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calculations illustrate the procedure for a class of practical shapes of the type that include aerodynamic and hydrodynamic surfaces. Equations are also included for computing the spreading of rays into a surrounding medium that will support waves. Author
N89-26812# International Centre for Theoretical Physics, Trieste (Italy). MHD FORCED AND FREE CONVECTION BOUNDARY LAYER FLOW NEAR THE LEADING EDGE M. A. Hossain and M. Ahmed (Dacca Univ., Bangladesh ) Jul. 1988 20 p Submitted for publication (DE88-705974; IC-88/140) Avail: NTIS (US Sales Only) HC A03/MF A01
Magnetohydrodynamic forced and free convection flow of an electrically conducting viscous incompressible fluid past a vertical flat plate with uniform heat flux in the presence of a magnetic field acting normal to the plate that moves with the fluid has been studied near the leading edge of the plate. The coupled non-linear equations are solved by the method of superposition for the values of the Prandtl number ranges from 0.01 to 10.0. The velocity and the temperature profiles are presented graphically and the values of the wall shear-stress as well as the heat transfer rate are presented in tabular form showing the effect of the buoyancy force and the applied magnetic field. To show the accuracy of the present method some typical values are compared with the available one.
(NASA Order L-29341-C) (NASA-CR-181841; NAS 1.26:181841; VS-1-88) Avail: NTIS HC A06/MF A01 CSCL 01A
A 1 inch circular jet moving over a fixed ground board was studied in the NASA Langley Research Center Vortex Research Center. The jet passing over the ground board at a height of three nozzle diameters creates a ground vortex which was measured by a pattern of Endevco high response pressure transducers. The results are compared to existing data to determine the effect of the ground boundary eliminated by the moving jet. The penetration of the vortex both forward of and latterly to the impact point of the jet on the ground. The resulting ground vortex penetration forward of the impact point is reduced by approximately 30 percent and the lateral penetration is reduced by 50 percent over that experienced from a stationary jet over a stationary ground board with a free stream velocity.
N89-26816*# National Aeronautics and Space Administration. Ames Research Center, Moffett Field, CA. EXPERIMENTAL PROGRAM FOR REAL GAS FLOW CODE VALIDATION AT NASA AMES RESEARCH CENTER George S. Deiwert, Anthony W. Strawa, Surendra P. Sharma, and Chul Park Jul. 1989 19 p Presented at the AGARD Symposium on Validation of Computational Fluid Dynamics, Lisbon, Portugal, 2-5 May 1988 Previously announced as N89-18630 (NASA-TM-100093; A-88135; NAS 1.15:100093) Avail: NTIS HC A03/MF A01 CSCL 01A
The experimental program for validating real gas hypersonic flow codes at NASA Ames Rsearch Center is described. Ground-based test facilities used include ballistic ranges, shock tubes and shock tunnels, arc jet facilities and heated-air hypersonic wind tunnels. Also included are large-scale computer systems for kinetic theory simulations and benchmark code solutions. Flight tests consist of the Aeroassist Flight Experiment, the Space Shuttle, Project Fire 2, and planetary probes such as Galileo, Pioneer Venus, and PAET.
N89-26813# Coleman Research Corp., Huntsville, AL. EXPENDABLE AIR VEHICLES/HIGH ALTITUDE BALLOON TECHNOLOGY Final Report, 13 Jul. 1988 - 28 Feb. 1989 Robert L. Hawkins 28 Feb. 1989 (Contract DAAH01-88-C-0581; ARPA Order 5916) (AD-A206972; CHR/89-1909) Avail: NTIS HC A05/MF A01 CSCL 01/3
Coleman Research Corporation demonstrates a capability to produce drift patterns for high-altitude zero-pressure and super-pressure balloons. A simplified balloon dynamics model and a highly detailed, statistical wind model are integrated into a proprietary flight simulation framework to enable the production of balloon drift patterns. The worldwide, time-dependent wind model in conjunction with the data-configurable balloon model allow the production and analysis of drift patterns for balloons launched from any point on the earth's surface at any time of year. Sample drift patterns are produced for a zero-pressure balloon floating at 70,000 feet for 24 hours and for a super-pressure balloon floating at 120,000 feet for one year.
