N74-17702*# National Aeronautics and Space Administration. Ames Research Center, Moffett Field, Calif. NORMAL LOADS PROGRAM FOR AERODYNAMIC LIFTING SURFACE THEORY Richard T. Medan and K. Susan Ray, (Computer Sci. Corp., Mt. View, Calif.) Feb. 1974 94 p refs (NASA-TM-X-62326) Avail: NTIS HC $7.75 CSCL 01A A description of and users manual are presented for a U.S.A. FORTRAN computer program which evaluates spanwise and chordwise loading distributions, lift coefficient, pitching moment coefficient, and other stability derivatives for thin wings in linearized, steady, subsonic flow. The program is based on a kernel function method lifting surface theory and is applicable to a large class of planforms including asymmetrical ones and ones with mixed straight and curved edges. Author N74-17703*# National Aeronautics and Space Administration. Flight Research Center, Edwards, Calif. DRAG REDUCTION OBTAINED BY ROUNDING VERTICAL CORNERS ON A BOX-SHAPED GROUND VEHICLE Edwin J. Saltzman and Robert R. Meyer, Jr. Mar. 1974 20 p refs (NASA-TM-X-56023) Avail: NTIS HC $4.00 CSCL 01A A box-shaped ground vehicle was used to simulate the aerodynamic drag of delivery vans, trucks, and motor homes. A coast-down method was used to define the drag of this vehicle in a configuration with all square corners and a modified configuration with the four vertical corners rounded. The tests ranged in velocity from 30 miles per hour to 65 miles per hour,. and Reynolds numbers ranged from 4.4 x 1,000,000 to 1.0 x 10 to the 7th power based on vehicle length. The modified configuration showed a reduction in aerodynamic drag of about 40 percent as compared to the square cornered configuration. Author N74-17704# Aeronautical Research Inst. of Sweden, Stockholm. Aerodynamics Dept. SUPERSONIC AND TRANSONIC WIND TUNNEL TESTS ON A SLENDER OGIVE-CYLINDER BODY SINGLE AND IN COMBINATION WITH CRUCIFORM WINGS AND TAILS OF DIFFERENT SIZES Final Report S. E. Gudmundson and L. Torngren Apr. 1972 115 p refs (Contracts INK-11-12-93490; INK-11-12-02871) (FFA-AU-772) Avail: NTIS HC $8.75 Wind tunnel tests were performed at different Mach numbers on a long cylindrical body with long ogive nose. Symmetrical forces were measured for the body alone and for different combinations of body and cruciform wings of two different sizes and cruciform tails of three different sizes. For one wing and tail size two different positions of the wing were tested. Normal force and pitching moment were also measured for the two wings alone. For two model configurations some investigations were made at two Mach numbers of the effect of different boundary layer transition trips. The results were compared with results from other wind tunnels. The agreement between the results is reasonably good. Author (ESRO) STROEMUNG] G. Gregoriou Bonn Bundeswehramt 1973 41 p refs In GERMAN; ENGLISH summary Sponsored by Bundesmin. der Verteidigung (BMVg-FBWT-73-33) Avail: NTIS HC $5.25; Bundeswehramt. Bonn 30 DM Based on potential theory an iterative singularity-method was developed which yields the pressure distribution of symmetric wing-body configurations at angle of attack at subsonic speed The body is axisymmetric and of finite length. The wing is infinitely thin and located at mid-wing position. The results obtained were compared to both the results of other theories and the results of several wind tunnel tests. Author (ESRO) N74-17708# Dornier-Werke G.m.b.H., Friedrichshafen (West P. Kuehl Bonn Bundeswehramt 1973 30 p refs In GERMAN; ENGLISH summary Sponsored by Bundesmin. der Verteidigung (BMVg-FBWT-73-34) Avail: NTIS HC $4.50; Bundeswehramt, Bonn 20 DM An existing computer program was used, after some modifications, to calculate pressures, forces, and moments acting on an aircraft with external-mounted stores. The program is a so-called panel-program, that is, the configuration of interest is replaced by a large number of small surface elements associ. ated with one or more special types of singularity. The strength of these singularities is determined by the given boundary conditions. Once the singularity strengths are known, velocities and pressures may be easily computed. This method seems to be successful for difficult interference problems. Calculations were carried out for simple configurations such as a parabolic body of revolution or a flat