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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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NASA NTRS1962

Collected Papers on Instability of Shell Structures - 1962

Shell structures are important components of airplanes, missiles, and space vehicles, but present capabilities for predicting the local and general instability of many such structures are inadequate. A large effort continues to be devoted to the stability analysis of shell structures, and considerable progress has been made. Results are slowly disseminated, however, and many engaged in research are not fully cognizant of the problems and practices of the vehicle designers who utilize research results. Therefore, an NASA SYMPOSIUM ON INSTABILITY OF SKELL STRUCTURES was organized by the Langley Research Center with sessions held there on October 24 and 25, 1962. Participants were limited to persons contributing papers and to certain officials of the U.S. Government. This symposium was planned to provide those persons concerned with shell instability at research laboratories, at educational institutions, and in the aerospace industry with a comprehensive view of the present state of the art, including the voids in present knowledge, important current problems, and the most fruitful directions for future theoretical and experimental research on the instability of all types of shell structures. Individuals actively engaged in research on shell stability or design were invited to contribute written papers for inclusion in a compilation to be distributed to the participants prior to the symposium. A few papers were selected by a steering committee for oral presentation at the symposium. Provision was made, also, for a discussion of all papers.

MISSILE↗
NASA NTRS1962

Axisymmetric Snap Buckling of Conical Shells

The authors give a brief account of some of their recent analytical and numerical studies of cone buckling. limiting the discussion to axisymmetric deformations. Pertinent numerical results for the relaxation buckling of full cones subjected to uniform external pressure and Belleville springs deformed by axial edge loads are presented. In addition. bifurcation buckling problems are discussed. For a specific case. the existence of Friedrichs' intermediate buckling load, P(m). as applied to cones. is established. Upper and lower bounds for its value are given.

LOADING↗
NASA NTRS1962

A CONSIDERATION OF THE U.S. NAVY STRATO-LAB BALLOON PROGRAM AND ITS CONTRIBUTIONS TO MANNED SPACE FLIGHT

As the coined name Strato-Lab implies, it is a program which provides a stratospheric laboratory utilizing a plastic balloon platform for manned research investigations. The project was originated in 1954; actual work began early in 1955 and the first manned stratospheric flights were made in 1956. It was conceived and has been continued with the following three objectives: (1) Provide a high-altitude research system, a scientific laboratory, permitting man's active scientific participation (2) Provide an opportunity for studies of man's reactions to an actual environment of physiological and psychological stress (3) Allow an opportunity for man to conduct tests and evaluate specific components and/or techniques in an extremely high altitude environment.

Stratosphere↗
NASA NTRS1972

Ballistic range investigation of sonic-boom overpressures in water.

An investigation of sonic-boom overpressures in water has been conducted by gun-launching small cone-cylinder models over water. Flights were conducted at Mach numbers of 2.7 and 5.7, in air, corresponding to Mach numbers of 0.6 and 1.3, respectively, in water. Shadowgraph pictures and underwater pressure measurements indicate that for horizontal flights at Mach numbers below Mach 4.4 in air (i.e., subsonic relative to the speed of sound in water) the resulting underwater disturbance is an acoustic wave whose peak pressure attenuates rapidly with water depth. In contrast, at supersonic Mach numbers, relative to water, the incident shock wave at the surface is transmitted into the water as a propagating shock wave and the peak pressure associated with it does not attenuate with water depth.

Malcolm, G. N.↗
NASA NTRS1975

Experimental determination of post-stall rotary derivatives for airplane-like configurations at several Reynolds numbers

Military and civilian airplane losses due to out-of-control spin motions are significant. Knowledge of rotary coefficients is necessary to understand the cause of spin entry and to devise proper recovery techniques. An exploratory wind-tunnel investigation has been conducted on simple airplane-like configurations on a rotary sting apparatus at rotation rates up to 10 rps. Rotary coefficients have been measured at unit Reynolds numbers from 2,000,000 to 24,600,000 per m and at angles of attack from 45 to 90 deg. Results show that the aerodynamic characteristics at steady spin rates are highly dependent on both spin rate and Reynolds number.

