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Orbital Mechanics
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This video details planetary motion or orbital mechanics. It explains Kepler's and Newton's Laws plus terminology including perigee, apogee, eccentricity, orbital inclination, launch window, etc. Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and Newton's law of universal gravitation. It is a core discipline within space mission design and control. Celestial mechanics treats more broadly the orbital dynamics of systems under the influence of gravity, including both spacecraft and natural astronomical bodies such as star systems,
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How Airplanes Fly
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The simple physics of aerodynamically generated lift and drag and other forces that enable an aircraft to fly is discussed. A fluid flowing past the surface of a body exerts a surface force on it. Lift is defined to be the component of this force that is perpendicular to the oncoming flow direction.It contrasts with the drag force, which is defined to be the component of the surface force parallel to the flow direction. If the fluid is air, the force is called an aerodynamic force. An
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SR 71 Blackbird
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The Lockheed SR-71 is an advanced, long range, Mach 3+ strategic reconnaissance aircraft developed from the Lockheed A-12 and YF-12 aircraft by the Lockheed Skunk Works as a Black project. The SR-71 was unofficially named the Blackbird, and called the Habu by its crews, referring to an Okinawan species of pit viper. Clarence "Kelly" Johnson was responsible for many of the design's innovative concepts. A defensive feature of the aircraft was its high speed and operating altitude, whereby, if a surface-to-air missile launch were detected, standard evasive action was simply to accelerate. The SR-71 line was in service from 1964 to 1998, with 12 of the 32 aircraft destroyed in accidents, though none was lost to enemy action. Since 1976, it has held the world record for the fastest air breathing manned aircraft, a record previously held by the YF-12. |
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Influence of a Streamwise Pressure Gradient o...
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In this video, Kiran Dellimore gives a broad overview of his research paper entitled 'Influence of a Streamwise Pressure Gradient on Film-Cooling Effectiveness' published in the JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER,Vol. 23, No. 1, January-March 2009. His co-authors are Carlos Cruz, Andre W. Marshall, and Christopher P. Cadou all from the University of Maryland, College Park, Maryland 20742. The paper may be accessed using the following DOI: 10.2514/1.35717 Film cooling is widely used in conventional gas turbine and rocket engines to minimize thermal loading of engine structures and to manage heat transfer between hot, reacting gases and cooler structural components. Previous experimental work has shown that streamwise pressure gradients strongly influence the performance of the film.This paper extends semi-empirical modeling ideas for wall-jet film cooling to include the effects of adverse and favorable pressure gradients. The extended model shows that a pressure gradient’s effect on cooling performance depends on whether the velocity of the film is greater than the core flow (a wall-jet... |
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Why Open Access Is So Important
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Why Open Access Is So Important by Dr. Richard Roberts.He shared the 1993 Nobel Prize for physiology or medicine. Born in Derby, Roberts was educated at the University of Sheffield where he gained his PhD in 1968. He moved soon after to America and, after spending a year at Harvard, he moved to the Cold Spring Harbor Laboratory, New York, in 1971. He is currently serving as research director at New England Biolabs, Beverly, Massachusetts. By the late 1970s it had become clear that the cells of some organisms seemed to have far too much DNA. Prokaryotic cells, i.e., cells without a nucleus, such as the bacteria Escherichia coli, have a single chromosome consisting of about 3 million DNA bases. A protein of about 300 amino acids will require 900 base pairs. Consequently a prokaryotic cell should be able to produce about 3000 proteins, a figure in reasonable agreement with experience. Eukaryotic cells, however, i.e., cells with a nucleus, as in mammals, have a genome of 3-4 billion base pairs, capable of producing some 3 million proteins, a number far in excess of the 150,000 or so proteins found in mammals. The disparity was solved in 1977 when Roberts, working with ade... |
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Cavitation driven weapon for Pistol Shrimp
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Acoustic weapon for Pistol Shrimp.The snapping shrimp competes with much larger animals, like the Sperm Whale and Beluga Whale, for the title of 'loudest animal in the sea'. The animal snaps a specialized claw shut to create a cavitation bubble that generates acoustic pressures of up to 80 kPa at a distance of 4 cm from the claw. The pressure is strong enough to kill small fish. It corresponds to a zero to peak pressure level of 218 decibels relative to one micropascal (dB re 1 μPa), equivalent to a zero to peak source level of 190 dB re 1 μPa at the standard reference distance of 1 m. Au and Banks measured peak to peak source levels between 185 and 190 dB re 1 μPa at 1 m, depending on the size of the claw. Similar values are reported by Ferguson and Cleary. The duration of the click is less than 1 millisecond. The snap can also produce sonoluminescence from the collapsing cavitation bubble. As it collapses, the cavitation bubble reaches temperatures of over 5,000 K (4,700 °C). In comparison, the surface temperature of the sun is estimated to be around 5,800 K (5,500 °C). The light is of lower intensity than the light produced by typical sonoluminescence and is not visi... |
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Circular bubbles produced by Whales and Dolph...
