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Induction machines (IM) are considered work horse for industrial applications due to their rugged, reliable and inexpensive nature; however, their low power density restricts their use in volume and weight limited environments such as an aerospace, traction and propulsion applications. Given recent advancements in additive manufacturing technologies, this paper presents opportunity to improve power density of induction machines by taking advantage of higher slot fill factor (SFF) (defined as ratio of bare copper area to slot area) is explored. Increase in SFF is achieved by deposition of copper in much more compact way than conventional manufacturing methods of winding in electrical machines. Thus a design tradeoff study for an induction motor with improved SFF is essential to identify and highlight the potentials of IM for high power density applications and is elaborated in this paper.

Small remotely piloted aircraft (10-25 kg) powered by internal combustion engines typically operate on motor gasoline, which has an anti-knock index (AKI) of >80. To comply with the single-battlefield-fuel initiative in DoD Directive 4140.25, interest has been increasing in converting the 1-10 kW power plants in the aforementioned size class to run on lower AKI fuels such as diesel and JP-8, which have AKIs of ~20. It has been speculated that the higher losses (short-circuiting, incomplete combustion, heat transfer) that cause these engines to have lower efficiencies than their conventional-scale counterparts may also relax the fuel-AKI requirements of the engines. To investigate that idea, the fuel-AKI requirement of a 3W-55i engine was mapped and compared to that of the engine on the manufacturer-recommended 98 octane number (ON) fuel.

This paper presents some of the challenges and successful outcomes in developing the aerodynamic characteristics of the Chevrolet Volt, an electric vehicle with an extended-range capability. While the Volt's propulsion system doesn't directly affect its shape efficiency, it does make aerodynamics much more important than in traditional vehicles. Aerodynamic performance is the second largest contributor to electric range, behind vehicle mass. Therefore, it was critical to reduce aerodynamic drag as much as possible while maintaining the key styling cues from the original concept car. This presented a number of challenges during the development, such as evaluating drag due to underbody features, balancing aerodynamics with wind noise and cooling flow, and interfacing with other engineering requirements. These issues were resolved by spending hundreds of hours in the wind tunnel and running numerous Computational Fluid Dynamics (CFD) analyses.

Micro-pitting is a fatigue effect that occurs in geared transmission systems due to high contact stress, and monitoring its progression is vital to prevent the eventual failure of the tooth flank. Parameter signature analysis has been successfully used to monitor bending fatigue failure and advanced phases of gear surface fatigue failure such as macro-pitting and scuffing. However, due to modern improvements in steel production the main cause of gear contact fatigue failure can be attributed to surface micro-pitting rather than sub-surface phenomena. Responding to the consequent demand to detect and monitor the progression of micro-pitting, this study experimentally evaluated the development of micro-pitting in spur gears using vibration and oil debris analysis. The paper presents the development of an online health monitoring system for use with back-to-back gear test rigs.

In the paper at hand a model-based development approach for a diagnostic system for a multifunctional fuel cell system architecture will be presented. The approach consists primarily of four parts. The first part is a description of general steps needed to build an accurate component-based model of the system using a state of the art model-based diagnostic reasoning tool. As a first result there will be a static simulation model for nominal system behavior. The second part of the approach deals with the identification of safety critical failure conditions (SCFC) at a system level, e.g. low Power. The SCFCs are then mapped into the model. This means that categorized physical quantities and monitoring executives are chosen, that are appropriate for representing the specific SCFCs, e.g. low voltage at outlet of DC-DC converter module. According to step two there will be conflicts, meaning discrepancies between the simulated nominal and the mapped behavior.

This paper addresses the issues of data reduction, visualization, clustering and classification for fault diagnosis and prognosis of the Liquid Cooling System (LCS) in an aircraft. LCS is a cooling system that consists of a left and a right loop, where each loop is composed of a variety of components including a heat exchanger, source control units, a compressor, and a pump. The LCS data and the fault correlation analysis used in the paper are provided by Hamilton Sundstrand (HS) - A United Technologies Company (UTC). This data set includes a variety of sensor measurements for system parameters including temperatures and pressures of different components, along with liquid levels and valve positions of the pumps and controllers. A graphical user interface (GUI) is developed in Matlab that facilitates extensive plotting of the parameters versus each other, and/or time to observe the trends in the data.

