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  • Journals
  • Other Sources  (1,345)
  • AIRCRAFT  (1,345)
  • 2020-2023
  • 1970-1974  (1,345)
Collection
  • Journals
  • Other Sources  (1,345)
Source
Keywords
Years
Year
  • 1
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    Aircraft noise in the region of the Bucharest-Otopeni Airport (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Aircraft noise, especially in the region adjoining airports, constitutes a problem that will be aggravated in the near future because of increasing aircraft traffic and the appearance of new types of large tonnage aircraft with continuously increasing powers and speeds. Criteria for the evaluation of aircraft noise are reported and some results of studies carried out in the region of Bucharest-Otopeni Airport are detailed.
    Keywords: AIRCRAFT
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 233-237
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  • 2
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    Use of cross-correlation measurements to investigate noise generating regions of a real jet engine and a model jet (1974)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: Cross-correlations are reported of the jet static pressure fluctuations (as measured with a B and K microphone fitted with a nose cone), with the far-field radiated sound pressure. These measurements were made for various probe positions and a large number of far-field positions (at various angles). In addition, the tests were run for a number of different jet exit velocities. The measured, normalized cross-correlation functions vary between 0.004 and 0.155. These values depend upon the angular position of the far-field microphone, the jet exit Mach number, and the position of the probe. In addition, the cross-correlation technique was employed to study the symmetry of the far-field radiated sound about the jet axis. Third-octave analyses of both the probe signal and the far-field radiated sound were made. This is the first time correlation measurements have been made on a jet engine. In addition, a report is given on an extensive noise survey of a model jet. The correlations are related to sound source functions and jet source regions are discussed.
    Keywords: AIRCRAFT
    Type: AGARD Noise Mech.; 13 p
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  • 3
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    Performance of an inlet for an integrated scramjet concept (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Review of the results of an experimental investigation of the performance of an inlet for an integrated scramjet engine concept at Mach 6. Following a description of the inlet design and test model, the Mach 6 experimental results obtained are presented in terms of integrated performance parameters.
    Keywords: AIRCRAFT
    Type: Journal of Aircraft; 11; Sept
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  • 4
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    Effect of upper-surface blowing on static longitudinal stability of a swept wing (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A low-speed wind-tunnel investigation was conducted on a sharp-edged 75 deg delta wing, to determine the effect of upper-surface blowing on static longitudinal stability characteristics. The model incorporated nozzles, located at 0.50 mean aerodynamic chord length, supplied by compressed air to provide blowing on the upper surface. A full span trailing-edge flap was also tested as an additional high-lift device. The angle of attack was varied from 0 to 24 deg for a range of thrust coefficients from 0 to 0.45. The results of the static force tests showed that favorable increments in static longitudinal stability and lift were obtained using upper-surface blowing.
    Keywords: AIRCRAFT
    Type: Journal of Aircraft; 11; Sept
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  • 5
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    RPVs - Exploring civilian applications (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Discussion of the civilian application possibilities for remotely piloted vehicle (RPV) systems. Following a listing of all possible desert, coastal, forest, agricultural, and urban RPV missions, a thorough examination is presented of such possible RPV aircraft applications as those of forest-fire detection and mapping. Some of the major obstacles to such civilian missions are also reviewed.
    Keywords: AIRCRAFT
    Type: Astronautics and Aeronautics; 12; Sept
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  • 6
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    V/STOL flying qualities research using the X-22A (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The X-22A has four ducted propellers and four engines. The engines are connected to a common system of rotating shafts which distribute propulsive power to the four propellers. Changes in the direction of the thrust vector are accomplished by rotating the ducts, which are interconnected so that all rotate through the same angle. Thrust magnitude is determined by a collective pitch lever, very similar to a helicopter. There are four variable stability system (VSS) controllers: thrust, pitch, roll, and yaw, and three artificial feel servos for the evaluation pilot cockpit controls, each employing electrohydraulic servos. Longitudinal flying qualities for STOL landing approach, and lateral-directional flying qualities and control power requirements for STOL landing approach are discussed. Attention is given to the data acquisition and processing system.
    Keywords: AIRCRAFT
    Type: Society of Experimental Test Pilots; vol. 12
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  • 7
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    Suspension-line wave motion during the lines-first parachute unfurling process (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A new mathematical approach to modeling the lines-first parachute unfurling process is presented. The unfurling process is treated as two distinct phases: a suspension-line unfurling phase, during which a massless-spring model of the suspension-line elasticity may be employed; and a canopy unfurling phase, during which a formulation considering suspension-line wave mechanics is employed. Histories of unfurled length and tension at the vehicle obtained using the model are compared with flight test data, and generally good agreement is observed.
    Keywords: AIRCRAFT
    Type: AIAA Journal; 12; Jan. 197
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  • 8
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    Transonic transport wings - Oblique or swept (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A comparative evaluation of fixed-geometry and variable-sweep wing designs, a fixed delta wing, and oblique wings with a single body or two bodies suggests that an oblique wing is preferable in a transonic transport aircraft in terms of gross weight, fuel consumption, and aircraft noise, and also shows an acceptable aeroelastic stability. Further studies are, however, needed to develop the full potential of the oblique-wing concept, including its economic implications.
    Keywords: AIRCRAFT
    Type: Astronautics and Aeronautics; 12; Jan. 197
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  • 9
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    Navy participation in the development of airframe parameter identification techniques (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The Navy is currently involved in the development of advanced parameter identification techniques for use in aircraft flight testing and refinement of aircraft dynamic systems modeling. An overview is presented of the Navy's research programs, capabilities, and facilities. The use of parameter identification techniques are related to the flight testing, development, and simulation of aircraft and aircraft systems in the areas of flying qualities, automatic flight controls, flight dynamics, and advanced landing systems. Preliminary analytical and flight test results are presented. The impact that new parameter identification technology has on Navy flight test philosophy is discussed. Future plans are outlined.
    Keywords: AIRCRAFT
    Type: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 39-42
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  • 10
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    Aircraft design for flight below the sonic boom speed limit (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The avoidance of sonic booms places a constraint on aircraft design and can lead to unusual new configurations. From a comparison among several candidate designs, it is shown that an oblique-wing aircraft offers many advantages when structure, stability, flight efficiency, and airport noise are considered jointly.
    Keywords: AIRCRAFT
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  • 11
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    Determination of propulsion-system-induced forces and moments of a Mach 3 cruise aircraft (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: During the joint NASA/USAF flight research program with the YF-12 airplane, the Dutch roll damping was found to be much less during automatic inlet operation than during fixed inlet operation at Mach numbers greater than 2.5 and with the yaw stability augmentation system off. It was concluded that the significant reduction in Dutch roll damping was due to the forces and moments induced by the variable-geometry features of the inlet. Two stability-derivative extraction techniques were applied to the flight data; the recently developed Newton-Raphson technique and the time vector method. These techniques made it possible to determine the forces and moments generated by spike and bypass door movement.
    Keywords: AIRCRAFT
    Type: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 369-374
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  • 12
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    Estimation of structural parameters from dynamic test data (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Parameters for a lumped linear model approximating a distributed elastic structure are determined from dynamic test data comprised of several mode shapes and frequencies. Measurement errors, nonlinear response, and nonmeasurable quantities such as mode slope components are accommodated. Some mass and stiffness parameters may be known accurately, whereas the remainder are to be estimated. The method entails minimizing a quadratic function of the difference between corresponding modes and frequencies of the theoretical model and the test specimen. This technique was applied to some actual vibration test data, and the special techniques that are required to overcome convergence problems are described.
    Keywords: AIRCRAFT
    Type: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 359-367
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  • 13
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    Estimation of elastic aircraft parameters using the maximum likelihood method (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The application of the maximum likelihood method to estimate the aerodynamic parameters of elastic flight vehicles in a symmetric flight condition is discussed. In this application, particular attention is directed toward the center of mass, elastic deformation, and sensor equations of motion. It is shown that the two major computational problems to be overcome are the inversion of large-sized matrices and the time-wise integration of a large number of linear, ordinary, differential equations.
    Keywords: AIRCRAFT
    Type: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 337-358
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  • 14
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    Helicopter derivative identification from analytic models and flight test data (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Recent results of stability derivative identification from helicopter analytic models and flight test data are presented. Six and nine degree-of-freedom (DOF) linear models are identified from an analytic nonlinear helicopter simulation using a least square technique. The identified models are compared with the convectional partial differentiation method for obtaining derivatives to form the basis for interpretation of derivatives identified from flight data. Six degree-of-freedom models are identified from CH-53A and CH-54B flight data, using an extended Kalman filter modified to process several maneuvers simultaneously. The a priori derivative estimate is obtained by optimal filtering of the data and then using a least square method. The results demonstrate that a six DOF identified model is sufficient to determine the low frequency modes of motion, but a nine DOF rotor/body model is necessary for proper representation of short-term response.
    Keywords: AIRCRAFT
    Type: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 175-186
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  • 15
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    A unified technology plan for fatigue and fracture design (1974)
    In:  Other Sources
    Details
    Publication Date: 2013-08-29
    Description: An integrated research program is proposed that seeks to improve the technology of designing against fatigue and fracture and to develop a computerized capability for assessing the adequacy of a given design. Both fatigue life prediction and damage tolerance considerations are incorporated. The research for each of these considerations is organized to account for material behavior, the effect of structural configurations, the cumulative effects of the operating loadings, and the effects of temperature and corrosion.
    Keywords: AIRCRAFT
    Type: RAE Fail-safe Aircraft Struct., Vol. 1; 22 p
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  • 16
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    Flight test of an automatic approach and landing concept for a simulated space shuttle represented by the NASA Convair 990 aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: Unpowered automatic approaches and landings were conducted to study navigation, guidance, and control problems associated with terminal area, approach, and landing operation for the space shuttle. A Convair 990 aircraft was equipped with a digital flight-control computer connected to the aircraft control systems and displays. The flight tests evaluated, from 11,300 m to touchdown, the performance of a navigation and guidance concept that utilized blended radio/inertial navigation with VOR, DME, and ILS as the ground radio navigation aids. The results from 36 automatic approaches and landings are analyzed. Preliminary results indicate that this concept may provide sufficient accuracy that automatic landing of the unpowered shuttle orbiter can be accomplished on a conventional size runway.
    Keywords: AIRCRAFT
    Type: AGARD Advan. in Control Systems; 9 p
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  • 17
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    Integrated propulsion/energy transfer control systems for lift-fan V/STOL aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: An integrated propulsion/control system for lift-fan transport aircraft is described. System behavior from full-scale experimental and piloted simulator investigations are reported. The lift-fan transport is a promising concept for short-to-medium haul civil transportation and for other missions. The lift-fan transport concept features high cruise airspeed, favorable ride qualities, small perceived noise footprints, high utilization, transportation system flexibility, and adaptability to VTOL, V/STOL, or STOL configurations. The lift-fan transport has high direct operating costs in comparison to conventional aircraft, primarily because of propulsion system and aircraft low-speed control system installation requirements. An integrated lift-fan propulsion system/aircraft low-speed control system that reduces total propulsion system and control system installation requirements is discussed.
    Keywords: AIRCRAFT
    Type: AGARD V(STOL Propulsion Systems; 8 p
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  • 18
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    Ejector-powered lift systems for V/STOL aircraft (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The paper takes a brief look at powered lift from the point of view of the operator and the designer, considers application of an ejector-powered lift system to both STOL and VTOL aircraft, and describes some of the advantages of an ejector concept. Performance and noise characteristics of a simple ejector are described, and some comments are made regarding the Buffalo/Spey Augmentor-Wing proof-of-concept aircraft.
    Keywords: AIRCRAFT
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  • 19
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    Identification of M2/F3 stability and control derivatives from flight data containing gust effects (1974)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The application of the maximum likelihood identification technique to M2/F3 lifting body flight data containing wind gust effects is discussed. With the objective of this effort being the identification of the stability and control derivatives, it is shown first that the output error technique (or modified Newton-Raphson) fails to fit the recorded data accurately. The means of applying the maximum likelihood technique to this problem are then discussed and the results given which indicate an accurate fit to the data. The question of derivative signs opposite to the wind tunnel values is then addressed and the results of three techniques for dealing with this problem are presented. These techniques are a priori weighting, fixing parameter values, and rank deficient inverses.
    Keywords: AIRCRAFT
    Type: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 115-124
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  • 20
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    A survey of AFFDL parameter estimation efforts and future plans (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An overview is presented of the applications of parameter estimation methods to the following areas of interest at the Air Force Flight Dynamics Laboratory (AFFDL): (1) conventional stability and control parameter estimation of rigid aircraft; (2) extension to elastic aircraft; (3) extension to stall/spin aerodynamics of rigid aircraft with a nonlinear model; (4) application to the pilot model identification; and (5) correlation of wind tunnel, drop model and flight test data. Only well-documented algorithms are used with modification to the model as required for the specific application. The genesis of each problem and other background information are discussed which enumerate the algorithms and explain how this information is used to improve existing operational aircraft characteristics as well as specify design criteria for future USAF aerospace vehicles.
    Keywords: AIRCRAFT
    Type: NASA. Flight Res. Center Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 19-38
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  • 21
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    An overview of parameter estimation techniques and applications in aircraft flight testing (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Parameter estimation is discussed as it applies to aircraft flight testing, and an overview of the symposium is presented. The evolution of techniques used in flight testing is reviewed briefly, and it is pointed out how the changing character of the aircraft tested and the availability of advanced data systems have promoted this evolution. Recent advances in optimal estimation theory have stimulated widespread interest and activity in parameter estimation. The framework of these advanced techniques is outlined to set the stage for subsequent papers. The session topics are introduced and related to the requirements of flight-test research.
    Keywords: AIRCRAFT
    Type: Parameter Estimation Tech. and Appl. in Aircraft Flight Testing; p 1-18
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  • 22
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    RPRVs - The first and future flights (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The merits of the RPRV (remotely piloted research vehicle) concept are discussed, along with its historical background and development culmination in the 3/8-scale F-15. The use of RPRVs is shown to be especially attractive when testing must be done at low cost, or in quick response to demand, or when hazardous testing must assure the safety of proceeding to manned vehicles.
    Keywords: AIRCRAFT
    Type: Astronautics and Aeronautics; 12; Apr. 197
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  • 23
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    The augmentor wing - Powered-lift STOL a proven concept (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A jet-STOL powered-lift aircraft has the ability to perform a relatively steep (7.5 deg) final approach at high power setting and a low speed. The DHC-5 Buffalo/Spey Augmentor-Wing research aircraft is the first machine of its kind to accomplish this performance. The aircraft uses an approach in which the cold bypass thrust is vectored by the augmentor flap. Aspects of aircraft reliability are discussed together with taxi trials, stalling characteristics, lateral directional control, single-engine operations, roll acceleration, and flight in turbulent conditions.
    Keywords: AIRCRAFT
    Type: Interavia; 29; Feb. 197
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  • 24
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    Long range view of materials research for civil transport aircraft (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The impact of various material technology advancements on the economics of civil transport aircraft is investigated. Benefits of advances in both airframe and engine materials are considered. Benefits are measured primarily by improvements in return on investment for an operator. Materials research and development programs which lead to the greatest benefits are assessed with regards to cost, risk, and commonality with other programs. Emphasis of the paper is on advanced technology subsonic/transonic transports (ATT type aircraft) since these are likely to be the next generation of commercial transports.
    Keywords: AIRCRAFT
    Type: SAMPE Quarterly; 5; Jan. 197
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  • 25
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    Design and flight experience with a digital fly-by-wire control system in an F-8 airplane (1974)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: A digital fly-by-wire flight control system was designed, built, and for the first time flown in an airplane. The system, which uses components from the Apollo guidance system, is installed in an F-8 airplane as the primary control system. A lunar module guidance computer is the central element in the three-axis, single-channel, multimode, digital control system. A triplex electrical analog system which provides unaugmented control of the airplane is the only backup to the digital system. Flight results showed highly successful system operation, although the trim update rate was inadequate for precise trim changes, causing minor concern. The use of a digital system to implement conventional control laws proved to be practical for flight. Logic functions coded as an integral part of the control laws were found to be advantageous. Although software verification required extensive effort, confidence in the software was achieved.
    Keywords: AIRCRAFT
    Type: AGARD Advan. in Control Systems; 10 p
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  • 26
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    Status of two studies on active control of aeroelastic response at NASA Langley Research Center (1974)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: The application of active control technology to the suppression of flutter was successfully demonstrated during two recent studies in the Langley transonic dynamics tunnel. The first study involved the implementation of an aerodynamic-energy criterion, using both leading- and trailing-edge controls, to suppress flutter of a simplified delta-wing model. Use of this technique resulted in an increase in the flutter dynamic pressure of approximately 12 percent for this model at a Mach number of 0.9. Analytical methods used to predict the open- and closed-loop behavior of the model are also discussed. The second study, which is a joint effort with the Air Force Flight Dynamics Laboratory, was conducted to establish the effect of active flutter suppression on a model of the Boeing B-52 Configured Vehicle (CCV). Some preliminary results of this study indicate significant improvements in the damping associated with the critical flutter mode.
    Keywords: AIRCRAFT
    Type: AGARD Active Control Systems for Load Alleviation, Flutter Suppression and Ride Control; p 23-48
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  • 27
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    Computer-aided design of control systems to meet many requirements (1974)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: A method is described for using nonlinear programing in the computer-aided design of airplane control systems. It is assumed that the quality of such systems depends on many criteria. These criteria are included in the constraints vector (instead of attempting to combine them into a single scalar criterion, as is usually done), and the design proceeds through a sequence of nonlinear programing solutions in which the designer varies the specification of sets of requirements levels. The method is applied to design of a lateral stability augmentation system (SAS) for a fighter airplane, in which the requirements vector is chosen from the official handling qualities specifications. Results are shown for several simple SAS configurations designed to obtain desirable handling qualities over all design flight conditions with minimum feedback gains. The choice of the final design for each case is not unique but depends on the designer's decision as to which achievable set of requirements levels represents the best for that system. Results indicate that it may be possible to design constant parameter SAS which can satisfy the most stringent handling qualities requirements for fighter airplanes in all flight conditions. The role of the designer as a decision maker, interacting with the computer program, is discussed. Advantages of this type of designer-computer interaction are emphasized. Desirable extensions of the method are indicated.
    Keywords: AIRCRAFT
    Type: AGARD Advan. in Control Systems; 7 p
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  • 28
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    Hingeless rotor theory and experiment on vibration reduction by periodic variation of conventional controls (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The reduction of the n per rev. pitch-, roll- and vertical vibrations of an n-bladed rotor by n per rev. sinusoidal variations of the collective and cyclic controls is investigated. The numerical results presented refer to a four-bladed, 7.5-foot model and are based on frequency response tests conducted under an Army-sponsored research program. The following subjects are treated: extraction of the rotor transfer functions (.073R hub flapping and model thrust versus servo valve command, amplitude and phase), calculation of servo commands (volts) required to compensate .073R hub flapping (3P and 5P) and model thrust (4P), evaluation of the effect of the vibratory control inputs on blade loads, and theoretical prediction of the root flapbending moments generated by 0 to 5P perturbations of the feathering angle and rotor angle of attack. Five operating conditions are investigated covering advance ratios from approximately 0.2 to 0.85. The feasibility of vibration reduction by periodic variation on conventional controls is evaluated.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 261-277
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  • 29
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    Engine/airframe interface dynamics experience (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Problems of engine/drive system torsional stability, engine and output shaft critical speeds, and engine vibration at helicopter rotor order frequencies are discussed, and test data and analyses presented. Also presented is a rotor/drive system dynamics problem not directly related to the engine.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 249-260
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  • 30
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    Multicyclic jet-flap control for alleviation of helicopter blade stresses and fuselage vibration (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Results of wind tunnel tests of a 12 meter-diameter-rotor utilizing multicyclic jet-flap control deflection are presented. Analyses of these results are shown, and experimental transfer functions are determined by which optimal control vectors are developed. These vectors are calculated to eliminate specific harmonic bending stresses, minimize rms levels (a measure of the peak-to-peak stresses), or minimize vertical vibratory loads that would be transmitted to the fuselage. Although the specific results and the ideal control vectors presented are for a specific jet-flap driven rotor, the method employed for the analyses is applicable to similar investigations. A discussion of possible alternative methods of multicyclic control by mechanical flaps or nonpropulsive jet-flaps is presented.
    Keywords: AIRCRAFT
    Type: Its Rotorcraft Dyn.; p 233-238
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  • 31
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    Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 219-222
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  • 32
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    Hub moment springs on two-bladed teetering rotors (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two-bladed teetering rotors with elastic flapping hinge restraint are shown to be suitable for zero-g flight. The alternating moment component introduced into the fuselage by the hinge spring can be balanced about the aircraft center of gravity by alternating hub shears. Such shears can be produced in proper magnitude, frequency, and phase by additional underslinging of the hub and by judicious choice of the location of the first inplane cantilevered natural frequency. Trends of theoretical results agree with test results from a small scale model and a modified OH-58A helicopter.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 199-204
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  • 33
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    Evaluation of a stall-flutter spring-damper pushrod in the rotating control system of a CH-54B helicopter (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Results of a design and flight test program conducted to define the effect of rotating pushrod damping on stall-flutter induced control loads are presented. The CH-54B helicopter was chosen as the test aircraft because it exhibited stall induced control loads. Damping was introduced into the CH-54B control system by replacing the standard pushrod with spring-damper assemblies. Design features of the spring-damper are described and the results of a dynamic analysis are shown which define the pushrod stiffness and damping requirements. Flight test measurements taken at 47,000 lb gross weight with and without the damper are presented. The results indicate that the spring-damper pushrods reduced high frequency, stall-induced rotating control loads by almost 50%. Fixed system control loads were reduced by 40%. Handling qualities in stall were unchanged, as expected.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 223-232
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  • 34
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    Comparison of flight data and analysis for hingeless rotor regressive inplane mode stability (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Analytical and experimental data obtained during the development of the AH-56A covering stability of the regressive inplane mode, including coupling with other modes such as body and rotor plunge are reported. Data were obtained on two distinctly different control systems; both gyro controlled, but one with feathering moment feedback and the other with direct flapping feedback. A review was made of analytical procedures employed in investigating the stability of this mode and a comparison was made of the analytical and experimental data. The effect of certain parameters including blade droop, sweep, delta 3, alpha 1, vehicle roll inertia, inplane frequency, and rpm and forward speed on the mode were also reviewed. It was shown that the stability of this mode is treatable by analysis and that adequate stability is achievable without recourse to auxiliary inplane damping devices.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 185-197
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  • 35
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    Rotor aeroelastic stability coupled with helicopter body motion (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A 5.5-foot-diameter, soft-in-plane, hingeless-rotor system was tested on a gimbal which allowed the helicopter rigid-body pitch and roll motions. Coupled rotor/airframe aeroelastic stability boundaries were explored and the modal damping ratios were measured. The time histories were correlated with analysis with excellent agreement. The effects of forward speed and some rotor design parameters on the coupled rotor/airframe stability were explored both by model and analysis. Some physical insights into the coupled stability phenomenon are suggested.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 137-146
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  • 36
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    An application of Floquet theory to prediction of mechanical instability (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The problem of helicopter mechanical instability is considered for the case where one blade damper is inoperative, and it is shown that if the hub is considered to be nonisotropic, the equations of motion have periodic coefficients which cannot be eliminated. The Floquet transition matrix method is shown to be an effective way of dealing with the nonisotropic hub and nonisotropic rotor situation. Time history calculations are examined and shown to be inferior to the Floquet technique for determining system stability. It is shown that instabilities which occur when one blade damper is inoperative may consist of nearly pure blade motion or they may be similar to the classical mechanical instability.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 147-158
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  • 37
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    Application to rotary wings of a simplified aerodynamic lifting surface theory for unsteady compressible flow (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A general method of predicting airloads is applied to helicopter rotor blades on a full three-dimensional basis using the general theory developed for a rotor blade at the psi = pi/2 position where flutter is most likely to occur. Calculations of aerodynamic coefficients for use in flutter analysis are made for forward and hovering flight with low inflow. The results are compared with values given by two-dimensional strip theory for a rigid rotor hinged at its root. The comparisons indicate the inadequacies of strip theory for airload prediction. One important conclusion drawn from this study is that the curved wake has a substantial effect on the chordwise load distribution.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 127-135
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  • 38
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    The effect of cyclic feathering motions on dynamic rotor loads (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The dynamic loads of a helicopter rotor in forward flight are influenced significantly by the geometric pitch angles between the structural axes of the hub and blade sections and the plane of rotation. The analytical study presented includes elastic coupling between inplane and out-of-plane deflections as a function of geometric pitch between the plane of rotation and the principal axes of inertia of each blade. The numerical evaluation is based on a transient analysis using lumped masses and elastic substructure techniques. A comparison of cases with and without cyclic feathering motion shows the effect on computed dynamic rotor loads.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 107-114
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  • 39
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    Helicopter gust response characteristics including unsteady aerodynamic stall effects (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The results of an analytical study to evaluate the general response characteristics of a helicopter subjected to various types of discrete gust encounters are presented. The analysis employed was a nonlinear coupled, multi-blade rotorfuselage analysis including the effects of blade flexibility and unsteady aerodynamic stall. Only the controls-fixed response of the basic aircraft without any aircraft stability augmentation was considered. A discussion of the basic differences between gust sensitivity of fixed and rotary wing aircraft is presented. The effects of several rotor configuration and aircraft operating parameters on initial gust-induced load factor and blade vibratory stress and pushrod loads are discussed.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 91-100
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  • 40
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    Flap-lag dynamics of hingeless helicopter blades at moderate and high advance ratios (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Equations for large amplitude coupled flaplag motion of a hingeless elastic helicopter blade in forward flight are derived. Only a torsionally rigid blade exicted by quasi-steady aerodynamic loads is considered. The effects of reversed flow together with some new terms due to forward flight are included. Using Galerkin's method the spatial dependence is eliminated and the equations are linearized about a suitable equilibrium position. The resulting system of equations is solved using multivariable Floquet-Liapunov theory, and the transition matrix at the end of the period is evaluated by two separate methods. Results illustrating the effects of forward flight and various important blade parameters on the stability boundaries are presented.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 55-66
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  • 41
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    Some approximations to the flapping stability of helicopter rotors (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The flapping equation for a helicopter in forward flight are reported which have coefficients that are periodic in time, and this effect complicates the calculation of stability. A constant coefficient approximation which will allow the use of all the well known methods for analyzing constant coefficient equations are presented. The flapping equation is first transformed into the nonrotating coordinate frame, where some of the periodic coefficients are transformed into constant terms. The constant coefficient approximation is then made by using time averaged coefficients in the nonrotating frame. Stability calculations based on the approximation are compared to results from a theory which correctly includes all of the periodicity. The comparison indicates that the approximation is reasonably accurate at advance ratios up to 0.5.