N89-26817# Advisory Group for Aerospace Research and
In ENGLISH and FRENCH Review held in
The papers presented at the AGARD Fluid Dynamics Panel Technical Status Review on, Drag Prediction and Analysis from Computational Fluid Dynamics: State of the Art, are contained. Speakers presented a state of the art review from their individual nation. The Program Chairman summarized the key conclusions from all the papers presented. It is recommended that the Fluid Dynamics Panel consider possibilities for further stimulation of progress in the field of CFD-based drag prediction and analysis. For individual titles, see N89-26818 through N89-26825.
N89-26814# California Univ., Irvine. Dept. of Physics. SUPERSONICS Final Report, Apr. 1985 - Jun. 1988 R. F. Wallis Mar. 1989 83 p (Contract F33615-85-K-2501) (AD-A207394; AFWAL-TR-88-2141) Avail: NTIS HC A05/MF A01 CSCL 20/12
The correlation between the infrared and Raman spectra of lithium borate glasses and their structure has been investigated. The results are consistent with the increasing incorporation of tetrahedrally coordinated boron into the boroxol rings with increasing Li2O content. The spectra reveal the onset of crystallization as the annealing temperature increases. The variation of the ionic conductivity with temperature and composition is shown to be well described by a weak electrolyte theory. The conductivity increases by an order of magnitude when the fractional content of Li2SO4 increases from 0.00 to 0.15. A tight binding method has been used to calculate the energy bands of Inse and the activation energy for motion of Li+ in the Van der Waals gap of Inse. The increase in resistance of a lithium borate glass sample when the Li + ions are required to flow into the Van der Waals gaps of a contiguous InSe sample has been investigated. GRA
N89-26818# Office National d'Etudes et de Recherches
Various two-dimensional and three-dimensional inviscid-flow methods for drag component analysis are presented which are based on solving either the potential equation or the Euler equations. Comparison with experimental results demonstrates that coupled methods can predict drag to within a few percent. It is suggested that the pressure term should be replaced in the
N89-26815*# Stewart (V. R.), Columbus, OH.
two-dimensional case by the shock drag term and in the three-dimensional case by the sum of the induced drag and the shock drag.
N89-26819# Dornier-Werke G.m.b.H., Friedrichshafen (Germany,
(For primary document see N89-26817 21-02) Copyright Avail: NTIS HC A08/MF A01
Consistent and accurate prediction of absolute drag for aircraft configurations is currently beyond reach computationally as well as experimentally using wind tunnel model testing. This is attributed to several elements ranging from lack of physical understanding up to limitations in numerical methods and scaling laws. To access drag by computational methods, drag components and the overall drag built-up have to be specified. For the individual drag component semi-empirical as well as theoretical estimates are discussed. Problems and limitations in drag estimates using computational fluid mechanics (CFD) are demonstrated for different types of flowfields. Within the scope of the present conference, our survey over the state-of-the-art in Germany will cover industrial aspects for commuter and transport aircraft, trainer, as well as fighter configurations, missiles, and space vehicles. Author
N89-26822# National Aerospace Lab., Amsterdam (Netherlands).
The state-of-the-art on computational drag prediction and diagnostics in The Netherlands for transport aircraft in the transonic flight regime is described. Subsequently, a method is discussed that is currently being developed at NLR to calculate wave drag in transonic potential flow. The method is a generalization and extension of Garabedian's and McFadden's idea of determining wave drag by volume-integration of the artificial viscosity. The generalization involves the introduction of a reference artificial viscosity which provides a solid theoretical basis. At the same time this ensures that calculated wave drag is to a certain extent independent of the specific details of the artificial viscosity in different codes. The extension accounts for the fact that artificial viscosity does not smear out supersonic/subsonic shock waves completely, but leaves room for a truly discontinuous sonic/ subsonic shock remainder that contributes substantially to the wave drag. A number of first results that illustrate the potential of the method are presented and discussed.