Clarkson, M. H.↗
NASA NTRS1975

Nutritional studies

Detailed metabolic studies were conducted of the Apollo 16 and Apollo 17 flight crews, and the results are presented in tabular form. Intake and absorption data are also included. Apollo nutrient intakes were found to be characteristically hypocaloric. Estimates of body composition changes from metabolic balance data, from preflight and postflight weights and volumes, and from total body water and potassium provide no evidence for diminished caloric requirements during a flight. As observed during the Gemini Program and during periods of bed rest, measurements of bone density and metabolic balance confirm a tendency toward loss of skeletal tissue in weightlessness. No evidence exists that any inflight metabolic anomaly, including hypokalemia, was induced by marginal or deficient nutrient intakes. In general, the Apollo crewmen were well nourished and exhibited normal gastroenterological functions, although appetite was somewhat diminished and the organoleptic response to food was somewhat modified during flight.

Paul C. Rambaut↗
NASA NTRS1975

Skeletal response

The effect of weightlessness on bone mineral content during prolonged space flight was investigated. The mineral content changes which occurred during Apollo 14, 15, and 16 as measured by photon absorptiometry techniques are presented and compared. Bed rest served as an experimental model to assess the bone mineral changes, and to determine what remedial measures might be used to stem the tide of bone mineral loss. It is concluded that loss of mineral from bone due to the state of weightlessness is comparable to that observed in bed rest subjects.

Paul C. Rambaut↗
NASA NTRS1975

Apollo food technology

Large improvements and advances in space food systems achieved during the Apollo food program are discussed. Modifications of the Apollo food system were directed primarily toward improving delivery of adequate nutrition to the astronaut. Individual food items and flight menus were modified as nutritional countermeasures to the effects of weightlessness. Unique food items were developed, including some that provided nutritional completeness, high acceptability, and ready-to-eat, shelf-stable convenience. Specialized food packages were also developed. The Apollo program experience clearly showed that future space food systems will require well-directed efforts to achieve the optimum potential of food systems in support of the physiological and psychological well-being of astronauts and crews.

Malcolm C. Smith↗
NASA NTRS1976

Asymmetric aerodynamic forces on aircraft at high angles of attack - some design guides

Aerodynamic side forces on forebodies are considered that are produced by two types of flow: asymmetric vortices on bodies of revolution and nonuniform flow separation on square bodies with rounded corners under spinning conditions. Steady side forces that can be as large as the normal force are produced by asymmetric vortices on pointed forebodies. This side force has a large variation with Reynolds number, decreases rapidly with Mach number, and can be nearly eliminated with small nose bluntness or strakes. The angle of attack where the side force first occurs depends primarily on body geometry. The theoretical techniques to predict these side forces are necessarily semi-empirical because the basic phenomenon is not well understood. The side forces produced by nonuniform flow separation under spinning conditions depend extensively on spin rate, angle of attack, and Reynolds number. The application of simple crossflow theory to predict this side force is inadequate much below angles of attack of 90 deg.

Chapman, G. T.↗
NASA NTRS1976

Wind-tunnel testing with a rotary-balance apparatus to simulate aircraft spin motions

Experiments have been conducted in the Ames 12-Foot Pressure Wind Tunnel on a simple airplane-like model using a rotary-balance apparatus to simulate a steady spin motion at high angles of attack. Tests were run at Mach numbers of 0.1 and 0.25 over a wide Reynolds number range with the angle of attack varying from 45 to 90 deg. During previous tests of the same research model, some difficulties were experienced with measurement accuracy in the low-to-medium range of Reynolds number because of limitations in the sensitivity of selected force balances. For the present tests, special balances were built to provide accurate measurements of the nose and tail contributions to spin motions and improvements were made to the overall test apparatus. The results of this test, including some interesting hysteresis effects with spin rate, are described. Some of the problems associated with rotary-balance tests at high Reynolds numbers are discussed. A new large-scale rotary apparatus now nearing completion for use in the Ames 12-Foot and 11- by 11-Foot Wind Tunnels is described briefly.

Malcolm, G. N.↗