    Keywords: AIRCRAFT
    Type: Its Rotorcraft Dyn.; p 45-53
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  • 42
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    Dynamic analysis of multi-degree-of-freedom systems using phasing matrices (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A mathematical technique is presented for improved analysis of a wide class of dynamic and aeroelastic systems characterized by several degrees-of-freedom. The technique enables greater utilization of the usual eigensolution obtained from the system dynamic equations by systematizing the identification of destabilizing and/or stiffening forces. Included, as illustrative examples of the use of the technique, are analyses of a helicopter rotor blade for bending-torsion divergence and flutter and for pitch-lag/flap instability.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 35-43
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  • 43
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    Computer experiments on periodic systems identification using rotor blade transient flapping-torsion responses at high advance ratio (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Systems identification methods have recently been applied to rotorcraft to estimate stability derivatives from transient flight control response data. While these applications assumed a linear constant coefficient representation of the rotorcraft, the computer experiments described in this paper used transient responses in flap-bending and torsion of a rotor blade at high advance ratio which is a rapidly time varying periodic system.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 25-34
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  • 44
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    Hingeless rotor frequency response with unsteady inflow (1974)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Hingeless rotor frequency response calculations are obtained by applying a generalized harmonic balance to the elastic blade flapping equations. Nonuniform, unsteady induced flow effects are included by assuming a simple three-degree-of-freedom description of the rotor wake. Results obtained by using various models of elastic blade bending and induced flow are compared with experimental data obtained from a 7.5-ft diameter wind tunnel model at advance ratios from 0.0 to 0.6. It is shown that the blade elasticity and nonuniform, unsteady induced flow can have a significant effect on the transient response characteristics of rotor systems.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 1-12
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  • 45
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    HFL-10 lifting body flight control system characteristics and operational experience (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A flight evaluation was made of the mechanical hydraulic flight control system and the electrohydraulic stability augmentation system installed in the HL-10 lifting body research vehicle. Flight tests performed in the speed range from landing to a Mach number of 1.86 and the altitude range from 697 meters (2300 feet) to 27,550 meters (90,300 feet) were supplemented by ground tests to identify and correct structural resonance and limit-cycle problems. Severe limit-cycle and control sensitivity problems were encountered during the first flight. Stability augmentation system structural resonance electronic filters were modified to correct the limit-cycle problem. Several changes were made to control stick gearing to solve the control sensitivity problem. Satisfactory controllability was achieved by using a nonlinear system. A limit-cycle problem due to hydraulic fluid contamination was encountered during the first powered flight, but the problem did not recur after preflight operations were improved.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-2956 , H-704
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  • 46
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    Analysis and calculation of lightning-induced voltages in aircraft electrical circuits (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Techniques to calculate the transfer functions relating lightning-induced voltages in aircraft electrical circuits to aircraft physical characteristics and lightning current parameters are discussed. The analytical work was carried out concurrently with an experimental program of measurements of lightning-induced voltages in the electrical circuits of an F89-J aircraft. A computer program, ETCAL, developed earlier to calculate resistive and inductive transfer functions is refined to account for skin effect, providing results more valid over a wider range of lightning waveshapes than formerly possible. A computer program, WING, is derived to calculate the resistive and inductive transfer functions between a basic aircraft wing and a circuit conductor inside it. Good agreement is obtained between transfer inductances calculated by WING and those reduced from measured data by ETCAL. This computer program shows promise of expansion to permit eventual calculation of potential lightning-induced voltages in electrical circuits of complete aircraft in the design stage.
    Keywords: AIRCRAFT
    Type: NASA-CR-2349 , SRD-72-066
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  • 47
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    Developmental design, fabrication, and test of acoustic suppressors for fans of high bypass turbofan engines (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analysis procedure was developed for design of acoustically treated nacelles for high bypass turbofan engines. The plan was applied to the conceptual design of a nacelle for the quiet engine typical of a 707/DC-8 airplane installation. The resultant design was modified to a test nacelle design for the NASA Lewis quiet fan. The acoustic design goal was a 10 db reduction in effective perceived fan noise levels during takoff and approach. Detailed nacelle designs were subsequently developed for both the quiet engine and the quiet fan. The acoustic design goal for each nacelle was 15 db reductions in perceived fan noise levels from the inlet and fan duct. Acoustically treated nacelles were fabricated for the quiet engine and quiet fan for testing. Performance of selected inlet and fan duct lining configurations was experimentally evaluated in a flow duct. Results of the tests show that the linings perform as designed.
    Keywords: AIRCRAFT
    Type: NASA-CR-2338 , D3-8952
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  • 48
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    Flight experience with the decelerating noise abatement approach (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The noise of older aircraft can be reduced in two principal ways: retrofitting the aircraft with a quiet propulsion system, and changing the flight operational procedures used in flying the aircraft. The former approach has already proved to be expensive, time consuming, and difficult to implement even though low-noise propulsion system technology exists. The latter method seems to hold promise of being less expensive and easier to implement. One operational technique which might reduce the noise beneath the landing approach path is the decelerating approach. This technique requires intercepting the 3 deg approach path at a relatively high speed with the aircraft in the cruise configuration, then reducing the thrust to idle and allowing the aircraft to decelerate along the 3 deg approach path. As the appropriate airspeed is achieved, the landing flaps and landing gear are deployed for a normal flare and landing. Because the engines, which are the predominant noise source on landing approach, are at idle thrust, a significant reduction in the noise beneath the approach path should be realized.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-56020
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  • 49
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    Flight test data for a Cessna Cardinal (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results of a flight test analysis of the performance of a standard Cessna 177B Cardinal airplane are presented. The airplane was fully instrumented to obtain steady state performance, stick-fixed dynamic stability characteristics, and roll response data. Results obtained include graphs of C sub L versus alpha, C sub D versus C sub L, and speed-power relationships. Dynamic data include Phugoid and Dutch characteristics, and roll response characteristics.
    Keywords: AIRCRAFT
    Type: NASA-CR-2337 , FRL-72-001
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  • 50
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    Analytical design and simulation evaluation of an approach flight director system for a jet STOL aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A program was undertaken to develop design criteria and operational procedures for STOL transport aircraft. As part of that program, a series of flight tests shall be performed in an Augmentor Wing Jet STOL Aircraft. In preparation for the flight test programs, an analytical study was conducted to gain an understanding of the characteristics of the vehicle for manual control, to assess the relative merits of the variety of manual control techniques available with attitude and thrust vector controllers, and to determine what improvements can be made over manual control of the bare airframe by providing the pilot with suitable command guidance information and by augmentation of the bare airframe dynamics. The objective of the study is to apply closed-loop pilot/vehicle analysis techniques to the analysis of manual flight control of powered-lift STOL aircraft in the landing approach and to the design and experimental verification of an advanced flight director display.
    Keywords: AIRCRAFT
    Type: NASA-CR-114697 , STI-TR-1015-1
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  • 51
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    Development of acoustically lined ejector technology for multitube jet noise suppressor nozzles by model and engine tests over a wide range of jet pressure ratios and temperatures (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental program comprising model nozzle and full-scale engine tests was undertaken to acquire parametric data for acoustically lined ejectors applied to primary jet noise suppression. Ejector lining design technology and acoustical scaling of lined ejector configurations were the major objectives. Ground static tests were run with a J-75 turbojet engine fitted with a 37-tube, area ratio 3.3 suppressor nozzle and two lengths of ejector shroud (L/D = 1 and 2). Seven ejector lining configurations were tested over the engine pressure ratio range of 1.40 to 2.40 with corresponding jet velocities between 305 and 610 M/sec. One-fourth scale model nozzles were tested over a pressure ratio range of 1.40 to 4.0 with jet total temperatures between ambient and 1088 K. Scaling of multielement nozzle ejector configurations was also studied using a single element of the nozzle array with identical ejector lengths and lining materials. Acoustic far field and near field data together with nozzle thrust performance and jet aerodynamic flow profiles are presented.
    Keywords: AIRCRAFT
    Type: NASA-CR-2382 , D6-60226
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  • 52
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    Direct measurement of sound sources in air jets using the crossed beam correlation technique (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Properties of density fluctuations were measured in the turbulent regions of a 2.54 cm air jet, at M = 0.7, 1.0 and 1.94. After calibration tests, it was found that the absorption of infrared radiation at 4.3 microns by the naturally present quantities of carbon-dioxide in air was directly proportional to the air density if a sufficiently wide bandpass (0.08 microns) was used. Moreover, regions of the band could be selected that adequately discriminated against temperature variations. The cross-correlation of two such beams intersecting in the jet gave a measure of the local properties at the intersection point. A derivation is presented relating the local density correlation function to the self and shear generated noise in the far field of the jet. The measured correlations are used to predict the axial distribution of source strengths and the spectrum of noise due to a unit volume of turbulence.
