The world is a mask that hides the real world.
Thatâs what everybody suspects, though the world we see wonât let us dwell on it long.
The world has ways - more masks - of getting our attention.
The suspicion sneaks in now and again, between the cracks of everyday existenceâ¦the bird song dips, rises, dips, trails off into blue sky silence before the note that would reveal the shape of a melody that, somehow, would tie everything together, on the verge of unmasking the hidden armature that frames this sky, this tree, this bird, this quivering green leaf, jewels in a crown.â¦
As the song dies, the secret withdraws.
The tree is a mask.
The sky is a mask.
The quivering green leaf is a mask.
The song is a mask.
The singing bird is a mask.
Monday, November 28, 2005
researchers prove bees can fly
Secrets of bee flight revealed
by Helen Phillips 28 November 2005, NewScientist.com news service
Combining robotic modelling with slow-motion videos of airborne honeybees may have helped researchers explain the curious aerodynamics of bee flight.
Aeronautical engineers had previously “proven” that bees cannot fly. So Michael Dickinson, an insect flight expert and colleagues at Caltech in Pasadena, California, US, decided to investigate the forces actually at work during honeybee flight.
In 1996, Charlie Ellington at Cambridge University, UK, showed how vortices rolling along the leading edge of many insects’ wings were a vital source of lift.
Most flying insects beat their wings in large strokes – typically flapping in arcs of 145° to 165° at a frequency determined by body size – to generate aerodynamic forces sufficient for flight. But this cannot explain how a heavy insect with a short wing beat, such as a bee, generates enough lift to fly.
Exotic forces
Dickinson and his colleagues filmed hovering bees at 6000 frames per second, and plotted the unusual pattern of wing beats. The wing sweeps back in a 90˚ arc, then flips over as it returns – an incredible 230 times a second. The team made a robot to scale to measure the forces involved. See a video of a bee in a flap, here (5MB, .avi format).
It is the more exotic forces created as the wing changes direction that dominate, says Dickinson. Additional vortices are produced by the rotation of the wing. “It’s like a propeller, where the blade is rotating too,” he says. Also, the wing flaps back into its own wake, which leads to higher forces than flapping in still air. Lastly, there is another peculiar force known as “added-mass force” which peaks at the ends of each stroke and is related to acceleration as the wings’ direction changes.
The work may help engineers design rotating propellers or more stable and manoeuvrable aircraft. But “it proves bees can fly, thank God”, adds Dickinson.
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073_pnas.0506590102)
Related Articles
* Power lines may provide a haven for bees
* http://www.newscientist.com/article.ns?id=dn7910
* 26 August 2005
* Creepy crawlies to explore other worlds
* http://www.newscientist.com/article.ns?id=mg18725096.700
* 23 July 2005
* Flight of the Martian bee
* http://www.newscientist.com/article.ns?id=mg17022932.700
* 03 June 2001
Weblinks
* Michael Dickinson’s lab, Caltech
* http://www.dickinson.caltech.edu/
* Charlie Ellington, Cambridge University
* http://www.zoo.cam.ac.uk/zoostaff/elling.htm
* Proceedings of the National Academy of Sciences
* http://www.pnas.org/
by Helen Phillips 28 November 2005, NewScientist.com news service
Combining robotic modelling with slow-motion videos of airborne honeybees may have helped researchers explain the curious aerodynamics of bee flight.
Aeronautical engineers had previously “proven” that bees cannot fly. So Michael Dickinson, an insect flight expert and colleagues at Caltech in Pasadena, California, US, decided to investigate the forces actually at work during honeybee flight.
In 1996, Charlie Ellington at Cambridge University, UK, showed how vortices rolling along the leading edge of many insects’ wings were a vital source of lift.
Most flying insects beat their wings in large strokes – typically flapping in arcs of 145° to 165° at a frequency determined by body size – to generate aerodynamic forces sufficient for flight. But this cannot explain how a heavy insect with a short wing beat, such as a bee, generates enough lift to fly.
Exotic forces
Dickinson and his colleagues filmed hovering bees at 6000 frames per second, and plotted the unusual pattern of wing beats. The wing sweeps back in a 90˚ arc, then flips over as it returns – an incredible 230 times a second. The team made a robot to scale to measure the forces involved. See a video of a bee in a flap, here (5MB, .avi format).
It is the more exotic forces created as the wing changes direction that dominate, says Dickinson. Additional vortices are produced by the rotation of the wing. “It’s like a propeller, where the blade is rotating too,” he says. Also, the wing flaps back into its own wake, which leads to higher forces than flapping in still air. Lastly, there is another peculiar force known as “added-mass force” which peaks at the ends of each stroke and is related to acceleration as the wings’ direction changes.
The work may help engineers design rotating propellers or more stable and manoeuvrable aircraft. But “it proves bees can fly, thank God”, adds Dickinson.
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073_pnas.0506590102)
Related Articles
* Power lines may provide a haven for bees
* http://www.newscientist.com/article.ns?id=dn7910
* 26 August 2005
* Creepy crawlies to explore other worlds
* http://www.newscientist.com/article.ns?id=mg18725096.700
* 23 July 2005
* Flight of the Martian bee
* http://www.newscientist.com/article.ns?id=mg17022932.700
* 03 June 2001
Weblinks
* Michael Dickinson’s lab, Caltech
* http://www.dickinson.caltech.edu/
* Charlie Ellington, Cambridge University
* http://www.zoo.cam.ac.uk/zoostaff/elling.htm
* Proceedings of the National Academy of Sciences
* http://www.pnas.org/
