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At least 55 records · Page 3

Evaluation of Gust and Draft Velocities from Flights of P-61c Airplanes within Thunderstorms. II - July 9, 1946 to July 11, 1946 at Orlando, Florida: July 9, 1946 to July 11, 1946 at Orlando, Florida - II

The results obtained from an evaluation for gust and draft velocities of acceleration and airspeed-altitude records taken by NACA recording instruments installed in P-61c airplanes participating in thunderstorm flights 6, 7, and 8 of July 9, 1946, July 10, 1946, and July 11, 1946, respectively, are presented herein. These data are summarized in tables I and II. In accordance with a recent discussion with a member of the U.S. Weather Bureau staff, the tabulated results for the present flight include in addition to data of the type presented in reference 1, the initial heading of the airplane for each traverse, the pressure altitude at the start of each traverse in increments of 500 feet, and the gust gradient distance when it could be evaluated. The cloud entry and exit times for the present data were taken from motion-picture records of the pilot's instrument panels whenever such records were available while the length fo the traverses in seconds and feet was taken from the airspeed-altitude records. In many cases, however, poor agreement is indicated between the duration of the cloud traverses as obtained from the motion-picture records and from the airspeed-altitude records. This result is believed to be due to camera stoppages, inaccurate spring mechanisms of the clocks, and loss of motion-picture record in exposure or development. With reference to the evaluation of gust data, the nominal threshold was about 2 feet per second. In making gust counts to this threshold, some gusts below that threshold have been included due to limitations of the procedure used. Thus, it will be noted that in some instances gust counts are given in table I although now corresponding gust velocities are listed.

Tolefson, Harold B.↗

Automated Production of Movies on a Cluster of Computers

A method of accelerating and facilitating production of video and film motion-picture products, and software and generic designs of computer hardware to implement the method, are undergoing development. The method provides for automation of most of the tedious and repetitive tasks involved in editing and otherwise processing raw digitized imagery into final motion-picture products. The method was conceived to satisfy requirements, in industrial and scientific testing, for rapid processing of multiple streams of simultaneously captured raw video imagery into documentation in the form of edited video imagery and video derived data products for technical review and analysis. In the production of such video technical documentation, unlike in production of motion-picture products for entertainment, (1) it is often necessary to produce multiple video derived data products, (2) there are usually no second chances to repeat acquisition of raw imagery, (3) it is often desired to produce final products within minutes rather than hours, days, or months, and (4) consistency and quality, rather than aesthetics, are the primary criteria for judging the products. In the present method, the workflow has both serial and parallel aspects: processing can begin before all the raw imagery has been acquired, each video stream can be subjected to different stages of processing simultaneously on different computers that may be grouped into one or more cluster(s), and the final product may consist of multiple video streams. Results of processing on different computers are shared, so that workers can collaborate effectively.

Nail, Jasper↗

Particle behavior in solid propellant rockets

The use of holography, high speed motion pictures, light scattering measurements, and post-fire particle collection/scanning electron microscopic examination to study the combustion of composite solid propellants is discussed. The relative advantages and disadvantages of the different experimental techniques for obtaining two-phase flow characteristics within the combustion environment of a solid propellant grain are evaluated. Combustion bomb studies using high speed motion pictures and post-fire residue analysis were completed for six low metal content propellants. Resolution capabilities and the relationships between post-fire residue and motion picture data are determined. Initial testing using a holocamera together with a 2D windowed motor is also described.

Netzer, D. W.↗

Automated Selection Of Pictures In Sequences

Method of automated selection of film or video motion-picture frames for storage or examination developed. Beneficial in situations in which quantity of visual information available exceeds amount stored or examined by humans in reasonable amount of time, and/or necessary to reduce large number of motion-picture frames to few conveying significantly different information in manner intermediate between movie and comic book or storyboard. For example, computerized vision system monitoring industrial process programmed to sound alarm when changes in scene exceed normal limits.

Rorvig, Mark E.↗

Direct integration of transient rotor dynamics

An implicit method was developed for integrating the equations of motion for a lumped mass model of a rotor dynamics system. As an aside, a closed form solution to the short bearing theory was also developed for a damper with arbitrary motion. The major conclusions are that the method is numerically stable and that the computation time is proportional to the number of elements in the rotor dynamics model rather than to the cube of the number. This computer code allowed the simulation of a complex rotor bearing system experiencing nonlinear transient motion and displayed the vast amount of results in an easily understood motion picture format - a 10 minute, 16 millimeter, color, sound motion picture supplement. An example problem with 19 mass elements in the rotor dynamics model took 0.7 second of central processing unit time per time step on an IBM 360-67 computer in a time sharing mode.