    Keywords: AIRCRAFT
    Type: AGARD Noise Mech.; 16 p
    Format: text
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  • 53
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    A Flight Investigation of the STOL Characteristics of an Augmented Jet Flap STOL Research Aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The flight test program objectives are: (1) To determine the in-flight aerodynamic, performance, and handling qualities of a jet STOL aircraft incorporating the augmented jet flap concept; (2) to compare the results obtained in flight with characteristics predicted from wind tunnel and simulator test results; (3) to contribute to the development of criteria for design and operation of jet STOL transport aircraft; and (4) to provide a jet STOL transport aircraft for STOL systems research and development. Results obtained during the first 8 months of proof-of-concept flight testing of the aircraft in STOL configurations are reported. Included are a brief description of the aircraft, fan-jet engines, and systems; a discussion of the aerodynamic, stability and control, and STOL performance; and pilot opinion of the handling qualities and operational characteristics.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-62334 , A-5418
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  • 54
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    Free-flight investigation of the stability and control characteristics of a STOL model with an externally blown jet flap (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The stability and control characteristics of a four-engine turbofan STOL transport model having an externally blown jet flap have been investigated by means of the flying-model technique in the Langley full-scale tunnel. The flight characteristics of the model were investigated under conditions of symmetric and asymmetric (one engine inoperative) thrust at lift coefficients up to 9.5 and 5.5, respectively. Static characteristics were studied by conventional power-on force tests over the flight-test angle-of-attack range including the stall. In addition to these tests, dynamic longitudinal and lateral stability calculations were performed for comparison with the flight-test results and for use in correlating the model results with STOL handling-qualities criteria.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7411 , L-9148
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  • 55
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    An analysis of pilot error-related aircraft accidents (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A multidisciplinary team approach to pilot error-related U.S. air carrier jet aircraft accident investigation records successfully reclaimed hidden human error information not shown in statistical studies. New analytic techniques were developed and applied to the data to discover and identify multiple elements of commonality and shared characteristics within this group of accidents. Three techniques of analysis were used: Critical element analysis, which demonstrated the importance of a subjective qualitative approach to raw accident data and surfaced information heretofore unavailable. Cluster analysis, which was an exploratory research tool that will lead to increased understanding and improved organization of facts, the discovery of new meaning in large data sets, and the generation of explanatory hypotheses. Pattern recognition, by which accidents can be categorized by pattern conformity after critical element identification by cluster analysis.
    Keywords: AIRCRAFT
    Type: NASA-CR-2444 , H-827
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  • 56
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    A methodology for boost-glide transport technology planning (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A systematic procedure is presented by which the relative economic value of technology factors affecting design, configuration, and operation of boost-glide transport can be evaluated. Use of the methodology results in identification of first-order economic gains potentially achievable by projected advances in each of the definable, hypersonic technologies. Starting with a baseline vehicle, the formulas, procedures and forms which are integral parts of this methodology are developed. A demonstration of the methodology is presented for one specific boost-glide system.
    Keywords: AIRCRAFT
    Type: NASA-CR-2346 , SD-73-SA-0064
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  • 57
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    Preliminary performance estimates of a highly maneuverable remotely piloted vehicle (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A computerized synthesis program has been used to assess the effects of various vehicle and mission parameters on the performance of a highly maneuverable remotely piloted vehicle (RPV) for the air-to-air combat role. The configuration used in the study is a trapezoidal-wing and body concept, with forward-mounted stabilizing and control surfaces. The study mission consists of an outbound cruise, an acceleration phase, a series of subsonic and supersonic turns, and a return cruise. Performance is evaluated in terms of both the required vehicle weight to accomplish this mission and combat effectiveness as measured by turning and acceleration capability. The report describes the synthesis program, the mission, the vehicle, and the results of sensitivity and trade studies.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7551 , A-5157
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  • 58
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    Initial results from flight testing a large, remotely piloted airplane model (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The first four flights of a remotely piloted airplane model showed that a flight envelope can be expanded rapidly and that hazardous flight tests can be conducted safely with good results. The flights also showed that aerodynamic data can be obtained quickly and effectively over a wide range of flight conditions, clear and useful impressions of handling and controllability of configurations can be obtained, and present computer and electronic technology provide the capability to close flight control loops on the ground, thus providing a new method of design and flight test for advanced aircraft.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-56024
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  • 59
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    Noise characteristics of jet flap type exhaust flows (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental investigation of the aerodynamic noise and flow field characteristics of internal-flow jet-augmented flap configurations (abbreviated by the term jet flap throughout the study) is presented. The first part is a parametric study of the influence of the Mach number (subsonic range only), the slot nozzle aspect ratio and the flap length on the overall radiated sound power and the spectral composition of the jet noise, as measured in a reverberation chamber. In the second part, mean and fluctuating velocity profiles, spectra of the fluctuating velocity and space correlograms were measured in the flow field of jet flaps by means of hot-wire anemometry. Using an expression derived by Lilley, an attempt was made to estimate the overall sound power radiated by the free mixing region that originates at the orifice of the slot nozzle (primary mixing region) relative to the overall sound power generated by the free mixing region that originates at the trailing edge of the flap (secondary mixing region). It is concluded that at least as much noise is generated in the secondary mixing region as in the primary mixing region. Furthermore, the noise generation of the primary mixing region appears to be unaffected by the presence of a flap.
    Keywords: AIRCRAFT
    Type: NASA-CR-2342
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  • 60
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    Applicability of NASA (ARC) two-segment approach procedures to Boeing Aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An engineering study to determine the feasibility of applying the NASA (ARC) two-segment approach procedures and avionics to the Boeing fleet of commercial jet transports is presented. This feasibility study is concerned with the speed/path control and systems compability aspects of the procedures. Path performance data are provided for representative Boeing 707/727/737/747 passenger models. Thrust margin requirements for speed/path control are analyzed for still air and shearing tailwind conditions. Certification of the two-segment equipment and possible effects on existing airplane certification are discussed. Operational restrictions on use of the procedures with current autothrottles and in icing or reported tailwind conditions are recommended. Using the NASA/UAL 727 procedures as a baseline, maximum upper glide slopes for representative 707/727/737/747 models are defined as a starting point for further study and/or flight evaluation programs.
    Keywords: AIRCRAFT
    Type: NASA-CR-114678 , D6-41336
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    Wind tunnel investigation of simulated helicopter engine exhaust interacting with windstream (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A wind tunnel investigation of the windstream-engine exhaust flow interaction on a light observation helicopter model has been conducted in the Langley V/STOL tunnel. The investigation utilized flow visualization techniques to determine the cause to determine the cause of exhaust shield overheating during cruise and to find a means of eliminating the problem. Exhaust flow attachment to the exhaust shield during cruise was found to cause the overheating. Several flow-altering devices were evaluated to find a suitable way to correct the problem. A flow deflector located on the model cowling upstream of the exhaust in addition to aerodynamic shield fairings provided the best solution. Also evaluated was heat transfer concept employing pin fins to cool future exhaust hardware. The primary flow visualization technique used in the investigation was a newly developed system employing neutrally buoyant helium-filled bubbles. The resultant flow patterns were recorded on motion picture film and on television magnetic tape.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-3016 , L-9430
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  • 62
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    Calculation of the longitudinal aerodynamic characteristics of STOL aircraft with externally-blown jet-augmented flaps (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A theoretical investigation was made to develop methods for predicting the longitudinal aerodynamic characteristics of externally-blown, jet-augmented wing-flap combinations. A potential flow analysis was used to develop two models: a wing-flap lifting surface model and a high-bypass-ratio turbofan engine wake model. Use of these two models in sequence provides for calculation of the wing-flap load distribution including the influence of the engine wake. The method can accommodate multiple engines per wing panel and part-span flaps but is limited to the case where the flow and geometry of the configuration are symmetric about a vertical plane containing the wing root chord. Comparisons of predicted and measured lift and pitching moment on unswept and swept wings with one and two engines per panel and with various flap deflection angles indicate satisfactory prediction of lift and moment for flap deflections up to 30 to 40 degrees. At higher flap angles with and without power, the method begins to overpredict lift, due probably to the appearance of flow separation on the flaps.
    Keywords: AIRCRAFT
    Type: NASA-CR-2358
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  • 63
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    Theoretical study of the effects of refraction on the noise produced by turbulence in jets (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The production of noise by turbulence in jets is an extremely complex problem. One aspect of that problem, the transmission of acoustic disturbances from the interior of the jet through the mean velocity profile and into the far field is studied. The jet (two-dimensional or circular cylindrical) is assumed infinitely long with mean velocity profile independent of streamwise location. The noise generator is a sequence of transient sources drifting with the surrounding fluid and confined to a short length of the jet.
    Keywords: AIRCRAFT
    Type: NASA-CR-2390
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  • 64
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    Sonic boom measurements from accelerating supersonic tracked sleds (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Supersonic sled tests on the Sandia 1524-m (5000-ft) track generate sonic booms of sufficient intensity to allow some airblast measurements at distance scales not obtained from wind tunnel or flight tests. During acceleration, an emitted curved boom wave propagates to a caustic, or focus. Detailed measurements around these caustics may help to clarify the overpressure magnification which can occur from real aircraft operations. Six fixed pressure gages have been operated to document the general noise field, and a mobile array of twelve gages.
    Keywords: AIRCRAFT
    Type: NASA-CR-132388 , SLA-73-714
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  • 65
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    A test technique for measuring lightning-induced voltages on aircraft electrical circuits (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The development of a test technique used for the measurement of lightning-induced voltages in the electrical circuits of a complete aircraft is described. The resultant technique utilizes a portable device known as a transient analyzer capable of generating unidirectional current impulses similar to lightning current surges, but at a lower current level. A linear relationship between the magnitude of lightning current and the magnitude of induced voltage permitted the scaling up of measured induced values to full threat levels. The test technique was found to be practical when used on a complete aircraft.
