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The aircraft development program, budgetary estimates in CY 1976 dollars, and cost reduction program variants are presented. Detailed cost matrices are also provided for the mechanical transmission system, turbotip transmission system, and the thrust vector hoods and yaw doors.
Structural member cross sections were sized with a system of integrated computer programs to satisfy strength and flutter design requirements for several variants of the arrow wing supersonic cruise vehicle. The resulting structural weights provide a measure of the structural efficiency of the planform geometry, structural layout, type of construction, and type of material including composites. The material distribution was determined for a baseline metallic structure and the results indicate that an approximate fatigue constraint has an important effect on the structural weight required for strength but, in all cases, additional material had to be added to satisfy flutter requirements with lighter mass engines with minimum fuel onboard. The use of composite materials on the baseline configuration was explored and indicated increased structural efficiency. In the strength sizing, the all-composite construction provided a lower weight design than the hybrid construction which contained composites only in the wing cover skins. Subsequent flutter analyses indicated a corresponding lower flutter speed.
An approximate method for the design and performance prediction of a multiaccess communication system which employs the ALOHA packet-switching technique is developed, based on the use of a diffusion process approximation of an ALOHA-like system (with or without time-slotting). A simple closed-form solution for the variable Q(t), a variant of the number of backlog messages at time t, is given in terms of a few system and user parameters. Final results are expressed in terms of ordinary performance measures such as throughput and average delay. Several numerical examples are given to demonstrate the usefulness of the approximation technique developed.
Test results on charge coupled device (CCD) imaging arrays (100 x 160 pixel and 400 x 400 pixel) employed as imaging detectors are reported, along with expected low light level (LLL) performance. Reasons for selection of a thinned backside-illuminated buried-channel three-phase CCD variant are indicated. The LLL performance and long storage time capability of the CCD imaging array recommend it for stellar photometry, detection and tracking of faint objects, and other astronomical applications.
Webeler's (1976) experimental results for the generation of atomic hydrogen in a hydrogen matrix by tritium decay are reexamined with a variant of Rosen's (1976) mathematical treatment. The analysis retains Rosen's equations for the number densities of trapped and mobile hydrogen atoms, but replaces his enthalpy equation with an equation for the directly measured temperature. Theoretical expressions are derived for the dependence of storage time, recombination time, and maximum density of trapped hydrogen atoms as a function of temperature for a given tritium concentration. A comparison of predictions for the maximum trapped atomic hydrogen number density as a function of storage time reveals that Rosen's estimate for the maximum number density of hydrogen atoms for the zero magnetic field case is a little more optimistic than the estimate obtained in the paper.
The status of space transportation systems analyses referable to the SPS (solar power satellite) is reviewed briefly. Propulsion systems (including magnetoplasmadynamic) and booster arrangements for the SPS mission and variants in recovery arrangements (including winged recovery) are summarized, along with proposals for production of SPS components in space from lunar and asteroidal materials. Transportation of the pilot plant into low circumterrestrial orbit or high geosynchronous orbit, transfers between those orbits, and construction of a large work bench structure (orbital construction demonstration article - OCDA) in low earth orbit are discussed.
The constant boundary-layer thickness (BLT) figuring in the Ventres (1975) Kernel function can be replaced by a slowly varying BLT, in the case of shear layers of slowly varying thickness. A simplification of the extension by Chi (1976) of Ventres' solution is put forward. The Kernel function in this instance relates pressure on the lifting surface to downwash over the surface. The results should also apply, formally, to three-dimensional compressible unsteady flows, but the accuracy in assuming slowly varying shear BLT remains to be determined. All variants of the shear layer model fail when the shear layer thickness varies rapidly.
In both physiologic and clinical studies, standing is often loosely equated with head-up tilt (HUT) although the cardiovascular effects of these variants of orthostasis have not been formally compared, except for heart rate. The effects of HUT and standing were measured noninvasively in male volunteers satisfying identical criteria for age and normal status. In both postures, there were significant increases in heart rate, pre-ejection period, isovolumic contraction time, and the ratio of pre-ejection to ejection period, and significant decreases in ejection period and ejection time index. All of these changes were greater for standing than for tilt. Pulse transmission time changed significantly (-14%) only with tilt. We conclude that head-up tilt and standing are rather comparable but not physiologically identical forms of orthostasis.
Application of a variant of the Thellier-Thellier method for paleomagnetic field intensity determination to an analog lunar sample revealed a peak at about 250 C on the partial thermoremanent magnetization (PTRM). Evidence suggests that this can be best explained by a partial self-reversal involving troilite becoming reversely magnetized in the presence of already magnetized intergrown iron. In lunar samples, an additional peak was observed. The results suggest that natural remanent magnetization of lunar samples is in part carried by interacting grains, so that paleointensity determinations on the basis of the assumption of noninteracting grains have to be discarded.
The Space Shuttle, Space Tug, and Spacelab are described as the basic transport vehicles for space exploration and operations in the coming decade, and some future space vehicle developments are anticipated. Components of Shuttle (Orbiter, external hydrogen-oxygen propellant tanks, solid boosters), basic maneuvers, and missions are described briefly. Expendable and reusable variants of the Interim Upper Stage (Space Tug) and Spacelab missions are described briefly. A future Large Lift Vehicle recoverable booster and an expendable chemical-nuclear system for the turn of the century are sketched.
