Beyond Gravity

Aviation has changed the way we travel and connect with the world forever. From commercial airliners to private jets and fighter jets, the ability to touch the skies has become a routine part of modern life. Yet, the science behind the mechanics of flight remains a mystery to many. How can a heavy metal machine, with powerful engines and a vast array of complex systems, stay up there and navigate the skies with such ease?

The answer lies in the fabulous principles of aerodynamics. By understanding the physics of lift, drag, and thrust, aviation engineers have been able to design aircraft that can take off, fly, and land with precision and control. From the shape of the wings to the placement of the engines, every aspect of an aircraft is carefully crafted to ensure maximum performance and safety. In this article, we’re going to dive into the beautiful world of aviation and its science. So fasten your seatbelts and prepare for takeoff! But wait… How do we do that?

To take off, a plane needs to fight its own weight that is keeping it to the ground. Like birds, planes have wings, which are flat and curved on the top. When a plane moves forward, the air flows over the top of the wing faster than it flows underneath the wing (see top-right scheme). This creates an area of low pressure on the top of the wing and an area of high pressure underneath the wing, this phenomenon is called the Bernoulli principle. The difference in pressure between the top and bottom of the wing creates this upward force called lift.

But, in order for a plane to take off and climb into the sky, it needs lift and thrust. The plane’s engines generate thrust, which propels it forward and gives it the speed it needs to create lift. Once the plane is in the air, it needs to keep generating both thrust and lift in order to keep flying. The engines provide the thrust to keep the plane moving forward, while the wings continue to generate lift to keep the plane aloft.

When a plane moves through the air, it has to push the air out of the way. This creates an area of turbulence behind the plane, which is known as a “wake”. This can result in higher fuel consumption and lower performance because it needs to use more thrust to counter this. Pilots and engineers work to minimize drag by designing airplanes with streamlined shapes, using smooth surfaces, and employing techniques such as winglets or other aerodynamic features to reduce turbulence and the resulting drag. By reducing drag, they can make airplanes more efficient and save fuel, which is good for the environment and for the airline’s bottom line.

But there is one aspect that still remains a mystery even to the professionals: if the plane is upside-down, the wings aren’t in the position they are meant to be but still, the plane flies and generates lift. How’s that possible? Today, we still don’t have a global theory to explain the lift in all cases. Two theories are usually used together to explain this: Bernoulli’s principle and Newton’s 3rd law. These two are complementary and mathematically accurate, but they don’t fully explain everything and it might become too difficult to explain later on. As John D. Anderson, curator of aerodynamics at the National Air and Space Museum, said: “There is no simple oneliner answer to this.”

Additionally, there are a lot of other factors that make a plane fly. From the pilot to the air controller, cabin crew members to the janitors in the airport, the aviation industry is very complex and relies on itself to make the 15000 planes that are flying while you’re reading this article, safe and on their way to their destination.

Even though we all know that planes are one of the most polluting industries in the world, we can still try to admire the complex engineering behind one of the oldest dreams of Humanity: to fly!

Hugo Lhomedet

Sources:

Comment les avions volent-ils?

- ScienceEtonnante

No one can explain why planes stay in the air - Scientific American What is Bernoulli’s equation?KhanAcademy

Bernoulli’s principle visualized. The slower the air goes under the wing, the more pressure (lift) it creates.

The infamously majestic Concorde after takeoff. Supersonic commercial airplane, its last flight occured on the 24th of October 2003.

The Mitsubishi A6M Zero, my personnal favorite airplaine. Manufactured by Japan during WWII, it controlled the whole Pacific Ocean until the late-1943.