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Circular bubbles produced by Whales and Dolphins. A bubble ring is an underwater ring vortex where an air bubble occupies the core of the vortex, forming a ring shape. The ring of air as well as the nearby water spins poloidally as it travels through the water, much like a flexible bracelet might spin when it is rolled off a person's arm. Some scuba divers can create bubble rings by blowing air out of their mouth in a particular manner. Long bubble rings also can form spontaneously in turbulent water such as in heavy surf. Bubble rings and smoke rings are both forms of vortex rings, and are sometimes studied in the field of fluid dynamics. Dolphins and humpback whales have also been seen to create bubble rings. Dolphins sometimes create bubble rings on purpose, seemingly for amusement.
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Kennedy Space Center STS 127 Launch
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Kennedy Space Center STS 127 LaunchSTS-127 (ISS assembly flight 2J/A) was a space shuttle mission to the International Space Station (ISS). It was the twenty-third flight of Space Shuttle Endeavour. The primary purpose of the STS-127 mission was to deliver and install the final two components of the Japanese Experiment Module: the Exposed Facility (JEM EF), and the Exposed Section of the Experiment Logistics Module (ELM-ES).[NASA 2] When Endeavour docked with ISS, it set a record for the most humans in space at the same time in the same vehicle, the first time thirteen people have been at the station at the same time. It also tied the record of thirteen people in space at any one time. The first launch attempt, on June 13, 2009, was scrubbed due to a gaseous hydrogen leak observed during tanking. The Ground Umbilical Carrier Plate (GUCP) on the external fuel tank experienced a potentially hazardous hydrogen gas leak similar to the fault that delayed the Space Shuttle Discovery, mission STS-119 in March 2009. Since a launch date of June 18, 2009 would have conflicted with the launch of the Lunar Reconnaissance Orbiter (LRO)/Lunar Crater Observation and Sensing Satellite (LCROSS), NASA ma... |
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Best of The Beautiful Universe
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From NASA JPL. Images obtained by the Chandrasekhar X ray telescope of galaxies. 30 Doradus, Abell 85, Stephans' Quintet, NGC 604, NGC 6240, Crab Nebula, PSR B1509-58, G292.01+8, E0102, Hydra A, MacsJ0717, Milky Way Center. |
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The Lunar Orbiter: A Spacecraft to Advance Lu...
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1966. The film describes the Lunar Orbiter's mission to photograph landing areas on the Moon. The Orbiter will be launched from Cape Kennedy using an Atlas Agena booster rocket. Once it is boosted in a trajectory toward the Moon, the Orbiter will deploy two-way earth communication antennas and solar panels for electricity. Attitude control jets will position the solar panels toward the sun and a tracker for a fix on its navigational star. The Orbiter will be put in an off-center orbit around the Moon where it will circle from four to six days. Scientists on Earth will study the effects of the Moon's gravitational field on the spacecraft, then the orbit will be lowered to 28 miles above the Moon's surface. Engineers will control the Orbiter manually or by computer to activate two camera lenses. The cameras will capture pictures of 12,000 square miles of lunar surface in 25 and 400 square mile increments. Pictures will be sent back to Earth using solar power to transmit electrical signals. The signals will be received by antennas at Goldstone, CA, and in Australia and Spain. Incoming photographic data will be electronically converted and processed to produce large-scale photographic images. The mission will be directed from the Spac... |
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