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Results are presented for tests made of the full scale model of the airplane in the NACA full scale tunnel. These tests were planned so as to cover as completely as possible the lateral flying quality requirements for pursuit-type airplanes contracted for by the United States Army Air Forces.
Important requirements were defined for a flight simulation facility to support Army helicopter development. In particular requirements associated with the visual and motion subsystems of the planned simulator were studied. The method used in the motion requirements study is presented together with the underlying assumptions and a description of the supporting data. Results are given in a form suitable for use in a preliminary design. Visual requirements associated with a television camera/model concept are related. The important parameters are described together with substantiating data and assumptions. Research recommendations are given.
Remote sensing programs that respond to the requirements of the water resources management and hydrologic communities are reviewed. The major areas where the needs of water resources management are being met involve the mapping and monitoring of snowcovered areas, hydrologic landuse, and surface water area. In the case of snowcovered area mapping the transfer of technology process is now being accomplished in the Western United States in a cooperative effort involving 6 federal agencies and 3 state agencies along with NASA. A new collaborative effort of the U.S. Army Corps of Engineers and NASA involves the mapping of landuse by Landsat and its use in hydrologic engineering watershed models employed in flood control/waterworks planning, design, and management. Improved systems planned for implementation in the 1978-1981 time frame can be expected to result in increased utilization of visible and near infrared remote sensing observations.
The survey procedures, developed during the winter and summer of 1976, employ color and color infrared aerial photography, thermal infrared imagery, and a handheld infrared imaging device. The resulting imagery was used to detect building heat losses, deteriorated insulation in built-up type building roofs, and defective underground steam lines. The handheld thermal infrared device, used in conjunction with the aerial thermal infrared imagery, provided a method for detecting and locating those roof areas that were underlain with wet insulation. In addition, the handheld infrared device was employed to conduct a survey of a U.S. Army installation's electrical distribution system under full operating loads. This survey proved to be cost effective procedure for detecting faulty electrical insulators and connections that if allowed to persist could have resulted in both safety hazards and loss in production.
A brief description is given of the GPU 3-2 hardware, the test methods used, and the result of these tests. Comparison is made to unpublished data from similar hydrogen tests performed by the U.S. Army.
Using superelements (substructures), modal and frequency response analysis was performed for a large model of the Advanced Attack Helicopter developed for the U.S. Army. Whiffletree concept was employed so that the residual structure along with the various superelements could be represented as beam-like structures for economical and accurate dynamic analysis. A very large DMAP alter to the rigid format was developed so that the modal analysis, the frequency response, and the strain energy in each component could be computed in the same run.
The relationship between the internal noise environment of helicopters and the ability of personnel to understand commands and instructions was studied. A test program was conducted to relate speech intelligibility to a standard measurement called Articulation Index. An acoustical simulator was used to provide noise environments typical of Army helicopters. Speech material (command sentences and phonetically balanced word lists) were presented at several voice levels in each helicopter environment. Recommended helicopter internal noise criteria, based on speech communication, were derived and the effectiveness of hearing protection devices were evaluated.
Methods of measuring the composite acoustic environment of helicopters in order to quantify the effective acoustic environment of the crewmen and to assess the real acoustic hazards of the personnel are examined. It is indicated that the attenuation characteristics of the helmets and hearing protectors and the variables of the physiology of the human ear be accounted for in determining the effective acoustic environment of Army helicopter crewmen as well as the acoustic hazards of voice communications systems noise.
The Army family of helicopters was analyzed to measure the polar octave band acoustic signature in various modes of flight. A static array of calibrated microphones was used to simultaneously acquire the signature and differential times required to mathematically position the aircraft in space. The signature was then reconstructed, mathematically normalized to a fixed radius around the aircraft.
A generalized, real time, piloted, visual simulation of a single rotor helicopter, suspension system, and external load is described and validated for the full flight envelope of the U.S. Army CH-54 helicopter and cargo container as an example. The mathematical model described uses modified nonlinear classical rotor theory for both the main rotor and tail rotor, nonlinear fuselage aerodynamics, an elastic suspension system, nonlinear load aerodynamics, and a loadground contact model. The implementation of the mathematical model on a large digital computing system is described, and validation of the simulation is discussed. The mathematical model is validated by comparing measured flight data with simulated data, by comparing linearized system matrices, eigenvalues, and eigenvectors with manufacturers' data, and by the subjective comparison of handling characteristics by experienced pilots. A visual landing display system for use in simulation which generates the pilot's forward looking real world display was examined and a special head up, down looking load/landing zone display is described.
