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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Feasibility study of modern airships, phase 1. Volume 2: Parametric analysis (task 3)

Various types of lighter-than-air vehicles from fully buoyant to semibuoyant hybrids were examined. Geometries were optimized for gross lifting capabilities for ellipsoidal airships, modified delta planform lifting bodies, and a short-haul, heavy-lift vehicle concept. It is indicated that: (1) neutrally buoyant airships employing a conservative update of materials and propulsion technology provide significant improvements in productivity; (2) propulsive lift for VTOL and aerodynamic lift for cruise significantly improve the productivity of low to medium gross weight ellipsoidal airships; and (3) the short-haul, heavy-lift vehicle, consisting of a simple combination of an ellipsoidal airship hull and existing helicopter componentry, provides significant potential for low-cost, near-term applications for ultra-heavy lift missions.

Lancaster, J. W.↗
NASA NTRS1975

Description and test results of a water basin to determine ground effect in hover using small models

A water basin test facility was established capable of measuring forces and moments of small models of VTOL aircraft, simulating hover in and out of ground effect. Because the models and the operation of the facility are inexpensive, the water basin is particularly suitable for testing the relative characteristics of a great number of model configurations for preliminary design development. Results from a variety of models are given. Lift, pitching moments, and rolling moments are given with and without engine failure simulation in ground effect, and with and without pitched and banked conditions.

Renselaer, D. J.↗
NASA NTRS1975

Advanced short haul systems in high density markets

The design requirements, performance, economics, and noise aspects of STOL and VTOL conceptual aircraft developed for short haul air transportation are reviewed, along with the characteristics of areas of high-density annual passenger flow in which the aircraft are intended to operate. It is shown that aircraft of 100 to 200 passenger capacity provide the best return on investment in high density markets. The various STOL propulsive lift concepts have the same general trends with field length; their wing loadings are 20 to 30 pounds per square foot higher than the nonpropulsive lift concepts. A comparison of the aircraft under consideration shows that no one aircraft concept will be optimum for all future operational environments.

Galloway, T. L.↗
NASA NTRS1974

An integrated PCM data system for full scale aeronautics testing

An integrated PCM data system is being developed at Ames Research Center to gather test data on advanced STOL propulsive lift, VTOL, rotary wing, and V/STOL control systems concepts as they pass through wind-tunnel, test-stand, flight-simulator and flight-test phases. Identical airborne signal conditioning and PCM encoding is used on test aircraft and wind tunnel models. An 80,000 word/second PCM installation will be the first all PCM-instrumented rotary wing development project. The system uses both dedicated and time-shared computers for fast data analysis with maximum use of resources. This system development shows one way to bring separate data user groups together over a common data base, while sharing computing resources for minimum cost.-

Reynolds, D. R.↗
NASA NTRS1974

Multilevel control optimization using subsystem relative performance index sensitivity

A method is presented for the design of optimal feedback controllers for large multivariable systems with subsystem sensitivity constraints. The weighted sum of subsystem and/or operational mode relative performance index sensitivities is defined as the overall performance index. The method is developed for linear systems with quadratic performance criteria and either full or partial state feedback. An example concerning the design of a stability augmentation system for a VTOL aircraft in the transition mode demonstrates the effectiveness of the design method.

Leininger, G. G.↗
NASA NTRS1975

Potential missions for advanced airships

The freight commodity transport and the intercity passenger travel markets in the U.S. for 1967 and 1972 are analyzed, along with 1985 estimates, in order to establish the size, speed and cost enabling use of the airship in these markets. Items examined include frozen meat, confectionary, drugs, electrical equipment, mechanical parts, clothing and plastic products. A 50 ton/500 passenger payload capacity, a cruise speed of 100 kt and a VTOL capability or at minimum short take-off and vertical landing capability are needed to make an LTA vehicle viable in the transport market if it had a direct operating cost of $500 to $800 per hour for freight carrying and $1100 to $2700 an hour in passenger service with utilizations between 2000 hours and 4000 hours a year.

