How Do Airplanes Fly - The Physics Of Airplane Flight - Aero Corner (2023)

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From Icarus’ wing-melting failure to Leonardo da Vinci’s sketches of an air screw to the Wright Brothers finally flying at Kitty Hawk, few things have held a greater place in the human imagination than the dream of flight.The reality of how airplanes make use of lift and gravity to stay airborne is even more astonishing. It’s nothing to be ashamed of if you’re wondering what it is that keeps a plane in the air. So let’s answer the question of how do airplanes fly today.

Table of Contents

  • How Do Airplanes Fly?
  • The Physics Of Airplane Flight

How Do Airplanes Fly?

In short: Wings, Lift, Air Molecules, and Conquering Gravity.

What Keeps A Plane In The Air?

The fact that airplanes fly because of something called “lift” is pretty common knowledge. However, there’s more to this phenomenon.

Most of us understand “lift” to mean generating or harnessing air pressure beneath the wings. The physics of how that happens are as complex as they are interesting.

For one thing, while we tend to focus on lift, a better way of imagining flight, as per Minute Physics’ video on the topic, may be to think of flight as a means of gravitational “balance” that just happens to take place in the air.

It isn’t as though planes simply float in mid-air. To fly, they have to generate thrust as well as lift while balancing different gravitational forces.

(Video) Understanding Aerodynamic Lift

How is that achieved?

For starters, as that Minute Physics video points out, it isn’t just lift acting on a plane, but drag and gravitational forces which pull it down as well.

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The plane has weight and mass, as does every piece of equipment and luggage as well as every passenger. All of this has to be accounted for in the calculations for making a plane flight-worthy.

That means not only generating lift but generating enough lift pushing the plane upward to counteract and thus balance the forces pushing it downward.

The Physics Of Airplane Flight

To begin this deeper dive into the physics of airplane flight, consider Newton’s Third Law of Motion: for every action, there is an equal and opposite reaction.

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This, in physics terms, is how balance is achieved – the air acts as an upward force on the plane, hence lift, and the weight and mass acts as a downward force, hence drag. Equalize these two opposing forces out, the result is balance.

When a plane is parked on the ground, the amount of air molecules striking the plane as a whole and the wings in particular is roughly equal. Hence, the plane stays put. Once that plane is off the ground, however, the air molecules strike the plane’s wings differently.

Looking at an airplane’s wing reveals that it isn’t straight but affixed at a slightly tilted angle, with the bottom straight and the top typically featuring a more gentle curve. This isn’t merely an aesthetic choice, but rather is integral to helping airplanes become and remain airborne.

As stated, equal force means balance, and the slant and curve of the wings disrupts that balance ever so slightly, causing more molecules to strike the bottom of the wing and in a “harder” fashion than the top.

Related Article:

  • Angle Of Attack (AOA) in Aviation

The upward slant of the wings ensures that the air strikes the bottom of the wing that way as well, resulting in the upward lift that is critical for flying.

The same principle is at play in the wing’s shape.

(Video) How aircraft turn?

Striking a flat surface head-on is bound to create greater force than striking something at an angle, which is precisely what happens when air molecules strike the curved top of the wing.

The curvature reduces the amount of molecules which hit the wing, and those that do hit it do so at an angle less conducive to releasing force.

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In addition, the centripetal manner in which air molecules move around the wing further lessens the amount of pressure exerted by air molecules hitting the top of the wing.

Minute Physics uses the analogy of running into a rainstorm. In this case, the frontmost parts of the runner’s body get soaking wet – but the back part of their body less so.

That’s because the angle at which the runner is moving coupled with forward motion means that most of the rain hits the face and front of the body and peels around the back, leaving it drier.

In essence, something similar is happening with wings and lift. As with the raindrops hitting a body in the above analogy, as the plane moves forward, air molecules skim past the curved top and back and instead hit the front and bottom – the places necessary to create and maintain lift.

Aerodynamic Design

Overall aerodynamic design also matters here. Anyone who has ever made a paper airplane knows that paper wings which slant diagonally result in far better flying paper airplanes than those with simple rectangular wings and boxy designs.

The same way that the curved top half of the wing lessen the amount of air molecules and thus force exerted on it, aerodynamic slanted wing designs in real airplanes help the air move around the wings and plane in such a way as to reduce resistance and thus make it sleeker and faster.

