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At least 91 records · Page 5

A summary of the Skylab crew/vehicle disturbances experiment T-013

A manned space flight experiment (designated experiment T-013) to assess the characteristics of astronaut crew-motion disturbances was conducted on the second manned Skylab mission. A brief description of the experiment hardware utilized is given, and a comprehensive discussion of the experiment data reduction and analysis is presented. Data obtained from a force-measuring system, an astronaut limb-motion measuring system, motion-picture film, and the Skylab attitude and pointing control system is described. Results show that astronaut crew members can produce significant disturbance inputs to a spacecraft's attitude control system. Total forces of up to 400 N were exerted during vigorous soaring activities, whereas ""restrained'' motions by the experiment subject generated total forces of up to 300 N. A discussion of potential applications of the experiment results is given and appendixes provide additional detail with respect to experiment operations and results.

Conway, B. A.↗

Effect of Moderate Air Flow on the Distribution of Fuel Sprays After Injection Cut-0ff

High-speed motion pictures were taken of fuel sprays with the NACA spray-photographic apparatus to study the distribution of the liquid fuel from the instant of injection cut-off until about 0.05 second later. The fuel was injected into a glass-walled chamber in which the air density was varied from 1 to 13 times atmospheric air density (0.0765 to 0.99 pound per cubic foot) and in which the air was at room temperature. The air in the chamber was set in motion by means of a fan, and was directed counter to the spray at velocities up to 27 feet per second. The injection pressure was varied from 2,000 to 6,000 pounds per square inch. A 0.20-inch single-orifice nozzle, an 0.008-inch single-orifice nozzle, a multiorifice nozzle, and an impinging-jets nozzle were used. The best distribution was obtained by the use of air and a high-dispersion nozzle.

Rothrock, A M↗

Comparison of MPEG digital video with super VHS tape for diagnostic echocardiographic readings

BACKGROUND: Digital recording of echocardiographic studies is on the clinical horizon. However, full digital capture of complete echocardiographic studies in traditional video format is impractical, given current storage capacity and network bandwidth. To overcome these constraints, we evaluated the diagnostic image quality of digital video by using MPEG (Motion Picture Experts Group) compression. METHODS AND RESULTS: Fifty-eight complete, consecutive studies were recorded simultaneously with the use of MPEG-1 and sVHS videotape. Each matched MPEG and sVHS study pair was reviewed by two from a total of six readers, and findings were recorded with the use of a detailed, computerized reporting tool. Intrareader and interreader discrepancies were characterized as major or minor and analyzed in total and for specific subgroups of findings (left and right ventricular parameters, valvular insufficiency, and left ventricular regional wall motion). Intrareader discrepancies were reviewed by a consensus panel for agreement with either MPEG or sVHS findings. There was an exact concordance between MPEG and sVHS readings in 83% of findings. The majority of discrepancies were minor, with major discrepancies in only 2.7% of findings. There was no difference in the rate of consensus panel agreement with MPEG or sVHS for instances of intrareader discrepancy, either in total or for any subgroup of findings. Interreader discrepancy rates were nearly identical for both MPEG and sVHS. CONCLUSIONS: MPEG-1 digital video is equivalent to sVHS videotape for diagnostic echocardiography. MPEG increases the range of practical options for digital echocardiography and offers, for the first time, the advantages of digital recording in a familiar video format.

Non-NASA Center↗

Ditching Tests of a 1/20-Scale Model of the Northrop B-35 Airplane

Tests of a 1/20-scale dynamically similar model of the Northrop B-35 airplane were made to study its ditching characteristics. The model was ditched in calm water at the Langley tank no. 2 monorail. Various landing attitudes, speeds,and conditions of damage were simulated during the investigation. The ditching characteristics were determined by visual observation and from motion-picture records and time-history acceleration records. Both longitudinal and lateral accelerations were measured. Results are given in tabular form and time-history acceleration curves and sequence photographs are presented. Conclusions based on the model investigation are as follows: 1. The best ditching of the B-35 airplane probably can be made by contacting the water in a near normal landing attitude of about 9 deg with the landing flaps full down so as to have a low horizontal speed. 2. The airplane usually will turn or yaw but the motion will not be violent. The maximum lateral acceleration will be about 2g. 3. If the airplane does not turn or yaw immediately after landing, it probably will trim up and then make a smooth run or porpoise slightly. The maximum longitudinal decelerations that will be encountered are about 6g or 7g. 4. Although the decelerations are not indicated to be especially large, the construction of the airplane is such that extensive damage is to be expected, and it probably will be difficult to find ditching stations where crew members can adequately brace themselves and be reasonably sure of avoiding a large inrush of water.