Grant, D. T.↗
NASA NTRS1975

Advanced subsonic aircraft concepts for passenger transportation

This paper discusses the potential for new subsonic transport aircraft designs that may evolve in the relatively near future, taking into account the added requirements for improved environmental compatibility and the potential constraints due to system congestion, substantial financial risk, and higher fuel costs or limited availability. Reflecting these additional requirements, potential aircraft developments are presented for new CTOL transports with significantly improved fuel economy, new STOL transports with improved short field capability, and new VTOL transports that could provide direct city-center service.

Waters, M. H.↗
NASA NTRS1975

Ultra-heavy vertical lift system: The Heli-Stat

A hybrid VTOL airship which is combined with helicopters is evaluated. The static lift of the airship supports approximately the full empty weight of the entire assembly. The helicopter rotors furnish the lift to support the payload as well as the propulsion and control about all axes. Thus existing helicopters, with no new technology required, can be made to lift payloads of ten times the capacity of each one alone, and considerably more than that of any airship built so far. A vehicle is described which has a 75-ton payload, based on four existing CH-53D helicopters and an airship of 3,600,000 cu. ft. The method of interconnection is described along with discussion of control, instrumentation, drive system and critical design conditions. The vertical lift and positioning capabilities of this vehicle far exceed any other means available today, yet can be built with a minimum of risk, development cost and time.

Piasecki, F. N.↗
NASA NTRS1975

Aerocrane: A hybrid LTA aircraft for aerial crane applications

The Aerocrane, a hybrid aircraft, combines rotor lift with buoyant lift to offer VTOL load capability greatly in excess of helicopter technology while eliminating the airship problem of ballast transfer. In addition, the Aerocrane concept sharply reduces the mooring problem of airships and provides 360 deg vectorable thrust to supply a relatively large force component for control of gust loads. Designed for use in short range, ultra heavy lift missions, the Aerocrane operates in a performance envelope unsuitable for either helicopters or airships. Basic design considerations and potential problem areas of the concept are addressed.

Perkins, R. G., Jr.↗
NASA NTRS1975

Development of the NASA VALT digital navigation system

The research to develop and fabricate a terminal area navigation system for use in the NASA VTOL Approach and Landing Technology (VALT) program. The results of that effort are reported. The navigation system developed and fabricated was based on a general purpose airborne digital computer. A set of flight hardware units was fabricated to create the necessary analog, digital and human interface with the computer. A comprehensive package of software was created to implement the control and guidance laws required for automatic and flight director approaches that are curved in two planes. A technique was developed that enables the generation of randomly shaped lateral paths from simple input data. The lateral path concept combines straight line and elliptical-curved segments to fit a continuous curved path to the data points. A simple, fixed base simulation was put together to assist in developing and evaluating the system. The simulation was used to obtain system performance data during simulated curved-path approaches.

Mcconnell, W. J., Jr.↗
NASA NTRS1975

Flight test and evaluation of Omega navigation in a general aviation aircraft. Volume 1: Technical

A low cost flight research program was conducted to evaluate the performance of differential Omega navigation in a general aviation aircraft. The flight program consisted of two distinct parts corresponding to the two major objectives of the study. The Wallops Flight Program was conducted to obtain Omega signal and phase data in the Wallops Flight Center vicinity to provide preliminary technical information and experience in preparation for a comprehensive NASA/FAA flight test program of an experimental differential Omega system. The Northeast Corridor Flight Program was conducted to examine Omega operational suitability and performance on low altitude area navigation (RNAV) routes for city-center to city-center VTOL commercial operations in the Boston-New York-Washington corridor. The development, execution and conclusions of the flight research program are discribed. The results of the study provide both quantitative and qualitative data on the Omega Navigation System under actual operating conditions.

Howell, J. D.↗
NASA NTRS1975

A Method for Calculating the Induced Pressure Distribution Associated with a Jet in a Crossflow

A model is presented which can be used to study the loss of lift during hovering and horizontal flight of the VTOL aircraft. The model numerically predicts the pressure distribution induced by a round, turbulent, unheated, subsonic jet exhausting normally through a flat plate into a subsonic crossflow. The complete model assumes that the predominant features of the flow are jet entrainment and a pair of contrarotating vortices which form downstream of the jet. Experimentally determined vortex properties and a reasonable assumption concerning jet entrainment were used. Potential flow considerations were used except in the wake region, where a simple method for approximating the pressure distribution was suggested. The calculated pressure distribution, lift, and pitching moments on the flat plate are presented for a jet to crossflow velocity ratio of 8 and were compared with experimental results. A computer program is given which was used to calculate the pressure distribution across the flat plate.