The Wright Brothers’ plane lacked the curved wings mentioned here, in favor of a bigger, boxier, flatter design.

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What remains constant between their most rudimentary plane and today’s biggest jets – and thus what serves as the critical factor in wing design, is the “angle of attack,” the degree to which a wing is slanted so as to produce that top/bottom air pressure imbalance.

Too much of a tilt, however, and the airflow around the wings becomes too choppy and irregular, and the plane fails to sustain lift and fly properly. A 15-degree tilt tends to be the maximum sustainable angle for aerodynamic flight.

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Thrust and Drag

All this talk of lift, force, and gravity, however, is only half of the equation.

After all, an airplane’s wings only work this way if the air hits the front and underside with enough force to counteract the amount hitting the top and thus create an imbalance great enough to conquer gravity.

(Video) Why Do Airplanes Fly in the Stratosphere?

That means the plane must keep moving forward with enough speed to maintain that imbalance.

And that takes us to the next part of our equation – thrust and drag.

In the simplest of terms, thrust propels the plane forward, while drag holds it back.

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In the same way that generating lift is all about that top/bottom wing force imbalance, generating thrust is all about pushing air backward with enough force and speed to counteract the force of drag operating on the plane.

From Kitty Hawk to the skies above Europe during the First World War, the first decades of flight saw thrust being achieved primarily via propellers. Then jet power was invented.

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Today, most planes make use of some combination of the two, which work together to push air backwards efficiently, forcefully, and quickly enough to counteract drag and thus help the plane conquer gravity.

The same principles of curvature, centripetal force, and the air force imbalances they create with wings works for propellers as well, which capture air beneath their propellers and propel them backward.

When they do so with enough force, the amount of thrust outweighs the amount of drag, and the plane moves forward.

How Planes Steer In The Air

All of that is well and good, but what about steering in the air? Getting a large metal plane off the ground is an impressive feat, but it won’t mean much if it can only fly in a straight line.

Of course, birds don’t just fly in a straight line, and it’s from them that we get our answer.

When we see birds fly and they turn, they dip one wing or the other, and thus fly at a slanted angle while turning.

Planes, of course, do the same thing. When a plane needs to turn, one side dips lower than the other as the plane slants in the direction the pilot wishes to turn.

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Given all the above points about lift and how air molecules strike the underside of wings, the reason for this may already be apparent.

(Video) SCIENCE BEHIND: How Planes Fly

By slanting and dipping the plane in such a way, the pilot creates yet another imbalance in how the air molecules strike the wings.

This time, it is done to increase the force of air on one wing compared to the other.

The same way that a top/bottom air pressure imbalance causes lift, a left/right imbalance in the amount of air pressure exerted on the wings enables the plane to steer.

A Final Tip on Wingtips

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Finally, it’s worth noting that modern airliners typically have wingtips, also called winglets, which come up at the end.

Why is that?

Wings don’t throw air back in perfect, smooth, neat distributions, but in “wing vortices,” that is, large swirls of air. While most of this passes behind the plane, some of it swirls upward, which can reduce lift.

Modern airplanes account for this via their upturned wingtips, which help minimize the effect these swirls of air can have on the plane’s ability to maintain lift and smooth forward flight.

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About the Author

(Video) Intro to Aerodynamics: How Do Airplanes Fly?

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Editorial Team

FAQs

How does an airplane fly physics? ›

Airplane wings are shaped to make air move faster over the top of the wing. When air moves faster, the pressure of the air decreases. So the pressure on the top of the wing is less than the pressure on the bottom of the wing. The difference in pressure creates a force on the wing that lifts the wing up into the air.

How does Bernoulli's principle explain how airplanes fly? ›

Air moving over the curved upper surface of the wing will travel faster and thus produce less pressure than the slower air moving across the flatter underside of the wing. This difference in pressure creates lift which is a force of flight that is caused by the imbalance of high and low pressures.

Why planes fly is explained by which principle? ›

Bernoulli's principle helps explain that an aircraft can achieve lift because of the shape of its wings. They are shaped so that that air flows faster over the top of the wing and slower underneath.

What are the 4 aerodynamic forces of flight? ›

The four forces acting on an aircraft in straight-and-level, unaccelerated flight are thrust, drag, lift, and weight. They are defined as follows: Thrust—the forward force produced by the powerplant/ propeller or rotor.

