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76-429: Many things can fly, from animal aviators such as birds , bats and insects , to natural gliders/parachuters such as patagial animals, anemochorous seeds and ballistospores , to human inventions like aircraft ( airplanes , helicopters , airships , balloons , etc.) and rockets which may propel spacecraft and spaceplanes . The engineering aspects of flight are the purview of aerospace engineering which

152-426: A hawk will use powered flight to rise, then soar on thermals, then descend via free-fall to catch its prey. While gliding occurs independently from powered flight, it has some ecological advantages of its own as it is the simplest form of flight. Gliding is a very energy -efficient way of travelling from tree to tree. Although moving through the canopy running along the branches may be less energetically demanding,

228-454: A rocket launch , which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called astrodynamics . Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry , and others reach

304-432: A sonic boom that can be heard from the ground, and is frequently startling. The creation of this shockwave requires a significant amount of energy; because of this, supersonic flight is generally less efficient than subsonic flight at about 85% of the speed of sound. Hypersonic flight is very high speed flight where the heat generated by the compression of the air due to the motion through the air causes chemical changes to

380-403: A C-shape, flattening its abdomen and making a motion of lateral undulation in the air makes it possible for the snake to glide in the air, where it also manages to save energy compared to travel on the ground and dodge earth-bound predators. The concave wing that the snake creates in flattening itself nearly doubles the width of its body from the back of the head to the anal vent, which is close to

456-428: A drag force that is proportion to surface area and to velocity squared, and this force will partially counter the force of gravity, slowing the animal's descent to a safer speed. If this drag is oriented at an angle to the vertical, the animal's trajectory will gradually become more horizontal, and it will cover horizontal as well as vertical distance. Smaller adjustments can allow turning or other maneuvers. This can allow

532-562: A factor. In Australia, many mammals (and all mammalian gliders) possess, to some extent, prehensile tails. Globally, smaller gliding species tend to have feather-like tails and larger species have fur covered round bushy tails, but smaller animals tend to rely on parachuting rather than developing gliding membranes. The gliding membranes, patagium , are classified in the 4 groups of propatagium, digipatagium, plagiopatagium and uropatagium. These membranes consist of two tightly bounded layers of skin connected by muscles and connective tissue between

608-415: A generally poor fossil record, and a particular lack of transitional forms. Furthermore, as fossils do not preserve behavior or muscle, it can be difficult to discriminate between a poor flyer and a good glider. Insects were the first to evolve flight , approximately 350 million years ago. The developmental origin of the insect wing remains in dispute, as does the purpose prior to true flight. One suggestion

684-426: A heavier aircraft gliding at a higher airspeed will arrive at the same touchdown point in a shorter time. Air pressure acting up against an object in air is greater than the pressure above pushing down. The buoyancy, in both cases, is equal to the weight of fluid displaced - Archimedes' principle holds for air just as it does for water. A cubic meter of air at ordinary atmospheric pressure and room temperature has

760-427: A low wing loading, that is a large wing area relative to their weight, which maximizes lift. Soaring is very energetically efficient. During a free-fall with no aerodynamic forces, the object accelerates due to gravity, resulting in increasing velocity as the object descends. During parachuting, animals use the aerodynamic forces on their body to counteract the force or gravity. Any object moving through air experiences

836-411: A mass of about 1.2 kilograms, so its weight is about 12 newtons . Therefore, any 1-cubic-meter object in air is buoyed up with a force of 12 newtons. If the mass of the 1-cubic-meter object is greater than 1.2 kilograms (so that its weight is greater than 12 newtons), it falls to the ground when released. If an object of this size has a mass less than 1.2 kilograms, it rises in the air. Any object that has

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912-604: A mass that is less than the mass of an equal volume of air will rise in air - in other words, any object less dense than air will rise. Thrust-to-weight ratio is, as its name suggests, the ratio of instantaneous thrust to weight (where weight means weight at the Earth 's standard acceleration g 0 {\displaystyle g_{0}} ). It is a dimensionless parameter characteristic of rockets and other jet engines and of vehicles propelled by such engines (typically space launch vehicles and jet aircraft ). If