    Keywords: AIRCRAFT
    Type: NASA-CR-2348 , SRD-72-065
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  • 66
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    A simplified flight-test method for determining aircraft takeoff performance that includes effects of pilot technique (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method for evaluating aircraft takeoff performance from brake release to air-phase height that requires fewer tests than conventionally required is evaluated with data for the XB-70 airplane. The method defines the effects of pilot technique on takeoff performance quantitatively, including the decrease in acceleration from drag due to lift. For a given takeoff weight and throttle setting, a single takeoff provides enough data to establish a standardizing relationship for the distance from brake release to any point where velocity is appropriate to rotation. The lower rotation rates penalized takeoff performance in terms of ground roll distance; the lowest observed rotation rate required a ground roll distance that was 19 percent longer than the highest. Rotations at the minimum rate also resulted in lift-off velocities that were approximately 5 knots lower than the highest rotation rate at any given lift-off distance.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7603 , H-802
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  • 67
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    Preliminary tests of vulnerability of typical aircraft electronics to lightning-induced voltages (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Tests made on two pieces of typical aircraft electronics equipment to ascertain their vulnerability to simulated lightning-induced transient voltages representative of those which might occur in flight when the aircraft is struck by lightning were conducted. The test results demonstrated that such equipment can be interfered with or damaged by transient voltages as low as 21 volts peak. Greater voltages can cause failure of semiconductor components within the equipment. The results emphasize a need for establishment of coordinated system susceptibility and component vulnerability criteria to achieve lightning protection of aerospace electrical and electronic systems.
    Keywords: AIRCRAFT
    Type: NASA-CR-2350 , SRD-72-067
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  • 68
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    Noise measurements obtained during engineering evaluation of two-segment approaches in a 727-200 aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A series of noise measurements were made during engineering evaluation tests of two-segment approaches in a 727-200 aircraft equipped with acoustically treated nacelles. A two-segment approach having a 6-degree upper glide slope angle intercepting the Instrument Landing System (ILS) 2.9-degree glide slope at an altitude of 690 feet gave a 5-EPNdB decrease in measured noise at distances greater than 3 nautical miles from the runway threshold when compared with a normal ILS approach. Several of the noise measurements were taken under adverse weather conditions which were outside the specified limits of FAR Part 36. This may introduce uncertainties into the data from several approaches.
    Keywords: AIRCRAFT
    Type: NASA-CR-114691 , HCI-TR-S-229
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  • 69
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    Design of a powered elevator control system (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The design, fabrication and flight testing of a powered elevator system for the Augmentor Wing Jet STOL Research Aircraft (AWJSRA or Mod C-8A) are discussed. The system replaces a manual spring tab elevator control system that was unsatisfactory in the STOL flight regime. Pitch control in the AWJSRA is by means of a single elevator control surface. The elevator is used for both maneuver and trim control as the stabilizer is fixed. A fully powered, irreversible flight control system powered by dual hydraulic sources was designed. The existing control columns and single mechanical cable system of the AWJSRA have been retained as has been the basic elevator surface, except that the elevator spring tab is modified into a geared balance tab. The control surface is directly actuated by a dual tandem moving body actuator. Control signals are transmitted from the elevator aft quadrant to the actuator by a linkage system that includes a limited authority series servo actuator.
    Keywords: AIRCRAFT
    Type: NASA-CR-114727
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  • 70
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    Evaluation of spoilers for light aircraft flight path control (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A fixed-base flight simulator was used to evaluate wing spoilers for longitudinal flight path control on a modified Cessna 177B aircraft. More than 100 simulated ILS approaches were flown by evaluation pilots using both conventional methods and spoiler controls. Three different spoiler control methods were evaluated. Spoilers provided precise glide path control with constant airspeed and attitude. Control is most effective when the steady-state trimmed aircraft lift coefficient remains independent of spoiler position.
    Keywords: AIRCRAFT
    Type: Journal of Aircraft; 11; Aug. 197
    Format: text
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  • 71
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    Maximum likelihood identification of aircraft stability and control derivatives (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Application of a generalized identification method to flight test data analysis. The method is based on the maximum likelihood (ML) criterion and includes output error and equation error methods as special cases. Both the linear and nonlinear models with and without process noise are considered. The flight test data from lateral maneuvers of HL-10 and M2/F3 lifting bodies are processed to determine the lateral stability and control derivatives, instrumentation accuracies, and biases. A comparison is made between the results of the output error method and the ML method for M2/F3 data containing gusts. It is shown that better fits to time histories are obtained by using the ML method. The nonlinear model considered corresponds to the longitudinal equations of the X-22 VTOL aircraft. The data are obtained from a computer simulation and contain both process and measurement noise. The applicability of the ML method to nonlinear models with both process and measurement noise is demonstrated.
    Keywords: AIRCRAFT
    Type: Journal of Aircraft; 11; Feb. 197
    Format: text
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  • 72
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    A flight investigation with a STOL airplane flying curved, descending instrument approach paths (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A flight investigation using a De Havilland Twin Otter airplane was conducted to determine the configurations of curved, 6 deg descending approach paths which would provide minimum airspace usage within the requirements for acceptable commercial STOL airplane operations. Path configurations with turns of 90 deg, 135 deg, and 180 deg were studied; the approach airspeed was 75 knots. The length of the segment prior to turn, the turn radius, and the length of the final approach segment were varied. The relationship of the acceptable path configurations to the proposed microwave landing system azimuth coverage requirements was examined.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7669 , L-9549
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  • 73
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    A study of subsonic transport aircraft configurations using hydrogen (H2) and methane (CH4) as fuel (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The acceptability of alternate fuels for future commercial transport aircraft are discussed. Using both liquid hydrogen and methane, several aircraft configurations are developed and energy consumption, aircraft weights, range and payload are determined and compared to a conventional Boeing 747-100 aircraft. The results show that liquid hydrogen can be used to reduce aircraft energy consumption and that methane offers no advantage over JP or hydrogen fuel.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-71994
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  • 74
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    Static performance and noise tests on a thrust reverser for an augmentor wing aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A 1/3 scale model static test program was conducted to measure the noise levels and reverse thrust performance characteristics of wing-mounted thrust reverser that could be used on an advanced augmentor wing airplane. The configuration tested represents only the most fundamental designs where installation and packaging restraints are not considered. The thrust reverser performance is presented in terms of horizontal, vertical, and resultant effectiveness ratios and the reverser noise is compared on the basis of peak perceived noise level (PNL) and one-third octave band data (OASPL). From an analysis of the model force and acoustic data, an assessment is made on the stopping distance versus noise for a 90,900 kg (200,000 lb) airplane using this type of thrust reverser.
    Keywords: AIRCRAFT
    Type: NASA-CR-137561 , D6-41926
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  • 75
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    Experimental investigation of the landing dynamics of three-legged spacecraft models (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental investigation was conducted to obtain accurate data from two three-legged spacecraft landing systems for purposes of validating current and future computer programs for legged landers. Two landing-gear systems were investigated: an inverted tripod system and a cantilever system. Tests were conducted for eight landing conditions chosen to obtain stability data, maximum loads, and maximum strokes for correlation with analytical results. Data from the two models are not directly comparable because of geometry and mass differences, but both are considered to be typical models of the respective landing-gear systems. Results indicate that maximum accelerations for both models, which occurred during a nearly flat landing on a horizontal surface, were nearly the same (approximately minus 18g). Maximum primary strut forces occurred for landings into a 20 deg slope and were 40 kiloNewtons (9000 lbf) and 47 kiloNewtons (10 500 lbf) for the inverted tripod and cantilever models, respectively; and maximum primary strut strokes for both models were 19 cm (7.4 in.). The inverted tripod model was slightly more stable than the cantilever model because of a larger ratio of footpad radius to center-of-gravity height.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7664 , L-9499
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  • 76
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    Wind-tunnel investigation to determine the low speed yawing stability derivatives of a twin jet fighter model at high angles of attack (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An investigation was conducted to determine the low-speed yawing stability derivatives of a twin-jet fighter airplane model at high angles of attack. Tests were performed in a low-speed tunnel utilizing variable-curvature walls to simulate pure yawing motion. The results of the study showed that at angles of attack below the stall the yawing derivatives were essentially independent of the yawing velocity and sideslip angle. However, at angles of attack above the stall some nonlinear variations were present and the derivatives were strongly dependent upon sideslip angle. The results also showed that the rolling moment due to yawing was primarily due to the wing-fuselage combination, and that at angles of attack below the stall both the vertical and horizontal tails produced significant contributions to the damping in yaw. Additionally, the tests showed that the use of the forced-oscillation data to represent the yawing stability derivatives is questionable, at high angles of attack, due to large effects arising from the acceleration in sideslip derivatives.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7721 , L-9664
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  • 77
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    High-transonic-speed transport aircraft study (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An initial design study of high-transonic-speed transport aircraft has been completed. Five different design concepts were developed. These included fixed swept wing, variable-sweep wing, delta wing, double-fuselage yawed-wing, and single-fuselage yawed-wing aircraft. The boomless supersonic design objectives of range = 5560 km (3000 nmi), payload = 18,143 kg (40,000 lb), Mach = 1.2, and FAR Part 36 aircraft noise levels were achieved by the single-fuselage yawed-wing configuration with a gross weight of 211,828 kg (467,000 lb). A noise level of 15 EPNdB below FAR Part 36 requirements was obtained with a gross weight increase to 226,796 kg (500,000 lb). The off-design subsonic range capability for this configuration exceeded the Mach 1.2 design range by more than 20%. Although wing aeroelastic divergence was a primary design consideration for the yawed-wing concepts, the graphite-epoxy wings of this study were designed by critical gust and maneuver loads rather than by divergence requirements. The transonic nacelle drag is shown to be very sensitive to the nacelle installation. A six-degree-of-freedom dynamic stability analysis indicated that the control coordination and stability augmentation system would require more development than for a symmetrical airplane but is entirely feasible. A three-plane development plan is recommended to establish the full potential of the yawed-wing concept.