delta wing in order to compare calculated results with exact theory available in these cases. Finally calculations were performed on configurations including stores. Results are presented and discussed, leading to proposals for an improvement of the program. Author (ESRO) N74-17709# National Physical Lab.. Teddington (England) Aerodynamics Div. LOW-SPEED AERODYNAMIC CHARACTERISTICS OF NACA 0012 AEROFOIL SECTION. INCLUDING THE EFFECTS OF UPPER-SURFACE ROUGHNESS SIMULATING HOAR FROST N. Gregory and C. L. OReilly Aeron. Res. Council 1973 35 p refs Supersedes ARC-31719; N71-11016 (ARC-R/M-3726; ARC-31719) Avail: NTIS HC $4.75; HMSO £1.35; PHI $5.30 Aerodynamic characteristics of NACA 0012 airfoil section at Reynolds numbers of 2.88 million and 1.44 million with some indications of scale effect at other Reynolds numbers are presented. The measurement of C sub Lmax at a Reynolds number of 2.88 million is uncertain. A laminar separation bubble disappears intermittently. The flow broke down into a three-dimensional pattern when an appreciable extent of separation was present. Boundary-layer control by suction in the vicinity of the wing/wall junction is shown to improve the two-dimensionality in the early stages of separation, but does not inhibit the appearance of three-dimensional flow at and beyond the stall. Distributed roughness was progressively applied from the trailing edge forwards over the upper surface of the airfoil. Both sparse and dense distributions were used and they were intended to simulate the hoar frost deposit remaining after partial cleaning of the forward part of the airfoil. Subject to the above qualifications C sub Lmax, is not greatly reduced until the front edge of the roughness extends forward of 0.1 chord, at which stage also the drag increment due to the roughness rapidly becomes much larger. Author (ESRO) N74-17710# Lockheed-Georgia Co., Marietta. Flight Sciences Div. THEORETICAL AND EXPERIMENTAL INVESTIGATIONS OF VORTEX LIFT CONTROL BY SPANWISE BLOWING. VOLUME 1: EXPERIMENTAL RESEARCH Final Technical Report, 15 Apr. 1972 15 Sep. 1973 C. J. Dixon, J. G. Theisen, and R. M. Scruggs 15 Sep. 1973 123 p refs 2 Vol. (Contract N00014-72-C-0237; NR Proj. 215-201) (AD-771290; LG73ER-0169-Vol-1) Avail: NTIS CSCL 01/1 Experimental investigations of spanwise blowing as a means of controlling leading edge vortices and flow separation have been conducted in five phases. Significant results from each phase are reported in this volume. The five (5) phases are: Smoke Tunnel Flow Visualization; Laser Doppler Velocimeter Investigations of the flow field of an under-expanded jet near and paralled to a flat plate; force tests of spanwise blowing over a 45 degree swept horizontal tail configuration; force test with spanwise blowing on an Aspect ratio 4.4. 20 degree swept wing; and pressure tests on the 20 degree wing. (Modified author abstract) GRA N74-17711# Lockheed-Georgia Co., Marietta. Jerome G. Theisen, Roy M. Scruggs, and Charles J. Dixon 15 Sep. 1973 108 p refs 2 Vol. (Contract N00014-72-C-0237) (AD-771304; LG73ER-0169-Vol-2) Avail: NTIS CSCL 01/1 A theoretical description is presented on the experimentally observed phenomenon of wing leading-edge vortex lift control by spanwise mass injection. The vortex and jet initial source/sink strengths and locations are established by a conformal mapping solution, and used as starting conditions for an iterative vortex-lattice simulation. The spanwise jet is shown to augment the stability of a vortex which forms at high angles-of-attack in the leading-edge region where wings of moderate-to-high aspect ratio otherwise exhibit fully turbulent separation. Definitive results are obtained on wing lift and corresponding pressure distributions for comparison with the test data presented in Volume I. (Modified author abstract) GRA N74-17712# Naval Weapons Lab., Dahlgren, Va. Frank L. Stevens Oct. 1973 44 p refs Maple-Synge theory is used to establish the analytical form of the aerodynamic forces and moments acting on a four-finned, curved-finned vehicle. The linearized equations of motion are solved, and the effects of the curved-finned aerodynamics on the stability of motion are investigated. It is shown that small and moderate values of yawing moment due to angle-of-attack, characteristic of curved-finned configurations, can