988-399: A means of evading predators. Animal aerial locomotion can be divided into two categories: powered and unpowered. In unpowered modes of locomotion, the animal uses aerodynamic forces exerted on the body due to wind or falling through the air. In powered flight, the animal uses muscular power to generate aerodynamic forces to climb or to maintain steady, level flight. Those who can find air that

1064-448: A parachuting animal to move from a high location on one tree to a lower location on another tree nearby. Specifically in gliding mammals, there are 3 types of gliding paths respectively being S glide, J glide, and "straight-shaped" glides where species either gain altitude post launch then descend, rapidly decrease height before gliding, and maintaining a constant angled descent. During gliding, lift plays an increased role. Like drag, lift

1140-535: A planetary or lunar surface for landing or impact. In 2018, researchers at Massachusetts Institute of Technology (MIT) managed to fly an aeroplane with no moving parts, powered by an " ionic wind" also known as electroaerodynamic thrust. Many human cultures have built devices that fly, from the earliest projectiles such as stones and spears, the boomerang in Australia , the hot air Kongming lantern , and kites . George Cayley studied flight scientifically in

1216-630: A reality in the 20th century following theoretical and practical breakthroughs by Konstantin Tsiolkovsky and Robert H. Goddard . The first orbital spaceflight was in 1957, and Yuri Gagarin was carried aboard the first crewed orbital spaceflight in 1961. There are different approaches to flight. If an object has a lower density than air, then it is buoyant and is able to float in the air without expending energy. A heavier than air craft, known as an aerodyne , includes flighted animals and insects, fixed-wing aircraft and rotorcraft . Because

1292-458: A retarding force called drag. Because lift and drag are both aerodynamic forces, the ratio of lift to drag is an indication of the aerodynamic efficiency of the airplane. The lift to drag ratio is the L/D ratio, pronounced "L over D ratio." An airplane has a high L/D ratio if it produces a large amount of lift or a small amount of drag. The lift/drag ratio is determined by dividing the lift coefficient by

1368-422: A similar purpose, and there are flying lizards which fold out their mobile ribs into a pair of flat gliding surfaces. "Flying" snakes also use mobile ribs to flatten their body into an aerodynamic shape, with a back and forth motion much the same as they use on the ground. Flying fish can glide using enlarged wing-like fins, and have been observed soaring for hundreds of meters. It is thought that this ability

1444-417: Is perpendicular to the flow direction. Aerodynamic lift results when the wing causes the surrounding air to be deflected - the air then causes a force on the wing in the opposite direction, in accordance with Newton's third law of motion . Lift is commonly associated with the wing of an aircraft , although lift is also generated by rotors on rotorcraft (which are effectively rotating wings, performing

1520-465: Is a very successful strategy once evolved. Bats , after rodents , have the most species of any mammalian order, about 20% of all mammalian species . Birds have the most species of any class of terrestrial vertebrates . Finally, insects (most of which fly at some point in their life cycle) have more species than all other animal groups combined. The evolution of flight is one of the most striking and demanding in animal evolution, and has attracted

1596-430: Is considerably more contentious, with various scientists supporting either a "trees down" origin (in which an arboreal ancestor evolved gliding, then flight) or a " ground up " origin (in which a fast-running terrestrial ancestor used wings for a speed boost and to help catch prey). It may also have been a non-linear process, as several non-avian dinosaurs seem to have independently acquired powered flight. Bats are

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1672-651: Is considered mildly venomous, with a few confirmed cases of medically significant envenomation. Chrysopelea species are not included in lists of snakes considered venomous to people. Chrysopelea is one of five genera belonging to the vine snake subfamily Ahaetuliinae , of which Chrysopelea is most closely related to Dendrelaphis , as shown in the cladogram below: Ahaetulla Proahaetulla Dryophiops Dendrelaphis Chrysopelea paradisi Chrysopelea ornata Chrysopelea pelias Chrysopelea taprobanica There are five recognized species of flying snake, found from western India to

