Mystery of Bumblebee Flight
Have you ever heard that the bumblebee flight is impossible, according to the aerodynamic theory? Is this just another urban myth or a reality?
In 1930 the scientists and engineers from the Gottingen University (Sweden) concluded that this insect should not be able to get of the ground.
Another team, this time from the Cambridge University (UK), tried to solve the mystery of the bumblebee flight with the help of a robot insect. In 1996 Charles Ellington’s team found that extra lift is generated during a downstroke through a vortex that travels along the leading edge of the insect’s wings.
Michael Dickinson and James Birch ,of the University of California, Berkeley concluded that this explanation is to simple. They studied a scaled-up robotic fruit fly, flapping in a tank of mineral oil to simulate the viscosity of the air as a tiny fly would experience. They concluded that the attachment of the vortex throughout the stroke can not be completely proved by Charles Ellington theory.
Watch here in slow motion, a Bumble Bee flight:
So how does a bumblebee fly?
“Downwash” might be responsible for the vortex remaining attached to the wing to maintain lift. “We still don’t know for sure,” said Prof Dickinson.
Bumblebees fly very differently than planes. While air flows smoothly over an aircraft wing or rotor blade, bees move their wings at an acute angle to the air, creating vortices that curl around the wing. Bees can maintain flight by rapidly moving their wings.
Why should we study the bumblebee flight? Are we going to duplicate the nature and build machines that will be as good as this small marvels?
Dr. Jim Usherwood, from the Royal Veterinary College has a different opinion. He concluded that scientists should, in this instance, be more hesitant before imitating nature.
Do bumblebees fly or vibrate?
Dr. Usherwood believes the reason that flying creatures don’t look like man made machines is all to do with the need to flap. “Animals’ wings, unlike propellers, have to keep stopping and starting in order produce lift (animals have forgotten to invent propellers, just as they forgot wheels),” he explains. “Think of vigorous waving, or perhaps exuberant rattling of a cocktail shaker – this takes a fair amount of power to overcome inertia. So, the idea is that both wing shape and how wings are used can be understood better if the effort of flapping is remembered, which explains why vultures don’t look like gliders, and most winged creatures, from insects to pigeons, fly so inefficiently.”
On the other hand just think about the amazing physical performance of this humble insects; bees beat their wings approximately 200 times a second, which is 10-20x as fast as nerve impulses can fire. They achieve this because their thorax muscles don’t expand and contract on each nerve firing, but rather vibrate like someone plucking a rubber-band.
What kind of materials are we going to need in order to equal this performance? How hard it will be to replicate the bumblebee flight?
There is lots of interest in making MAVs/UAVs (micro/unmanned air vehicles) that flap, which may present all sorts of advantages in terms of maneuverability, speed and so on. However, there is a tendency to presume that biology is efficient, and I would say that, even at very small sizes, if you want to hover efficiently, be a helicopter not a flapper…”
“The problem of studying how air moves around flying animals has attracted attention from zoologists, aeronautical engineers and computational fluid dynamicists, but has remained generally unresolved.” concluded George Lauder, of Harvard University.
Still confused? Watch this video where the Bumble Bee themselves are revealing the secret of their flight!