The major geochemical properties of the moon are briefly considered along with the significant facts of the moon's geologic history, and then the three current hypotheses regarding the moon's origin, namely, fission, capture, and binary accretion, are reviewed. The individual merits and improbabilities associated with each mechanism are taken into consideration. Special attention is given to the binary accretion model as the most promising one. In the variants of this model, of crucial importance is the nature of the more general hypothesis assumed for planetary formation from the solar nebula. The two main models differ considerably in the amount of chemical fractionation they allow to accompany planetary formation.
Since the energy input to solar thermal conversion systems is both time variant and probabilistic, it is unlikely that simple steady-state methods for estimating lifetime performance will provide satisfactory results. The work described here uses dynamic modeling to begin identifying what must be known about input radiation and system dynamic characteristics to estimate performance reliably. Daily operation of two conceptual solar energy systems was simulated under varying operating strategies with time-dependent radiation intensity ranging from smooth input of several magnitudes to input of constant total energy whose intensity oscillated with periods from 1/4 hour to 6 hours. Integrated daily system output and efficiency were functions of both level and dynamic characteristics of insolation. Sensitivity of output to changes in total input was greater than one.
A baseline implementation plan, including alternative implementation approaches for critical software elements and variants to the plan, was developed. The basic philosophy was aimed at: (1) a progressive release of capability for three major computing systems, (2) an end product that was a working tool, (3) giving participation to industry, government agencies, and universities, and (4) emphasizing the development of critical elements of the IPAD framework software. The results of these tasks indicate an IPAD first release capability 45 months after go-ahead, a five year total implementation schedule, and a total developmental cost of 2027 man-months and 1074 computer hours. Several areas of operational cost increases were identified mainly due to the impact of additional equipment needed and additional computer overhead. The benefits of an IPAD system were related mainly to potential savings in engineering man-hours, reduction of design-cycle calendar time, and indirect upgrading of product quality and performance.
Peak distortion data taken from a subscale inlet model were studied to determine if the data can be used to predict peak distortion levels for a full scale flight test vehicle, and to provide a better understanding of the time variant total pressure distortion and the attendant effects of Reynolds number/scale and frequency content. The data base used to accomplish this goal covered a range from Mach 0.4 to 2.5 and an angle of attack range from -10 degrees to +12 degrees. Data are presented which show that: (1) increasing the Reynolds number increases total pressure recovery, decreases peak distortion, and decreases turbulence, (2) increasing the filter cutoff frequency increases both peak distortion and turbulence, and (3) the effect of engine presence on total pressure recovery, peak distortion, and turbulence is small but favorable.
The Monitor Proportional Counter Instrument for the HEAO-B X-ray Telescope satellite is designed to observe celestial X-ray sources in the range of 1 to 20 keV with intensities exceeding .0002 Crab. It provides both spectral and temporal data, to complement the data from the other HEAO-B instruments, to compare with observations from previous flights, as well as to allow detailed study of time variant X-ray phenomena. The basic detector is a large area proportional counter system, consisting of two counters, high voltage power supplies and preamplifiers, mounted behind a collimator with a 2/3 degree square field of view. The signal processing, power distribution and control electronics are contained in a separate unit, which includes circuitry to perform pulse height analysis, background rejection, time interval measurement, redundancy switching and control, housekeeping and telemetry interfacing.
This paper surveys a number of activities aimed at applying optimum design techniques to structures where high temperatures are important design considerations. An improved variant of fully-stressed design (FSD), denoted thermal fully-stressed design (TFSD), is described which converges significantly faster than FSD for problems where thermal stresses are comparable in magnitude to mechanical stresses. Second, an optimality criterion is described for sizing structures subjected to temperature constraints. Simultaneous requirements on strength and temperatures are handled by two different techniques: (1) a state-of-the-art mathematical programming method and (2) the optimality criterion technique for temperature constraints combined with FSD for strength constraints. A method is described to optimize the insulation and ply thicknesses of an insulated composite panel with a time-varying temperature applied to the outer surface of the insulation and a general set of in-plane loads applied to the panel.
A theory is developed in which a perfectly conducting cylindrical wall is used to describe incompressible MHD turbulence. Dynamic equations of incompressible MHD and its associated fields are expanded in a system of vector eigenfunctions of the curl. The total energy, magnetic helicity, and cross helicity have simple quadratic expressions in the expansion coefficients. The invariants are temporally constant for a truncation at a large, but finite, number of coefficients. The invariants are used to construct canonical distributions. It is noted that for all initial conditions, including quiescent ones, the mean-square velocity fields have finite values. The stability problem is transformed into a search for values of the integral variants which minimize the mean-square velocity fields. This leads to an extremal helicity principle.
A sheet of clast-laden impact melt 230 m thick and 55 km in diameter forms an annular plateau surrounding an uplift of shocked anorthosite within the moderately eroded Manicouagan structure. Three gradational units of the melt sheet are characterized with respect to grain size, inclusions, texture, and mineralogy. The melt rocks as a group are chemically homogeneous with a bulk composition similar to that of latite and with no statistically significant regional chemical variations. The melt is not completely chemically homogeneous as a local mafic variant represented by two samples with poikilitic texture was found. These poikilitic rocks texturally resemble some Apollo 17 impact melt rocks and are inferred to have had a similar origin and thermal history.