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The concept of using parametric bicubic patch surface definitions with bilinear vorticity or biquadratic doublet distributions was tested by modeling the vortex sheet and predicting its shape numerically in the vicinity of the wing. For the purpose of computing induced velocities, it was shown that higher order of vorticity would not improve the truncation error. The bilinear distribution, used to model the tip vorticity, was satisfactory but gave rise to some difficulty. The bicubic geometric surface representation proved very suitable for curved surfaces such as the rolled-up vortex sheet, with the surface fit scheme failing only for complex wings, far downstream beyond the region of concern.

A method is presented for predicting the geometry of a vortex sheet trailing a lift generating wing in its vicinity. It differs from others in that it uses a continuous vorticity distribution rather than discrete vortex filaments. It was found that the results were in good agreement with available experimental data, after the initial cycle of what was to be a relaxation scheme, so that iterations for this end were unnecessary. While the technique is computing intensive, it becomes attractive when used in conjunction with panel methods applications for complete aircraft configurations. The panel method solution needs to be found only once for each streamwise station downstream of the wing. Corrections applied are geometric in nature and are independent of other computational aspects.

Full-scale wind-tunnel tests, conducted to determine the effects of three different airfoil sections on the aft-fuselage drag of a low-wing aircraft, are described. The measurements indicate a maximum difference in aft fuselage drag between the three airfoils of about 0.002. Measured changes in the locations of the fuselage pressure contours with airfoil section correlated well with the changes predicted by a three dimensional paneling code. A criterion, based on the inviscid computer code, is then proposed as an indicator for possible adverse viscous interactions at the wing-fuselage juncture.

Experimental observations of loss of bone mineral due to prolonged bedrest or weightlessness are reported. A new, precise method was employed that featured an essentially monoergetic photon source (125I) and a scintillation detector operating in a rectilinear scanning mode to measure bone mineral in the radius, ulna, and os calcis by the absorptiometric technique. Variable but small losses were found during 4-6 weeks of bedrest; losses of up to 40% were noted in the os calcis after 9 months. When the technique was used during the Apollo 14, 15, and 16 missions, only one crewmen showed significant losses in the os calcis and none in the radius or ulna. The variability recorded during bedrest was connected with the initial 24-hr urinary hydroxyproline excretion and the initial os calcis mineral content. The relevance of prediction terms based on bedrest data to Skylab and longer missions is discussed.

In the course of Apollo 15, physiologic abnormalities, manifested by ectopic activity on the ECG and unusual alterations in exercise tolerance, occurred in the crew of the Lunar Excursion Module. These were associated with decreases in total body potassium, measured by K-42, of 10% and 15%. The possibility of inadequate potassium (K+) intake existed. A simulation study was performed prior to Apollo 16, corresponding in duration to Apollo 15. Subjects endured the same sleep aberrations and caloric expenditure as the Apollo 15 astronauts. Subjects consumed a diet containing only 15 mEq/d of K+ during the entire 12 days of absolute bedrest. Study implications and reasons for discrepancies between K+ loss measured by balance techniques and K-42 are reviewed.

Wind tunnel tests show that the aerodynamic performance of a rectangular 3-D wing is increased by changing its tip to an ogee shape. Potential gains in both cruise and climb performances for a modified Beech Baron aircraft indicate that incremental changes in performance are on the order of the data scatter associated with applied flight test techniques.

Methods for the simultaneous determination of equilibrium space of I-125/RISA(radio-iodinated serum albumin) (plasma volume), Cr-51 red cell mass, Br-82 space (extracellular fluid volume), and tritiated water space (total body water) are described. Determinations were made on two occasions separated by a 1 week interval in 43 healthy young men who were on a strict metabolic diet. Hourly samples were taken for 6 hours after injection of the radionuclides. Correlation of these values to the inscribed exponential disappearance curve was high. In 15 subjects, earlier and more-frequent sampling led to no improvement in the accuracy of estimation of the I-125/RISA space. Use of this method gave results in 12 subjects for Br-82 space and in 11 subjects for tritiated water space which were not significantly different from those obtained by correction for urine loss.

Gamma ray absorptiometric measurements on bone mineral content, in addition to calcium balance studies, were performed on male volunteers during bed rest periods of 24 to 36 weeks duration and compared to Skylab mission data. Results show that mineral losses occur from the bones of the lower extremities during missions of up to 84 days and that in general they follow the loss patterns of the bed rest situation. The level of loss observed in Spacelab crews are not of clinical concern.

The mineral content of the left central os calcis was determined using the photon absorptiometric technique modified for the space missions to permit area scanning, and was compared with total body calcium balance changes. The instrument consists of a rectilinear scanner that is programmed by a specially designed control module to move a low energy X-ray emitting radionuclide placed in opposition to a detector to scan the foot which is places between them. The foot is placed in a plexiglas box filled with water to provide tissue equivalence and to compensate for irregularities in thickness of tissue cover that surrounds the bone. The mineral content is obtained from basic attenuation equation.