1748-404: Is equal to the drag D divided by the (density r times half the velocity V squared times the reference area A). [Cd = D / (A * .5 * r * V^2)] Lift-to-drag ratios for practical aircraft vary from about 4:1 for vehicles and birds with relatively short wings, up to 60:1 or more for vehicles with very long wings, such as gliders. A greater angle of attack relative to the forward movement also increases

1824-493: Is harder to obtain as animal size increases. Larger animals need to glide from much higher heights and longer distances to make it energetically beneficial. Gliding is also very suitable for predator avoidance, allowing for controlled targeted landings to safer areas. In contrast to flight, gliding has evolved independently many times (more than a dozen times among extant vertebrates); however these groups have not radiated nearly as much as have groups of flying animals. Worldwide,

1900-430: Is proportional to velocity squared. Gliding animals will typically leap or drop from high locations such as trees, just as in parachuting, and as gravitational acceleration increases their speed, the aerodynamic forces also increase. Because the animal can utilize lift and drag to generate greater aerodynamic force, it can glide at a shallower angle than parachuting animals, allowing it to cover greater horizontal distance in

1976-449: Is pushed in the direction opposite to flight. This can be done in several ways including by the spinning blades of a propeller , or a rotating fan pushing air out from the back of a jet engine , or by ejecting hot gases from a rocket engine . The forward thrust is proportional to the mass of the airstream multiplied by the difference in velocity of the airstream. Reverse thrust can be generated to aid braking after landing by reversing

2052-472: Is rising faster than they are falling can gain altitude by soaring . These modes of locomotion typically require an animal start from a raised location, converting that potential energy into kinetic energy and using aerodynamic forces to control trajectory and angle of descent. Energy is continually lost to drag without being replaced, thus these methods of locomotion have limited range and duration. Powered flight has evolved at least four times: first in

2128-415: Is subdivided into aeronautics , the study of vehicles that travel through the atmosphere, and astronautics , the study of vehicles that travel through space, and ballistics , the study of the flight of projectiles. Humans have managed to construct lighter-than-air vehicles that raise off the ground and fly, due to their buoyancy in the air. An aerostat is a system that remains aloft primarily through

2204-581: Is termed soaring . However most other birds and all powered aircraft need a source of propulsion to climb. This is termed powered flight. The only groups of living things that use powered flight are birds , insects , and bats , while many groups have evolved gliding. The extinct pterosaurs , an order of reptiles contemporaneous with the dinosaurs , were also very successful flying animals, and there were apparently some flying dinosaurs (see Flying and gliding animals#Non-avian dinosaurs ). Each of these groups' wings evolved independently , with insects

2280-446: Is that wings initially evolved from tracheal gill structures and were used to catch the wind for small insects that live on the surface of the water, while another is that they evolved from paranotal lobes or leg structures and gradually progressed from parachuting, to gliding, to flight for originally arboreal insects. Pterosaurs were the next to evolve flight, approximately 228 million years ago. These reptiles were close relatives of

2356-491: Is the use of space technology to achieve the flight of spacecraft into and through outer space . Examples include ballistic missiles , orbital spaceflight , etc. Spaceflight is used in space exploration , and also in commercial activities like space tourism and satellite telecommunications . Additional non-commercial uses of spaceflight include space observatories , reconnaissance satellites and other Earth observation satellites . A spaceflight typically begins with

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2432-408: Is the use of a machine to fly. These machines include aircraft such as airplanes , gliders , helicopters , autogyros , airships , balloons , ornithopters as well as spacecraft . Gliders are capable of unpowered flight. Another form of mechanical flight is para-sailing, where a parachute-like object is pulled by a boat. In an airplane, lift is created by the wings; the shape of the wings of

2508-457: The Cenozoic era. The non-flying penguins have wings adapted for use under water and use the same wing movements for swimming that most other birds use for flight. Most small flightless birds are native to small islands, and lead a lifestyle where flight would offer little advantage. Among living animals that fly, the wandering albatross has the greatest wingspan, up to 3.5 meters (11 feet);

2584-501: The University of Chicago , scientists discovered a negative correlation between size and gliding ability, in which smaller flying snakes were able to glide longer distances horizontally. According to research performed by Professor Jake Socha at Virginia Tech , these snakes can change the shape of their body in order to produce aerodynamic forces so they can glide in the air. Scientists are hopeful that this research will lead to

2660-588: The great bustard has the greatest weight, topping at 21 kilograms (46 pounds). Most species of insects can fly as adults. Insect flight makes use of either of two basic aerodynamic models: creating a leading edge vortex, found in most insects, and using clap and fling , found in very small insects such as thrips . Many species of spiders , spider mites and lepidoptera use a technique called ballooning to ride air currents such as thermals , by exposing their gossamer threads which gets lifted by wind and atmospheric electric fields . Mechanical flight

2736-430: The insects , then in pterosaurs , next in birds , and last in bats . Studies on theropod dinosaurs do suggest multiple (at least 3) independent acquisitions of powered flight however, and a recent study proposes independent acquisitions amidst the different bat clades as well. Powered flight uses muscles to generate aerodynamic force , which allows the animal to produce lift and thrust. The animal may ascend without

2812-482: The thrust-to-weight ratio is greater than the local gravity strength (expressed in g s), then flight can occur without any forward motion or any aerodynamic lift being required. If the thrust-to-weight ratio times the lift-to-drag ratio is greater than local gravity then takeoff using aerodynamic lift is possible. Flight dynamics is the science of air and space vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are

2888-417: The aid of rising air. Ballooning and soaring are not powered by muscle, but rather by external aerodynamic sources of energy: the wind and rising thermals , respectively. Both can continue as long as the source of external power is present. Soaring is typically only seen in species capable of powered flight, as it requires extremely large wings. Many species will use multiple of these modes at various times;

2964-459: The air at a constant speed moves its wings up and down (usually with some fore-aft movement as well). Because the animal is in motion, there is some airflow relative to its body which, combined with the velocity of its wings, generates a faster airflow moving over the wing. This will generate lift force vector pointing forwards and upwards, and a drag force vector pointing rearwards and upwards. The upwards components of these counteract gravity, keeping

3040-896: The air to overcome the drag associated with lift all takes energy. Different objects and creatures capable of flight vary in the efficiency of their muscles, motors and how well this translates into forward thrust. Propulsive efficiency determines how much energy vehicles generate from a unit of fuel. The range that powered flight articles can achieve is ultimately limited by their drag, as well as how much energy they can store on board and how efficiently they can turn that energy into propulsion. Flying and gliding animals A number of animals are capable of aerial locomotion, either by powered flight or by gliding . This trait has appeared by evolution many times, without any single common ancestor. Flight has evolved at least four times in separate animals: insects , pterosaurs , birds , and bats . Gliding has evolved on many more occasions. Usually

3116-612: The air, which due to its shape and angle deflects the air. For sustained straight and level flight, lift must be equal and opposite to weight. In general, long narrow wings are able deflect a large amount of air at a slow speed, whereas smaller wings need a higher forward speed to deflect an equivalent amount of air and thus generate an equivalent amount of lift. Large cargo aircraft tend to use longer wings with higher angles of attack, whereas supersonic aircraft tend to have short wings and rely heavily on high forward speed to generate lift. However, this lift (deflection) process inevitably causes

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3192-477: The air. Hypersonic flight is achieved primarily by reentering spacecraft such as the Space Shuttle and Soyuz . Some things generate little or no lift and move only or mostly under the action of momentum, gravity, air drag and in some cases thrust. This is termed ballistic flight . Examples include balls , arrows , bullets , fireworks etc. Essentially an extreme form of ballistic flight, spaceflight

3268-422: The airplane are designed specially for the type of flight desired. There are different types of wings: tempered, semi-tempered, sweptback, rectangular and elliptical. An aircraft wing is sometimes called an airfoil , which is a device that creates lift when air flows across it. Supersonic flight is flight faster than the speed of sound . Supersonic flight is associated with the formation of shock waves that form