The Global Positioning System (GPS) will make possible cost effective vehicle navigation and position reporting systems. A hybrid system which uses a GPS receiver aided by external sensors which will provide position information even when satellite signals are blocked is described. Elements of the communications system which will provide vehicle locating and monitoring is presented.

The Harrier is still the world's most mis-understood fighter and V/STOL the world's most neglected military art. This paper, based on almost 30 years of V/STOL experience, attempts to remove some of the fog of misconception that surrounds tactical jet V/STOL and uncover its proven merits in a CTOL-dominated field. The need for V/STOL in tactical aviation is discussed and the Harrier set in its historical frame alongside the many essays in this field over the past 30 years. Operational experience with jet V/STOL is examined in the context of the flexibility and simplicity of Harrier's powered lift systems and flight modes, compared with other jet V/STOL vehicles. The paper goes on to discuss the military compulsions of jet V/STOL and show its practical worth in many tactical scenarios including an outline of its success in the 1982 Falklands campaign.

This paper provides an update of operational, procedural, and systems information regarding on ground deicing and anti-icing of aircraft certified for Federal Aviation Regulations (FAR) Parts 91, 121, 135 operations. The data presented reflects general aviation and the airlines' perception of the clean aircraft concept and highlights the need for an increased awareness of the various types of deicing fluids and facilities available. Two important issues surrounding the aircraft deicing fluids (ADFs) used in North America and Europe are addressed. First, the Federal Aviation Administration's (FAA's) Advisory Circular (AC) 20-117 stresses the clean aircraft concept which some members of the deicing community argue is violated by the Association of European Airline's (AER's) Type II thixotropic ADFs. Second, the environmental and health effects which may result from the various glycols contained in ADFs is the subject of some debate in the North American and European deicing community.

A mathematical model has been developed and computerized that provides aerospace engineers and managers direct, accurate knowledge of how designated time between overhauls (TBO) affects the reliability, availability, and operational cost of an engine system. The model's inputs include: the Weibull parameters of the components making up the system; the average active repair time required to restore the system to its initial condition; and average cost estimates for engine overhaul. The final result is a set of curves: one depicts mean time between failure versus TBO; another depicts engine availability versus TBO; and a third depicts maintenance cost per operating hour versus TBO. From these curves the optimal TBO can be determined. Specific examples are presented.

With the introduction of the Payload Assist Module (PAM) the McDonnell Douglas Astronautics Company pioneered the development of the first commercial US orbital transfer vehicle. The PAM program was initiated in 1976 to provide spacecraft developers with an orderly transition from the Delta expendable launch vehicle to the space shuttle. With the PAM system, medium-sized payloads designed to be placed in orbit from the Delta vehicle could, without any redesign, be launched from the space shuttle when it became operational. During the late 1970s and early 1980s, an evolutionary increase in the weight of spacecraft to be launched and the introduction of the operational space shuttle system produced a need for new, economical transfer vehicle systems. To meet this need, and also take advantage of the larger payload volume available in the shuttle orbiter, several companies initiated the commercial development of additional upper-stage systems.

The flow around a circular cylinder is a classical problem of fluid dynamics, and its study is of great importance since the cylinder is one of the most commonly occuring shapes in engineering structures. The current experimental investigation examines both the mean drag and the unsteady flow parameters (in the form of a nondimensional eddy-shedding frequency) at critical, supercritical, and transcritical Reynolds numbers (Re > 3 × 105). The tests were conducted in the NASA Langley Low Turbulence Pressure Tunnel over a Reynolds number range of 2.5 × 105 to 6.2 × 106 and a Mach range of 0.05 to 0.40. The unsteady flow phenomena was measured in the wake and on the test section walls with miniature pressure transducers. The determination of the Strouhal number in the supercritical regime was complicated by the presence of broadband signatures in the frequency domain.

