SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 25 - DECEMBER 16, 2005
05 AIRCRAFT DESIGN, TESTING AND PERFORMANCE
Includes all stages of design of aircraft and aircraft structures and systems.
Also includes aircraft testing, performance and evaluation, and aircraft and flight simulation technology.
For related information see also 18 Spacecraft Design, Testing and Performance and 39 Structural Mechanics.
For land transportation vehicles see 85 Technology Utilization and Surface Transportation.
20050240921 Airbus Industrie, Blagnac, France
Lateral Attenuation Based on A300 Noise Measurements
van Boven, M. W. P.; January 2005; 10 pp.; In English Report No.(s): PB2006-100888; No Copyright; Avail.: National Technical Information Service (NTIS)
For the prediction of aircraft noise levels perceived at positions lateral to the flight track, lateral attenuation of noise has to be taken into account. Lateral attenuation contains all sound emission and propagation effects on noise, in addition to separately modeled spherical spreading and atmospheric absorption. AIR-1751 provides a method for prediction of lateral attenuation, established by the Society of Automotive Engineers (SAE) in 1981. A particularity of this standard is that it is based on a noise measurements dataset dominated by aircraft with tail-mounted engines. Today' commercial wide-body aircraft fleet is dominated by aircraft with wing-mounted engines. A number of dedicated noise measurement projects have identified an overestimation of lateral noise attenuation in AIR1751 for aircraft with wing-mounted engines and the update process has been initiated by SAE. Airbus applies AIR-1751 in its operational noise level calculation program and therefore required insight in the quality of this standard. For this reason and to support the update work of SAE, supplementary noise measurements at lateral positions were conducted during a planned A300 external noise measurement campaign. This report describes these measurements and provides results in terms of lateral attenuation derived from the measurements. NTIS
Noise Measurement; Aircraft Noise
20050240929 Wichita State Univ., Wichita, KS, USA
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Damage Tolerance of Composite Sandwich Airframe Structures -Additional Results
Tomblin, J. S.; Raju, K. S.; Walker, T.; Acosta, J. F.; Oct. 2005; 86 pp.; In English Contract(s)/Grant(s): 01-C-AQ-WISU-002 Report No.(s): PB2006-101515; No Copyright; Avail.: National Technical Information Service (NTIS)
The behavior of sandwich panels with open holes subjected to in-plane tensile and compressive loads were investigated experimentally. The objective of this study was to establish whether the open-hole damage was more severe compared to an impact damage of equal planar size. Hole diameters of 1, 2, and 4 inches were selected as they represented the planar dimensions of impact damage that produced contrasting failure modes in sandwich panels. The experimental results indicated that the open holes are more severe when compared to impact damage created with different impactor sizes. Comparison with past data revealed that residual strengths of impact damaged sandwich panels tend to approach that of the open hole with increasing residual indentation depth. Similar to impact damage, the single facesheet holes in sandwich panels under compression produced distinct failure modes, which was a function of the hole diameter. A facesheet fracture failure mode was observed for small diameter holes (and through holes of all sizes investigated), while a local instability mode was observed for the 4-inch-diameter hole. The buckling mode seen in sandwich panels with 4-inch-diameter single facesheet holes appeared to blunt the strain concentration due to facesheet bending, resulting in higher compressive strengths compared to smaller size holes. NTIS
Aircraft Structures; Airframe Materials; Airframes; Composite Materials; Composite Structures; Damage; Sandwich Structures; Tolerances (Mechanics)
20050242986 Naval Postgraduate School, Monterey, CA USA
Explanatory Factors for Marine Corps Aviation Maintenance Performance
Chesterton, Gregory L.; Sep. 1, 2005; 131 pp.; In English; Original contains color illustrations Report No.(s): AD-A439388; No Copyright; Avail.: Defense Technical Information Center (DTIC)
