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Technical Paper

10 KWe Dual-Mode Space Nuclear Power System for Military and Scientific Applications

1992-08-03
929078
A 10 KWe dual-mode space power system concept has been identified which is based on INEL's Small Externally-fueled Heat Pipe Thermionic Reactor (SEHPTR) concept. This power system will enhance user capabilities by providing reliable electric power and by providing two propulsion systems; electric power for an arc-jet electric propulsion system and direct thrust by heating hydrogen propellant inside the reactor. The low thrust electric thrusters allow efficient station keeping and long-term maneuvering. The direct thrust capability can provide tens of pounds of thrust at a specific impulse of around 730 seconds for maneuvers that must be performed more rapidly. The direct thrust allows the nuclear power system to move a payload from Low Earth Orbit (LEO) to Geosynchronous Earth Orbit (GEO) in less than one month using approximately half the propellant of a cryogenic chemical stage.
Journal Article

A Comparison between Regular and Vibration-Assisted Drilling in CFRP/Ti6Al4V Stack

2014-09-16
2014-01-2236
As aircraft programs currently ramp up, productivity of assembly processes needs to be improved while keeping quality, reliability and manufacturing cost requirements. Efficiency of the drilling process still remains an issue particularly in the case of CFRP/metal stacks: hot and long metallic chips are difficult to remove and often damage the surface of CFRP holes. Low frequency axial vibration drilling has been proposed to solve this issue. This innovative drilling process allows breaking up the metallic chips in such a way that jamming is avoided. This paper presents a case of CFRP/Ti6Al4V drilling on a CNC machine where productivity must be increased. A comparison is made between the current regular process and the MITIS drilling process. First the analysis and comparison method is presented. The current process is analyzed and its limits are highlighted. Then the vibration process is implemented and its performances are studied.
Technical Paper

A Comparison of Propulsion Systems for V/STOL Supersonic Combat Aircraft

1980-09-01
801141
Three lift/propulsion concepts for a V/STOL supersonic combat aircraft have been compared. The intention was to show the effect of the propulsion system on aircraft weight and size, performance, and life cycle costs for: 1 Vectored thrust with Plenum Chamber Burning (bypass air augmentation) 2 Lift engines and a lift/cruise reheated turbofan 3 A reheated lift/cruise turbofan with a remote augmented lift system (RALS) For a postulated deck-launched intercept mission, the vectored thrust propulsion system with Plenum Chamber Burning gives the smallest and cheapest aircraft having the required performance. In addition, for a given take-off ground run the vectored thrust powered aircraft has the longest fighter escort mission radius.
Technical Paper

A Computer Model of a Pulsejet Engine

1982-02-01
820953
This paper deals with the performance prediction of one member of a family of thrust producing intermittent combustion engines, namely the pulsejet. The first part is concerned with formulating basic concepts of how pulsejets work. It describes the different methods of providing intake valving action and derives theory to demonstrate the operation of the aerodynamic tuned valve in particular. The second part is concerned with devising a computer program to simulate and predict the performance of valveless pulsejets. The program is based on the method of characteristics for calculating unsteady gas flow. Theories and techniques are given to handle the major problems associated with this application. These problems include the large range of discontinuous temperature and entropy, flow through an area discontinuity and the calculation of mean thrust.
Technical Paper

A Design Approach to Integrated Flight and Propulsion Control

1983-10-03
831482
A decentralized, multivariable controls methodology is being developed for the functional integration of a fighter's aerodynamic controls with those of its propulsion system (inlet, engine, and thrust vectoring/reversing nozzle). Integrated controls account for, and take advantage of the significant cross-coupling between these system elements. A high-fidelity, six-degrees-of-freedom (6 DOF) aircraft simulation has been developed, incorporating advanced tactical fighter features such as variable cycle engines, variable geometry inlets, 2D-CD TV/TR nozzles, canards and a propulsive lift concept. A comprehensive evaluation test plan, including a piloted simulation, has been developed to validate this integrated-controls design methodology. Preliminary results show significant benefits of integrated control in terms of enhanced aircraft maneuverability, precise flight path control, reduced pilot workload, and fault tolerant system design.
Technical Paper

A General Three-Dimensional Potential-Flow Method Applied to V/STOL Aerodynamics

1968-02-01
680304
This paper describes a numerical method for solving three-dimensional incompressible flow problems and its use in predicting the aerodynamic characteristics of V/STOL aircraft. Arbitrary configuration and inlet geometry, fan inflow distributions, thrust vectoring, jet entrainment, angles of yaw, and flight speeds from hover through transition can be treated. Potential-flow solutions are obtained with the method of influence coefficients, using source and doublet panels distributed on the boundary surfaces. The results include pressure distributions, lift, induced drag and side force, and moments. Theoretical solutions are presented for clean lifting wings and for a NASA fan-in-wing model. Comparisons with the experimental NASA data demonstrate the validity of the approach and uncover the importance of viscous effects, fan inflow distribution, and jet entrainment.
Technical Paper

A Ground Test Program to Support Condition Monitoring of a Spacecraft Attitude Control Propulsion System