3344-601: The angles of rotation in three dimensions about the vehicle's center of mass , known as pitch , roll and yaw (See Tait-Bryan rotations for an explanation). The control of these dimensions can involve a horizontal stabilizer (i.e. "a tail"), ailerons and other movable aerodynamic devices which control angular stability i.e. flight attitude (which in turn affects altitude , heading ). Wings are often angled slightly upwards- they have "positive dihedral angle " which gives inherent roll stabilization. To create thrust so as to be able to gain height, and to push through

3420-466: The attention of many prominent scientists and generated many theories. Additionally, because flying animals tend to be small and have a low mass (both of which increase the surface-area-to-mass ratio), they tend to fossilize infrequently and poorly compared to the larger, heavier-boned terrestrial species they share habitat with. Fossils of flying animals tend to be confined to exceptional fossil deposits formed under highly specific circumstances, resulting in

3496-475: The body in the air, while the forward component provides thrust to counteract both the drag from the wing and from the body as a whole. Pterosaur flight likely worked in a similar manner, though no living pterosaurs remain for study. Insect flight is considerably different, due to their small size, rigid wings, and other anatomical differences. Turbulence and vortices play a much larger role in insect flight, making it even more complex and difficult to study than

3572-447: The car stable on the road. For a solid object moving through a fluid, the drag is the component of the net aerodynamic or hydrodynamic force acting opposite to the direction of the movement. Therefore, drag opposes the motion of the object, and in a powered vehicle it must be overcome by thrust . The process which creates lift also causes some drag. Aerodynamic lift is created by the motion of an aerodynamic object (wing) through

3648-485: The craft is heavier than air, it must generate lift to overcome its weight . The wind resistance caused by the craft moving through the air is called drag and is overcome by propulsive thrust except in the case of gliding . Some vehicles also use thrust in the place of lift; for example rockets and Harrier jump jets . Forces relevant to flight are These forces must be balanced for stable flight to occur. A fixed-wing aircraft generates forward thrust when air

3724-722: The design of robots that can glide in the air from one place to another. Their range is in Southeast Asia (the mainland ( Vietnam , Cambodia , Thailand , Myanmar , and Laos ), Indonesia , and the Philippines ), southernmost China , India , and Sri Lanka . Chrysopelea are diurnal , which means they hunt during the day. Their diets are variable depending on their range, but they are known to eat lizards , rodents , frogs , birds, and bats . They are mildly venomous snakes, but their tiny, fixed rear fangs make them dangerous only to their small prey. The genus

3800-475: The development is to aid canopy animals in getting from tree to tree, although there are other possibilities. Gliding, in particular, has evolved among rainforest animals, especially in the rainforests in Asia (most especially Borneo ) where the trees are tall and widely spaced. Several species of aquatic animals , and a few amphibians and reptiles have also evolved this gliding flight ability, typically as

3876-487: The dinosaurs, and reached enormous sizes, with some of the last forms being the largest flying animals ever to inhabit the Earth, having wingspans of over 9.1 m (30 ft). However, they spanned a large range of sizes, down to a 250 mm (10 in) wingspan in Nemicolopterus . Birds have an extensive fossil record, along with many forms documenting both their evolution from small theropod dinosaurs and

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3952-628: The distribution of gliding animals is uneven, as most inhabit rain forests in Southeast Asia . (Despite seemingly suitable rain forest habitats, few gliders are found in India or New Guinea and none in Madagascar.) Additionally, a variety of gliding vertebrates are found in Africa , a family of hylids ( flying frogs ) lives in South America and several species of gliding squirrels are found in

4028-442: The drag coefficient, CL/CD. The lift coefficient Cl is equal to the lift L divided by the (density r times half the velocity V squared times the wing area A). [Cl = L / (A * .5 * r * V^2)] The lift coefficient is also affected by the compressibility of the air, which is much greater at higher speeds, so velocity V is not a linear function. Compressibility is also affected by the shape of the aircraft surfaces. The drag coefficient Cd

4104-562: The end of the snake's tail, causing the cross section of the snake's body to resemble the cross section of a frisbee or flying disc . When a flying disc spins in the air, the designed cross sectional concavity causes increased air pressure under the centre of the disc, causing lift for the disc to fly , and the snake continuously moves in lateral undulation to create the same effect of increased air pressure underneath its arched body to glide. Flying snakes are able to glide better than flying squirrels and other gliding animals , despite

