What is flight? As Douglas Adams once said, flight is “to throw yourself at the ground and miss.” Ok, it might be a tad bit more complicated than that, but that’s why we’re here: to explain the science and future of flight.
All aircraft generate some form of lift, either through buoyancy or Bernoulli’s principle. Lift is a force that pushes objects upward. Once lift overcomes the force of gravity acting on an object, that object begins to rise. The story of human flight begins in 1783 with the invention of the hot air balloon. The hot air balloon is based on the principles of buoyancy. A hot air balloon heats the air inside of a silk balloon. Since hot air is less dense than cold air, the hot air balloon rises taking the passengers in the basket with it. While the ability to float is all fine and dandy, it’s useless without a method of directing your movement. Thus, you need thrust. Thrust is a force that pushes flying objects. Most aircraft rely on some form of propeller or jet engine to generate thrust. In 1852, Jules Giffard built the first powered dirigible. While it had a measly top speed of 6 miles per hour, courtesy of a 3 horsepower steam engine, it proved to the world that controlled flight was possible. Unfortunately, dirigibles and other buoyancy-based aircraft are not scalable. They are massive, inefficient, and couldn’t fly through storms. Thus, the fledgling aviation industry looked to non-buoyancy-based aircraft for the future.
Throughout the late 18th and 19th-century, people began to design gliders that rely on Bernoulli’s principle instead of buoyancy to generate lift. Bernoulli’s principle states that the faster a fluid moves the less pressure it exerts. So what does that mean and how does that generate lift? Air, like other liquids and gases, is a fluid, thus it obeys Bernoulli’s principle. A wing is specifically shaped to accelerate air flowing over its top. Due to this, there is an area of high pressure below the wing and an area of low pressure above it. As there is a greater force pushing up than pushing down, the wing generates lift. In 1903, the Wright brothers combined Benournili’s principle, material science, advances in internal combustion technology, and the knowledge of those who came before them to build the first heavier than air aircraft capable of controlled flight, birthing the airplane as we know it.
Diagram of a wing generating lift (Source)
Aviation hasn’t changed much in the past 50 years. But as climate change intensifies and oil reserves decline, the aviation industry has looked to eVTOLs for the future. An eVTOL is an electrically-powered aircraft capable of vertical takeoff and landing (electric vertical take-off and landing = eVTOL). Due to their unique nature eVTOLs solve many problems that traditional aircraft face.
Traditional aircraft require a runway to take off and land. This drastically constrains a plane’s range to locations with well-maintained runways. However, eVTOLs can take off and land from virtually anywhere. Instead of having to drive through traffic to reach the airport, you could just hail an eVTOL like an Uber. Additionally, planes can’t just stay on the runway, they need to give way to the next incoming plane. As eVTOLs can land vertically they don’t need to move for the next eVTOL. The incoming eVTOL could just land next to the previous one.
In addition to their ability to operate from anywhere, eVTOLs run on electricity. Typical airplanes and helicopters consume volatile fossil fuels. These fuels are liquids and require large tankers to transport. A typical Boeing 747 consumes 5 gallons of fuel per mile. A trip from SFO to LAX, a journey of 380 miles(610km) would set you back 2000 gallons (7570 liters) of high octane fuel. An eVOTL can be charged via a standard power outlet. Ultimately this allows eVTOLs to recharge almost anywhere, even your backyard.
EVTOLs are extraordinarily simple.in comparison to gas-powered aircraft. All gas-powered aircraft use some form of an internal combustion engine. Internal combustion engines explosively burn fuel to generate mechanical energy. Unfortunately, as fuel is burned, energy is lost as heat, lowering efficiency. Electric propulsion directly converts energy stored in batteries to mechanical energy. As there are no intermediate steps from energy source to thrust, energy efficiency is maximized. Additionally, jet engines have many moving parts. Each one of these parts is a source of potential failure, endangering the passengers. Electric propulsion systems have only one part, the motor. Many eVTOLs distribute power across multiple motors, like the Volocopter above. These features increase safety ensuring that even in the worst conditions, the passengers are safe.
Flight requires the generation of two forces, thrust and lift. While the physics of flight will never change (hopefully), eVTOLs are swooping in (pun shamelessly intended), increasing aircraft versatility, efficiency, and safety. On a fateful morning over a century ago, the Wright brothers cracked the secrets of flight. Now, eVTOLs are shaking up the aviation industry, forever changing the way we move.
Post By: Armaan G.
Photos Credits: Wikimedia Commons, link
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