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The second USS Thresher (SSN-593) was the lead ship of her class of nuclear-powered attack submarines in the United States Navy. Her loss at sea during deep-diving tests in 1963 is often considered a watershed event in the implementation of the rigorous submarine safety program SUBSAFE. The contract to build Thresher was awarded to Portsmouth Naval Shipyard on 15 January 1958, and her keel was laid on 28 May 1958. She was launched on 9 July 1960, was sponsored by Mrs. Frederick B. Warder, and was commissioned on 3 August 1961, Commander Dean L. Axene commanding. Accompanied by the submarine rescue ship Skylark, she sailed to an area some 190 nmi east of Cape Cod, Massachusetts, and on the morning of 10 April started deep-diving tests. As Thresher neared her test depth, Skylark received garbled communications over underwater telephone indicating "... minor difficulties, have positive up-angle, attempting to blow." When Skylark received no further communication, surface observers gradually realized Thresher had sunk. Publicly it took some days to announce that all 129 officers, crewmen, and military and civilian technicians aboard were presumed dead. After an extensive underwater search using the bathyscaphe Trieste, oceanographic ship Mizar and other ships, Thresher's remains were located on the sea floor, some 8,400 ft below the surface, in six major sections. The majority of the debris had spread over an area of about 134,000 m2. The major sections were the sail, sonar dome, bow section, engineering spaces section, operations spaces section, and the stern planes. Deep sea photography, recovered artifacts, and an evaluation of her design and operational history permitted a Court of Inquiry to conclude Thresher had probably suffered the failure of a joint in a salt water piping system, which relied heavily on silver brazing instead of welding; earlier tests using ultrasound equipment found potential problems with about 14% of the tested brazed joints, most of which were determined not to pose a risk significant enough to require a repair. High-pressure water spraying from a broken pipe joint may have shorted out one of the many electrical panels, which in turn caused a shutdown ("scram") of the reactor, with a subsequent loss of propulsion. The inability to blow the ballast tanks was later attributed to excessive moisture in the ship's high-pressure air flasks, which froze and plugged the flasks' flowpaths while passing through the valves. This was later simulated in dock-side tests on Thresher's sister ship, Tinosa. During a test to simulate blowing ballast at or near test depth, ice formed on strainers installed in valves; the flow of air lasted only a few seconds. Air driers were later retrofitted to the high pressure air compressors, beginning with Tinosa, to permit the emergency blow system to operate properly. [READ THE REST OF THIS ARTICLE]



The Boeing 727 is a mid-size, narrow-body, three-engine, T-tailed commercial jet airliner. The first Boeing 727 flew in 1963 and for over a decade it was the most produced commercial jet airliner in the world. When production ended in 1984, a total of 1,831 aircraft had been produced. The 727's sales record for the most jet airliners ever sold was broken in the early 1990s by its younger stablemate, the Boeing 737. The 727 was produced following the success of the Boeing 707 quad-jet airliner. Designed for short-haul routes, the 727 became a mainstay of airlines' domestic route networks. A stretched variant, the 727-200, debuted in 1967. In August 2008, there were a total of 81 Boeing 727-100 aircraft and 419 727-200 aircraft in airline service. The 727 design arose as a compromise between United Airlines, American Airlines, and Eastern Air Lines requirements over the configuration of a jet airliner to service smaller cities which often had shorter runways and correspondingly smaller passenger demand.[3] United Airlines wanted a four-engined aircraft for its flights to high-altitude airports, especially its hub at Stapleton International Airport at Denver, Colorado. American, which was operating the four-engined Boeing 707 and 720, wanted a twin-engined aircraft for efficiency reasons. Eastern wanted a third engine for its overwater flights to the Caribbean, since at that time twin-engined commercial flights were limited by regulations to routes with 60-minute maximum flying time to an airport. Eventually, the airlines agreed on a trijet, and thus the 727 was born. In 1971, passenger D. B. Cooper hijacked Northwest Airlines Flight 305 while it was en route from Portland, Oregon to Seattle, Washington. After receiving a payment of $200,000 and 4 parachutes when he was in Seattle, he told the pilots to fly to Mexico, and jumped out of the aircraft from the aft airstairs over Washington or Oregon. Cooper's fate is unknown. On September 25, 1978, Pacific Southwest Airlines Flight 182, a Boeing 727, crashed after colliding with a Cessna 172 aircraft in San Diego, killing 144 people. On May 25, 2003, a 727 registration number N844AA, formerly used by American Airlines, was stolen from Luanda's international airport in Angola. The mechanic who was on the plane, Ben Charles Padilla, has never been heard from again. Faced with higher fuel costs, lower passenger volumes due to the post-9/11 economic climate, increasing restrictions on airport noise, and the extra expenses of maintaining older planes and paying flight engineers' salaries, most major airlines have phased 727s out of their fleets. Delta Air Lines, the last major U.S. carrier to do so, retired its last 727 in March, 2003. However, the 727 is still flying for smaller start-up airlines, cargo airlines, and charter airlines, and it is also sometimes used as a private means of transportation. The official replacement for the 727 in Boeing's lineup was the Boeing 757. However, the smallest 757 variant, the 757-200, is significantly larger than the 727-200, so many airlines replaced their 727s with either the 737-800 or EADS' Airbus A320, both of which are closer in size to the 727-200. [READ THE REST OF THIS ARTICLE]