4180-411: The extent of deflection, and thus generates extra lift. However a greater angle of attack also generates extra drag. Lift/drag ratio also determines the glide ratio and gliding range. Since the glide ratio is based only on the relationship of the aerodynamics forces acting on the aircraft, aircraft weight will not affect it. The only effect weight has is to vary the time that the aircraft will glide for –

4256-399: The faster transition between trees allows for greater foraging rates in a particular patch. Glide ratios can be dependent on size and current behavior. Higher foraging rates are supported by low glide ratios as smaller foraging patches require less gliding time over shorter distances and greater amounts of food can be acquired in a shorter time period. Low ratios are not as energy efficient as

4332-634: The first animal group to evolve flight. The wings of the flying vertebrate groups are all based on the forelimbs, but differ significantly in structure; insect wings are hypothesized to be highly modified versions of structures that form gills in most other groups of arthropods . Bats are the only mammals capable of sustaining level flight (see bat flight ). However, there are several gliding mammals which are able to glide from tree to tree using fleshy membranes between their limbs; some can travel hundreds of meters in this way with very little loss in height. Flying frogs use greatly enlarged webbed feet for

4408-458: The first half of the 19th century, and in the second half of the 19th century Otto Lilienthal made over 200 gliding flights and was also one of the first to understand flight scientifically. His work was replicated and extended by the Wright brothers who made gliding flights and finally the first controlled and extended, manned powered flights. Spaceflight, particularly human spaceflight became

4484-432: The flight of vertebrates. There are two basic aerodynamic models of insect flight. Most insects use a method that creates a spiralling leading edge vortex . Some very small insects use the fling-and-clap or Weis-Fogh mechanism in which the wings clap together above the insect's body and then fling apart. As they fling open, the air gets sucked in and creates a vortex over each wing. This bound vortex then moves across

4560-423: The fore and hind limbs. Powered flight has evolved unambiguously only four times— birds , bats , pterosaurs , and insects (though see above for possible independent acquisitions within bird and bat groups). In contrast to gliding, which has evolved more frequently but typically gives rise to only a handful of species, all three extant groups of powered flyers have a huge number of species, suggesting that flight

4636-662: The forests of northern Asia and North America. Various factors produce these disparities. In the forests of Southeast Asia, the dominant canopy trees (usually dipterocarps ) are taller than the canopy trees of the other forests. Forest structure and distance between trees are influential in the development of gliding within varying species. A higher start provides a competitive advantage of further glides and farther travel. Gliding predators may more efficiently search for prey. The lower abundance of insect and small vertebrate prey for carnivorous animals (such as lizards) in Asian forests may be

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4712-420: The higher ratios, but an argument made is that many gliding animals eat low energy foods such as leaves and are restricted to gliding because of this, whereas flying animals eat more high energy foods such as fruits , nectar , and insects. Mammals tend to rely on lower glide ratios to increase the amount of time foraging for lower energy food. An equilibrium glide, achieving a constant airspeed and glide angle,

4788-636: The lack of limbs, wings, or any other wing-like projections, gliding as far as 100 meters through the forests and jungles they inhabit. Their destination is mostly predicted by ballistics ; however, they can exercise some in-flight attitude control by "slithering" in the air. Their ability to glide has been an object of interest for physicists and the United States Department of Defense in recent years, and studies continue to be made on what other, more subtle, factors contribute to their gliding. According to recent research conducted by

4864-496: The level of inclination it wishes to use to control its glide path, and selects a desired landing area. Once it decides on a destination, it propels itself by thrusting its body up and away from the tree, sucking in its abdomen and flaring out its ribs to turn its body into a "pseudo concave wing", all the while making a continual serpentine motion of lateral undulation parallel to the ground to stabilise its direction in midair in order to land safely. The combination of forming

4940-417: The most recent to evolve (about 60 million years ago), most likely from a fluttering ancestor, though their poor fossil record has hindered more detailed study. Only a few animals are known to have specialised in soaring : the larger of the extinct pterosaurs , and some large birds. Powered flight is very energetically expensive for large animals, but for soaring their size is an advantage, as it allows them