The thesis identifies F/A-18 squadron characteristics that are important predictors of maintenance performance and draws insights on the linkage between the utilization of engineering and technical services (ETS) and maintenance performance measures. Statistical analysis is conducted to identify squadron characteristics that have a detectable contribution to the variability of the performance measure man-hours per maintenance action, and how much additional variability is explained by the squadron that is not accounted for by the squadron characteristics already considered. Thirty months of data were collected for thirteen active duty Marine Corps F/A-18 squadrons. Regression is used to model man-hours per maintenance action as a linear combination of explanatory variables that describe the squadrons in terms of manpower, inventory, and ETS metrics. The test for significance indicates that the model developed in this study is highly likely to have better explanatory power than an intercept-only (average) estimate of the response variable. The study concludes with recommendations for data collection methods that would facilitate the correlation of squadron characteristics to ETS utilization. Critical to the success of this approach is the linkage of ETS utilization to specific squadron maintenance activities, and the development of methods to quantify maintainer training currency. DTIC
Aircraft Maintenance; Maintenance
20050243094 Naval Postgraduate School, Monterey, CA USA
Performance Analysis for a Vision-Based Target Tracking System of a Small Unmanned Aerial Vehicle
Trago, Todd M.; Sep. 1, 2005; 87 pp.; In English; Original contains color illustrations Report No.(s): AD-A439564; No Copyright; Avail.: Defense Technical Information Center (DTIC)
This thesis analyzes performance of the vision-based target-tracking system developed at the Naval Postgraduate School using the Monte Carlo method. Specifically, sensitivities of the target position estimation algorithm to various sensor errors are computed and analyzed. Furthermore, dependence of this algorithm on the performance of the target-tracking control system is established. DTIC
Drone Vehicles; Pilotless Aircraft; Radar Tracking; Reliability Analysis; Tracking (Position)
20050243108 Maryland Univ., College Park, MD USA
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The Hybrid Motor Prototype: Design Details and Demonstration Results
Venkataraman, R.; Dayawansa, W. P.; Krishnaprasad, P. S.; Jan. 1, 1998; 15 pp.; In English Contract(s)/Grant(s): DAAG55-97-1-0114; DAAL03-92-G0121 Report No.(s): AD-A439584; CDCSS-TR-98-2; ISR-TR-98-2; No Copyright; Avail.: Defense Technical Information Center (DTIC)
A novel hybrid rotary motor incorporating piezoelectric and magnetostrictive actuators has been designed and demonstrated.
The novelty of this motor was the creation of an electrical resonant circuit, whereby reactive power requirement on the power source is reduced.
It was envisaged that the motor would be suitable for low output speed, high torque applications because of its design.
This report presents the constructional details of this motor and the results of the demonstration.
DTIC
Actuators; Computerized Simulation; Electric Motors; Prototypes
20050243123 Washington Univ., Seattle, WA USA
Seaglider in AUVFEST 2005
Stewart, Marc S.; Newton, Jan; Oct. 1, 2005; 5 pp.; In English Report No.(s): AD-A439604; No Copyright; Avail.: CASI: A01, Hardcopy
Use existing glider operation and maintenance procedures to prepare, employ, and recovery a glider in Dabob Bay and Hood Canal. Use existing glider interface software to 1) automatically reformat measured environmental data from the glider into Navy standard message format files, and 2) transmit those files to Navy channels for assimilation and application. DTIC
Computer Programs; Gliders; Message Processing
20050243144 Naval Postgraduate School, Monterey, CA USA
Unmanned Aerial Vehicle Survivability: The Impacts of Speed, Detectability, and Enemy Capabilities
McMindes, Kevin L.; Sep. 1, 2005; 175 pp.; In English; Original contains color illustrations Report No.(s): AD-A439645; No Copyright; Avail.: CASI: A08, Hardcopy