N89-26820# National Technical Univ., Athens (Greece). Lab. of Thermal Turbomachines. SOME RESULTS ON FLOW CALCULATIONS INVOLVING DRAG PREDICTION K. D. Papailiou In AGARD, Technical Status Review on Drag Prediction and Analysis from Computational Fluid Dynamics: State of the Art Jun. 1989
(For primary document see N89-26817 21-02) Copyright Avail: NTIS HC A08/MF A01
Different calculation methods were developed in the Thermal Turbomachinery Lab. of the Athens National Technical University concerning drag prediction. A Navier-Stokes solver, based on a fractional step method, was developed in order to solve viscous incompressible flow in ducts. A second Navier-Stokes solver was developed for transonic flow using, again, a fractional step method, but this time for quasi-three dimensional cascade flow. Integral methods were developed as well in order to predict secondary flows in compressors and shear layer development on blades. High speed laminar and turbulent flow is predicted, attached and separated. Viscous inviscid interaction techniques were developed for the stabilization of the separated flow calculation. Phenomena such as transitional flow, laminar separation bubbles and shock/shear layer interaction for turbulent flow are predicted with good accuracy. The general methods will be reviewed briefly and results will be presented.
N89-26823# Royal Aircraft Establishment, Bedford (England).
(For primary document see N89-26817 21-02) Copyright Avail: NTIS HC A08/MF A01
Computational methods developed in UK for the prediction of the drag of aircraft components at subsonic and supersonic speeds are critically reviewed. In many cases, the flow modeling is found to be lacking in certain respects. Despite this, however, the review suggests that these methods have a useful function both in the early stages of aircraft design, when they may be used to study differences in the drag of various shapes, and later in support of wind-tunnel tests as a diagnostic tool and also to extrapolate the data to full scale.
N89-26824*# National Aeronautics and Space Administration.
Previously announced as N88-22009 (For primary document see N89-26817 21-02) Copyright Avail: NTIS HC A08/MF A01 CSCL 01A
Results from the Viscous Transonic Airfoil Workshop held in January 1987, are compared with each other and with experimental data. Test cases used include attached and separated transonic flows for the NACA 0012 airfoil. A total of 23 sets of numerical results from 15 different author groups are included. The numerical methods used vary widely and include: 16 Navier-Stokes methods, 2 Euler/boundary-layer methods, and 5 potential/boundary-layer methods. The results indicate a high degree of sophistication among the numerical methods with generally good agreement between the various computed and experimental results for attached or moderately separated cases. The agreement for cases with larger separation is only fair and suggests additional work is required in this area.
N89-26821# Aeritalia S.p.A., Turin (Italy). Combat Aircraft
(For primary document see N89-26817 21-02) Copyright Avail: NTIS HC A08/MF A01
The state-of-the-art in Italy on the aerodynamic drag prediction, based on theoretical methods, is presented and discussed. A brief description of the methods used is given, with examples of application for typical aircraft configurations. A survey of critical areas is provided, together with present research activities to improve the drag prediction capabilities and accuracy. Author
N89-26825# Grumman Aerospace Corp., Bethpage, NY. Aircraft
Consistent and accurate Computation Fluid Dynamics (CFD) prediction of absolute drag level for aircraft configurations is currently beyond reach. This is attributed to several elements characterizing state-of-the-art computer algorithms and hardware. With considerable research focused on the 2-D airfoil analysis problem, an exercise is conducted to quantify the implications for 3-D wings. Recent highlights in the U.S.A. which have advanced drag prediction capabilities or improved understanding of the problem are described. Examples are taken from the areas of computational physics, viscous airfoil simulation, component analysis, hypersonics, and conceptual design/configuration optimization. Primary attention is concentrated on aircraft but helicopter, missile, and automobile cases are also included. A near term solution to the CFD drag prediction problem can not be identified. Instead, means based on CFD's strengths are discussed which make computational methods valuable for drag reduction/prediction during aerodynamic design processes.
