MATE - User's manual. Study simulation of space station dynamics Final report
Computer manual for implementing digital program in space station dynamics simulation
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Computer manual for implementing digital program in space station dynamics simulation
Development of techniques for estimating plasma parameters from data observed by Pioneer 9 space probe instruments
Flight characteristics of jet-flap STOL transport aircraft during approach and landing
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A miniature solid propellant rocket motor has been developed to be used in a program to determine those parameters which must be duplicated in a cold gas flow to produce aerodynamic effects on an experimental model similar to those produced by hot, particle-laden exhaust plumes. Phenomena encountered during the testing of the miniature solid propellant motors included erosive propellant burning caused by high flow velocities parallel to the propellant surface, regressive propellant burning as a result of exposed propellant edges, the deposition of aluminum oxide on the nozzle surfaces sufficient to cause aerodynamic nozzle throat geometry changes, and thermal erosion of the nozzle throat at high chamber pressures. A series of tests was conducted to establish the stability of the rocket chamber pressure and the repeatibility of test conditions. Data are presented which define the tests selected to represent the final test matrix. Qualitative observations are also presented concerning the phenomena experienced based on the results of a large number or rocket tests not directly applicable to the final test matrix.
To improve the ride quality in short takeoff aircraft, several means have been investigated. In general, these methods consist of placing sensors in the aircraft which sense aircraft motion, usually linear accelerations and angular rates. These signals are then used to deflect control surfaces which generate aerodynamic forces and moments which tend to minimize the motion which the passenger feels. One of the disadvantages of some of these systems is that they may tend to degrade the handling qualities or controllability of the airplane, making it more difficult or annoying for the pilot to fly. Rather than using active control systems to control ride quality, one might possibly design aircraft so that they are inherently pleasant to ride. The purpose of this study is to determine the relationship between characteristic aircraft motions and aircraft ride quality.
In this decoupled concept, the natural interactions of the flight variables were suppressed, and the pilot operated a separate controller for each (fore-and-aft control column for flight path angle without speed or pitch attitude change, for example). The handling qualities of the decoupled airplane were judged to be very favorable. The precise path control led to small touchdown point dispersion along with consistently low sink rates. The decoupled control system provided significantly better flying qualities than did conventional SAS applied to the same basic airframe.
A new philosophy for the second generation of in situ experiments in the area of plasma flows over bodies is discussed. A brief review of the present state of the theory and terrestrial laboratory and in situ studies is given, which points toward the need for further in situ investigations which utilize independently maneuverable test bodies and diagnostic instrument packages on board the Shuttle/Spacelab. The possibility of utilizing the Space Shuttle/Spacelab in the broader context of a general in situ plasma laboratory is considered, as well as the possibility of addressing questions of geo/astrophysical interest if the principle of qualitative scaling is used in conjunction with such a facility.
For abstract, see N78-13038.
Conventional and powered lift concepts for supersonic approach and landing tasks are considered. Results indicated that the transport concepts had unacceptable low-speed handling qualities with no augmentation, and that in order to achieve satisfactory handling qualities, considerable augmentation was required. The available roll-control power was acceptable for the powered-lift concept.
In the present paper, the status of the Drexel/NCAR regional numerical weather forecast system is summarized to show the extent of our experience and our immediate requirements for data within the United States on scales smaller than rawinsonde spacing (approximately 300 km). Preliminary experiments are described, and data assimilation problems are examined. It is shown that data requirements, assimilation methods, and forecast sensitivity differ for regional and large-scale models. Forecast verification statistics suggest that middle-troposphere temperature is well known but relative humidity is not. In some cases, regional forecasts require much better humidity data than available from rawinsondes. Numerics, lateral boundary conditions, model physics, and computing power are adequate for near real-time experimental regional prediction with horizontal mesh sizes down to 35 km. Subsynoptic data and assimilation are the primary challenges facing regional NWP.
Upper bounds for the ground-state energies of liquid and solid phases of metallic hydrogen and metallic deuterium have been calculated with variational methods and Monte Carlo techniques. At four densities (0.8, 1.2, 1.36, and 1.488) crystalline phases are clearly preferred in the sense that the energy difference, when compared to the liquid, is in excess of the errors inherent in the numerical procedures. At a fifth density (1.6), the energy differences between solid and liquid phases are smaller than these errors.