The Shuttle version of the NAVSTAR Block II Global Positioning System (GPS) Space Vehicle (SV) will be injected into the transfer orbit with a Perigee Kick Motor (PKM) contained in an attached PAM-DII stage. Mission “drift” orbit injection will occur near the 4th apogee of the transfer orbit with an Apogee Kick Motor (AKM) burn. Final mission orbit will be attained following any necessary corrections by the Reaction Control System (RCS) which will also be used throughout the SV lifetime for orbit maintenance. A primary concern in the transfer procedure is GPS/PAM-DII separation following PKM burnout because of the possibility of SV and PAM-DII recontact if large coning angles have developed during the burn. Hence, initial flights will need substantial instrumentation to monitor PKM burn and separation data. The most desirable method of instrumentation readout is by telemetry transmission to an Air Force Remote Tracking station (RTS).

Simulation of spacecraft on-orbit operations is discussed in reference to Martin Marietta's Space Operations Simulation laboratory's use of computer software models to drive a six-degree-of-freedom moving base carriage and two target gimbal systems. In particular, key simulation issues and related computer software models associated with providing real-time, man-in-the-loop simulations of the Manned Maneuvering Unit (MMU) are addressed with special attention given to how effectively these models and motion systems simulate the MMU's actual on-orbit operations.

The proposed AIR 1939, “Aircraft Engine Life Cycle Cost Guide,” states the need for a methodology capable of relating input and output data on a consistent basis. This paper demonstrates that a methodology consistent with the proposed guidelines of AIR 1939 is practical. A generic example was constructed based on the design-to-cost/life cycle cost (DTC/LCC) requirements for an Allison engine full-scale development program. The example is presented using concepts and terminology from AIR 1939 in order to demonstrate the applicability of the document.

This paper describes some of the unique features of an integrated throttle-elevator control law known as the Total Energy Control System (TECS) which has been flight tested on NASA Langley's Transport Systems Research Vehicle. The TECS concept is designed around total energy principles. It utilizes a full-time autothrottle to control the total energy of the aircraft and the elevator to distribute the energy between speed and flight path objectives. Time histories of selected parameters generated from flight data are used to illustrate the pilot-like control strategy of the system and the priority logic employed when throttle limiting is encountered.

This paper discusses the side stick and fly by wire elements of the Airbus Industrie A320. After discussion of the cockpit and the effect on it of the side sticks, the arrangements of the side sticks themselves is discussed, travel, forces and electronic coupling. The control laws form the body of the paper with some emphasis on the new things that become possible with fly by wire that Airbus Industrie has vested in A320. Pitch roll and yaw control are discussed in detail and so to are the protection systems that will contain the flight path within safe limits. Some illustrations of the functioning of the protection system in flight on a test A300 equiped with the A320 control laws will be presented.

The manipulator subsystem, an anthropomorphic device, has been analysed in terms of Features and characteristics that are peculiar to its application. Extensive preflight analysis and testing (Fig. #1) using various finite analysis methods, computer programs, and techniques (Appendix A) has satisfied the unique and stringent constraints the remote manipulator system is required to operate under (Appendix B). The system is the pioneer of the space payload transportation system. Future generations will satisfy a diversity of needs through variations of design. Employment of this system will, through time, dictate the tolerances that may be relaxed or tightened.

A new method is proposed for the identification of stiffness parameters for linear elastic structures subjected to static loads. The structural stiffnesses are identified at the element level utilizing forces and displacements measured on a subset of the degrees of freedom used to define the structural model. This method is capable of determining major changes in structural properties at the element level, including element failure. The effect of errors in force and displacement measurements are investigated utilizing a Monte Carlo analysis. This stochastic simulation may be performed prior to the actual test in order to establish an acceptable error limit for instrumentation. Also, this procedure provides important information regarding the best degrees of freedom to measure in order to identify a specific subset of the structural parameters.

Current AF-NASA architecture level studies project future need for a heavy-lift, unmanned launch vehicle with low Earth orbit (LEO) payload delivery capability. To achieve this capability, vehicle concepts considered range from fully expendable to fully recoverable. Expendables entail high operations costs; recoverables, high development costs and, in the minds of many, high technical/cost risk. A concept that has been extensively studied is the partially reusable Shuttle-Derived Vehicle (SDV), seen as a potential candidate offering two to three times more cost-effectiveness than Titan or Shuttle ($/lb payload), and based on available hardware elements and current technology upgrades. The SDV is currently considered a viable candidate launch vehicle in ongoing systems studies.