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Integrating the seemingly divergent objectives of aircraft seat configuration is a difficult task. Aircraft manufacturers look to design seats to maximize customer satisfaction and in-flight safety, but these objectives can conflict with the profit motive of airline companies. In order to boost revenue by increasing the number of passengers per aircraft, airline companies may increase seat height and decrease seat pitch. This results in disaccommodation of a greater percentage of the passenger population and is a reason for rising customer dissatisfaction. This paper describes an effort to bridge this gap by incorporating digital human models, layout optimization, and a profit-maximizing constraint into the aircraft seat design problem. A simplified aircraft seat design experiment is conceptualized and its results are extrapolated to an airline passenger population.

The commercial turbofan trend of increasing bypass ratio and decreasing fan pressure ratio has seen its latest market entry in Pratt & Whitney's PurePower™ product line, which will power regional aircraft for the Bombardier and Mitsubishi corporations, starting in 2013. The high-bypass-ratio, low-fan-pressure-ratio trend, which is aimed at diminishing noise while increasing propulsive efficiency, combines with contemporary business factors including the escalating cost of testing and limited availability of simulated altitude test sites to pose formidable challenges for engine certification and performance validation. Most fundamentally, high bypass ratio and low fan pressure ratio drive increased gross-to-net thrust ratio and decreased fan temperature rise, magnifying by a factor of two or more the sensitivity of in-flight thrust and low spool efficiency to errors of measurement and assumption, i.e., physical modeling.

As aircraft programs currently ramp up, productivity of assembly processes needs to be improved while keeping quality, reliability and manufacturing cost requirements. Efficiency of the drilling process still remains an issue particularly in the case of CFRP/metal stacks: hot and long metallic chips are difficult to remove and often damage the surface of CFRP holes. Low frequency axial vibration drilling has been proposed to solve this issue. This innovative drilling process allows breaking up the metallic chips in such a way that jamming is avoided. This paper presents a case of CFRP/Ti6Al4V drilling on a CNC machine where productivity must be increased. A comparison is made between the current regular process and the MITIS drilling process. First the analysis and comparison method is presented. The current process is analyzed and its limits are highlighted. Then the vibration process is implemented and its performances are studied.

This paper presents a set of numerical computations with different turbulence model on an air jet flowing tangentially over the curved surface. It has been realized that jet deflection angle and the corresponding thrust are important parameter to determine with great care. Through the grid independence analysis, it has been found that without resolution of the viscous sub-layer, it is not possible to determine the computationally independent angle of jet deflection and boundary layer thickness. The boundary layer analysis has been performed at different radius of curvature and at jet Reynolds number ranging from approximately about 2400-10,000. The boundary layer thickness has been determined at the verge of separation and found a relation with the radius of curvature and jet Reynolds number. The skin-friction coefficient has been also studied at the verge of separation in relation to the surface radius and jet Reynolds number.

This study investigates the self-adjusted cutting parameter technique to improve the drilling of multi-stacked material. The technique consists in changing the cutting strategy automatically, according to the material being machined. The success of this technique relies on an accurate signal analysis, whatever the process setting. Motor current or thrust force are mostly used as incoming signals. Today, analyses are based on the thresholding method. This consists in assigning lower and upper limits for each type of material. The material is then identified when the signal level is stabilized in between one of the thresholds. Good results are observed as long as signal steps are significantly distinct. This is the case when drilling TA6V-CFRP stacks. However, thrust force level remains roughly unchanged for AA7175-CFRP stacks, leading to overlapping thresholds. These boundary limits may also change with tool geometry, wear condition, cutting parameters, etc.

Radical new electrically propelled aircraft are being considered to meet strict future performance goals. One concept design proposed is a Turboelectric Distributed Propulsion (TeDP) aircraft that utilises a number of electrically driven propulsors. Such concepts place a new and significant reliance on an aircraft's electrical system for safe and efficient flight. Accordingly, in addition to providing certainty that supply reliability targets are being met, a contingency analysis, evaluating the probability of component failure within the electrical network and the impact of that failure upon the available thrust must also be undertaken for architecture designs. Solutions that meet specified thrust requirements at a minimum associated weight are desired as these will likely achieve the greatest performance against the proposed emissions targets.