Fisher, Lloyd J.↗

Landing Characteristics of a Reentry Capsule with a Torus-Shaped Air Bag for Load Alleviation

An experimental investigation has been made to determine the landing characteristics of a conical-shaped reentry capsule by using torus-shaped air bags for impact-load alleviation. An impact bag was attached below the large end of the capsule to absorb initial impact loads and a second bag was attached around the canister to absorb loads resulting from impact on the canister when the capsule overturned. A 1/6-scale dynamic model of the configuration was tested for nominal flight paths of 60 deg. and 90 deg. (vertical), a range of contact attitudes from -25 deg. to 30 deg., and a vertical contact velocity of 12.25 feet per second. Accelerations were measured along the X-axis (roll) and Z-axis (yaw) by accelerometers rigidly installed at the center of gravity of the model. Actual flight path, contact attitudes, and motions were determined from high-speed motion pictures. Landings were made on concrete and on water. The peak accelerations along the X-axis for landings on concrete were in the order of 3Og for a 0 deg. contact attitude. A horizontal velocity of 7 feet per second, corresponding to a flight path of 60 deg., had very little effect upon the peak accelerations obtained for landings on concrete. For contact attitudes of -25 deg. and 30 deg. the peak accelerations along the Z-axis were about +/- l5g, respectively. The peak accelerations measured for the water landings were about one-third lower than the peak accelerations measured for the landings on concrete. Assuming a rigid body, computations were made by using Newton's second law of motion and the force-stroke characteristics of the air bag to determine accelerations for a flight path of 90 deg. (vertical) and a contact attitude of 0 deg. The computed and experimental peak accelerations and strokes at peak acceleration were in good agreement for the model. The special scaling appears to be applicable for predicting full-scale time and stroke at peak acceleration for a landing on concrete from a 90 deg. flight path at a 0 deg. It appears that the full-scale approximately the same as those obtained from the model for the range of attitudes and flight paths investigated.

McGehee, John R.↗

Ditching Tests of a 1/10-Scale Model of the North American XFJ-1 Airplane Ted No. NACA 314

Tests were made of a 1/10-scale dynamically similar model of the North American XFJ-1 airplane to study its behavior when ditched. The model was landed in calm water at the Langley tank no. 2 monorail. Various landing attitudes, speeds, and conditions of damage were simulated. The behavior of the model was determined from visual observations, by recording the accelerations, and by taking motion pictures of the ditchings. Data are presented in tabular form, sequence photographs, and time-history acceleration curves. From the results of the tests it was concluded that the airplane should be ditched at the near-stall, tail-down landing attitude of 12 deg. The flaps should be fully extended to obtain the lowest possible landing speed. The wing-tip tanks should be jettisoned if any appreciable load of fuel remains; if empty, they should be retained for additional buoyancy. In a calm-water ditching the airplane will probably run about 600 feet Maximum longitudinal decelerations of about 2.5g and maximum vertical acceleration of about 2g will be encountered. The nose-intake duct will be clear of the water until practically all forward motion has stopped.

Fisher, Lloyd J.↗

Ditching Investigation of a 1/18-Scale Model of the North American B-45 Airplane

An investigation of a 1/18-scale dynamically similar model of the North American B-45 airplane was made to observe the ditching behavior and determine the proper landing technique to be used in an emergency water landing. Various conditions of damage were simulated to determine the behavior which probably would occur in a full-scale ditching. The behavior of the model was determined from high-speed motion-picture records, time-history acceleration records, and visual observations. It was concluded that the airplane should be ditched at the maximum nose-high attitude with the landing flaps full down for minimum landing speed. During the ditching, the nose-wheel and bomb-bay doors probably will be torn away and the rear of the fuselage flooded. A violent dive will very likely occur. Longitudinal decelerations of approximately 5g and vertical accelerations of approximately -6g (including gravity) will be experienced near the pilots' compartment. Ditching braces installed in the bomb bay will tend to improve the behavior slightly but will be torn away along with the bomb-bay doors. A hydroflap installed ahead of the nose-wheel doors will eliminate the dive and failure of the nose-wheel doors, and substantially reduce the motions and accelerations.

