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Swifts can stay in flight in very windy conditions without breaking a sweat – how?

Swifts are amazing birds. They stay in the air for prolonged periods of time. They sleep and eat in flight, only coming down for some time when it is necessary, for example, when they have offspring to take care of. Swifts are flying even when the wind is strong and stormy conditions ground pretty much all other birds. How can they do that?

Swifts are the best flyers of animal kingdom – sometimes they stay in flight for 10 months. Image credit: Alan Manson via Wikimedia(CC BY-SA 2.0)

Swifts fly to high altitudes and then slowly glide down. Sometimes sleeping. Scientists from The University of Edinburgh have looked at the construction of the flying mechanism of swifts to understand how they manage to stay in flight when weather is horrible. Wind with quickly changing direction and power often upsets other birds, but not swifts. Scientists now say that it is because of their wing shape, which allows them to adapt quickly and effortlessly to changing weather conditions.

Having in mind that swifts stay in flight for the majority of their life, the main question is energy. Scientists say that the crescent shape of swift’s wings lessens the effects of blustery conditions and so the bid can easily fly stable. Researchers constructed a wing model, mimicking the characteristic trailing edge shape of swifts’ wings. Water flume was used to replicate airflow and a laser sheet and a digital camera helped tracking the movement of tiny glass balls in the water. This allowed scientists to see that when air passes on top of the swift’s wing it forms several circulating regions of airflow, known as leading-edge vortices.

Some aircrafts with delta wing design actually capitalise on these leading-edge vortices, because they create extra lift. For example, the famous Concorde supersonic airliner employed these vortices to reach higher altitudes without consuming too much of extra fuel. However, swifts use these leading-edge vortices for a little bit different purpose than simply generating lift. In turbulent conditions these vortices actually have a dampening effect, helping the bird to stay stable. Dr Ignazio Maria Viola, one of the scientists from the research team, said: “One of the most fascinating secrets in nature is how birds and insects can fly so effortlessly in turbulence. These results provide a small breakthrough towards unravelling this precious secret”.

While it is interesting to know, it actually has some practical implications as well. Swifts use these vortices to save their energy and to avoid accidents while gliding through some tough conditions. Human-made aircrafts, such as drones, could benefit from understanding how swift’s wings work.

 

Source: The University of Edinburgh

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