have significant effects on both transient and steady-state stability. Author (GRA) N 74-17713# National Aeronautical Establishment, Ottawa (Ontario). Low Speed Aerodynamics Section. THE AERODYNAMICS OF BRIDGE ROAD DECKS AND THE ROLE OF WIND TUNNEL INVESTIGATIONS Final Report R. L. Wardlaw Sep. 1973 42 p refs Presented at the 1st FCP Res. Progr. Rev. for Category 4 and 5, San Francisco, 17-20 Sep. 1973 Sponsored by DOT (PB-224876/3GA; FHWA-RD-73-76) Avail: NTIS HC $4.25 CSCL 13B The report presents a review of aerodynamic bridge deck instability. Wind tunnel section model tests of cable-stayed bridge decks are presented. A degree of streamlining of the bridge deck profile is shown to reduce vibrational amplitudes due to critical wind velocities to insignificant levels. Results of dynamic sectional model tests of the proposed Pasco-Kennewick Intercity cable-stayed bridge are presented. Author (GRA) N74-17714# Army Missile Test and Evaluation Directorate, White Sands Missile Range, N. Mex. RESULTS OF A TRANSONIC WIND TUNNEL INVESTIGATION OF THRUST EFFECTS ON THE AERODYNAMICS OF THE LONGBOW MISSILE CONFIGURATION J. H. Henderson 12 Nov. 1973 81 p refs (DA Proj. 1M2-62303-A-214) (AD-771943; RD-TR-73-18) Avail: NTIS CSCL 20/4 Transonic wind tunnel tests were conducted on a strutmounted model of the LONGBOW missile configuration to determine thrust effects on a body of revolution afterbody with fins located at various longitudina! positions. Thrust was simulated by a cold air axial jet. Base pressure and afterbody forces and moments were measured. The test was conducted at Mach numbers from 0.4 to 1.25 and at angles of attack from -2 degrees to 10 degrees. Jet thrust was varied from 0 to 400 pounds. Reynolds number per foot varied from 0.7 to 1.7 million. (Modified author abstract) GRA The report describes an experimental research program in which the outer section of a UH-1D helicopter blade was modified to incorporate a system for injecting the trailing tip vortex produced by the blade with a mass of linearly-directed air, and also an Ogee-tip section to study its effect as a passive system on vortex dissipation. The effects of mass injection were investigated at low mass flow rates, at near-sonic injection velocities, and with a two-section nozzle. The results are presented in terms of quantitative measurements of circulation strength as a function of mass flow rate and thrust, and are correlated with the results from previous research done at RASA. Also presented are flow-visualization studies which were conducted using illuminated helium bubbles, smoke, and tuft grids. The results of this research program present additional confirming evidence that mass injection of the concentrated tip vortex is a practical approach to the elimination of the strong induced effects on a lifting surface of the circulatory flow associated with a concentrated vortex generated at the tip of a helicopter rotor blade. Author (GRA) N74-17716# Ballistic Research Labs., Aberdeen Proving Ground, Md. Exterior Ballistics Lab. ESTIMATION OF THE STATIC AERODYNAMIC CHARACTERISTICS OF ORDNANCE PROJECTILES AT SUPERSONIC SPEEDS Robert L. McCoy Nov. 1973 69 p refs (DA Proj. 1T5-62603-A-041) (AD-771148; BRL-1682) Avail: NTIS CSCL 19/1 A simplified flow field solution has been programmed in an attempt to improve the accuracy of estimates of the static aerodynamic characteristics of ordnance projectiles. It provides estimates of drag, normal force, static moment, and roll damping moment for pointed bodies of revolution at supersonic speed. The program combines the Van Dyke hybrid theory for potential flow, the Van Driest compressible turbulent boundary layer theory, and the Chapman-Sternberg model for supersonic base pressure. Good agreement is demonstrated between the theoretical and experimental data. Author (GRA) N74-17717# Minnesota Univ., Minneapolis. Dept. of Aerospace Engineering and Mechanics. AERODYNAMIC COEFFICIENTS AND PRESSURE DISTRIBUTION OF SOLID FLAT AND RINGSLOT MODELS IN ONE-DIMENSIONAL VELOCITY GRADIENTS Final Report, Feb. 1970 - Jul. 1972 H. G. Heinrich, R. A. Noreen, and J. N. Dale Dec. 1973 88 p refs (Contract F33615-68-C-1227: AF Proj. 6065) (AD-771771) Avail: NTIS CSCL 01/3 The results of wind tunnel studies of the aerodynamic characteristics of solid flat and ringlsot parachute