Fisher, Lloyd J.↗

Operation Teapot

As part of Operation Teapot, reporter Joan Collin came to the Nevada Test Site in early May 1955 to narrate a Federal Civil Defense Administration motion picture film on the explosive and radioactive effects of a nuclear detonation on food supplies, houses, communication systems, and energy sources. After watching efforts to feed the many people involved in test site activities, Collin asked the question of how to mass feed people after a nuclear attack. She was one of the few persons perceptive enough to recognize the significance of this issue.

99 GENERAL AND MISCELLANEOUS↗

NSRC makes vital vintage films accessible to today's weapons researchers

A few years ago, archivists at the Lab’s National Security Research Center (NSRC) rediscovered 65 special reels of nitrate motion picture film among the 20,000 film reels in the NSRC’s collections. Because nitrate film stock was discontinued in 1951, they realized that the films contained footage from the Lab’s earliest days of nuclear testing. However, nitrate film is highly toxic and flammable. Confirming this hunch would have to wait until the NSRC team devised a strategy for safely preserving and digitizing the reels. Now, after many months of planning and collaboration with LANL fire safety and industrial hygiene teams, the reels – which include footage from Operation Sandstone, Operation Ivy, and the Trinity test – have been digitized by the NSRC archivist team and are accessible to today’s researchers.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗

Fielding Freedom of Information Act (FOIA) requests at the National Security Research Center

For staff at the Lab’s National Security Research Center, fulfilling requests for information can sometimes be a bit otherworldly. Some of these requests are made under the Freedom of Information Act or FOIA, which are submitted to NNSA by the public and directed to LANL for records search and review. The topics of these requests range from technical reports to records on unidentified flying objects. “Fulfilling FOIA requests is an important part of what we do here,” said NSRC senior archivist Daniel Alcazar (WRS-NSRCMS). “It’s critical to our mission to ensure the public has access to information it has the right to see.” Congress passed the FOIA in 1967, giving any person the right to request access to federal agency records so they can better understand the U.S. Government’s operations and activities. Federal agencies are required to disclose information requested under the FOIA, unless it falls under one or more of nine exemptions protecting interests such as personal privacy, national security, and law enforcement. Often described as the law that keeps citizens in the know about the government, the FOIA is a vital part of U.S. democracy. The Laboratory’s FOIA program works with over a hundred requests for records each year. As the Lab’s classified research and technical library dedicated to information stewardship and education, the National Security Research Center (NSRC) regularly assists with these requests– as many as 45 per year. Public queries cover a spectrum of topics, but most common include requests for Manhattan Project era documents and memoranda, Los Alamos technical reports, Los Alamos-produced historical and scientific motion picture film and videos, as well as those seeking any documents or files pertaining to a former scientist, engineer or employee. While less common, Alcazar estimates that he receives a few FOIA requests a year related to unidentified flying objects (UFOs) and unexplained aerial phenomena (UAP).

99 GENERAL AND MISCELLANEOUS↗

Simplified Free-Flight Testing in a Conventional Wind Tunnel

In order to incorporate the advantages of ballistic range testing with the convenience of wind tunnel testing, simplified techniques have been developed at the Jet Propulsion Laboratory (JPL) for free-flight testing of models in a conventional wind tunnel. So far, only a small number of the many possibilities have been investigated, but the preliminary results indicate that such techniques are both practical and useful. The model to be investigated is suspended on a single traverse wire at the upstream end of the test section window, then is released from this position by causing the wire to break within the model. High speed motion pictures taken of the model oscillating during its travel across the viewing area make it possible to determine various aerodynamic parameters such as drag, lift, pitching moment, and pitch damping in much the same manner as is done in ballistic range testing. Also, a spark schlieren photograph can be taken of the model in flight in order to observe details of an undisturbed (from support interference) wake.

FREE FLIGHT↗

Electronic visualization of gas bearing behavior

Visualization technique produces a visual simulation of gas bearing operation by electronically combining the outputs from the clearance probes used to monitor bearing component motion. Computerized recordings of the probes output are processed, displayed on an oscilloscope screen and recorded with a high-speed motion picture camera.

Evans, R. C.↗

Reducing streak film data via electronic cross correlator

Continuous /nonframing/ motion picture projector, two photocells, a cross-correlator, and a ground glass screen where the photocells intercept the stream image determine the time delay between successive streak images. Velocities corresponding to the streaks are determined from the delay together with the distance separating the photocells.

Dickerson, R. A.↗