An analytic methodology, based on the optimal-control pilot model, was demonstrated for assessing longitidunal-axis handling qualities of transport aircraft in final approach. Calibration of the methodology is largely in terms of closed-loop performance requirements, rather than specific vehicle response characteristics, and is based on a combination of published criteria, pilot preferences, physical limitations, and engineering judgment. Six longitudinal-axis approach configurations were studied covering a range of handling qualities problems, including the presence of flexible aircraft modes. The analytical procedure was used to obtain predictions of Cooper-Harper ratings, a solar quadratic performance index, and rms excursions of important system variables.
A numerical model is presented for testing theories of the physical mechanisms of noctiluminescent clouds. The time-dependent, one-dimensional model describes the formation, evolution, and properties of the clouds as interactive ice crystals, meteoric dust, water vapor, and ionized air. Mesopause temperatures below 140 K are found to be necessary for the formation of the clouds, conditions existing only at high latitudes in the summer. No predominant nucleation particle could be identified for the formation of the clouds, although a time period of up to a day was determined as necessary for materialization, which lasts several days. Several atmospheric and environmental conditions were characterized which enhance the appearance of the noctiluminescent clouds. One conclusion reached is that the numerous launches necessary to build a solar power satellite system would not significantly exacerbate noctiluminescent cloud formation.
The effect of varying the two important display parameters of a pictorial display on pilot opinion performance, and pilot aircraft display system servomechanism response is examined. The display presents a picture of a three dimensional box that moves along the desired path ahead of the aircraft. The two display parameters examined are the field of view of the picture (from + or - 5 deg to + or - 45 deg) and the distance to the box (from 92 m (300 ft) to 6100 m (20 000 ft)). The results show that the pilots prefer a distance to the box of 915 m (3000 ft) and a field of view of + or - 30 deg. The best performance, both in the sense of quickness of error correction and lowest standard deviation, is obtained with a distance to the box of 92 m (300 ft) and a field of view of + or - 15 deg. A pilot model analysis is used to determine the gains used by the pilots and the servomechanism response characteristics of the pilot aircraft display system.
A combined physical statistical method for the retrieval of atmospheric water vapor column densities has been developed at the Goddard Laboratory for Atmospheric Sciences. In this method differences between observed and calculated clear column brightness temperatures are used in a regression formalism to obtain estimates of integrated column densities in given atmospheric layers. The physics of the radiative transfer problem is contained in the calculated clear column brightness temperatures and in accounting for the effects of clouds on the observed radiances. The regression matrix is equivalent to a set of empirical sensitivity factors.
The present investigation is concerned with results from an initial set of comparative experiments in a project which utilize a three-dimensional convective storm model. The modeling results presented are related to four comparative experiments, designated Cases A through D. One of two scientific questions considered involves the dynamical processes, either near the cloud top or well within the cloud interior, which contribute to organize cloud thermal patterns such as those revealed by IR satellite imagery for some storms having strong internal cloud-scale rotation. The second question is concerned with differences, in cloud-top height and temperature field characteristics, between thunderstorms with and without significant internal cloud-scale rotation. The four experiments A-D are compared with regard to both interior and cloud-top configurations in the context of the second question. A particular strong-shear experiment, Case B, is analyzed to address question one.
From intermolecular force studies, it is now known that the overall non-additive contribution to the lattice enegy is positive so that analysis based on only pairwise additivity suggests a shallower intermolecular potential than the true value. Two body contributions alone are also known to be categorically unable to even qualitatively describe some configurations of molecular clusters in the gas phase or the general relaxation and reconstruction of fcc crystal surfaces. In addition, the many-body contribution was shown to play a key role in the stability of certain crystal structures. In these recent analyses, a relatively simple potential energy function (PEF), comprising only a two-body Mie-type potential plus a three-body Axilrod-Teller-type potential, was found to be extremely effective. This same parametric PEF is applied to describe the bulk stability and surface energy for the diamond cubic structure. To test the stability condition, the FCC, BCC, diamond cubic, graphite and beta-tin structures were considered.