N89-26828# Naval Air Development Center, Warminster, PA.
Color coding of aircraft display information, when used properly, can decrease the pilot's workload in performing certain visual tasks. In order to be effective, the luminance levels and chromaticity coordinates (with limits) need to be specified. This report provides human factors design guidelines for developing color display criteria. The issues addressed include luminance contrast, color differences, sunlight ambient illumination, and chromaticity recommendations.
N89-26826*# Old Dominion Univ., Norfolk, VA. Dept. of Mechanical Engineering and Mechanics. NUMERICAL STUDY OF THREE-DIMENSIONAL SEPARATION AND FLOW CONTROL AT A WING/BODY JUNCTION Progress Report, period ended 30 Apr. 1989 Robert L. Ash and Balakrishnan Lakshmanan Aug. 1989 214 p (Grant NAG1-530) (NASA-CR-185819; NAS 1.26:185819) Avail: NTIS HC A10/MF A01 CSCL 01A
The problem of three-dimensional separation and flow control at a wing/body junction has been investigated numerically using a three-dimensional Navier-Stokes code. The numerical code employs an algebraic grid generation technique for generating the grid for unmodified junction and an elliptic grid generation technique for filleted fin junction. The results for laminar flow past a blunt fin/flat plate junction demonstrate that after grid refinement, the computations agree with experiment and reveal a strong dependency of the number of vortices at the junction on Mach number and Reynolds number. The numerical results for pressure distribution, particle paths and limiting streamlines for turbulent flow past a swept fin show a decrease in the peak pressure and in the extent of the separated flow region compared to the laminar case. The results for a filleted juncture indicate that the streamline patterns lose much of their vortical character with proper filleting. Fillets with a radius of three and one-half times the fin leading edge diameter or two times the incoming boundary layer thickness, significantly weaken the usual necklace interaction vortex for the Mach number and Reynolds number considered in the present study.
N89-26829# Textron Bell Helicopter, Fort Worth, TX.
Special energy attenuating seats are used to provide a controlled deceleration over a vertical stroking distance to keep aircraft crash loads within human tolerance. Present energy attenuating crew seats use this approach of translating the entire seat vertically. This requires an area clear of equipment and structure between the seat and the fuselage floor. Installation of an energy attenuating seat in the OH-58 could provide reduced spinal loading in some crashes. However, the OH-58 crew seat is integral with the aircraft structure with no room for an energy attenuating seat which gave rise to the belief that a stroking energy attenuating seat was not technically feasible. An innovative approach was needed to provide such seats with a minimum of OH-58 structural modification. A pivoting seat pan design was conceived and feasibility study was performed for the U.S. Army to provide this preliminary design, fabricate test seats, and modify a dynamic test fuselage and a flyable aircraft. Dynamic testing was performed to prove the feasibility of the pivoting seat pan energy attenuating crew seat approach. This report discusses the approach which can provide energy attenuating crew seats to be installed in an OH-58, while providing a concept which could potentially provide similar solutions for other aircraft. GRA
N89-26827# Technische Univ., Delft (Netherlands).
The application of the nonlinear multigrid method to three-dimensional transonic potential flow is discussed. The flow is described by the full potential equation, which is discretized using a finite volume method. The smoothing algorithm in the multigrid method is a combination of Incomplete Lower Upper decomposition and Strongly Implicit Procedure. In general this algorithm is a faster smoothing algorithm than the often used successive line relaxation, while it is also more robust, because it
N89-26830# Federal Aviation Administration, Washington, DC.