models in flow with several linear one-dimensional dynamic pressure gradients are presented. The models had nominal diameters of about 16 in. Gradients of 0%, 10%, 20%, and 40% of centerline dynamic pressure per foot with centerline velocities of 60 ft/sec and 90 ft/sec were established for the tests. Surface pressure measurements were made on rigid porous models, and drag coefficients obtained by integration of the pressure distribution. Aerodynamic force and moment coefficients were determined from force measurements on flexible models. Author (GRA) N74-17718# Aerospace Research Labs., Wright-Patterson AFB, Ohio. WORK UNIT 08 (V/STOL AERODYNAMICS) Final Report, May 1967 - Jun. 1973 J. S. Petty Nov. 1973 12 p refs (AF Proj. 7064) (AD-771811; ARL-73-0164) Avail: NTIS CSCL 01/1 The objective of Work Unit 08(V/STOL Aerodynamics) was the study of the low speed aerodynamics of V/STOL configurations, with particular emphasis on the fan-in-wing. Principal items of research accomplished under WU 08 include studies of airfoils with single and double inlets on their upper surfaces and lift fan inlet interference phenomena. A definitive paper from the German literature on the roll-up of a jet in a cross flow was translated into English. (Modified author abstract) GRA 02 AIRCRAFT Includes fixed-wing airplanes, helicopters, gliders, balloons. ornithopters, etc; and specific types of complete aircraft (e.g.. ground effect machines, STOL, and VTOL); flight tests; operating problems (e.g., sonic boom); safety and safety devices; economics; and stability and control. For basic research see: 01 Aerodynamics. For related information see also: 31 Space Vehicles; and 32 Structural Mechanics. N74-17720# Advisory Group for Aerospace Research and (AGARD-CP-140) Avail: NTIS HC $21.25 The proceedings of a conference on the effects of atmospheric turbulence on aircraft operation are presented. The subjects discussed include the following: (1) characteristics of atmospheric turbulence, (2) aircraft operational problems created by atmospheric turbulence, (3) analysis of wake vortices and wind shear, (4) structural loads and gust criteria. (5) aircraft design for performance under turbulent conditions, and (6) application of energy management concepts to flight path control in turbulence For individual titles, see N74-17721 through N74-17746. N74-17719# Naval Postgraduate School, Monterey, Calif. Dept. of Aeronautics. AN ALTERNATIVE FORMULATION OF THE LIFTING LINE The In the report, the standard wing equation, as normally derived from lifting line theory, is further refined and a solution procedure more basic than the usual collocation technique is developed. The calculation method adopted avoids the necessity of performing an explicit matrix inversion; all equations can be solved sequentially, one at a time. On the other hand this technique involves the evaluation of numerous integrals over the span. calculations are cumulative, and can be carried as far as necessary to achieve any required degree of accuracy. The analysis is interesting not only for purposes of practical calculation but also for the light it sheds on the essential mathematical structure of the basic aerodynamic phenomena involved. This same general method of calculation can also be readily adapted to the solution of other common types of engineering problems. Author (GRA) George H. Ficht! In AGARD Flight in Turbulence Nov. 1973 14 p refs (For availability see N74-17720 09-02) The realistic simulation of flow in the atmospheric boundary layers at heights greater than two kilometers is discussed Information concerning horizontally homogeneous and statistically stationary atmospheric boundary layer flows is presented. The problems related to the incorporation of the information into atmospheric wind simulation programs are analyzed. The information which the meteorologist must acquire in order to provide a basis for improving the simulation of atmospheric boundary flows is explained. Author N74-17723 National Aeronautical Establishment, Ottawa (Ontario). Flight Research Lab. TURBULENCE AND MESOSCALE HORIZONTAL TEMPERATURE GRADIENTS IN THE LOWER STRATOSPHERE c20 lan MacPherson In AGARD Flight in Turbulence Nov. 1973 15 prefs (For availability see N74-17720 09-02) Data are presented on the frequencies of occurrence of turbulence and