    Keywords: AIRCRAFT
    Type: NASA-CR-2465 , D6-60231
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  • 78
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    Perturbation solutions for the influence of forward flight on helicopter rotor flapping stability (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The stability of the flapping motion of a helicopter rotor blade in forward flight is investigated, using a perturbation technique which gives analytic expressions for the eigenvalues, including the influence of the periodic aerodynamic forces in forward flight. The perturbation solutions are based on small advance ratio (the ratio of the helicopter forward speed to the rotor tip speed). The rotor configurations considered are a single, independent blade; a teetering rotor; a gimballed rotor with three, four, and five or more blades; and a rotor with N independent blades. The constant coefficient approximation with the equations and degrees of freedom in the nonrotating frame represents the flap dynamic reasonably well for the lower frequency modes, although it cannot, of course, be completely correct. The transfer function of the rotor flap response to sinusoidal pitch input is examined, as an alternative to the eigenvalues as a representation of the dynamic characteristics of the flap motion.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-62361
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  • 79
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    Low-speed aerodynamic characteristics of a hypersonic research airplane concept having a 70 deg swept delta wing (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental investigation of the low-speed static longitudinal, lateral and directional stability characteristics of a hypersonic research airplane concept having a 70 deg swept delta wing was conducted in a low-speed tunnel with a 12-foot (3.66 meter) octagonal test section. Aircraft component variations included: (1) fuselage shape modifications, (2) tip fins, (3) center vertical fin, (4) wing camber, and (5) wing planform. This investigation was conducted at a dynamic pressure of 262.4 Pa (5.48 psf), a Mach number of 0.06, and a Reynolds number of 2.24 million, based on body length. Tests were conducted through an angle-of-attack range of 0 deg to 30 deg with elevon deflections from +5.0 deg to minus 30.0 deg. The complete configuration exhibited positive static longitudinal, lateral and directional stability up to angles of attack of at least 20 deg and was trimmable to lift coefficients of at least 0.70 with elevon deflections of minus 30 deg.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-71974
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  • 80
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    Computer programs for estimating aircraft takeoff performance in three dimensional space (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A set of computer programs has been developed to estimate the takeoff and initial climb-out maneuver of a given aircraft in three-dimensional space. The program is applicable to conventional, vectored lift and power-lift concept aircraft. The aircraft is treated as a point mass flying over a flat earth with no side slip, and the rotational dynamics have been neglected. The required input is described and a sample case presented.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-62366
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  • 81
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    Small scale model static acoustic investigation of hybrid high lift systems combining upper surface blowing with the internally blown flap (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A static acoustic and propulsion test of a small radius Jacobs-Hurkamp and a large radius Flex Flap combined with four upper surface blowing (USB) nozzles was performed. Nozzle force and flow data, flap trailing edge total pressure survey data, and acoustic data were obtained. Jacobs-Hurkamp flap surface pressure data, flow visualization photographs, and spoiler acoustic data from the limited mid-year tests are reported. A pressure ratio range of 1.2 to 1.5 was investigated for the USB nozzles and for the auxiliary blowing slots. The acoustic data were scaled to a four-engine STOL airplane of roughly 110,000 kilograms or 50,000 pounds gross weight, corresponding to a model scale of approximately 0.2 for the nozzles without deflector. The model nozzle scale is actually reduced to about .17 with deflector although all results in this report assume 0.2 scale factor. Trailing edge pressure surveys indicated that poor flow attachment was obtained even at large flow impingement angles unless a nozzle deflector plate was used. Good attachment was obtained with the aspect ratio four nozzle with deflector, confirming the small scale wind tunnel tests.
    Keywords: AIRCRAFT
    Type: NASA-CR-114757 , LG74ER0096
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  • 82
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    Digital flight control actuation system study (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Flight control actuators and feedback sensors suitable for use in a redundant digital flight control system were examined. The most appropriate design approach for an advanced digital flight control actuation system for development and use in a fly-by-wire system was selected. The concept which was selected consisted of a PM torque motor direct drive. The selected system is compatible with concurrent and independent development efforts on the computer system and the control law mechanizations.
    Keywords: AIRCRAFT
    Type: NASA-CR-132447 , NR74H-47A
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  • 83
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    Parametric study of STOL short-haul transport engine cycles and operational techniques to minimize community noise impact (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of aircraft operational techniques in the terminal area on community noise impact of future short haul aircraft was investigated. Aircraft equipped with mechanical flap (MF) and aircraft with externally blown flap (EBF) were used to study the noise impact at four U.S. airports. The four airports were: (1) Hanscom Field (Boston), (2) Washington National (D.C.), (3) Midway (Chicago) and (4) Orange County (California). With the exception of Washington National (D.C.), the study showed that a reduction of approximately 40 percent in the number of people highly annoyed can be obtained by using the recommended operational techniques. The evaluation procedures and methodology developed in the study represent an advance in acoustical state-of-the-art and provide an effective and useful tool for determining aircraft noise impact on the airport community.
    Keywords: AIRCRAFT
    Type: NASA-CR-114759 , MDC-J4437
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  • 84
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    Flyover noise characteristics of a tilt-wing V/STOL aircraft (XC-142A) (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A field noise measurement investigation was conducted during the flight testing of an XC-142A tilt-wing V/STOL aircraft to define its external noise characteristics. Measured time histories of overall sound pressure level show that noise levels are higher at lower airspeeds and decrease with increased speed up to approximately 160 knots. The primary noise sources were the four high-speed, main propellers. Flyover-noise time histories calculated by existing techniques for propeller noise prediction are in reasonable agreement with the experimental data.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-3074 , L-9037
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  • 85
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    A simulator investigation of engine failure compensation for powered-lift STOL aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A piloted simulator investigation of various engine failure compensation concepts for powered-lift STOL aircraft was carried out at the Ames Research Center. The purpose of this investigation was to determine the influence of engine failure compensation on recovery from an engine failure during the landing approach and on the precision of the STOL landing. The various concepts include: (1) cockpit warning lights to cue the pilot of an engine failure, (2) programmed thrust and roll trim compensation, (3) thrust command and (4) flight-path stabilization. The aircraft simulated was a 150 passenger four-engine, externally blown flap civil STOL transport having a 90 psf wing loading and a .56 thrust to weight ratio. Results of the simulation indicate that the combination of thrust command and flight-path stabilization offered the best engine-out landing performance in turbulence and did so over the entire range of altitudes for which engine failures occurred.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-62363
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  • 86
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    Data and results from a study of internal convective cooling systems for hypersonic aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An extensive survey of current and future airframe construction materials and coolants was conducted, so that the most promising candidates could be examined for cooled-panel, cooling-system and airframe concepts. Consideration was given to over 100 structural materials, 50 coolants, 6 classes of structural panel concepts, 4 classes of thermal panel concepts with numerous variations, and 3 overall cooled airframe design approaches, including unshielded, shielded, and dual temperature types. The concept identification and parametric comparison phase examined all major elements of the convectively cooled airframe, including the differing requirements at various locations on the aircraft. The parametric results were used for the investigation to two separate vehicles, a hypersonic transport with a length of 96 meters (314 feet) and a weight of 24,000 kg (528,600 lb) and a hypersonic research airplane, with a length of 25m (80 ft) and a weight of 20,300 kg (447,000 lb).
    Keywords: AIRCRAFT
    Type: NASA-CR-132432
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  • 87
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    A method of automatically stabilizing helicopter sling loads (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of geometric and aerodynamic characteristics on the stability of the lateral degrees of freedom of a typical helicopter sling load is examined. The feasibility of stabilizing the suspended load by controllable fins was also studied. Linear control theory was applied to the design of a simple control law that stabilized the load over a wide range of helicopter airspeeds.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7593 , L-9371
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  • 88
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    Investigation of the large scale coherent structure in a jet and its relevance to jet noise (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A study was conducted to determine the causes of aircraft noise in large jet aircraft. It was determined that jet noise varies strongly with velocity and that significant pure tones are generated by rotor-stator interaction in the jet engines. An objective method for deducing the large eddy structure in a large jet is described. The provisions of lighthill's theory are analyzed and applied to investigating the nature of jet noise. There is considerable evidence that a large scale coherent structure exists in a jet and that this structure can play a major role in sound radiation. Mathematical models are developed to define the parameters of orthogonal decomposition, finite extent velocity field, homogeneous fields, and periodic velocity fields.