1991-09-01
912167
The Comet Rendezvous Asteroid Flyby (CRAF) mission involves seven years of flight from 0.6 to 4.57 Astronomical Units (AU), followed by about 915 days of maneuvering around a comet. Ground testing will characterize the very critical attitude control system thrusters' fuel consumption and performance for all anticipated fuel temperatures over thruster life. The ground test program characterization will support flight condition monitoring. A commercial software application hosted on a commercial microcomputer will control ground test operations and data acquisition using a newly designed thrust stand. The data acquisition and control system uses a graphics-based language and features a visual interface to integrate data acquisition and control.
Technical Paper

A High-Speed Fuel Lubricated Hybrid Thrust Bearing for Limited-Life Turbine Engines

1990-09-01
902023
The feasibility of operating a mainshaft thrust bearing at high speeds with jet fuel mist as the coolant and lubricant has been demonstrated in both rig and engine testing. A split-inner ring hybrid thrust bearing ( silicon nitride balls ) was successfully operated to 1.67 x 106 DN at maximum Hertzian contact stresses up to 322,000 psi. The bearing configuration also included BG-42 inner and outer rings and a Dupont polyimide Vespel separator. The incorporation of a fuel lubrication system for limited-life turbine engines has many advantages, including; Lower cost ( elimination of oil system related hardware ). Enhanced long-term storage reliability Increased cold start reliability.
Journal Article

A Method for the Evaluation of the Effectiveness of Turboelectric Distributed Propulsion Power System Architectures

2014-09-16
2014-01-2120
Radical new electrically propelled aircraft are being considered to meet strict future performance goals. One concept design proposed is a Turboelectric Distributed Propulsion (TeDP) aircraft that utilises a number of electrically driven propulsors. Such concepts place a new and significant reliance on an aircraft's electrical system for safe and efficient flight. Accordingly, in addition to providing certainty that supply reliability targets are being met, a contingency analysis, evaluating the probability of component failure within the electrical network and the impact of that failure upon the available thrust must also be undertaken for architecture designs. Solutions that meet specified thrust requirements at a minimum associated weight are desired as these will likely achieve the greatest performance against the proposed emissions targets.
Technical Paper

A New Reaction Control Approach for Sounding Rockets

1970-02-01
700783
This paper concerns a new technique designed to provide high performance reaction control systems for sounding rockets. Proportional control of differential thrust and simple adaptive control of thrust magnitude (based on the level of demanded thrust) is utilized. The control is being implemented with a combination of electronic and fluidic components for an Aerobee 150 sounding rocket payload whose goal is a pointing stability of 0.1 arc second.
Technical Paper

A PARAMETRIC STUDY OF THE TAKE-OFF PERFORMANCE OF GETOL AIRCRAFT

1961-01-01
610118
The concept of using the air cushion ground effect principle to aid an aircraft's take-off and landing is relatively new. This allows the airplane to hover and accelerate to flying speed at a definite height, i. e., free of the ground. This study was initiated to determine whether such a procedure is feasible for the take-off of an airplane, and in so doing, to examine some dominating parameters. This study is limited in scope: the take-off consists of a constant height acceleration to flying speed, then a pull-up to clear an obstacle; a low aspect ratio wing is assumed, furthermore, all thrust is obtained from the lifting fan during take-off. In addition, stability considerations were neglected, augmentation is assumed unaffected by forward speed, the lift fans are operated at constant power and at only one pressure ratio, and the total ram drag was used.
Technical Paper

A Parametric Evaluation of Supersonic STOVL

1985-06-01
851163
This paper describes the results of a study to evaluate parametric variations to a single engine short-takeoff vertical-landing fighter/attack aircraft design. The variables considered involved thrust vectoring, thrust degradation, maximum lift, and other changes to determine the impact on short-takeoff performance, but subject to a vertical-landing capability. The results indicate that there are certain parameters that have a significant effect on short-field performance. Also, the optimal control strategies for transitions from a short-takeoff to forward flight and from forward flight to hover are determined. The results have applicability beyond the configuration evaluated.
Technical Paper

A Perspective on Short-Haul STOL

1974-02-01
740502
This paper discusses the basic incentives motivating the development of the short-haul STOL air transportation system and the technological impact of propulsion lift on fundamental aircraft parameters and related economics. The incentives are aimed at alleviating some of the current accrued ills of the existing CTOL system. Specifically ground and air congestion, environmental impact relief, and customer service can be improved by the introduction of the potential system. The technological impact on the aircraft and its related economics required to achieve short field performance is generally detrimental. Considerations such as wing and empennage sizing, engine thrust sizing and cycle selection, thrust reverser requirements, cruise Mach number effects, noise, and fuel usage impacts are discussed. The direct operating economics are adversely affected although it is thought that the indirect costs can be correspondingly reduced.
Technical Paper

A Probabilistic Evaluation of Turbofan Engine Cycle Parameters for a Mach 1.8 Interceptor Aircraft