What are the 3 basic movements of an airplane? ›

An airplane rotates in bank, pitch, and yaw while also moving horizontally, vertically, and laterally. The four fundamentals (straight-and-level flight, turns, climbs, and descents) are the principle maneuvers that control the airplane through the six motions of flight.

What law of motion is airplane? ›

An aircraft in flight is a particularly good example of the first law of motion. There are four major forces acting on an aircraft; lift, weight, thrust, and drag. If we consider the motion of an aircraft at a constant altitude, we can neglect the lift and weight.

How does aerodynamics allow planes to fly? ›

Airplanes' wings are curved on top and flatter on the bottom. That shape makes air flow over the top faster than under the bottom. As a result, less air pressure is on top of the wing. This lower pressure makes the wing, and the airplane it's attached to, move up.

How do airplanes stay in the air without moving? ›

Can an airplane stay up in the air without moving forward just like helicopter? A: Techincally, there is only one way for the aircraft to remain hanging motionless in the air: if weight and lift cancel each other out perfectly, and at the same time thrust and drag cancel each other out too. But this is incredibly rare.

How do airplanes stay in the air without falling? ›

The way air moves around the wings gives the airplane lift. The shape of the wings helps with lift, too. Weight is the force that pulls the airplane toward Earth. Airplanes are built so that their weight is spread from front to back.

What are the 7 stages of flight? ›

3.1.

The general flight phases are divided into: planning phase, takeoff phase, climb phase, cruise phase, descent phase, approach phase, and taxi phase.

What are the 6 motions of flight? ›

An airplane rotates in bank, pitch, and yaw while also moving horizontally, vertically, and laterally. The four fundamentals (straight-and-level flight, turns, climbs, and descents) are the principal maneuvers that control the airplane through the six motions of flight.

What are the three laws of aerodynamics? ›

Weight, lift, thrust, and drag are the four principles of aerodynamics.

How do planes fly Newton's third law? ›

Isaac Newton learned that for every action there is an equal but opposite reaction. For exam- ple, as an engine forces air backward, the airplane will move with an equal but opposite force forward. Each engine is throwing air out one way so the plane can move the opposite way. This reaction force is known as thrust.

How does Newton's third law affect flight? ›

Newton's third law of motion states that, for every action, there is an equal and opposite reaction. Based on this law, wings are forced upwards because they are tilted, pushing air downwards so the wings get pushed upwards. This is the angle of attack or the angle at which the wing meets the airflow.

Why do planes tilt when turning? ›

Increased drag slows the airplane. Also, in a turn, there's less area of lift under a wing, causing it to lose altitude. However, to compensate, pilots angle the airplane up as well as increase thrust (speed) to maintain a constant altitude during a turn. You'll probably feel those changes in your stomach.

What is the most important part of a plane? ›

The Fuselage

Its long hollow tube, also known as the body of the airplane, holds the passengers along with cargo. This area includes the cockpit, so the pilots are in front of the fuselage. Despite there being different types of fuselages, they connect the major parts of an airplane.

How do planes turn left and right? ›

Most airplanes have a pair of ailerons — one on each wing. When turning, the pilot will engage the wheel to raise one of the ailerons while simultaneously lowering the other aileron. The alternating positions of the airplane's ailerons allow the airplane to roll towards the left or right side.

What kind of physics do pilots use? ›

Ohm's Law, Turn Radius, Law of Moments, Point of Equal Time, Point of No Return, Departure formula and the Lift formula are just some examples of what you will face during the training. Airlines have different mathematics and physics tests in order to select & assess people quickly during their selections.

Do you need physics to fly a plane? ›

Becoming a Pilot Requires a significant amount of knowledge and skill that you'll receive throughout your flight training. You'll learn everything from science and weather to even principles of physics. The job as well as the training also requires a signficant amount of math.

What controls the plane in the air? ›

The ailerons, elevator (or stabilator), and rudder constitute the primary control system and are required to control an aircraft safely during flight.

How do planes travel in curves? ›

Or why is it that when you see flight paths on a map they always take a curved route between 2 cities? It's because planes travel along the shortest route in a 3-dimensional space. This route is called a geodesic or great circle route. They are common in navigation, sailing, and aviation.

Can a plane fly with one wing? ›

Yes an aircraft can fly with one wing shorter. The winglets on a commercial airliner like the 747 or A330 can be missing on either side as per the minimum equipment list.