Dietz, W. E., Jr.↗
NASA NTRS1976

Conceptual design study of 1985 commercial tilt rotor transports. Volume 3: STOL design summary

A conceptual design study is presented of 1,985 commercial tilt rotor STOL transports for a NASA 200 n. mi. (370 km) STOL Mission. A 100-passenger STOL Variant (Bell D313) of the Phase I VTOL Tilt Rotor Aircraft is defined. Aircraft characteristics are given; with the aircraft redesigned to meet 2,000-foot (610 m) field criteria, with emphasis on low fuel consumption and low direct operating cost. The 100-passenger STOL Tilt Rotor Aircraft was analyzed for performance, weights, economics, handling qualities, noise footprint and aeroelastic stability.

Sambell, K. W.↗
NASA NTRS1976

Methodology for design of active controls for V/STOL aircraft

An effort to develop techniques for the design of integrated, fully automatic flight control systems for powered lift STOL and VTOL aircraft is described. The structure is discussed of the control system which has been developed to deal with the strong nonlinearities inherent in this class of aircraft, to admit automatic coupling with the advanced ATC requiring accurate execution of complex trajectories, and to admit a variety of active control tasks. The specific case considered is the Augmentor Wing Research Aircraft.

Meyer, G.↗
NASA NTRS1976

A technique for generating arbitrarily shaped curved approach paths

A technique for creating and using arbitrarily curved flight paths is described, in conjunction with either automatic or manual guidance. Operating techniques for VTOL aircraft in the terminal area environment are investigated. Straight lines and elliptical segments to connect a series of data points into a continous approach path were developed. Software was created to allow the generation of arbitrarily shaped altitude and speed profiles in conjunction with the lateral curved paths.

Mcconnell, W. J., Jr.↗
NASA NTRS1976

NASA's goal - Keeping the US number one in aeronautics

This article discusses the wide range of efforts being pursued by NASA to maintain the preeminence of the United States in military and commercial aircraft design. Emphasis is placed on the question of where industry should concentrate its research and technology efforts to support the aviation needs of the future. The major military and civil aircraft developments forseen for the period from 1985 to 2000 are identified, and NASA's role in the Highly Maneuverable Aircraft Technology program is briefly considered. Other programs discussed include those concerning airfoils, propulsion systems, aviation safety, next-generation subsonic transports, STOL and VTOL vehicles, and supersonic cruise aircraft.

Lovelace, A. M.↗
NASA NTRS1976

Inlets for high angles of attack

Different inlet designs for high angle of attack STOL and VTOL applications were tested in a subsonic wind tunnel. Three removable entry lips having contraction ratios of 1.30, 1.34 and 1.38 were tested with a single diffuser. The internal contour of each entry lip was an ellipse with a major to minor axis of 2.0. Each lip and diffuser assembly was tested to determine its tolerance to angle of attack, first with a conventional centerbody and then with an extended centerbody. Results indicate that a large improvement in separation angle (determined as a function of lip contraction ratio and inlet flow) was obtained for the extended centerbody for all contraction ratios. Improved inlet tolerance to angle of attack was obtained by reducing the adverse pressure gradient downstream of the throat.

Miller, B. A.↗
NASA NTRS1976

A review of some tilt-rotor aeroelastic research at NASA-Langley

An overview of an experimental and analytical research program conducted within the Aeroelasticity Branch of the NASA Langley Research Center for studying the aeroelastic and dynamic characteristics of tilt-rotor VTOL aircraft is presented. Selected results from several joint NASA/contractor investigations of scaled models in the Langley transonic dynamics tunnel are shown and discussed with a view toward delineating various aspects of dynamic behavior peculiar to proprotor aircraft. Included are such items as proprotor/pylon stability, whirl flutter, gust response, and blade flapping. Theoretical predictions, based on analyses developed at Langley, are shown to be in agreement with the measured stability and response behavior.

Kvaternik, R. G.↗