5016-511: The numerous bird-like forms of theropod which did not survive the mass extinction at the end of the Cretaceous. Indeed, Archaeopteryx is arguably the most famous transitional fossil in the world, both due to its mix of reptilian and avian anatomy and the luck of being discovered only two years after Darwin's publication of On the Origin of Species . However, the ecology of this transition

5092-437: The objects that generate lift (wings) and thrust (engine or propeller) are separate and the wings remain fixed, flying animals use their wings to generate both lift and thrust by moving them relative to the body. This has made the flight of organisms considerably harder to understand than that of vehicles, as it involves varying speeds, angles, orientations, areas, and flow patterns over the wings. A bird or bat flying through

5168-443: The only freely flying mammals . A few other mammals can glide or parachute; the best known are flying squirrels and flying lemurs . Chrysopelea Chrysopelea , commonly known as the flying snake or gliding snake , is a genus of snakes that belongs to the family Colubridae . They are found in Southeast Asia , and are known for their ability to glide between trees. Flying snakes are mildly venomous , though

5244-410: The pitch of variable-pitch propeller blades, or using a thrust reverser on a jet engine. Rotary wing aircraft and thrust vectoring V/STOL aircraft use engine thrust to support the weight of the aircraft, and vector sum of this thrust fore and aft to control forward speed. In the context of an air flow relative to a flying body, the lift force is the component of the aerodynamic force that

5320-427: The same function without requiring that the aircraft move forward through the air). While common meanings of the word " lift " suggest that lift opposes gravity, aerodynamic lift can be in any direction. When an aircraft is cruising for example, lift does oppose gravity, but lift occurs at an angle when climbing, descending or banking. On high-speed cars, the lift force is directed downwards (called "down-force") to keep

5396-572: The same loss of altitude, and reach trees further away. Successful flights for gliding animals are achieved through 5 steps: preparation, launch, glide, braking, and landing. Gliding species are better able to control themselves mid-air, with the tail acting as a rudder, making it capable to pull off banking movements or U-turns during flight. During landing, arboreal mammals will extend their fore and hind limbs in front of itself to brace for landing and to trap air in order to maximize air resistance and lower impact speed. Unlike most air vehicles, in which

5472-480: The surrounding air mass to effect a lifting force. By contrast, aerodynes primarily use aerodynamic lift , which requires the lateral movement of at least some part of the aircraft through the surrounding air mass. Some things that fly do not generate propulsive thrust through the air, for example, the flying squirrel . This is termed gliding . Some other things can exploit rising air to climb such as raptors (when gliding) and man-made sailplane gliders . This

5548-453: The use of buoyancy to give an aircraft the same overall density as air. Aerostats include free balloons , airships , and moored balloons . An aerostat's main structural component is its envelope , a lightweight skin that encloses a volume of lifting gas to provide buoyancy , to which other components are attached. Aerostats are so named because they use "aerostatic" lift, a buoyant force that does not require lateral movement through

5624-414: The venom is dangerous only to their small prey. There are five species within the genus. Chrysopelea climbs using ridge scales along its underside, pushing against the rough bark of tree trunks, allowing it to move vertically up a tree. Upon reaching the end of a branch, the snake continues moving until its tail dangles from the end of the branch. It then makes a J-shape bend, leans forward to select

5700-600: The wing and, in the clap, acts as the starting vortex for the other wing. Circulation and lift are increased, at the price of wear and tear on the wings. Gliding has evolved independently in two families of tree frogs, the Old World Rhacophoridae and the New World Hylidae. Within each lineage there are a range of gliding abilities from non-gliding, to parachuting, to full gliding. Several lizards and snakes are capable of gliding: Bats are

5776-487: Was chosen by natural selection because it was an effective means of escape from underwater predators. The longest recorded flight of a flying fish was 45 seconds. Most birds fly ( see bird flight ), with some exceptions. The largest birds, the ostrich and the emu , are earthbound flightless birds , as were the now-extinct dodos and the Phorusrhacids , which were the dominant predators of South America in

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