Open Eye: Open View: BBC Learning Zone - No longer strictly for the birds
Simon Newton launches some of this month's highlights
Thursday 04 March 1999
This weekend's open.saturday programme Flying Machines shows that, although flying is no longer strictly for the birds, nobody does it better. Even pigeons can achieve vertical take-off and briefly hover. Swans need a high take-off speed, and land with some difficulty. But both are more graceful performers in the air than any flying machine.
This programme reveals secrets of bird navigation and the dramatic effect of frosted contact lenses on a sparrow's sense of direction. From Cranfield airfield, presenter Kate Bellingham explores aspects of flight from the Wright Brothers 1903 triumph at Kittyhawk to the skylab and the shuttle. In less than a century, flying machines have moved from contraptions of wood and string to precision engineered rockets controlled by lasers.
Birds use wings to give lift and propulsion but the flapping wing has never been successfully adapted by humans. Gliding is perhaps the closest we can get to bird flight, and the glider pilot needs to understand the maths of flight. The mass and angle of glide are critical. The pilot needs to read the cumulus cloud formations like a road map to locate the thermals which enable the glider to gain height.
But Flying Machines confirms that flying is much more than hot air. With help from Newton's laws of motion and an explanation of aerofoil angles, Kate Bellingham explains why jumbo jets are never likely to have flapping wings.
In a rare interview with the British father of the jet engine Sir Frank Whittle, this open.saturday looks at the single major innovation in this century's development of powered flight. In the search for planes that would fly both higher and faster, Whittle realised that the piston engine would simply not perform at altitudes where the air became thinner.
Any child knows what happens when they let go of a balloon filled with air. Using the same principle and a machine with a single moving part - a compressor-turbine - Whittle revolutionised the future of air travel.
Flying Machines also includes rare footage of German experiments with jet engines at the close of the war. Using an almost brief-case-sized engine, the tiny Messerschmidt jet could fly up to four times faster than a Mustang. However, its fuel ran out after seven minutes, with the pilot having to glide back to base. The prototypes managed to kill more German test pilots in accidents than Allied pilots accounted for in combat.
Modern travel in jet aircraft has actually become remarkably safe. Statistics show that passengers are 19 times more likely to die driving to the airport. This programme looks at Helen Muir's research into aircraft safety at Cranfield. Although most people survive air crashes, smoke and fire remain the greatest threats to life. Professor Muir outlines her experiments involving volunteers escaping from a mock fuselage. She reveals the startling effect on individual behaviour of the promise of five pound notes to the first people down the chute.
Yet accidents do happen, as in the mysterious crashes of two Lockheed Electras in 1959, when their wings separated from the fuselages. Flying Machines uses compelling footage of the famous Tacoma Bridge disaster to illustrate the cause. The design of both the bridge and the aircraft had not taken sufficient account of the basic principle of resonance.
But the sky is not the limit. Breaking free of the earth's protective layer into space makes unique demands on the human body. Jet pilots can already experience up to 10G and the pilots shown spinning in a centrifuge in an indoor "test flight" at Farnborough develop tunnel vision and loss of consciousness.
Beyond the earth's atmosphere humans need to carry their own environment with them in the form of a space suit. Using a mix of state-of-the-art materials it is designed for lightness and resilience: it is six times stronger than sprung steel and can stop a bullet, so it is unlikely to tear when repairing the outside of Skylab. This open.saturday looks at the technology of the space suit and why, if it was off the peg, it would cost around pounds 6 million.
With fuel taking up 90% of a rocket's weight, solving the power problem is the holy grail of space flight. Scientists are now working on sources of power that will knock current space technology out of orbit.
One method discussed in Flying Machines is the beautiful notion of "space sailing" with a spacecraft "blown" by a laser beam aimed from the moon. Certainly, laser power seems to be the best alternative to a heavy fuel load. A laser could potentially drive a space ship along a highway of light all the way to its ultimate destination.
Einstein dreamed of riding on a beam of light and produced the theory of relativity. This edition of open.saturday contains a cartoon Einstein who produces one of the clearest-ever explanations of his theory. Technically, it is already feasible to "teleport" objects as they do in Star Trek.
Scientist John Gribbin observes that "there is nothing in the laws of physics that says time travel is impossible."
However, it does seem that the journey into the future may prove easier than travelling back again. Birds fly, humans fly and, since Einstein, time really flies.
Flying Machines, open.saturday, BBC2 9.15am Saturday 6 March
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