It is also possible that the heat transfer through the wing surface can be controlled. This paper reports an investigation into the possible benefits to aerodynamics that will occur if such machines become available. It is found that imposing an isothermal wing surface can increase the lift drag ratio of wing at transonic cruise and allowing slip at the surface can have the same effect. Both these effects are additive. It is found that control of heat transfer on a wing at hypersonic wing can act as a control device, comparable to that due a moderate flap deflection.

Driving cycles have been used in Federal Test Procedures to establish fuel economy and emissions characteristics for automobiles. Reasonable driving cycles for trucks and buses have been more difficult to establish because of the great variety of uses which these vehicles experience. The truck cycle has been divided into three different use categories—the local cycle, the short haul cycle, and the highway cycle. Only recently, has actual field data been obtained, and this paper proposes a method of utilizing this data to develop a more realistic local cycle than those previously proposed.

There is an ongoing interest in biodegradable hydraulic fluids. Biodegradable fluids are often considered to include only vegetable oils, polyol esters and diester base stocks. However, other fluid base stocks including highly refined mineral oils, poly(alpha olefins) and fire-resistant fluids such as water-glycol hydraulic fluids are also biodegradable fluid alternatives. This paper will provide an overview of the international literature on biodegradable fluids, various international testing protocol, fluid base stocks, effect of oxidative stability, material compatibility and pump performance.

Modern project management including brake testing includes the exchange of reliable results from different sources and different locations. The ISO TC22/SWG2-Brake Lining Committee established a task force led by Ford Motor Co. to determine and analyze root causes for variability during dynamometer brake performance testing. The overall goal was to provide guidelines on how to reduce variability and how to improve correlation between dynamometer and vehicle test results. This collaborative accuracy study used the ISO 26867 Friction behavior assessment for automotive brake systems. Future efforts of the ISO task force will address NVH and vehicle-level tests. This paper corresponds to the first two phases of the project regarding performance brake dynamometer testing and presents results, findings and conclusions regarding repeatability (within-lab) and reproducibility (between-labs) from different laboratories and different brake dynamometers.

The ISO TC22/SWG2 - Brake Lining Committee established a task force to determine and analyze root causes for variability during dynamometer brake performance testing. SAE paper 2010-01-1697 “Brake Dynamometer Test Variability - Analysis of Root Causes” [1] presents the findings from the phases 1 and 2 of the “Test Variability Project.” The task force was created to address the issue of test variability and to establish possible ways to improve test-to-test and lab-to-lab correlation. This paper presents the findings from phase 3 of this effort-description of factors influencing test variability based on DOE study. This phase concentrated on both qualitative and quantitative description of the factors influencing friction coefficient measurements during dynamometer testing.

This paper shows the use of dedicated short range communications, DSRC, as a resource as implemented in a LAN environment. Customer wants and needs are reviewed in light of the requirements for trucking companies to reach 100% utilization of assets and to pursue the constant goal of lowering operating costs. The user perspective of applications are discussed with respect to lane based versus area based data collection. Multiple applications are satisfied from multiple departmental needs. Application design considerations are discussed for using this wireless communication.

The aerodynamics of the STOL aircraft can experience significant changes in proximity to the ground. A review of the existing data base and methodologies has been made and the results of that review are presented in this paper. The existing data show that in ground proximity the STOL aircraft will generally experience a reduction in the lift component regardless of the lifting configuration. Those configurations with integrated power and lift systems will have an additional effect of ground induced aerodynamic changes. This paper will discuss the existing data base and the deficiencies of that data base.

Evaporative and running loss emissions were measured in a fleet of ten (1 989) current and seven (1983-85) older vehicles with fuels whose compositions varied in aromatic, olefin, and MTBE content and 90 percent distillation temperature (T9O). Emission compositions from each test were analyzed for individual hydrocarbon species. The individual hydrocarbon profiles were used to calculate evaporative and running loss emission reactivities using Carter maximum incremental reactivity (MIR) and maximum ozone reactivity (MOR) scales. Ozone reactivity estimates were expressed as Ozone Forming Potential (gO3/test) and Specific Reactivity (gO3/gNMOG) for both reactivity scales. The data were analyzed by regression analysis to estimate changes in the mass and reactivity of evaporative emissions due to changes in fuel composition. Previous studies have focused on how fuel volatility affects evaporative emissions without regard for the chemical composition of the fuels.

Reported tensile and fatigue properties of die cast AZ91D and AM60B magnesium alloys indicate that those values depend on the size and shape of the test samples and their global porosities. This paper reviews the mechanical properties reported in the open literature for these die cast alloys and indicates that section thickness and global porosity are inadequate for predicting the tensile and fatigue properties of die cast AZ91D and AM60B magnesium alloys.

