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Aircraft WingletsWhy Are Aircraft Wings Curved At The End?
Team ScienceABC
If you’re a frequent flyer, you may have seen something odd about the
aircraft’s wings.
You will likely have noticed that the wings have an additional
component at the ends. It makes it look rather stylish, doesn’t it?
In some ways, it looks like the fins or the tail of a fish. Some
ends are bent upwards, while some others are oval in shape!
These sections of an aircraft wing are called winglets.
“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.”
That’s the kind of definition that would make your professor’s knees
weak in admiration, but let’s work through this definition in small
steps.
To understand the winglet, let’s first understand why an aircraft
needs it.
What are Vortices?
A wing works as a result of Bernoulli’s principle, which
essentially states, ‘the pressure of a fluid is inversely
proportional to the velocity of the same in space’.
When an aircraft is in motion, the airflow is split at the leading
edge (front) of the wing.
Due to the angle at which the wing is fixed to the aircraft fuselage,
higher air pressure is experienced on the lower surface of the wing than
on the upper surface.
This creates a pressure difference between the top and bottom sections
of the wing, which generates lift (upward movement of the aircraft).
The property of fluids is that they flow from a region of higher
pressure to a region of lower pressure.
Following this principle, the air tends to move from the high pressure
below the wing to the low pressure above the wing around the wingtips, thus
forming and leaving behind vortices (mini-tornadoes) as the aircraft moves.
Why is This a Concern for Aircrafts?
A significant source of drag (air resistance) is actually caused by
the high pressure under the wing, which causes air to flow up and over the
wingtip before spinning off in a vortex.
Wingtip vortices hamper performance, cut into fuel mileage, range, and
the speed of the aircraft.
It may look beautiful in the sky, but it actually may cause an
aircraft that flies through the same region to lose stability and
even result in an emergency situation.
Environmental factors also factor into the need for a solution.
Due to the drag caused by the vortices, a larger consumption of fuel
is required, which results in higher emissions of CO2, other artificial particulates and noise.
The Solution – Winglets:
To avoid the formation of the vortices, two solutions were explored as
being possible. One was to manufacture an infinitely long wing.
There would be total separation of the airflow from the lower and
upper surface, therefore preventing any vortices from being formed.
Sound rather outrageous? Obviously, there were some major issues with
this.
The other solution was to create a separation between the
two differential pressure regions by introducing a structural component. This
was to be called a ‘winglet’, a term that was first coined by Richard
Whitcomb.
Since the 1980’s, winglets have been a major part of future aircraft
designs. For some old aircrafts, winglets were fitted after the plane’s
introduction into the market.
Winglets are a proven way to reduce drag, save fuel, cut carbon
dioxide and nitrogen oxide emissions, and reduce community noise.
This helps the operating airlines save money by decreasing the amount
of fuel consumed, as well as landing charges at airports.
In other words, if you ever make a paper plane, be sure to bend the
ends of the wing upwards just a little, and it will fly a bit further. It’s not
cheating, it’s just science!
Fun Fact:
In 1897, British engineer Frederick W. Lanchester
conceptualized wing end-plates to reduce the impact of wingtip vortices six
years before the first powered flight was operated by the Wright Brothers
(1903). Talk about being ahead of your times!
Team ScienceABC is the handle of a
team of engineers and science graduates who come up with brilliant ideas every
now and then, but are too lazy to sit at one spot to complete an article, and
dread the idea of being considered ‘regular writers’.