A series of 55 light-airplane accidents was examined in an effort to demonstrate the role of seats in the genesis of injury in seat occupants. Good engineering design of airplane seats is an important related issue which is not treated in this study. Case selection attempted to include only those events in which significant but not extreme accelerations occurred. Ten of the fifty-five cases involved joint failure of seats and restraint systems. The majority of the observations were provided by aviation medical examiners who were typically very highly motivated practitioners of medicine with special interests and accomplishments in aviation. The other cases were reported by FAA accident investigators. No reliable marker of energy level was found in the data collected to control the finding that large accelerations tend to injure people and damage seats as well as most other structures regardless of the other interrelationships that might be involved.
04 AIRCRAFT COMMUNICATIONS AND
Includes digital and voice communication with aircraft; air navigation systems (satellite and ground based); and air traffic control.
For related information see also 17 Space Communications, Spacecraft Communications, Command and Tracking and Communications and Radar.
N89-26831# Federal Aviation Administration, Atlantic City, NJ.
An analysis by the Federal Aviation Administration predicted Loran C coverage could be expanded throughout the interior of Alaska by modification of an existing Loran C transmitter. The modification would include adding Loran C station Port Clarence as a secondary on the Gulf of Alaska chain (7960) by dual rating the station. A flight test probe conducted in the summer of 1987 into the interior of Alaska to determine the extent of usable signals after dual rating Loran C station Port Clarence is described. Flight measurements indicated a largely increased operational area located in the middle to southern interior of Alaska. Author
the MLS at Miami/Tamiami, Florida Airport. The demonstration/ flight test was conducted in conjunction with an MLS seminar jointly sponsored by U.S. Department of Transportation, FAA, and Transport Canada Aviation Group. The Technical Center's MLS test bed, consisting of a 1.5 deg beamwidth elevation station and a 2 deg beamwidth azimuth station, was transported to, and temporarily installed at the Miami/Tamiami Airport on runway 9R, collocated with the commissioned instrument landing system (ILS). Additionally, an E-Systems preproduction model precision distance measuring equipment (DME/P) transponder was also installed adjacent to the runway 9R localizer equipment shelter. On March 29, 1989, seven 1-hour demonstration and data collection flights were flown for over 60 aviation, industry, and U.S. and international Government attendees. By careful siting of the MLS on runway 9R, proportional MLS signal coverage was also obtained in the approach regions of runways 9L and 13. By utilizing an FAA Technical Center designed and fabricated MLS area navigation (RNAV) computer on board the demonstration aircraft, precision approaches were flown not only to runway 9R, but also to runways 9L and 13. This demonstrated the tremendous flexibility and operational capability of MLS. The MLS signalin-space on runway 9R met Category 2 ILS tolerances. No degradation of the ILS performance due to the MLS collocation was detected during this demonstration.
Author N89-26834# University of Southern California, Los Angeles. Inst. for Robotics and Intelligent Systems. RESEARCH IN KNOWLEDGE-BASED VISION TECHNIQUES FOR THE AUTONOMOUS LAND VEHICLE PROGRAM Annual Technical Report No. 3, 1 Jun. 1987 - 31 May 1988 R. Nevatia, ed., K. Price, ed., W. Franzen, S. Gazit, G. Medioni, I. Paolin, and S. Peng Dec. 1988 87 p Prepared in cooperation with Defense Advanced Research Projects Agency, Arlington, VA; and Army Engineer Topographic Labs., Fort Belvoir, VA (Contract DACA76-85-C-0009) (AD-A208546; IRIS-248; ETL-0522) Avail: NTIS HC A05/MF A01 CSCL 12/9
This report describes our research in motion analysis and estimation techniques. This research is of particular relevance to the DARPA Autonomous Land Vehicle (ALV) program, but should also be of other general utility. Our basic approach for detecting and tracking motion is to extract and match features, such as lines and regions, from a sequence and to generate emotion estimates from these. We present one report on matching edge elements in connected line segments (contours) in a sequence of views. This work assumes relatively small motions between views. We also present a report on an alternative representation for motion and a technique to use occlusion in spatio-temporal analysis. We also present results from a basic integrated system that combines feature extraction, matching and motion estimation.