A review of the research accomplished in 2009 in the System-Level Design, Analysis and Simulation Tools (SLDAST) of the NASA's Airspace Systems Program is presented. This research thrust focuses on the integrated system-level assessment of component level innovations, concepts and technologies of the Next Generation Air Traffic System (NextGen) under research in the ASP program to enable the development of revolutionary improvements and modernization of the National Airspace System. The review includes the accomplishments on baseline research and the advancements on design studies and system-level assessment, including the cluster analysis as an annualization standard of the air traffic in the U.S. National Airspace, and the ACES-Air MIDAS integration for human-in-the-loop analyzes within the NAS air traffic simulation.

This paper outlines power system architecture trades performed on the N3-X hybrid wing body aircraft concept under NASA's Research and Technology for Aerospace Propulsion (RTAPS) study effort. The purpose of the study to enumerate, characterize, and evaluate the critical dynamic and safety issues for the propulsion electric grid of a superconducting Turboelectric Distributed Propulsion (TeDP) system pursuant to NASA N+3 Goals (TRL 4-6: 2025, EIS: 2030-2035). Architecture recommendations focus on solutions which promote electrical stability, electric grid safety, and aircraft safety. Candidate architectures were developed and sized by balancing redundancy and interconnectivity to provide fail safe and reliable, flight critical thrust capability. This paper outlines a process for formal contingency analysis used to identify these off-nominal requirements. Advantageous architecture configurations enabled a reduction in the NASA's assumed sizing requirements for the propulsors.

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 methods developed for analyses of the winds and of aircraft performance during an investigation of a downburst wind-shear-induced accident have been utilized in a more general study of aircraft performance in such encounters. The computed responses of a generic, large transport aircraft to take-off and approach encounters with a downburst wind field were used in examining the effects of performance factors and control procedures on the ability of the aircraft to survive. Obvious benefits are seen for higher initial encounter speeds, maximum thrust-weight values typical of two-engined aircraft, and immediacy of pilot response. The results of controlling to a constant, predetermined, pitch attitude are demonstrated. Control algorithms that sacrifice altitude for speed appear to provide a higher level of survivability, but guidance displays more explicitly defining flightpath than those commonly in use might be required.

An exploratory simulation study of a novel approach to pitch control for a tilt wing aircraft was conducted in 1990 on the NASA-Ames Vertical Motion Simulator. The purpose of the study was to evaluate and compare the handling qualities of both a conventional and a geared flap tilt wing control configuration. The geared flap is an innovative control concept which has the potential for reducing or eliminating the horizontal pitch control tail rotor or reaction jets required by prior tilt wing designs. The handling qualities results of the geared flap control configuration are presented in this paper and compared to the conventional (programmed flap) tilt wing control configuration. This paper also describes the geared flap concept, the tilt wing aircraft, the simulation model, the simulation facility and experiment setup, and the pilot evaluation tasks and procedures.

In addition to designing fighter engines for stall-free idle to maximum power operation and stall recoverability, it is important to give proper emphasis to sub-idle operation for successful starting. This permits the pilot to confidently bring the engine on-line following an inadvertent flameout caused by either the airplane departing the flight envelope or by a fuel interrupt due to a malfunction. Thus reliable and fast airstart capability enhances flight safety especially of single engine airplanes. Flight testing, therefore, is substantially devoted to airstart evaluation. The paper first explains the influence of engine design features on airstarting, particularly the advantages of the low bypass ratio cycle F100-PW-229 (PW229) engine, which is an increased thrust derivative (IPE) of the highly successful F100-PW-220 engine. Enhancing airstarting capability of the PW229 using variable geometry features and digital control flexibility is discussed.

The Diagnostics Tested Facility (DTF) at NASA's John C. Stennis Space Center (SSC) in Mississippi was designed to provide a testbed for development of rocket engine exhaust plume diagnostics instrumentation. A 1200-lb thrust liquid oxygen (LOX)/gaseous hydrogen (GH2) thruster is used as the plume source for experimentation and instrument development. Theoretical comparative studies have been performed with aero-thermodynamic codes to ensure that the DTF thruster (DTFT) has been optimized to produce a plume with pressure and temperature conditions as much like the plume of the Space Shuttle Main Engine (SSME) as possible. Operation of the DTFT is controlled by an icon-driven software program using a series of soft switches. Data acquisition is performed using the same software program. A number of plume diagnostics experiments have utilized the unique capabilities of the DTF.