An insect repellent is a substance applied to skin, clothing, or other surfaces which discourages insects (and arthropods in general) from landing or climbing on that surface. There are also insect repellent products available based on sound production, particularly ultrasound (inaudibly high frequency sounds). These electronic devices have been shown to have no effect as a mosquito repellent by studies done by the EPA and many universities. Insect repellents help prevent and control the outbreak of insect-borne diseases such as malaria, Lyme disease, Dengue fever, bubonic plague, and West Nile fever. Pest animals commonly serving as vectors for disease include the insects flea, fly, and mosquito; and the arachnid tick. Common insect repellents include: DEET , Essential oil of the lemon eucalyptus and its active compound p-menthane-3,8-diol (PMD), Citronella oil, Neem oil, Bog Myrtle, or IR3535 (ethyl ester). Usually insect repellents work by masking human scent, or by using a scent which insects naturally avoid. Permethrin is different in that it is actually a contact insecticide. Synthetic repellents tend to be more effective and/or longer lasting than "natural" repellents. In comparative studies, IR3535 was as effective or better than DEET in protection against mosquitoes. However, some plant-based repellents may provide effective relief as well. Essential oil repellents can be short-lived in their effectiveness, since essential oils can evaporate completely. Regardless of which repellent product used, it is recommended to read the label before use and carefully follow directions. Usage instructions for repellents vary from country to country. Some insect repellents are not recommended for use on younger children. he EPA states that citronella oil shows little or no toxicity and has been used as a topical insect repellent for 60 years. However, the EPA also states that citronella may irritate skin and cause dermatitis in certain individuals. Canadian regulatory authorities concern with citronella based repellents is primarily based on data-gaps in toxicology, not on incidents. There are many preparations from naturally occurring sources that are repellent to certain insects, such as Oleic acid, repels bees and ants by simulating the "Smell of death" produced by their decomposing corpses. It is a 400 millions years old natural mechanisms helping to sanitise the hives or to escape predators. [READ THE REST OF THIS ARTICLE]



The Wilhelm scream is a frequently-used film and television stock sound effect first used in 1953 for the film The Charges At Feather River. The effect gained new popularity (its use often becoming an in-joke) after it was used in Star Wars and many other blockbuster films as well as television programs and video games. The scream is often used when someone is falling to his death from great height. The Wilhelm scream has become a well-known cinematic sound cliché, and is claimed to have been used in over 140 films. The sound effect originates from a series of sound effects recorded for the 1951 film Distant Drums. In a scene from the film, soldiers are wading through a swamp in the everglades and one of them is bitten and dragged underwater by an alligator. The scream for that scene was recorded later in a single take along with five other short pained screams, which were slated as "man getting bit by an alligator, and he screams." The fifth scream was used for the soldier in the alligator scene—but the 4th, 5th, and 6th screams recorded in the session were also used earlier in the film—when three Indians are shot during a raid on a fort. Although takes 4 through 6 are the most recognizable, all of the screams are referred to as "Wilhelm" by those in the sound community. The Wilhelm scream's revival came from motion picture sound designer Ben Burtt, who re-discovered the original recording (which he found as a studio reel labeled "Man being eaten by alligator") and incorporated it into a scene in Star Wars Episode IV: A New Hope, when Luke Skywalker shoots a Stormtrooper who screams as he falls. Burtt named the scream after Private Wilhelm, a minor character who emitted the same scream in the 1953 film The Charge at Feather River. Burtt began incorporating the effect in other films he worked on, including most projects involving George Lucas and/or Steven Spielberg. Other sound designers picked up on the effect, and inclusion of the sound in films became a tradition among the community of sound designers. [READ THE REST OF THIS ARTICLE]



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