N89-26832*# Federal Aviation Administration, Atlantic City, NJ. ILS/MLS COLLOCATION TESTS AT MIAMI/TAMIAMI, FLORIDA AIRPORT John Townsend Jun. 1989 23 p (NASA Order T-0604-L) (NASA-CR-185715; NAS 1.26:185715; DOT/FAA/CT-TN89/38) Avail: NTIS HC A03/MF A01 CSCL 17G
A series of tests were performed by the Federal Aviation Administration (FAA) Technical Center at the Miami/Tamiami, Florida, Airport to verify the guidance material contained in the proposed amendments to Attachment G to Part 1 of the International Civil Aviation Organization (ICAO) Annex 10. A mock-up of the Technical Center's Test Bed Microwave Landing System (MLS) was collocated with the category 1 instrument landing system (ILS) on runway 9R. Several engineering flight tests were flown with ILS data collected and analyzed. These results were later verified by actually installing the MLS test bed at one of the locations used for the mockup tests. The results indicate that the proposed guidelines are adequate as published, but several items should be considered when implementing these guidelines. These items are presented as recommendations.
05 AIRCRAFT DESIGN, TESTING AND
Includes aircraft simulation technology.
For related information see also 18 Spacecraft Design, Testing and Performance and 39 Structural Mechanics. For land transportation vehicles see 85 Urban Technology and Transportation
N89-26833# Federal Aviation Administration, Atlantic City, NJ. AN OPERATIONAL DEMONSTRATION AND FLIGHT TEST OF THE MICROWAVE LANDING SYSTEM (MLS) AT THE MIAMI/TAMIAMI, FLORIDA AIRPORT Technical Report, Apr. 1989 Vincent L. Bencivenga and Robert H. Pursel Jul. 1989 37 p (DOT/FAA/CT-TN89/37) Avail: NTIS HC A03/MF A01
At the request of the Microwave Landing System (MLS) Program Office, the Federal Aviation Administration (FAA) Technical Center conducted an operational demonstration and flight test of
N89-26835# National Aerospace Lab., Tokyo (Japan). STOL
The possibility of applications to various types of transports of the overwhelming high lift capability inherent in the USB powered lift concept was investigated with the use of a computer aided design (CAD) program. Emphasis is placed on the application of USB technology to regional transports of both land based and amphibian types, because of their relatively high probability of (e.g., less than 0.05') and to large through-the-thickness cracks (e.g., 0.5' to 0.75') associated with fuel leakage/ligament breakage.
realization relating to the 4th national comprehensive development plan. In addition to the CAD study, some relevant subjects such as examination of the predicted demand for regional air transportation, an evaluation of the engine cross shafting concept, an estimation of aerodynamic derivatives due to side-slip motion, consideration of common aircraft structure for both land based and amphibian type aircraft, and a survey of advanced navigation systems were also studied.
N89-26836 Department of the Air Force, Washington, DC.
A bank of comparators is used to control a logic circuit which indicates proper system operation when measured hydraulic reel motor control pressures are within normal limits for the current airspeed after hose deployment. Also, before such deployment, simulated test signals are applied to the comparators to ensure proper operation of the comparators and logic circuitry. GRA
N89-26839# Army Aviation Engineering Flight Activity, Edwards
The U.S. Army Aviation Engineering Flight Activity conducted a limited Airworthiness and Flight Characteristics test of the EH-60A (Quick Fix) helicopter. During the test program, 49 flights were conducted for a total of 63.5 hours, of which 47.1 were productive. Initially the EH-60A was modified to the utility configuration where 22.3 productive hours were flown airspeed calibration, level flight performance, and vibration characteristics. All tests were performed at a Quick Fix mission center of gravity of approximately 361.9 fuselage station for both the utility and Quick Fix configuration. The Quick Fix configuration resulted in a 5.2 square feet increase in equivalent flat plate area which results in a 5 percent degradation in specific range at the recommended cruise airspeed, a 2 percent increase in fuel flow at the maximum endurance airspeed, and a 4 knot degradation in maximum level flight airspeed at sea level standard day conditions and mission gross weight (17,200 pound). The handling qualities of the Quick Fix configured EH-60A were essentially unchanged from the standard UH-60A helicopter. The clearance between the main rotor blades and direction finding dipole antennas during nose down slope landings was adequate. The absence of lower console lighting for the communication and navigation equipment was identified as a deficiency. GRA
N89-26837 Department of the Air Force, Washington, DC.