Kascak, A. F.↗

The solid surface combustion space shuttle experiment hardware description and ground-based test results

The Lewis Research Center is developing a series of microgravity combustion experiments for the Space Shuttle. The Solid Surface Combustion Experiment (SSCE) is the first to be completed. SSCE will study flame spreading over thermally thin fuels (ashless filter paper) under microgravity conditions. The flight hardware consists of a combustion chamber containing the sample and a computer which takes the data and controls the experiment. Experimental data will include gas-phase and solid-phase temperature measurements and motion pictures of the combustion process. Flame spread rates will be determined from the motion pictures.

Vento, D. M.↗

The solid surface combustion Space Shuttle experiment hardware description and ground-based test results

The Lewis Research Center is developing a series of microgravity combustion experiments for the Space Shuttle. The Solid Surface Combustion Experiment (SSCE) is the first to be completed. SSCE will study flame spreading over thermally thin fuels (ashless filter paper) under microgravity conditions. The flight hardware consists of a combustion chamber containing the sample and a computer which takes the data and controls the experiment. Experimental data will include gas-phase and solid-phase temperature measurements and motion pictures of the combustion process. Flame spread rates will be determined from the motion pictures.

Vento, D. M.↗

Selective image area control of X-ray film exposure density

A system for accurately determining the exposure density required for X-ray photography of a particular area of interest is provided. The light received from an X-ray image intensifier is applied to a beam splitting mirror which divides the light between a motion picture film camera and a television film camera. Between the beam splitter and the motion picture film camera, there is positioned another light beam splitter to direct some of the light at a mask having an opening which encloses only the image area of interest. Behind that opening there is positioned a photomultiplier intensity sensor for determining the exposure required and varying X-ray beam intensity accordingly.

Berdahl, C. M.↗

A Study of Air Flow in an Engine Cylinder

A 4-stroke-cycle test engine was equipped with a glass cylinder and the air movements within it were studied while the engine was being motored. Different types of air flow were produced by using shrouded intake valves in various arrangements and by altering the shape of the intake-air passage in the cylinder head. The air movements were made visible by mixing feathers with the entering air, and high-speed motion pictures were taken of them so that the air currents might be studied in detail and their velocities measured. Motion pictures were also taken of gasoline sprays injected into the cylinder on the intake stroke. The photographs showed that: a wide variety of induced air movements could be created in the cylinder; the movements always persisted throughout the compression stroke; and the only type of movement that persisted until the end of the cycle was rotation about the cylinder axis.

Lee, Dana W↗

Holographic cinematography of time-varying reflecting and time-varying phase objects using a Nd:YAG laser

The use of a Nd:YAG laser to record holographic motion pictures of time-varying reflecting objects and time-varying phase objects is discussed. Sample frames from both types of holographic motion pictures are presented. The holographic system discussed is intended for three-dimensional flow visualization of the time-varying flows that occur in jet-engine components.

Decker, A. J.↗

A study of the air movement in two aircraft-engine cylinders

Studies were made of the air movements in the NACA glass-cylinder apparatus using cylinder heads similar to those on the Wright R-1820-G engine and the Pratt & Whitney Wasp engine as modified by the Eclipse Aviation Corporation to use fuel-injection equipment. The air movements were made visible by mixing small feathers with the air; high-speed motion pictures were than taken of the feathers as they swirled about the inside the glass cylinder. The test engine speeds were 350, 500, and 1,000 r.p.m. Motion pictures were also taken of gasoline sprays injected into the cylinder during the intake stroke. The air flow produced by each cylinder head is described and some results of the velocity measurements of feathers are presented. The apparent time intervals required for vaporization of the gasoline sprays are also given.

Lee, Dana W↗

Preknock Vibrations in a Spark-Ignition Engine Cylinder as Revealed by High-Speed Photography

The high-speed photographic investigation of the mechanics of spark-ignition engine knock recorded in three previous reports has been extended with use of the NACA high-speed camera and combustion apparatus with a piezoelectric pressure pickup in the combustion chamber. The motion pictures of knocking combustion were taken at the rate of 40,000 frames per second. Existence of the preknock vibrations in the engine cylinder suggested in Technical Report no.727 has been definitely proved and the vibrations have been analyzed both in the high-speed motion pictures and the pressure traces. Data are also included to show that the preknock vibrations do not progressively build up to cause knock. The effect of tetraethyl lead on the preknock vibrations has been studied and results of the tests are presented. Photographs are presented which in some cases clearly show evidence of autoignition in the end zone a considerable length of time before knock occurs.

Miller, Cearcy D↗

Analysis of Spark-Ignition Engine Knock as Seen in Photographs Taken at 200,000 Frames Per Second

A motion picture of the development of knock in a spark-ignition engine is presented, which consists of 20 photographs taken at intervals of 5 microseconds, or at a rate of 200,000 photographs per second, with an equivalent wide-open exposure time of 6.4 microseconds for each photograph. A motion picture of a complete combustion process, including the development of knock, taken at the rate of 40,000 photographs per second is also presented to assist the reader in orienting the photographs of the knock development taken at 200,000 frames per second.

