In his article in The Conversation magazine, Clarkson University Professor of Mechanical and Aerospace Engineering Craig Merrett explains in detail why planes fly, what physical laws allow this, and what the mechanics and physics of flight are. 24 Channels has translated this article and is publishing it in an adapted form.

The force is always with us

There are four forces that aerospace engineers consider when designing an aircraft:

• weight,
• traction,
• resistance,
• Lifting force

Engineers use these forces to design the shape of the plane, the size of the wings, and to determine how many passengers the plane can carry.

For example, when an airplane takes off, the thrust force must be greater than the drag force, and the lift force must be greater than the weight. If you watch a plane take off, you will see that the wings change shape with the flaps on the back of the wings. Flaps help create more lift, but they also create more drag, so a powerful engine is needed to create more thrust.

Once the plane climbs high enough and moves toward its target, lift must balance the weight, and thrust must balance drag. Therefore, the pilot retracts the flaps and can set the engine to lower power.

The force everyone faces every day is gravity, which keeps us grounded. When you weigh yourself at the doctor’s office, what is actually measured is the force your body exerts on the scale. When your weight is listed in kilograms, this is a measure of strength.

When a plane flies, gravity pulls it down. This force is the weight of the aircraft.

But its engines push the plane forward because they create a force called thrust. Engines pull in air with mass and quickly push it out the back; This is how mass multiplied by acceleration occurs.

According to Newton’s third law, for every action there is an equal and opposite reaction. When air is pushed out from behind the engines, a reaction force is created that pushes the aircraft forward; This is called thrust force.

When a plane flies through the air, the shape of the plane pushes air out of its path. Again, according to Newton’s third law, this air is pushed back and drag occurs.

You may experience something similar to frontal drift while swimming. Paddle in the pool; your arms and legs create traction. Stop rowing, you will continue to move forward because you have mass, but you will slow down. The reason you slow down is because the water pushes you; This is resistance.

How does buoyancy work?

Buoyancy is more complex than other forces of weight, traction and resistance. It is formed by the wings of the aircraft and the shape of the wing is very important; This form is called the air wing. Basically, this means that the upper and lower parts of the wing are curved, but the shapes of the curves can differ from each other.

When air flows around the wing, pressure is created, a force distributed over a large area. Less pressure is created in the upper part of the aerodynamic wing than in the lower part. Or in other words, air moves faster above the airfoil than below it.

Understanding why the pressure and speed at the top and bottom of the wing differ is critical to understanding lift. By improving our understanding of lift, engineers can design more fuel-efficient aircraft and provide passengers with more comfortable flights.

the mystery of air

Why air moves at different speeds around the wing remains a mystery, and scientists are still investigating this question.

Aerospace engineers measured this pressure on the wing both in wind tunnel experiments and during flight. We can make models of different wings to predict whether they will fly well. We can also change lift by changing the shape of the wing to create planes that can fly long distances or fly very fast.

Although we still don’t fully understand why lift occurs, aerospace engineers work with mathematical equations that reproduce the different speeds at the top and bottom of the wing. These equations describe a process known as circulation.

Circulation gives aerospace engineers the ability to model what’s happening around a wing, even if we don’t fully understand why it’s happening. In other words, we can build safe and efficient airplanes using math and science, even if we don’t fully understand the process behind their operations.

After all, if aerospace engineers can figure out why air moves at different speeds depending on which side of the wing it is on, we could build planes that use less fuel and pollute less.