This patent comprises a combination boundary layer control system that uses both suction and cryogenic wall cooling to reduce aircraft drag. The invention is particulary useful in circumstances where liquid hydrogen or other cryogenic fuels are used to operate the aircraft. In the preferred embodiment, a network of D-tube ducts are provided that are fluidly connected to a cryogenic fluid source. These cryogenic fluid ducts are selectively fed cryogenic fluid to reduce aircraft surface temperature and promote adhesion of boundary layer air to the aircraft. An air duct system is also provided to apply suction to the aircraft surface in order to remove the boundary layer at low altitude. The suction is applied by means of a multitude of minute holes in the aircraft skin which are fluidly connected to the air duct system.
N89-26838# General Dynamics Corp., Fort Worth, TX. ADVANCED DURABILITY ANALYSIS. VOLUME 2: ANALYTICAL PREDICTIONS, TEST RESULTS AND ANALYTICAL CORRELATIONS Final Report, Oct. 1984 - Feb. 1989 S. D. Manning and J. N. Yang (United Analysis, Inc., Vienna, VA.) 27 Feb. 1989 286 p (Contract F33615-84-C-3208) (AD-A207215; AFWAL-TR-86-3017-Vol-2) Avail: NTIS HC A13/MF A01 CSCL 01/3
Advanced durability analysis design tools have been developed for metallic aircraft structures. These tools can be used to evaluate durability design requirements for functional impairments due to: (1) excessive cracking, and (2) fuel leakage ligament breakage. The methodology accounts for the initial fatigue quality variation of structural details, the crack growth accumulation for a population of structural details under specified design conditions and structural properties. Step by step procedures are provided. This volume is limited to the analytical methods, technical aspects, concepts and philosophy for the durability analysis of metallic aircraft structures. The methodology reflects a probabilistic approach, a fracture mechanics philosophy and both deterministic and stochastic crack growth methods. It can be used to predict the probability of crack exceedance at any service time and/or the cumulative distribution of the time to reach any crack size. The methodology applies to the small crack size range associated with excessive cracking
N89-26840# Army Aviation Engineering Flight Activity, Edwards
Testing was conducted to determine the effects of the installation of the External Fuel System (EFS) on the performance and handling qualities of the UH-60A helicopter. A total of 27 productive flight hours were flown at Edwards Air Force Base, California between 21 March and 20 May 1988. The evaluation did not reveal any problems that should preclude airworthiness qualification. The installation of the EFS with two 230-gallon tanks caused an increase in power required to hover in ground effect (10-foot wheel height) and out of ground effect of approximately 5 percent and 6 percent, respectively. The change in equivalent flat plate area in the EFS configuration with two 230-gallon tanks varied from 6.2 to 12.4 square feet when compared to the UH-60A in the normal utility configuration. The drag of the UH-60A in the EFS configuration with two 230-gallon tanks is significantly increased when the cargo doors and gunner windows are open. Three shortcomings and two Prime Item Development Specification noncompliances were identified during the handling qualities evaluation of the UH-60A in the EFS configuration. Two of the shortcomings have been noted during previous evaluations of the UH-60A in the normal utility configuration. Handling qualities were not significantly different than those of the UH-604 in the normal utility configuration.
N89-26841*# McDonnell-Douglas Corp., Long Beach, CA.