2003-09-08
2003-01-3056
A supersonic engine for a high Mach interceptor mission is modeled, and the requirements for the engine at different flight conditions are discussed. These include low fuel consumption at a non-afterburning supersonic dash Mach number for interception, and high thrust, both afterburning and non-afterburning, at a high subsonic Mach number for combat engagement. In addition, the engine should have low frontal area and low weight for a given sea level thrust rating. For the design point, the sea level static, standard day non-afterburning thrust is fixed at 20,000 lbs. The primary independent parameters varied in the study are fan pressure ratio, overall pressure ratio, turbine inlet temperature, throttle ratio, and extraction ratio. A design of experiments (DoE) is set up to vary the independent parameters to produce a meta-model for engine performance, geometry and weight.
Technical Paper

A Propulsion System for Orbit-to-Orbit Shuttle

1971-02-01
710770
This paper describes an advanced development program for the demonstration of the aerospike rocket engine system. This three-task, 31-month program consists of the analytical and design studies to be accomplished under Task I; aerospike thrust chamber experimental segment testing to be accomplished under Task II; and demonstration of the full aerospike thrust chamber to be accomplished under Task III. The program is being conducted at Rocketdyne, a division of North American Rockwell Corporation, under the sponsorship of the Air Force Rocket Propulsion Laboratory under Contract F04611-67-C-0116. This paper summarizes the accomplishments of the program to date, and describes the engine system and its possible application to the orbit-to-orbit shuttle (OOS).
Technical Paper

A Review of The de Havilland Augmentor-Wing Powered-Lift Concept and Its Future Applications

1987-12-01
872312
The development of the de Havilland Aircraft of Canada (DHC) augmentor-wing powered-lift concept is briefly reviewed from the mid-1960's to the present day. A parallel DHC research program over the period from the mid-1970's to the present day has developed a very thick high speed compound or multi-foil wing section for the Augmentor-Wing concept. This program proved more successful than initially anticipated and has led to the development of both blown and unblown wing sections up to 24% thickness-chord with CL (cruise) greater than 0.6 and design cruise Mach numbers around 0.7, two-dimensionally. This research is also reviewed. More recently, design studies have shown that integration of these technologies leads to very efficient transport aircraft which can achieve Ultra-Stol capability with only the thrust installed for cruise.
Technical Paper

A Spacecraft for Ion Thrustor Flight Tests

1964-01-01
640231
A spacecraft that will be used for flight tests of ion thrustors is described. The spacecraft has been designed to provide measurements of thrustor electrical parameters and thrust. The tests to be carried out will determine the validity of ion thrustor performance data which have been obtained in vacuum chambers. The spacecraft, to carry two thrustors of different construction, will be launched into a ballistic trajectory by the NASA Scout vehicle. The test time will be approximately one hour.
Technical Paper

A Subscale Facility for Liquid Rocket Propulsion Diagnostics at Stennis Space Center

1991-04-01
911126
The Diagnostics Tested Facility (DTF) at NASA's John C. Stennis Space Center (SSC) in Mississippi was designed to provide a testbed for development of rocket engine exhaust plume diagnostics instrumentation. A 1200-lb thrust liquid oxygen (LOX)/gaseous hydrogen (GH2) thruster is used as the plume source for experimentation and instrument development. Theoretical comparative studies have been performed with aero-thermodynamic codes to ensure that the DTF thruster (DTFT) has been optimized to produce a plume with pressure and temperature conditions as much like the plume of the Space Shuttle Main Engine (SSME) as possible. Operation of the DTFT is controlled by an icon-driven software program using a series of soft switches. Data acquisition is performed using the same software program. A number of plume diagnostics experiments have utilized the unique capabilities of the DTF.
Technical Paper

A Technique for Lunar Landing Site Selection by Earth-Based Control

1965-02-01
650592
The report describes the results of a study of the techniques, system dynamics, and component characteristics required to control the landing point of a lunar landing vehicle by manual control from earth. The controller is presented with a television picture of the landing area from which he selects the desired landing point and designates that point by transmitting an appropriate command to the landing craft. A vehicle -borne guidance system then controls vehicle attitude and thrust magnitude to cause a soft landing to occur at the desired point. System operation results in a soft landing even if no command is received. An important aspect of the study is the consideration of means of compensating for earth-moon transmission time delay. The study shows that a continuous prediction of the landing point can effectively stabilize the entire earth-moon control loop and that additional compensation of the operator's display and controls will be required for precise accuracy.
Journal Article

A Theoretical Approach of UNIT (Unified Nuclear Integral Technology) Propulsion and its Potential for Future Applications in Space Exploration

2015-09-01
2015-01-9004
Space exploration is the present inevitable challenge for researchers. Various theoretical propulsion concepts have been evolved over the past years for space missions. Their potential remains as a key factor for the spacecraft to travel deeper into space in a shorter mission duration. The propulsion concept UNIT is an integrated nuclear propulsion technique that provides high entry, descent and landing (EDL) performance in such short duration to conquer other galaxies. This paper describes the theoretical approach of the UNIT propulsion system in detail. UNIT produces the highest energy possible by consuming nuclear fuel and possess the highest potential that opens new opportunities for space exploration. The principle is that the neutrons from the fusion are deliberately allowed to induce fission. It uses National Ignition Facility's laser beam for inertial confinement fusion followed by utilizing the power from tubular solid fuel cell.
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