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Unpowered Flight
Unpowered flight is the ability to stay airborne for a period of time without using any power source. There are several types of unpowered flight. Some have been exploited by nature, others by humankind, and some by both. Unpowered aircraft are aerial vehicles that can fly without any propulsion mechanism. The ability to fly short or long distances without power has evolved many times in nature. Many creatures capable of sustained wing-powered flight also soar unpowered for much of the time they are airborne. Flight without power Classification of flight methods Pennycuick divides animal flight into three types: parachuting, gliding and powered. He observes however that these have no sharp boundaries. For example, at one point he sees parachutes as unpowered and as a primitive form of soaring, while soaring itself he sees as being powered by air movement (wind). Other methods, such as lighter-than-air flight, are used only by man. This article makes the following distinctions b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unpowered Aircraft
Unpowered aircraft can remain airborne for a significant period of time without onboard propulsion. They can be classified as gliders, lighter-than-air balloons and tethered kites. In the case of kites, lift is obtained by tethering to a fixed or moving object, perhaps another kite, to obtain a flow of wind over the lifting surfaces. In the case of balloons, lift is obtained through inherent buoyancy and the balloon may or may not be tethered. Free balloon flight has little directional control. Gliding aircraft include sailplanes, hang gliders, and paragliders that have full directional control in free flight. History The first manned aircraft were kites, balloons and gliders. Man-lifting kites were used in ancient China and Japan, often as a punishment for prisoners. Unmanned hot-air balloons and toy "bamboo-copters" are also recorded in Chinese history. The first manned free flight was in a hot-air balloon built by the brothers Joseph-Michel and Jacques-Etienne Montgolf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helium
Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the Chemical element, elements, and it does not have a melting point at standard pressures. It is the second-lightest and second-most Abundance of the chemical elements, abundant element in the observable universe, after hydrogen. It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and Jupiter, because of the very high nuclear binding energy (per nucleon) of helium-4 with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. The most common isotope of helium in the universe is helium-4, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flying Frog
A flying frog (also called a gliding frog) is a frog that has the ability to achieve gliding flight. This means it can descend at an angle less than 45° relative to the horizontal. Other nonflying arboreal frogs can also descend, but only at angles greater than 45°, which is referred to as parachuting.Emerson, S.B., Travis, J., & Koehl, M.A.R. (1990). "Functional complexes and additivity in performance: A test case with 'flying' frogs." ''Evolution'', 44(8), 2153-2157. Evolution Gliding flight has evolved independently several times among frogs from both New World ( Hylidae) and Old World ( Rhacophoridae) families.Emerson, S.B., & Koehl, M.A.R. (1990). "The interaction of behavioral and morphological change in the evolution of a novel locomotor type: 'Flying' frogs." ''Evolution'', 44(8), 1931-1946. This parallel evolution is seen as an adaptation to their life in trees, high above the ground. Characteristics of the Old-World species include "enlarged hands and feet, full ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sycamore
Sycamore is a name which has been applied to several types of trees, but with somewhat similar leaf forms. The name derives from the Ancient Greek () meaning . Species of otherwise unrelated trees known as sycamore: * ''Acer pseudoplatanus'', a species of maple native to central Europe and southwestern Asia * ''Ficus sycomorus'', the sycamore (or sycomore) of the Bible; a species of fig, also called the sycamore fig or fig-mulberry, native to the Middle East and eastern Africa * '' Platanus orientalis'', chinar tree (Old World sycamore) * Some North American members of the genus ''Platanus ''Platanus'' ( ) is a genus consisting of a small number of tree species native to the Northern Hemisphere. They are the sole living members of the family Platanaceae. All mature members of ''Platanus'' are tall, reaching in height. The type ...'', including ** '' Platanus occidentalis'', the American sycamore ** '' Platanus racemosa'', the California sycamore or western sycamore ** '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as current, with additional synonyms, and ''Plants of the World Online'' 126 species-rank taxa (113 species and 13 nothospecies), making it the largest genus among the conifers. The highest species diversity of pines is found in Mexico. Pines are widely species distribution, distributed in the Northern Hemisphere; they occupy large areas of boreal forest, but are found in many habitats, including the Mediterranean Basin, and dry tropical forests in southeast Asia and Central America. Wood from pine trees is one of the most extensively used types of timber, and some pines are widely used as Christmas trees. Description Pine trees are evergreen, coniferous resinous trees (or, rarely, shrubs) growing tall, with the majority of species reachin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maple
