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Getting back into my stride the km run to the second TP is great fun so I extend into the sector. Turning for home with a km final leg I was getting low at 8,ft and desperately in need of the 12kt thermal that took me back to 14,ft cloudbase. One more climb needed to get home, and that happens km later in a dust devil. The final glide is a bone shaking Vne run to race across the airfield and pull up to ft. The average speeds in Africa are high and the winners are making over kph. Gliding with a Difference. New Tempe Weather Cloud Height 0 ft.

Soaring into the Heavens

Wind Speed knots. Powered flight has evolved unambiguously only four times— birds , bats , pterosaurs , and insects.

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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 is a very successful strategy once evolved. 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 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 a generally poor fossil record, and a particular lack of transitional forms.


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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 million years ago. The developmental origin of the insect wing remains in dispute, as does the purpose prior to true flight. One suggestion is that wings initially were used to catch the wind for small insects that live on the surface of the water, while another is that they functioned in parachuting, then gliding, then flight for originally arboreal insects. Pterosaurs were the next to evolve flight, approximately million years ago.

These reptiles were close relatives of the dinosaurs and sometimes mistakenly considered dinosaurs by laymen , 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. Birds have an extensive fossil record, along with many forms documenting both their evolution from small theropod dinosaurs and the numerous bird-like forms of theropod which did not survive the mass extinction at the end of the Cretaceous.


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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 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.

Bats are the most recent to evolve about 60 million years ago , most likely from a fluttering ancestor, [5] 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 a low wing loading, that is a large wing areas relative to their weight, which maximizes lift.

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 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 a parachuting animal to move from a high location on one tree to a lower location on another tree nearby. During gliding, lift plays an increased role.

SOARING WINGS

Like drag, lift 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 the same loss of altitude, and reach trees further away.

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 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 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 the flight of vertebrates.

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Most insects use a method that creates a spiralling leading edge vortex. As they fling open, the air gets sucked in and creates a vortex over each wing. This bound vortex then moves across 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.

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Bats are the only mammal with flapping or powered flight [ citation needed ]. A few other mammals glide or parachute; the best known are flying squirrels and flying lemurs. The runway is fairly long but the tug pilot still has to choose the gap between the trees to climb out through as ft ground level and 30 degree temperatures make their mark. Getting up to start height of 11,ft is easier once the thermals become more established. Getting back into my stride the km run to the second TP is great fun so I extend into the sector.

Turning for home with a km final leg I was getting low at 8,ft and desperately in need of the 12kt thermal that took me back to 14,ft cloudbase. One more climb needed to get home, and that happens km later in a dust devil. The final glide is a bone shaking Vne run to race across the airfield and pull up to ft. The average speeds in Africa are high and the winners are making over kph. Gliding with a Difference.