Warfighters are increasingly relying on Unmanned Aerial Vehicle (UAV) systems at all levels of combat operations. As these systems weave further into the fabric of our tactics and doctrine, their loss will seriously diminish combat effectiveness. This makes the survivability of these systems of utmost importance. Using Agent-based modeling and a Nearly Orthogonal Latin Hypercube design of experiment, numerous factors and levels are explored to gain insight into their impact on, and relative importance to, survivability. Factors investigated include UAV speed, stealth, altitude, and sensor range, as well as enemy force sensor ranges, probability of kill, array of forces, and numerical strength. These factors are varied broadly to ensure robust survivability results regardless of the type of threat. The analysis suggests that a speed of at least 135 knts should be required and that increases in survivability remain appreciable up to about 225 knts. The exception to speed' dominance is in the face of extremely high capability enemy assets. In this case, stealth becomes more important than speed alone. However, the interactions indicate that as both speed and stealth increase, speed yields a faster return on overall survivability and that speed mitigates increased enemy capabilities. DTIC
Combat; Detection; Drone Vehicles; Pilotless Aircraft
20050243148 Naval Postgraduate School, Monterey, CA USA
Error Analysis of Sensor Measurements in a Small UAV
Ackerman, James; Sep. 1, 2005; 63 pp.; In English; Original contains color illustrations Report No.(s): AD-A439651; No Copyright; Avail.: CASI: A04, Hardcopy
This thesis focuses on evaluating the measurement errors in the gimbal system of the SUAV autonomous aircraft developed at NPS. These measurements are used by the vision based target position estimation system developed at NPS. Analysis of the errors inherent in these measurements will help direct future investment in better sensors to improve the estimation system' performance. DTIC
Detection; Drone Vehicles; Error Analysis; Target Acquisition
20050243210 Air Force Logistics Management Center, Gunter AFS, AL USA
Kadena F-15 C/D Cost per Flying Hour Analysis
Howe, Jeremy; Dawson, Kevin; Aug. 16, 2005; 8 pp.; In English Report No.(s): AD-A439752; AFLMA-LM20050700; No Copyright; Avail.: CASI: A02, Hardcopy
Although largely focused on illustrating the impact ofAverage Sortie Duration (ASD) changes on Cost per Flying Hour (CPFH) calculations, this study was also an effort to broadly examine the variety of component failure modes and their influence on aircraft break events during sorties. In conjunction with a notional CPFH calculation moded, correlation and regression techniques were used to examine historical PACAF F-15C/D maintenance data, to include Break Rate, Pilot Reported Discrepancies (PRD) and Total Non-mission Capable for Maintenance (TNMCM) time. The findings of this research indicate that CPFH will increase as ASD decreases, irrespective of the amount of sorties or hours flown. DTIC
Cost Analysis; F-15 Aircraft; Fighter Aircraft; Flight; Maintenance
20050243230 Air Force Inst. of Tech., Wright-Patterson AFB, OH USA
Examining the Impact of Quality Assurance Manning Practices in USAF Aircraft Maintenance Units
Moore, Terry D.; Mar. 1, 2005; 297 pp.; In English; Original contains color illustrations Report No.(s): AD-A439793; AFIT/GLM/ENS/05-18; No Copyright; Avail.: CASI: A13, Hardcopy
The purpose of this research was to examine the impact that current USAF quality Assurance (QA) manning practices has on key aircraft wing-and unit-level metrics. Interviews and surveys culminated in development of a QA Manning Effectiveness Matrix. We then used the matrix to calculate historical QA manning effectiveness at 16 ACC bases. Effectiveness scores were regressed with associated historical data for 26 metrics derived from a Delphi survey. Nine metrics were deemed statistically significant, including break rates, cannibalization rates, flying schedule effectiveness rates, key task list pass rates, maintenance scheduling effectiveness rates, quality verification inspection pass rates, repeat rates, dropped objects counts and safety/technical violations counts. An example benefit cost analysis for changes in QA manning effectiveness was performed, using reasonable cost values. The results present compelling evidence for maintenance managers to carefully weigh decisions to leave QA manning slots empty, or to assign personnel possessing other than authorized credentials. Maintenance managers can use this tool to help determine mitigating strategies for improving unit performance with respect to the nine metrics. DTIC
Maintenance; Procedures; Quality Control
Source: NASA.
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