''Acer'' is a genus of trees and shrubs commonly known as maples. The genus is placed in the soapberry family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http://www.mobot.org/MOBOT/research/APweb/. There are approximately 132 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America. Only one species, '' Acer laurinum'', extends to the Southern Hemisphere.Gibbs, D. & Chen, Y. (2009The Red List of Maples Botanic Gardens Conservation International (BGCI) The type species of the genus is the sycamore maple ''Acer pseudoplatanus'', one of the most common maple species in Europe.van Gelderen, C. J. & van Gelderen, D. M. (1999). '' Maples for Gardens: A Color Encyclopedia'' Most maples usually have easily identifiable palmate leaves (with a few exceptions, such as '' Acer carpinifolium'', '' Acer laurinum'', and '' Acer negundo'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Populus
''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood. The western balsam poplar (Populus trichocarpa, ''P. trichocarpa'') was the first tree to have its full DNA code determined by DNA sequencing, in 2006. Description The genus has a large genetic diversity, and can grow from tall, with trunks up to in diameter. The Bark (botany), bark on young trees is smooth and white to greenish or dark gray, and often has conspicuous lenticels; on old trees, it remains smooth in some species, but becomes rough and deeply fissured in others. The shoots are stout, with (unlike in the related willows) the terminal bud present. The leaves are spirally arranged, and vary in shape from triangular to circular or (rarely) lobed, and with a long petiole (botany), petiole; in species in the sections ''Populus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milkweed
''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to humans and many other species, primarily due to the presence of cardenolides. However, as with many such plants, some species feed upon milkweed leaves or the nectar from their flowers. A noteworthy feeder on milkweeds is the monarch butterfly, which uses and requires certain milkweeds as host plants for its larvae. The ''Asclepias'' genus contains over 200 species distributed broadly across Africa, North America, and South America. It previously belonged to the family Asclepiadaceae, which is now classified as the subfamily Asclepiadoideae of the dogbane family, Apocynaceae. The genus was formally described by Carl Linnaeus in 1753, who named it after Asclepius, the Greek god of healing. Flowers Members of the genus produce some of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dandelion
''Taraxacum'' () is a genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus has a near-cosmopolitan distribution, absent only from tropical and polar areas. Two of the most common species worldwide, '' T. officinale'' (the common dandelion) and '' T. erythrospermum'' (the red-seeded dandelion), are European species introduced into North America, where they are non-native. Dandelions thrive in temperate regions and can be found in yards, gardens, sides of roads, among crops, and in many other habitats. Like other members of the family Asteraceae, they have very small flowers collected together into a composite flower head. Each single flower in a head is called a ''floret''. In part due to their abundance, along with being a generalist species, dandelions are one of the most vital early spring nectar sources for a wide host of polli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parachute
A parachute is a device designed to slow an object's descent through an atmosphere by creating Drag (physics), drag or aerodynamic Lift (force), lift. It is primarily used to safely support people exiting aircraft at height, but also serves various purposes like slowing cargo, aiding in space capsule recovery, and stabilizing vehicles or objects. Modern parachutes are typically made from durable fabrics like nylon and come in various shapes, such as dome-shaped, rectangular, and inverted domes, depending on their specific function. The concept of the parachute dates back to ancient attempts at flight. In 852 AD, Armen Firman, in Córdoba, Spain, made the first recorded jump with a large cloak to slow his fall. Renaissance figures like Francesco di Giorgio Martini and Leonardo da Vinci later sketched designs resembling modern parachutes, but it wasn’t until the 18th century that the first successful jumps occurred. French Louis-Sébastien Lenormand made the first public jump i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paratrooper At Spanish Drop Zone During Exercise Iberian Eagle
A paratrooper or military parachutist is a soldier trained to conduct military operations by parachuting directly into an area of operations, usually as part of a large airborne forces Airborne forces are ground combat units carried by aircraft and airdropped into battle zones, typically by parachute drop. Parachute-qualified infantry and support personnel serving in airborne units are also known as paratroopers. The main ... unit. Traditionally paratroopers fight only as light infantry armed with small arms and light weapons, although some paratroopers can also function as artillerymen or mechanized infantry by utilizing field guns, infantry fighting vehicles and light tanks that are often used in surprise attacks to seize strategic positions behind enemy lines such as airfields, bridges and major roads. Overview Paratroopers jump out of aircraft and use parachutes to land safely on the ground. This is one of the three types of "forced entry" strategic techniques ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orchid
Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Earth except glaciers. The world's richest diversity of orchid genera and species is in the tropics. Orchidaceae is one of the two largest families of flowering plants, the other being the Asteraceae. It contains about 28,000 currently accepted species in 702 genera. The Orchidaceae family encompasses about 6–11% of all species of seed plants. The largest genera are '' Bulbophyllum'' (2,000 species), '' Epidendrum'' (1,500 species), '' Dendrobium'' (1,400 species) and '' Pleurothallis'' (1,000 species). It also includes '' Vanilla'' (the genus of the vanilla plant), the type genus '' Orchis'', and many commonly cultivated plants such as '' Phalaenopsis'' and '' Cattleya''. Moreover, since the introduction of tropical species into cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