significant horizontal temperature gradients along with their dependence on altitude, season, underlying terrain. geographical location, and jet stream position. These factors are important both in the forecast problem and in the comparison of these results with those of other observing programs Specific examples of encounters with atmospheric turbulence during the course of a research project on atmospheric instability are provided. Author N74-17724 Tennessee Univ. Space Inst., Tullahoma. A review of experimental data and analytical models related to flow over bluff obstacles is presented to provide a survey of basic flow theory available to analyze atmospheric wind patterns and man-made surface obstructions. Primary emphasis is placed on the distortion of shear flows approaching and passing over buildings or bluff surfaces such as fences or steps. The various physical phenomena of pressure and velocity variation in the separated flow regions surrounding the body, velocity profiles in the displaced flow over the body, and the origin and decay of induced turbulence along the boundaries of the separated regions are described. Author N74-17725 Delft Univ. of Technology (Netherlands). Dept. of Aeronautical Engineering. PROGRESS IN THE MATHEMATICAL MODELLING OF FLIGHT IN TURBULENCE O. H. Gerlach, G. A. J. Vande Moesdijk, and J. C. VanderVaart In AGARD Flight in Turbulence Nov. 1973 38 p refs (For availability see N74-17720 09-02) Problems of mathematical modelling of aircraft flight in turbulence are discussed. The simulation of flight in the lower atmosphere during the approach and landing portions of the flight are emphasized. The discrepancy between the usual Gaussian representation of atmospheric turbulence and the actual non-Gaussian atmosphere is analyzed. A parameter is introduced to characterize the actual turbulence sensed by the pilot. A method is presented for finding the range of altitudes at which the most significant disturbances are encountered during the approach. Author N74-17726 British Overseas Airways Corp., London (England). BOAC EXPERIENCE WITH TURBULENCE Ernest Chambers In AGARD Flight in Turbulence Nov. 1973 13 p (For availability see N74-17720 09-02) The effectiveness of airborne radar in giving adequate warning of convective turbulence in clouds is discussed. Some encounters with turbulence in clear air are described and matters relating to the forecasting, reporting, and dissemination of turbulence occurence are presented. The development of an airborne clear air turbulence detector is recommended and the performance requirements of the detector are developed. Problems with low level wind shear are also examined. Author A compilation of the replies of airline pilots to a questionnaire on different areas concerned with atmospheric turbulence is presented. An assessment is made on flight times in turbulence, strength and type of turbulence, and the potential effect of turbulence on airline operations. Specific geographical areas as well as airports with specific turbulence encounters are listed, and potential energy sources are mentioned. The turbulence penetration speed is discussed as well as means to avoid turbulent encounters or to alleviate turbulent conditions through air traffic control, meteorological reports, or pilot experience. Author N74-17728 Royal Aircraft Establishment, Farnborough (England). INFLUENCE OF PILOT AND AIRCRAFT CHARACTERISTICS ON STRUCTURAL LOADS IN OPERATIONAL FLIGHT J. R. Sturgeon In AGARD Flight in Turbulence Nov. 1973 24 P refs Presented at the 35th Meeting of the Struct. and Mater. Panel, Toulouse, France, 24-29 Sep. 1972 (For availability see N74-17720 09-02) (AGARD-608) Some aircraft handling problems met in operational conditions are described and compared with flight test conditions. It is concluded that errors in flight instrumentation and physiological cues have a substantial influence on control capability. A procedure for minimizing structural loads and aerodynamic problems in all flight conditions is proposed. The procedure will restore to the pilot and to the autopilot controlled flying the positive stability in pitch and yaw which is required for aircraft operating in the stick free mode. Proposals are made for improving the requirements of flight instruments to reduce control problems during complex