This story now
IN Science & Technology ON 07 Nov, 2016
Besides cramped up leg spaces and that uncomfortable upright position you got to stick to while in an airplane, what else do you notice about these flying mammoths? Some of you may love to watch those gorgeous air hostesses walking up and down the aisle while others may be content securing a window seat for some scenic treasures.
Talking about the window seat, have you observed that the wings of some airplanes have a slight curve at the end? For those who have nodded in affirmative, have you tried to find an answer to this curvaceous mystery?
Let me not embarrass you by challenging your knowledge and do the honors of sharing a little technology behind those curved wingtips of the air crafts. Trust me; you will be elated to observe that curve the next time you board a flight and will not be able to resist flaunting your aircraft knowledge with your fellow passengers.
Please tighten your seat belts as we take off with our mini airplane technology class.
If I were asked the reason behind these curved wings, I'd say it was done to enhance the beauty of the aircraft and make them look even more stylish. If you too are as lame as me, then please read on further.
Not all airplanes have curved wingtips as of now, but there are basically two types of wingtip bends - either oval in shape or bent vertically upwards.
The English language has never had any dearth of terminologies and there indeed is a term coined for these curved wingtips. These are called winglets!
Now that you know they are called "winglets," let us define the term for you in a more sophisticated manner. A winglet is an additional structural component of a wing structure with the primary function of reducing wingtip vortex, which is produced due to the pressure difference between the upper and lower surface of a wing while an aircraft is moving.
Before you could settle your mind to absorb a new term "winglet," another new term popped up from its definition called "Vortex." If you look at the image above, you will see the pictorial representation of a vortex. Vortices can be broadly explained as mini tornadoes caused by the movement of airplanes in the air.
Before we explain how do winglets help, let us first tell you why are these vortices a concern. Don't they look incredibly beautiful and harmless? For starters, you should know that wingtip vortices affect the speed, range, performance, and fuel mileage of the aircraft. And if that seems like just a petty problem, then here's something to convince you. If another aircraft was to pass through the same region where a vortex was created, then it would either lose its stability or in the worst case scenario, could even result in an emergency situation.
Vortices are not good even from an environmental concern. Due to the drag resulting from vortices, airplanes consume higher fuel that means higher emissions of carbon dioxide and other particulates besides adding to the noise pollution.
Now that you know why vortices are not good, let us now explain how they are formed. When the aircraft moves, the airflow gets split in front of the wings, and due to the angular placement of the wings, higher pressure is experienced below the wing and lower pressure above it. This, in turn, generates air pressure difference between the top and bottom parts of the wing that enable the plane to lift.
And as we know, the property of fluids is to flow from higher pressure region to lower pressure region; the air keeps flowing from bottom to top part of the wing at its tips (where the wings end), creating mini whirlpools/tornadoes called vortices.
To prevent the formation of vortices, there were two solutions suggested by aircraft engineers and researchers. One idea was to create infinitely long wings for a complete separation of airflow from the lower to the upper region of the wings, and as you must have already guessed, this wasn't an idea that could be implemented. The second option was to introduce a structural component to create a separation between the two differential pressure regions.
Well, that sounds like a cool plan, and it was accepted. With winglets in practice, airplanes could save on fuel and money besides reducing carbon dioxide and nitrogen oxide emissions. Though winglets cannot stop the creation of vortices completely, they go a long way in mitigating them.
Well, it has become mandatory for all airplanes to have winglets owing to their aerodynamic benefits, which were observed by NASA in the 1970's. Boeing had seen a rise in the demand of winglets from a mere 10% in 2001 to a 50% in 2005. Since 1980's, winglets have been a prominent part of all airplane designs. For the aircraft built earlier, winglets were fitted after their manufacturing was complete.
To witness the importance of winglets at your end, you can make a paper plane and bend the end of the wings a little as shown in the picture. Fly it off, and you will realize it goes a longer way as compared to the paper plane sans those curved wings.
Aren't you feeling enlightened today? Let us know if you try the paper plane experiment.