There is a need for a space launch system that can provide ready, reliable, unencumbered access to space. The need exists for a highly reliable launch system that can operate from numerous available sites, that can provide all azimuth launch capability, that is fully reusable, and that can carry significant payloads into low earth orbit. A vehicle concept was developed to demonstrate the ability of near term aeromechanics and propulsion technology to support such a system. The vehicle was composed of two stages. The system takes off horizontally and both stages return to a horizontal landing. Turbojet, ramjet, and rocket propulsion is used. The sensitivity of the system to thrust, drag, weight, and staging Mach number was examined. The two stage system is able to accommodate a range of performance variations yet still retain significant mission potential.

Using LH2 heat sink capacity for air precooling in turbojets allows to increase specific impulse and in many cases to reduce specific mass (mass-to-sea level thrust ratio). A number of precooled turbojet schemes are considered. Classification of turbojet according to the cooled air amount and depth of cooling is proposed. ATR with extended precooling (Tout=100K) is examined in more detail. For propulsion systems including different types of engines, running simultaneously the concept of LH2 heat sink capacity concentration for turbojet air precooling is proposed.

A main objective of the STOL and Maneuver Technology Demonstrator, (S/MTD) Program was to evaluate the operability and performance of its unique engine/nozzle configuration which can deliver thrust in three different modes; conventional, vectored and through variable vanes which give the option of going from forward to reverse thrust. The two-dimensional nozzle and the modified engine were extensively tested during sea level and altitude testing to satisfy all flight clearance requirements. This paper concentrates on the flight test results of the various modes of vectoring and reversing ending with a compilation of the actual usage of the propulsive controls that could be used by designers of similar advanced propulsion systems.

Aerodynamic effects induced from vectoring an exhaust jet are investigated using a well established thin-layer Reynolds averaged Navier-Stokes code. This multiple block code has been modified to allow for the specification of jet properties at a block face. The applicability of the resulting code for thrust vectoring applications is verified by comparing numerically and experimentally determined pressure coefficient distributions for a jet-wing afterbody configuration with a thrust-vectoring 2-D nozzle. Induced effects on the body and nearby wing from thrust vectoring are graphically illustrated.

This paper presents an overview on an Air Force initiative aimed at increasing the performance and reliability of aircraft batteries. A major thrust of the initiative is the elimination of flight line battery maintenance shops. Cost savings, increased mission capability and battle readiness are the pay-offs that will be realized from this effort. Current maintenance requirements for vented nickel-cadmium (Ni-Cd) batteries used in most U.S. military aircraft are unacceptable. This paper addresses other available technology options, decisions made to date and benefits that will result from this effort to increase the performance and reliability of aircraft batteries.

An elementary analysis has been made of generic wing-body configurations with variable volume allotment in wing and body, for constant total useful volume, including the all-wing configuration. These aircraft were compared on the basis of the Lift-to-Drag (L/D) ratio, for specified flight conditions. In addition the parameter ML/D for constant corrected thrust has been optimized, resulting in certain combinations of altitude and speed for maximum specific range (if corrected TSFC = constant). Finally, the effect of volume allotment on L/D for given engine size was studied. It has been found that in many cases optimum volume allotments indicate that wing-body combinations are to be favored. Only in the case of relatively low Mach numbers and high-altitude flight the flying wing outperforms conventional aircraft, but it will generally require larger engines.

The Airbus A320 has an autothrust system which is unique among transport aircraft in not having feedback movement provided to the pilots' thrust levers. There has been some controversy in the airline world over the operational aspects of this system. As British Airways was one of the earliest operators of the type, a survey was conducted to determine the views of line pilots as to the advantages and disadvantages of the system compared with conventional moving levers. This paper contains the results of that survey. It was concluded that the A320 design provides advantages in respect to engagement and selection of rated power settings, and that movement provides better disengagement and information on system function. BA concludes that from a Flight Operations perspective a future system should consider providing movement between the idle and climb power positions, whilst retaining the A320 thrust setting and engagement “detents” technique.