A 10 horsepower single-cylinder rhombic-drive Stirling engine was converted to a research configuration to obtain data for validation of Stirling computer simulations. The engine was originally built by General Motors Research Laboratories for the U.S. Army in 1965 as part of a 3 kW engine-generator set, designated the GHU 3 (Ground Power Unit). This report presents test results for a range of heater gas temperatures, mean compression-space pressures, and engine speeds with both helium and hydrogen as the working fluids. Also shown are initial data comparisons with computer simulation predictions.
A representative of the U.S. Army Research and Technology Laboratories was called upon to brief the workshop on results of flight test experiments with ice-phobic coatings applied to helicopter rotor blades. An overview of the Applied Technology Laboratory helicopter icing R and D program is presented.
The Navy's maintenance and materials management data base was used in a study to determine the feasibility of predicting unscheduled maintenance costs for the dynamic systems of military rotary wing aircraft. The major operational and design variables were identified and the direct maintenance man hours per flight hour were obtained by step-wise multiple regression analysis. Five nonmilitary helicopter users were contacted to supply data on which variables were important factors in civil applications. These uses included offshore oil exploration and support, police and fire department rescue and enforcement, logging and heavy equipment movement, and U.S. Army military operations. The equations developed were highly effective in predicting unscheduled direct maintenance man hours per flying hours for military aircraft, but less effective for commercial or public service helicopters, probably because of the longer mission durations and the much higher utilization of civil users.
Standard overhaul procedures for U.S. Army helicopter engines require operational vibration acceptance testing after rebuild. Engines frequently experience vibrations which exceed allowable overhaul work requirement limits. The rework/retest cycle for these engines constitute a significant cost penalty to the overhaul center. This paper reviews both analytical and test data which indicate bending critical speeds within the operating speed range of the low-speed power turbine rotor as the cause of most test cell rejections. High-speed balancing techniques are applicable and are capable of significantly reducing this reject rate. A complete prototype computer-assisted high-speed balancing system for assembled T53 and T55 power turbine rotors is described.
The Little Joe II Qualification Test Vehicle, Model 12-50-1, was launched from Army Launch Area 3 {ALA-3) at White Sands Missile Range, New Mexico, on 28 August 1963. This was the first launch of this class of boosters. The Little Joe II Launch Vehicle was designed as a test vehicle for boosting payloads into flight. For the Apollo Program, its mission is to serve as a launch vehicle for flight testing of the Apollo spacecraft. Accomplishment of this mission requires that the vehicle be capable of boosting the Apollo payload to parameters ranging from high dynamic pressures at low altitude to very high altitude flight. The fixed-fin 12-50 version was designed to accomplish the low-altitude parameter. The 12-51 version incorporates an attitude control system to accomplish the high altitude mission. This launch was designed to demonstrate the Little Joe II capability of meeting the high dynamic pressure parameter for the Apollo Program. For this test, a boiler-plate version of the Apollo capsule, service module and escape tower were attached to the launch vehicle to simulate weight, center of gravity and aerodynamic shape of the Apollo configuration. No attempt was made to separate the payload in flight. The test was conducted in compliance with Project Apollo Flight Mission Directive for QTV-1, NASA-MSC, dated 3 June 1963, under authority of NASA Contract NAS 9-492,
The flight-acceptance test results obtained during the acceptance tests of the V/STOLAND (versatile simplex digital avionics system) digital avionics system on a Bell UH-1H helicopter in 1977 at Ames Research Center are presented. The system provides navigation, guidance, control, and display functions for NASA terminal area VTOL research programs and for the Army handling qualities research programs at Ames Research Center. The acceptance test verified system performance and contractual acceptability. The V/STOLAND hardware navigation, guidance, and control laws resident in the digital computers are described. Typical flight-test data are shown and discussed as documentation of the system performance at acceptance from the contractor.
A joint study has been conducted by NASA and Army installations collocated in a dense forest in southwestern Mississippi in order to determine the technical and economic feasibility of using wood waste as a renewable energy source. The study has shown that, with proper forest management, the timber on government lands could eventually support the total energy requirements of 832 billion Btu/yr. Analysis of the current conversion technologies indicates that the direct combustion spreader stoker approach is the best demonstrated technology for this specific application. The economics of the individual powerplants reveal them as attractive alternatives to fossil fueled plants. Environmental aspects are also discussed.
A list of icing instrumentation requirements are presented. Because of the Army's helicopter orientation, many of the suggestions are specific to rotary wing aircraft; however, some of the instrumentation are also suitable for general aviation aircraft.