Recreational marine engine operation effects water quality as well as air quality. Significant quantities of hydrocarbons are discharged into the rivers, lakes, and estuaries used as recreational boating waters. In order to investigate the impact of recreational marine engine operation on water quality, a MerCruiser 3.0LX four-cylinder four-stroke inboard engine and a Mercury 650 two-cylinder two-stroke outboard engine were tested using EPA required certification procedures. Both engines were tested with exhaust gas/cooling water mixing (scrubbing) in the exhaust stream using both freshwater and saltwater. Additionally, the inboard engine was tested without exhaust scrubbing. Gaseous emissions (HC, NOX, CO, and CO2) from the engines were continuously measured using a constant volume sampling system. Both exhaust gas and cooling water samples were collected and speciated for hydrocarbon species present.

A novel two stroke cycle diesel engine is evaluated as a general aviation aircraft powerplant. Two certificated spark-ignited gasoline reciprocating engines are also evaluated in the same aircraft. The evaluation of aircraft propulsion performance considered only the effects of altered powerplant parameters on the range of an aircraft having a fixed gross weight and payload cruising at a given lift/drag ratio. Thermodynamic analysis finds the diesel engine can have a sea level power rating exceeding the 10,000 foot cruise power requirement by 55% with nearly equal specific fuel consumption, a low engine speed and a modest cylinder pressure. It uses a single-stage, radial turbocharger without intercooling or auxiliary mechanical scavenging. The diesel engine can significantly increase the range of a particular airplane now powered by a certificated turboprop engine. The candidate gasoline engines could not equal the turboprop-powered aircraft performance.

This paper provides a review of the fatigue properties reported in the open literature for die cast magnesium-based alloys. Recently developed fatigue data, in the form of stress versus number of cycles to failure for bending fatigue (R=-1), are presented for die cast AM60B and AZ91D alloy specimens with thicknesses between 1 and 10 mm. The effects of specimen thickness and macrostructural features, such as porosity distributions and surface features (parting line and ejection pin marks), on the fatigue data are discussed.

The continued availability of leaded specialty aviation gasolines remains as an item of crucial importance in the near-term future of general aviation; however, the development of new piston engines capable of operation with other transportation fuels available in large pools is considered an indispensable element in the long-range survival of the industry. This paper offers a road map that while allowing the continued utilization of the current fleet of piston aircraft, sets the stage for a transition to new piston powerplants and associated aircraft, compatible with widely available transportation fuels such as motor gasoline based aviation fuels for the lower and some medium performance aircraft, and aviation turbine fuels for the balance of medium and high performance airplanes.

The purpose of this paper is to survey the adverse environmental impacts resulting from motor vehicles, to review technologies developed to address these problems, and to summarize the current status of pollution control programs around the world.

Rapidly industrializing developing countries are now starting to note similar air pollution problems to those of the industrialized world. This paper surveys the adverse environmental impacts resulting from motor vehicles, reviews technologies developed to address these problems, and summarizes the current status of pollution controls around the world. Special focus is on the design of strategies to address the emerging problems of developing countries.

Gear rattle, clunk, and other such noises, commonly referred to as impulsive or unusual noise, are often classified as unique problems without common origins. This paper examines the underlying structure that promotes them and traces physical system behaviors that predispose them to such noises. Though the audible noise itself is not modeled directly, a good deal of the disposable energy that sustains it can be inferred from the impulsive dynamics that underlies the whole process. Further effort quantifies the energies involved and appraises the distinctiveness of the perceived noise. Whether one hears gear rattle or clunk depends on the initiating site within the system and the impulsivity index of the prevailing dynamics. Observable indicators suggest that periodic noise is supported by periodic dynamics and, similarly, impulsive noise, by impulsive dynamics and that the latter is non-deterministic, discontinuous and even chaotic.

The efforts of the ISO “Test Variability Task Force” have been aimed at improving the understanding and at reducing brake dynamometer test variability during performance testing. In addition, dynamometer test results have been compared and correlated to vehicle testing. Even though there is already a vast amount of anecdotal evidence confirming the fact that different procedures generate different friction coefficients on the same brake corner, the availability of supporting data to the industry has been elusive up to this point. To overcome this issue, this paper focuses on assessing friction levels, friction coefficient sensitivity, and repeatability under ECE, GB, ISO, JASO, and SAE laboratory friction evaluation tests.

Development of Terrain-Vehicle Systems Analysis involving statistically variable ground, has necessitated the development of field instrumentation for mass measurement of soil parameter input. To this end, the idea originally conceived and tested at U.S. Army's Land Locomotion Laboratory in Detroit, was revived and adapted to modern requirements. The Wheeled Automated Bevameter (WAB) was presented as a better vehicle analog for measuring soil parameters than the conventional plate-shearing instrument hitherto used. It yields itself to mass production of terrain input, without which further progress in Terramechanics, based on statistical changes of the environment may be impossible.

Die cast AZ91D and AM60 magnesium alloy components are finding increasing usage in automotive applications. Both hot and cold chamber die cast components of these alloys generally exhibit several common microstructural features, including “skin”, porosity banding, and porosity distributed about the component centerline. Methods for quantitatively characterizing these microstructural features are described and representative values for skin thicknesses, porosity band dimensions and porosity band locations from selected die castings will be presented. The expected influence of these common microstrucutral features on mechanical properties and acceptability of die cast magnesium components for given applications are discussed.