Miller, Cearcy D↗

Analysis of Spark-Ignition Engine Knock as Seen in Photographs Taken at 200,000 Frames Per Second

A motion picture of the development of knock in a spark-ignition engine, is presented, which consists of 20 photographs taken at intervals of 5 microseconds, or at a rate of 200,000 photographs a second, with an equivalent wide-open exposure time of 6.4 microseconds for each photograph. A motion picture of a complete combustion process, including the development of knock, taken at the rate of 40,000 photographs a second is also presented to assist the reader in orienting the photographs of the knock development taken at 200,000 frames per second. The photographs taken at 200,000 frames per second are analyzed and the conclusion is made that the type of knock in the spark-ignition engine involving violent gas vibration originates as self-propagating disturbance starting at a point in the.burn1ig or autoigniting gases and spreading out from that point through the incompletely burned gases at a rate as high as 6800 feet per second, or about twice the speed of sound in the burned gases. Apparent formation of free carbon particles in both the burning and the burned gas is observed within 10 microseconds after passage of the knock disturbance through the gases.

CAMERAS-NACA (MOVING PICTURE)(HIGH SPEED)↗

A high-speed photographic system for flow visualization in a steam turbine

A photographic system was designed to visualize the moisture flow in a steam turbine. Good performance of the system was verified using dry turbine mockups in which an aerosol spray simulated, in a rough way, the moisture flow in the turbine. Borescopes and fiber-optic light tubes were selected as the general instrumentation approach. High speed motion-picture photographs of the liquid flow over the stator blade surfaces were taken using stroboscopic lighting. Good visualization of the liquid flow was obtained. Still photographs of drops in flight were made using short duration flash sources. Drops with diameters as small as 30 micrometers (0.0012 in.) could be resolved. In addition, motion pictures of a spray of water simulating the spray off the rotor blades and shrouds were taken at normal framing rates. Specially constructed light tubes containing small tungsten-halogen lamps were used. Sixteen millimeter photography was used in all cases. Two potential problems resulting from the two-phase turbine flow (attenuation and scattering of light by the fog present and liquid accumulation on the borescope mirrors) were taken into account in the photographic system design but not evaluated experimentally.

Barna, G. J.↗

Investigation of television transmission using adaptive delta modulation principles

The results are presented of a study on the use of the delta modulator as a digital encoder of television signals. The computer simulation of different delta modulators was studied in order to find a satisfactory delta modulator. After finding a suitable delta modulator algorithm via computer simulation, the results were analyzed and then implemented in hardware to study its ability to encode real time motion pictures from an NTSC format television camera. The effects of channel errors on the delta modulated video signal were tested along with several error correction algorithms via computer simulation. A very high speed delta modulator was built (out of ECL logic), incorporating the most promising of the correction schemes, so that it could be tested on real time motion pictures. Delta modulators were investigated which could achieve significant bandwidth reduction without regard to complexity or speed. The first scheme investigated was a real time frame to frame encoding scheme which required the assembly of fourteen, 131,000 bit long shift registers as well as a high speed delta modulator. The other schemes involved the computer simulation of two dimensional delta modulator algorithms.

Schilling, D. L.↗

The effect of interference on delta modulation encoded video signals

The results of a study on the use of the delta modulator as a digital encoder of television signals are presented. The computer simulation was studied of different delta modulators in order to find a satisfactory delta modulator. After finding a suitable delta modulator algorithm via computer simulation, the results are analyzed and then implemented in hardware to study the ability to encode real time motion pictures from an NTSC format television camera. The effects were investigated of channel errors on the delta modulated video signal and several error correction algorithms were tested via computer simulation. A very high speed delta modulator was built (out of ECL logic), incorporating the most promising of the correction schemes, so that it could be tested on real time motion pictures. The final area of investigation concerned itself with finding delta modulators which could achieve significant bandwidth reduction without regard to complexity or speed. The first such scheme to be investigated was a real time frame to frame encoding scheme which required the assembly of fourteen, 131,000 bit long shift registers as well as a high speed delta modulator. The other schemes involved two dimensional delta modulator algorithms.

Schilling, D. L.↗

Real time moving scene holographic camera system

A holographic motion picture camera system producing resolution of front surface detail is described. The system utilizes a beam of coherent light and means for dividing the beam into a reference beam for direct transmission to a conventional movie camera and two reflection signal beams for transmission to the movie camera by reflection from the front side of a moving scene. The system is arranged so that critical parts of the system are positioned on the foci of a pair of interrelated, mathematically derived ellipses. The camera has the theoretical capability of producing motion picture holograms of projectiles moving at speeds as high as 900,000 cm/sec (about 21,450 mph).

Kurtz, R. L.↗