maneuvers and flight in severe wind shear conditions. Author N74-17729 British Aircraft Corp., Warton (England). Military Aircraft Div. Brian Young In AGARD Flight in Turbulence Nov. 1973 9 p refs (For availability see N74-17720 09-02) The effects of atmospheric turbulence on the efficiency of a flight crew are analyzed. The factors are identified as: (1) atmospheric turbulence levels, (2) the characteristics of the aircraft in responding to turbulence, including the effects of structural modes, and (3) the tolerance of the crew to the level and duration of vibration at the crew station. The use of power spectral density techniques for assessing crew ride comfort is explained. In addition to defining aircraft response in both vertical and lateral turbulence, it is possible to include the effects of structural modes, assess the effects of autostabilization, and include crew proficiency degradation as a parameter in operational studies. Author N74-17730 Bodenseewerk Geraetetechnik G.m.b.H., Ueberlingen (West Germany). Nov. THE EFFECT OF GUSTS AND WIND SHEAR FOR AUTOMATIC STOL APPROACH AND LANDING Gunther Schaenzer In AGARD Flight in Turbulence 1973 17 p refs (For availability see N74-17720 09-02) The characteristics of a flight control system for short takeoff aircraft are discussed. The system is used during steep and curved approaches. The system was simulated and flight tested during more than 500 automatic STOL approaches and landings. The effects of gusts and wind shear, especially at extremely low indicated airspeeds during approach and flare, with respect to the pilot's workloads, passenger comfort, throttle activity, angle of attack measurement, and precision in approach and landing are analyzed. Author N74-17731 Transportation Systems Center, Cambridge, Mass. The hazards created by the trailing vortices deposited in the wakes of heavy jet aircraft are discussed. In the terminal area this hazard leads to longer separation standards and reduced runway capacity. In order to shorten the required separations without compromising safety it is necessary to be able to detect the presence and motion of vortices in regions where they constitute a threat. The sensing techniques that have been developed are reported. The characteristics of acoustic and wind pressure sensors for detecting vortices are described. Author N74-17732 Federal Aviation Administration, Washington, D.C. A wake vortex avoidance system (WVAS) program is described. The objective of the program is to design and implement a ground based monitoring and predictive system at airports which will increase runway capacity by eliminating the need for larger separations between aircraft for safety from wake vortices. The program consists of three major tasks: (1) sensor development, (2) vortex behavior characterization and hazard definition, and (3) integration of these tasks into an overall system design. The meteorological factors which affect the performance of the proposed system are analyzed. Author N74-17733* National Aeronautics and Space Administration. John A. Zalovcik and R. Earl Dunham, Jr. In AGARD Flight in 09-02) NASA investigations of aircraft trailing vortices are reviewed. Results obtained in flight on vortex characteristics, such as decay of maximum velocity and vortex drift, are presented for distances behind a generating C-5 aircraft from 0.6 to 13.0 nautical miles. The lateral control activity of a CV-990 aircraft probing the vortices generated by the C-5 aircraft is illustrated and the effect of the C-5 aircraft configuration on this activity is indicated. Results are presented from near-field and far-field studies of accelerated vortex dissipation through the use of various devices such as mass ejection, spoilers, vortex generators, and trailing drag devices. Author M. Hacklinger In AGARD Flight in Turbulence Nov. 1973 9 pref (For availability see N74-17720 09-02) The influence of atmospheric turbulence on the design of military aircraft is analyzed. The subject is treated in two main categories: (1) turbulence as a sizing factor in itself which determines static and fatigue strength of major parts of low load factor aircraft and (2) turbulence as an important design parameter of high load factor aircraft where stability of the augmented aircraft in manual or automatic terrain following