Neuron Ring's Blog

Have you ever noticed the sky when flock birds migrate from one place to another?
Yes,of course?  Had you ever think the reason for that.

 

There is a strong reason and mystery behind it.
Before getting that revealed let me define two technical words.
Upwash: The term upwash is used to refer to regions around an aircraft or airfoil where the air is moving in the opposite direction to downwash.The wingtip vortices induce an upwash outside the wingspan of an aircraft or airfoil balancing downwash produced by upper wing surfaces. Birds which migrate make use of this upwash and they form the V shape and make a easy fly.

Downwash: The meaning used most often by non-engineers, refers to the forcing of air downward during the creation of lift. This usage is most common with regard to helicopters where the effect is most dramatic.Now in terms of aerodynamics: The downwash immediately behind a wing is a consequence of the wing vortex system. This downwash is experienced by a horizontal tail placed in the flow behind a wing.

What Researchers Say?

The researchers found that there are 2 strong reasons behind this flying habit of birds. They are

1.The shape of the formation reduces the drag force that each bird experiences compared to if it were flying alone. Tthe decrease in drag occurs thanks to the formation of wingtip vortices.2.The second strong reason holds for the V-Formation flying is that this orientation allows the birds to communicate more easily.
This V-formation provides the birds with good visual contact of each other to keep the flock together. This eye before communication minimizes the possibility of losing birds along the way as the formation crosses vast distances during migration.These kind of groups of birds will fly in a large V-shape with one bird in the lead and other birds trailing behind in two lines.A bird which is flying in one of these upwash regions gains free lift so that it can fly at a lower angle of attack. (click here to know more)

Since the angle of attack is reduced, the induced drag is lowered so that the bird does not need to flap its wings so hard or as often to generate the thrust needed for forward flight. This obviously proves that bird’s muscle do not work harder. So its heart rate drops.

Yes, absolutely the bird does get not tired and can fly longer. 

Analysis proves: A flock of 25 birds in V-Formation can fly as much as 71% further than a single bird using the same amount of energy.

Do all Birds share drag force equally?

Because of spacing themselves apart in a proper distance, these birds can achieve optimum positions that reduce the drag of every bird in the V-Formation. But, not all birds benefit equally.

The first bird has to work the hardest since it flies into undisturbed air. The upwash this bird creates improves the aerodynamics of the two behind it, and these two further improve conditions for the next two birds in line.Although this kind of fly benefit all the birds, the bird which is in the lead position has to work harder. At the time when the bird in lead position this bird tires, it will move out of the lead position and fall back into one of the lines of the “V”. To substitute this another bird from further back will rapidly move forward to take the leading position and maintain the V-Formation.The two birds in the trailing positions of V also tire more rapidly than those in the middle. The birds in trailing positions are also rotated frequently to share the tiredness throughout the flock.This kind of self management gives all birds in leading the flock and also they can relax by being in the middle of the flock.

Who taught them?

This V-Fly sense of teamwork comes by nature since the young birds in the flock realizes the ease of flying in the middle or V-Formation than flying alone.

This entry was posted on Thursday, July 9th, 2009 at 4:02 pm and is filed under Space Science. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.