    Keywords: AIRCRAFT
    Type: NASA-CR-138908
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  • 89
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    An economic assessment of STOL aircraft potential including terminal area environmental considerations, volume 1 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results of an economic and environmental study of short haul airline systems using short takeoff and landing (STOL) aircraft are presented. The STOL system characteristics were optimized for maximum patronage at a specified return on investment, while maintaining noise impact compatibility with the terminal area. Supporting studies of aircraft air pollution and hub airport congestion relief were also performed. The STOL concept specified for this study was an Augmentor Wing turbofan aircraft having a field length capability of 2,000 ft. and an effective perceived noise level of 95 EPNdB at 500 ft. sideline distance. An economic and environmental assessment of the defined STOL system and a summary of the methodology, STOL system characteristics and arena characteristics are provided.
    Keywords: AIRCRAFT
    Type: NASA-CR-2424
    Format: application/pdf
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  • 90
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    Bibliography on aircraft fire hazards and safety. Volume 2: Safety. Part 1: Key numbers 1 to 524 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Bibliographic citations are presented to describe and define aircraft safety methods, equipment, and criteria. Some of the subjects discussed are: (1) fire and explosion suppression using whiffle balls, (2) ultraviolet flame detecting sensors, (3) evaluation of flame arrestor materials for aircraft fuel systems, (4) crash fire prevention system for supersonic commercial aircraft, and (5) fire suppression for aerospace vehicles.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-71553-VOL-2-PT-1
    Format: application/pdf
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  • 91
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    Bibliography on aircraft fire hazards and safety. Volume 1: Hazards. Part 1: Key numbers 1 to 817 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Ignition temperatures of n-hexane, n-octane, n-decane, JP-6 jet fuel, and aircraft engine oil MIL-7-7808 (0-60-18) were determined in air using heated Pyrex cylinders and Nichrome wires, rods, or tubes. Ignition temperature varied little with fuel-air ratio, but increased as the size of the heat source was decreased. Expressions are given which define the variation of the hot surface ignition temperatures of these combustibles with the radius and the surface area of the heat source. The expressions are applicable to stagnant or low velocity flow conditions (less than 0.2 in./sec.). In addition, the hot gas ignition temperatures of the combustible vapor-air mixtures were determined with jets of hot air. These ignition temperatures also varied little with fuel-air ratio and increased as the diameter of the heat sources was decreased.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-71553-VOL-1-PT-1 , E-7986-VOL-1-PT-1
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  • 92
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    Control load envelope shaping by live twist (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Rotor control systems experience a rapid load growth resulting from retreating blade stall during flight conditions of high blade loading or airspeeds. An investigation was undertaken to determine the effect of changing blade torsional properties over the rotor flight envelope. The results of this study show that reducing the blade stiffness to introduce more blade live twist significantly reduces the large retreating blade control loads, while expanding the flight envelope and reducing retreating blade stall loads.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 115-125
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  • 93
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    Coupled rotor/airframe vibration prediction methods (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The problems of airframe structural dynamic representation and effects of coupled rotor/airframe vibration are discussed. Several finite element computer programs (including NASTRAN) and methods for idealization and computation of airframe natural modes and frequencies and forced response are reviewed. Methods for obtaining a simultaneous rotor and fuselage vibratory response, determining effectiveness of vibration control devices, and energy methods for structural optimization are also discussed. Application of these methods is shown for the vibration prediction of the model 347 helicopter.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 81-90
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  • 94
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    Dynamic stall modeling and correlation with experimental data on airfoils and rotors (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Two methods for modeling dynamic stall have been developed. The alpha, A, B method generates lift and pitching moments as functions of angle of attack and its first two time derivatives. The coefficients are derived from experimental data for oscillating airfoils. The Time Delay Method generates the coefficients from steady state airfoil characteristics and an associated time delay in stall beyond the steady state stall angle. Correlation with three types of test data shows that the alpha, A, B method is somewhat better for use in predicting helicopter rotor response in forward flight. Correlation with lift and moment hysteresis loops generated for oscillating airfoils was good for both models.
    Keywords: AIRCRAFT
    Type: NASA. Ames Res. Center Rotorcraft Dyn.; p 13-23
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  • 95
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    Measurements of sonic booms generated by an airplane flying at Mach 3.5 and 4.8 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Sonic booms generated by the X-15 airplane flying at Mach numbers of 3.5 and 4.8 were measured. The experimental results agreed within 12 percent with results obtained from theoretical methods. No unusual phenomena related to overpressure were encountered. Scaled data from the X-15 airplane for Mach 4.8 agreed with data for an SR-71 airplane operating at lower Mach numbers and similar altitudes. The simple technique used to scale the data on the basis of airplane lift was satisfactory for comparing X-15 and SR-71 sonic boom signatures.
    Keywords: AIRCRAFT
    Type: NASA-TM-X-3126 , H-838
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  • 96
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    Experiments with a four-bladed cyclic pitch stirring model rotor, part 3 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The experimental work with the 2-bladed 16-inch diameter model rotor has been continued with a 4-bladed 16.5 inch diameter rotor capable of progressing and regressing cyclic pitch excitation (cyclic pitch stirring). Advance ratios of 0, .19 and .38 were tested at rotor speeds corresponding to non-dimensional blade natural frequencies of 1:14 and 1.19. The results are presented in the form of the first 5 Fourier components of the periodic response modulating function which for a periodic system takes the place of the complex response amplitude ratio of a constant system. In addition, the first and second harmonics of the trim response are presented. The test data are compared to analytical data without rotor wake and to the test data obtained earlier with the two-bladed rotor model of half the blade solidity ratio.
    Keywords: AIRCRAFT
    Type: NASA-CR-137572
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  • 97
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    Computer experiments in preparation of system identification from transient rotor model tests, part 2 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: System identification methods which can extract model rotor paramenters with reasonable accuracy from noise polluted blade flapping transient measurements were developed. Usually parameter identification requires data on the state variables, that is on deflections and on rate of deflections. The small size of rotor models makes it, however, difficult to measure more than the blade flapping deflections. For the computer experiments it was, therefore, assumed that only noisy deflection measurements are available. Parameter identifications were performed for one and two unknown parameters. Both rotating coordinates and multiblade coordinates were used. It was found that data processing with a digital filter allowed by numerical differentiation a sufficiently accurate determination of the rates of deflection and of the accelerations to obtain reasonable parameter estimates with a simple linear estimator.
    Keywords: AIRCRAFT
    Type: NASA-CR-137571
    Format: application/pdf
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  • 98
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    Methods studies toward simplified rotor-body dynamics, part 1 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: This report is directed to the problem of developing an adequate but not overly complex linear flight dynamics analytical model of a rotorcraft to study stability, control, gust and random turbulence responses. Since the conventional flight dynamics analysis using quasisteady rotor derivatives is adequate for the long period modes like the phugoid mode, only short time responses are considered here, where rotor-body coupling is of importance. Thus the body motion consists of pitch, roll and vertical motion, omitting linear longitudinal and lateral and yaw perturbations. Five analytical models of varying degree of sophistication are applied to a hypothetical hingeless compound helicopter operating up to .8 rotor advance ratio. Stability and response data are obtained for the basic helicopter and for the vehicle with two simple control feedback systems.
    Keywords: AIRCRAFT
    Type: NASA-CR-137570
    Format: application/pdf
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  • 99
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    Experimental investigation of the braking and cornering characteristics of 30 x 11.5-14.5, type 8, aircraft tires with different tread patterns (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An investigation was conducted at the aircraft landing loads and traction facility to study the braking and cornering characteristics, including the drag-force and cornering-force friction coefficients, of 30 by 11.5-14.5, type VIII aircraft tires with five different tread patterns. Test data were obtained on dry, damp, and flooded runway surfaces over a range of yaw angles from 0 deg to 12 deg at ground speeds from 5 knots to 100 knots. The results of this investigation indicate that a tread pattern consisting of transverse cuts across the entire width of the tread slightly improved the tire traction performance on wet surfaces. The braking and cornering capability of the tires was degraded by thin-film lubrication and tire hydroplaning effects on the wet runway surfaces. The braking capability of the tires decreased when the yaw angle was increased.
    Keywords: AIRCRAFT
    Type: NASA-TN-D-7743 , L-9687
    Format: application/pdf
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  • 100
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    Non-engine aerodynamic noise investigation of a large aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A series of flyover noise measurements have been accomplished utilizing a large jet transport aircraft with engine power reduced to flight idle. It was determined that the aerodynamic (nonengine) noise levels did occur in the general range that had been predicted by using small aircraft (up to 17,690 kg gross weight) prediction techniques. The test procedures used are presented along with discussions of the effects of aerodynamic configuration on the radiated noise, identification of noise sources, and predicted aerodynamic noise as compared with measurements.
    Keywords: AIRCRAFT
    Type: NASA-CR-2378
    Format: application/pdf
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