flight, pilot proficiency under vibration, and the attitude accuracy of the aircraft as a weapons platform become important. The problem of designing for proper flight qualities in high speed tactical fighter missions is described with emphasis on analytical prediction of pilot task proficiency under the vibration environment created by airframe and flight control system characteristics. Author N74-17736 Messerschmitt-Boelkow G.m.b.H., Ottobrunn (West Germany). INFLUENCE OF TURBULENCE ON HELICOPTER DESIGN AND OPERATION G. Reichert and M. Rade In AGARD Flight in Turbulence Nov. 1973 16 p refs (For availability see N74-17720 09-02) The sensitivity of the helicopter to atmospheric turbulence because of the relatively low disc loading is discussed. The influences of other parameters such as rotor stiffness and damping are analyzed. The effects of these influences on different helicopters are compared. The main design problems of meeting operational and certification requirements and methods for improving the performance of helicopters are examined. Author N74-17737 De Havilland Aircraft Co., Ltd., Downsview (Ontario). DATA REQUIREMENTS ON TURBULENCE IN THE EARTH'S ATMOSPHERIC SHEAR LAYER FOR STOL DESIGN CRITERIA J. J. Glaser In AGARD Flight in Turbulence Nov. 1973 8 p refs (For availability see N74-17720 09-02) The factors which affect the airworthiness of short takeoff aircraft, especially during the landing and takeoff phase of the operation. Atmospheric turbulence is one of the most important factors affecting aircraft behavior at low altitudes, and its description in terms of a realistic model is an essential step in the design, certification, and operation of STOL aircraft. A study to devise a low altitude gust model and to determine the relative importance of the gust model parameters of the responses of typical STOL aircraft was conducted. The significant features of N74-17739 British Aircraft Corp., Weybridge (England). Commercial Aircraft Div. STRUCTURAL LOADS AND GUST CRITERIA D. O. N. James In AGARD Flight in Turbulence Nov. 1973 13 p refs (For availability see N74-17720 09-02) The effects of atmospheric turbulence on aircraft design criteria are analyzed. The discrete gust methods are compared with the power spectral density methods to determine the degree of application to aircraft gust load problems. The application of continuous turbulence design procedure was investigated. Mission analysis results are shown to be very sensitive to the assumed operating technique. Graphs of specific aircraft design envelope limit loads against the discrete gust load limit are provided. J. Yff In AGARD Flight in Turbulence Nov. 1973 11 prefs (For availability see N74-17720 09-02) An analysis of accurately calculated gust loads for three short haul aircraft was conducted. The results are applied to the following conditions: (1) comparison of power spectral density and discrete gust methods, (2) comparison of power spectral density mission analysis and design envelope results, (3) comparison of power spectral density results for vertical and lateral gusts, and (4) a study of the specific problems of T-tail configurations. Graphs of load conditions for various aircraft components are provided. Author A. G. Barnes In AGARD Flight in Turbulence Nov. 1973 14 p refs (For availability see N74-17720 09-02) The design objectives for aircraft control and stability augmentation systems are discussed with respect to the effects of atmospheric turbulence. The subjects presented include the following: (1) handling qualities requirements for flight in turbulence, (2) performance of unaugmented aircraft in turbulence, (3) performance of augmented aircraft in turbulence. and (4) approaches to stability augmentation systems development. Specific emphasis is placed on the aircraft parameters of planform, excitation derivatives, control power. and aircraft size. Author N74-17742* National Aeronautics and Space Administration TURBULENCE Boyd Perry, Ill and Kermit G. Pratt In AGARD Flight in Turbulence Nov. 1973 9 p refs (For availability see N74-17720 09-02) An exploratory analytical study was conducted to analyze problem areas associated with a rigid aircraft controlled by a simple autopilot. The aircraft motion is constrained to the longitudinal phugoid and short period modes. The autopilot |