The instant the sail opened into the wind, a huge force was generated and the column was raised to the vertical in a mere 40 seconds.' 'We were absolutely stunned,' Gharib says. The kite lifted the column clean off the ground. The idea was that as one end of the column rose, the base would roll across the ground on a trolley.Įarlier this year, the team put Clemmons's unlikely theory to the test, using a 40-square-metre rectangular nylon sail. So they rigged up a tent-shaped scaffold directly above the tip of the horizontal column, with pulleys suspended from the scaffold's apex. The key was to use a pulley system that would magnify the applied force. Even a modest force, if sustained over a long time, would do. Their initial calculations and scale-model wind-tunnel experiments convinced them they wouldn't need a strong wind to lift the 33.5-tonne column. Gharib and Graff set themselves the task of raising a 4.5-metre stone column from horizontal to vertical, using no source of energy except the wind. And since he needed a summer project for his student Emilio Graff, investigating the possibility of using kites as heavy lifters seemed like a good idea. The possibility certainly existed that it was a kite/ he says. The object in the sky apparently had wings far too short and wide for a bird. He too was puzzled by the picture that had sparked Clemmons's interest. 'Coming from Iran, I have a keen interest in Middle Eastern science/ he says. Intrigued, Clemmons contacted Morteza Gharib, aeronautics professor at the California Institute of Technology. She wondered if perhaps the bird was actually a giant kite, and the men were using it to lift a heavy object. They were holding what looked like ropes that led, via some kina of mechanical system, to a giant bird in the sky. While perusing a book on the monuments of Egypt, she noticed a hieroglyph that showed a row of men standing in odd postures. Now a Californian software consultant called Maureen Clemmons has suggested that kites might have been involved. But there is no evidence to back this up. The conventional picture is that tens of thousands of slaves dragged stones on sledges. The pyramids of Egypt were built more than three thousand years ago, and no one knows how. Marcus Chown reckons the answer could be 'hanging in the air'. Overall, currently, Black kites are classified as Least Concern (LC) on the IUCN Red List and their numbers today are stable.No one knows exactly how the pyramids were built. In Europe, the breeding population is estimated to number 186,000-254,000 breeding pairs, equating to 372,000-507,000 mature individuals. The eagle-owl freely picks off kites of any age from the nestling stage to adulthood and was noted to precipitously decrease kite breeding success when nesting within kilometers of the kites in the Italian Alps.Īccording to the IUCN Red List, the total Black kite population size is around 4,000,000-5,700,000 mature individuals. However, they do have a single serious predator: the Eurasian eagle-owl. As a large raptorial bird, the Black kite has few natural predators. They are also a major nuisance at some airports, where their size makes them a significant birdstrike hazard. Their habit of swooping to pick up dead rodents or other roadkill leads to collisions with vehicles. These birds also often perch on electric wires and are frequent victims of electrocution. The main threats to Black kites include poisoning, shooting, and the pollution of water by chemicals. Black kites are able to breed after their second year. After 50 days, they begin to move to branches next to the nest. The nestlings are able to stand on their legs after 17-19 days and begin flapping their wings after 27-31 days. Body feathers begin to appear after 18 to 22 days. Newly hatched chicks have a sepia down on the back and black around the eye and buff on the head, neck, and underparts. The incubation period varies from 30-34 days. The typical clutch size is 2 or sometimes 3 eggs. Both the male and female take part in nest building, incubation, and care of chicks. They are made from sticks and twigs and may sometimes be decorated with bright materials such as white plastic. The nests are built on tree branches, cliff ledges, or buildings and may be reused in subsequent years. Black kites nest singly or in loose groups. In India, it begins in winter (mainly January and February), while European birds breed in summer. The time of breeding varies with location. Black kites are monogamous and form strong pair bonds that may last for life.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |