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Skydiving
Parachuting, including also skydiving, is a method of transiting from a high point in the Atmosphere of Earth, atmosphere to the surface of Earth with the aid of gravity, involving the control of speed during the descent using a parachute or parachutes. For human skydiving, it may involve a phase of more or less free-falling (the skydiving segment) which is a period when the parachute has not yet been deployed and the body gradually accelerates to terminal velocity. For cargo parachuting, the parachute descent may begin immediately, such as a parachute-airdrop in the Troposphere, lower atmosphere of Earth, or be significantly delayed, such as in a planetary atmosphere where an object is descending "under parachute" following atmospheric entry from outer space, space, and may begin only after the hypersonic entry phase and initial deceleration that occurs due to aerodynamic drag, friction with the thin upper atmosphere. History Common uses Parachuting is performed a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, who can exit from an aircraft at height and descend safely to earth. A parachute is usually made of a light, strong fabric. Early parachutes were made of silk. The most common fabric today is nylon. A parachute's canopy is typically dome-shaped, but some are rectangles, inverted domes, and other shapes. A variety of loads are attached to parachutes, including people, food, equipment, space capsules, and bombs. History Middle Ages In 852, in Córdoba, Spain, the Moorish man Armen Firman attempted unsuccessfully to fly by jumping from a tower while wearing a large cloak. It was recorded that "there was enough air in the folds of his cloak to prevent great injury when he reached the ground." Early Renaissance The earliest eviden ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Parachute Association
The United States Parachute Association (USPA) is a private sports governing body for the sport of skydiving in the United States. Its headquarters are located in Fredericksburg, Virginia. The USPA's roots go back to the National Parachute Riggers-Jumpers, Inc., which was formed in the 1930s. Functions USPA performs the following functions: * Issues sport skydiving licenses * Publishes and maintains skydiving training manuals and course guidelines from which instructional ratings are issued * Serves as legal advocate and political lobbyist for skydiving * Provides third-party insurance for skydivers * Maintains the Basic Safety Requirements (BSRs) as a set of voluntarily followed safety guidelines * Coordinates skydiving competitions and awards * Issues awards for longevity, skill and achievement * Publishes ''Parachutist'', a monthly magazine for members In November 2020, USPA announced their plans for a National Skydiving Museum to be built in Central Florida, but didn't specif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Velocity
Terminal velocity is the maximum velocity (speed) attainable by an object as it falls through a fluid ( air is the most common example). It occurs when the sum of the drag force (''Fd'') and the buoyancy is equal to the downward force of gravity (''FG'') acting on the object. Since the net force on the object is zero, the object has zero acceleration. In fluid dynamics an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving. As the speed of an object increases, so does the drag force acting on it, which also depends on the substance it is passing through (for example air or water). At some speed, the drag or force of resistance will equal the gravitational pull on the object (buoyancy is considered below). At this point the object stops accelerating and continues falling at a constant speed called the terminal velocity (also called settling velocity). An object moving downward faster t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars Rover
A Mars rover is a motor vehicle designed to travel on the surface of Mars. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control. They serve a different purpose than orbital spacecraft like '' Mars Reconnaissance Orbiter''. A more recent development is the Mars helicopter. , there have been six successful robotically operated Mars rovers; the first five, managed by the American NASA Jet Propulsion Laboratory, were (by date of Mars landing): ''Sojourner'' (1997), '' Spirit'' (2004–2010), '' Opportunity'' (2004–2018), ''Curiosity'' (2012–), and '' Perseverance'' (2021–). The sixth, managed by the China National Space Administration, is '' Zhurong'' (2021–). On January 24, 2016, NASA reported that then current studies on Mars by ''Oppor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aviators
An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its directional flight controls. Some other aircrew members, such as navigators or flight engineers, are also considered aviators, because they are involved in operating the aircraft's navigation and engine systems. Other aircrew members, such as drone operators, flight attendants, mechanics and ground crew, are not classified as aviators. In recognition of the pilots' qualifications and responsibilities, most militaries and many airlines worldwide award aviator badges to their pilots. History The first recorded use of the term ''aviator'' (''aviateur'' in French) was in 1887, as a variation of ''aviation'', from the Latin ''avis'' (meaning ''bird''), coined in 1863 by in ''Aviation Ou Navigation Aérienne'' ("Aviation or Air Navigation"). The term ''aviatrix'' (''aviatrice'' in French), now archaic, was formerly used for a female aviator. These terms were used more in the ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smokejumpers