The mineral content of the central os calcis, and distal radius and ulna was measured by the monoenergetic photon absorptiometric technique pre- and postflight on the SL-3 crewmen. No significant changes were observed in the radius and ulna. Only the SPT showed a loss in calcaneal mineral which slowly returned to preflight levels by the 87th postflight day.

Left ventricular end-diastolic volume was determined by cardiac visualization after peripheral venous injection of a gamma-emitting isotope in 10 patients with organic heart disease. The left ventricular end-diastolic volume measured by the isotope method consistently averaged 9% less than that determined by the X-ray method. The mean difference in left ventricular end-diastolic volume was 21 ml. Excellent correlation between the two methods was observed. It is pointed out that peripheral venous scintillation angiocardiography compares well with left ventriculography in the determination of left ventricular end-diastolic volume in man.

Extravascular dehydration produced by bed rest simulating weightlessness - data tables

Extravascular dehydration effects in production of cardiovascular deconditioning by bed rest simulating weightlessness

Bone mineral changes in prolonged bed rest subjects determined by gamma ray absorption technique

Bacterial population of vehicle and test pilots during 14-day simulated lunar flight

Tables summarizing blood chemistries, hemodynamic responses, fluid and mineral balances, urine components, and other data obtained on males subjected to bed rest and tilt tolerance tests

Physiological alterations in blood pressure, heart functioning, and metabolism following bed rest and tilt tolerance tests

Loss of mineral from bone during periods of immobilization, recumbency, or weightlessness is examined. This report describes the instrumentation, technique, and bone mineral changes observed preflight and postflight for the Apollo 14, 15, and 16 missions. The bone mineral changes documented during the Apollo Program are reviewed, and their relevance to future missions is discussed.

A portable rectilinear transmission scanner and associated computerized data reduction techniques for estimating bone mineral content are described. This unit can be easily disassembled for transport to various measurement sites and has been used to estimate the bone mineral content of the os calcis, radius, and ulna in the Apollo and Skylab astronauts. The scanner is used to obtain multiple rows of data from which a bone profile is derived. Bone edges are determined with the aid of a digital computer program which employs an algorithm that determines the greatest rate of change of the counting rate.

The phenomenon of calcium loss during bed rest was found to be analogous to the loss of bone material which occurs in the hypogravic environment of space flight. Ways of preventing this occurrence are investigated. A group of healthy adult males underwent 24-30 weeks of continuous bed rest. Some of them were given an exercise program designed to resemble normal ambulatory activity; another subgroup was fed supplemental potassium phosphate. The results from a 12-week period of treatment were compared with those untreated bed rest periods. The potassium phosphate supplements prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. The exercise program did not diminish the negative calcium balance. Neither treatment affected the heavy loss of mineral from the calcaneus. Several additional studies are developed to examine the problem further.

Loss of mineral from bone during periods of immobilization, recumbency or weightlessness have been observed. These losses are more apparent in the lower extremity than the upper and have been observed to exceed 30% in the case of the central os calcis during 36 weeks of bedrest. In early Gemini studies using X-ray densitometry, large losses of bone mineral were observed in the radius and ulna. This observation was not validated in the Apollo 14, 15 and 16 crewmen when a more precise technique, gamma ray absorptiometry, was used. The large losses reported for the early Gemini missions were not seen when this new measuring technique was employed.

Measurement tests revealed few deviations from baseline bone mineral measurements after 56 days in a Skylab-type environment. No mineral change was observed in the right radius. One individual, however, showed a possible mineral loss in the left os calcis and another gained mineral in the right ulna. The cause of the gain is unclear but may be attributable to the heavy exercise routines engaged in by the crewmember in question. Equipment problems were identified during the experiment and rectified.

Numerical calculations were made of flow fields generated by various aerodynamic configurations. Data cover flow fields generated by a finitely thick lifting three dimensional wing with subsonic tips moving at supersonic speeds, cross flow instability associated with lifting delta wing configurations such as space shuttles, and flow fields produced by a lifting elliptic cone. Finite difference techniques were used to determine elliptic cone flow.

The calculation of the outer inviscid flow about a rectangular wing moving at supersonic speeds is reported. The inviscid equations of motion governing the flow generated by the wing form a set of hyperbolic differential equations. The flow field about the rectangular wing is separated into three regions consisting of the forebody, the afterbody, and the wing wake. Solutions for the forebody are obtained using conical flow techniques while the afterbody and the wing wake regions are treated as initial value problems. The numerical solutions are compared in the two dimensional regions with known exact solutions.

The solutions to the equations of motion for inviscid fluid flow around a pointed elliptic cone at incidence are presented. The numerical method used, MacCormack's second order preferential predictor-corrector finite difference approximation, is applied to the fluid flow equations derived in conservation-law form. The entropy boundary condition, hitherto unused for elliptic cone problems, is investigated and compared to reflection boundary condition solutions. The stagnation streamline movement of the inclined elliptic cone is noted and surface pressure coefficients are plotted. Also presented are solutions for an elliptic cone and a circular cone at zero incidence and a circular cone at a small angle of attack. Comparisons are made between these present solutions and previously published theory.