Smokejumpers are specially trained wildland firefighters who provide an initial attack response on remote wildland fires. They are inserted at the site of the fire by parachute. In addition to performing the initial attack on wildfires, they may also provide leadership for extended attacks on wildland fires. Shortly after smokejumpers touch ground, they are supplied by parachute with food, water, and firefighting tools, making them self-sufficient for 48 hours. Smokejumpers are usually on duty from early spring through late fall. Smokejumpers worldwide Smokejumpers are employed by the Russian Federation, United States (namely the United States Forest Service and Bureau of Land Management), and Canada (in British Columbia). History Prior to the full establishment of smokejumping, experiments with parachute insertion of firefighters were conducted in 1934 in Utah and in the Soviet Union. Earlier, aviation firefighting experiments had been conducted with air delivery of equipm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forest Firefighter
Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated areas. Working in conjunction with specially designed aerial firefighting aircraft, these wildfire-trained crews suppress flames, construct fire lines, and extinguish flames and areas of heat to protect resources and natural wilderness. Wildfire suppression also addresses the issues of the wildland–urban interface, where populated areas border with wild land areas. In the United States and other countries, aggressive wildfire suppression aimed at minimizing fire has contributed to accumulation of fuel loads, increasing the risk of large, catastrophic fires. History Australia Wildland fire, known in Australia as bush fire, has played a major role in Australia due to arid conditions. Notable fire services tasked with wildfire suppressio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Operations
Special operations (S.O.) are military activities conducted, according to NATO, by "specially designated, organized, selected, trained, and equipped forces using unconventional techniques and modes of employment". Special operations may include reconnaissance, unconventional warfare, and counter-terrorism actions, and are typically conducted by small groups of highly-trained personnel, emphasizing sufficiency, stealth, speed, and tactical coordination, commonly known as " special forces". History Australia In World War II following advice from the British, Australia began raising special forces. The first units to be formed were independent companies, which began training at Wilson's Promontory in Victoria in early 1941 under the tutelage of British instructors. With an establishment of 17 officers and 256 men, the independent companies were trained as "stay behind" forces, a role that they were later employed in against the Japanese in the South West Pacific Area during 1942 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airborne Forces
Airborne forces, airborne troops, or airborne infantry are ground combat units carried by aircraft and airdropped into battle zones, typically by parachute drop or air assault. Parachute-qualified infantry and support personnel serving in airborne units are also known as paratroopers. The main advantage of airborne forces is their ability to be deployed into combat zones without land passage, as long as the airspace is accessible. Formations of airborne forces are limited only by the number and size of their transport aircraft; a sizeable force can appear "out of the sky" behind enemy lines in merely hours if not minutes, an action known as ''vertical envelopment''. Airborne forces typically lack enough supplies for prolonged combat, so they are utilized for establishing an airhead to bring in larger forces before carrying out other combat objectives. Some infantry fighting vehicles have also been modified for paradropping with infantry to provide heavier firepower. Due ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extreme Sport
Action sports, adventure sports or extreme sports are activities perceived as involving a high degree of risk. These activities often involve speed, height, a high level of physical exertion and highly specialized gear. Extreme tourism overlaps with extreme sport. The two share the same main attraction, " adrenaline rush" caused by an element of risk, and differ mostly in the degree of engagement and professionalism. Definition The definition of extreme sports is not exact and the origin of the terms is unclear, but it gained popularity in the 1990s when it was picked up by marketing companies to promote the X Games and when the Extreme Sports Channel and Extreme International launched. More recently, the commonly used definition from research is "a competitive (comparison or self-evaluative) activity within which the participant is subjected to natural or unusual physical and mental challenges such as speed, height, depth or natural forces and where fast and accurate cogniti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