How do planes not run out of oxygen? ›

Answer: In most airliners, air is compressed by the engines, cooled by the air conditioning system and then sent to the cabin. Fresh air can also be routed to the cabin from a small jet engine in the back of the airplane, known as an auxiliary power unit, or via a hose when at the gate.

Can an airplane go in reverse? ›

Some aircraft can do a so-called 'powerback', but in most cases, airplanes either don't have this technical capability. Most airplanes can taxi backwards by using reverse thrust. This entails directing the thrust produced by the plane's jet engines forward, rather than backwards.

Why planes Cannot fly in storms? ›

Flying through a thunderstorm can sometimes be unsettling as windy storms and jetstreams increase flight turbulence. This may cause the plane to jump about and feel rather uncomfortable, but the reality is that flying in particularly windy conditions is generally safe.

Why can't planes fly in storms? ›

Jet aircraft can safely fly over thunderstorms only if their flight altitude is well above the turbulent cloud tops. The most intense and turbulent storms are often the tallest storms, so en route flights always seek to go around them.

Will a plane crash if it loses cabin pressure? ›

Description. Loss of pressurisation is a potentially serious emergency in an aircraft flying at the normal cruising altitude for most jet passenger aircraft. Loss of cabin pressure, or depressurisation, is normally classified as explosive, rapid, or gradual based on the time interval over which cabin pressure is lost.

What is the most fatal phase of flight? ›

The most dangerous part of any flight is the landing with nearly half of all fatal accidents occurring in the last fraction of a journey, according to US manufacturer Boeing.

What are the 5 stresses in aircraft? ›

The fuselage of an aircraft is subject the fives types of stress—torsion, bending, tension, shear, and compression.

What is the most critical part of flight? ›

Boeing research shows that takeoff and landing are statistically more dangerous than any other part of a flight. 49% of all fatal accidents happen during the final descent and landing phases of the average flight, while 14% of all fatal accidents happen during takeoff and initial climb.

What are the 10 phases of flight? ›

Phases of Flight :
  • Pre-departure. This is the preparation time for flight. ...
  • Clearance to Taxi. ...
  • Take-off. ...
  • Initial climb. ...
  • Climb to cruise altitude. ...
  • Cruise altitude. ...
  • Descent. ...
  • Approach.
Nov 23, 2020

What does yaw mean in flight? ›

A yaw motion is a side to side movement of the nose of the aircraft as shown in the animation. The yawing motion is being caused by the deflection of the rudder of this aircraft. The rudder is a hinged section at the rear of the vertical stabilizer.

What is the tilt of plane called? ›

Pitch -- The angle between the airplane's body (lengthwise) and the ground. An airplane going straight up would have a pitch attitude of ninety degrees and one in level flight, about zero degrees. Pitch. Relative Wind -- The direction that the air is going as it passes the airplane relative to the airplane.

At what speed do aerodynamics make a difference? ›

Aerodynamics start to have a more noticeable affect on a vehicle at around 50 mph. If you're traveling slower than 50 mph, the weight of the aerodynamic devices are probably more of a penalty than any perceived gain in performance.

What is the most aerodynamic shape? ›

The most aerodynamic shape in the world, the teardrop, comes from nature. With its rounded nose at the front that tapers towards the rear, the shape is formed by the flow of water down an object meeting opposition from the air around it.

What is the most important aerodynamic factor? ›

The most significant aerodynamic force that applies to nearly everything that moves through the air is drag. Drag is the force that opposes an aircraft's motion through the air, according to NASA. Drag is generated in the direction the air is moving when it encounters a solid object.

How do planes fly without colliding? ›

TCAS. Almost all modern large aircraft are fitted with a traffic collision avoidance system (TCAS), which is designed to try to prevent mid-air collisions. The system, based on the signals from aircraft transponders, alerts pilots if a potential collision with another aircraft is imminent.

How does Newton's 2nd law relate to flight? ›

Newton's second law states that Force equals mass times acceleration, or F=ma. This means that the force needed to accelerate an airplane in any direction is equal to the mass of the airplane times the desired acceleration.

How does gravity make an airplane fly? ›

Planes do not actually defy gravity, though. Instead, the tilt and area of a plane's wings manipulate the air particles around the plane, creating a strong enough lift that the force of gravity is overcome by the force of the air beneath the wings.

What are the 4 things that make a plane fly? ›

There are four forces that act on things that fly. These are weight, lift, thrust, and drag. Each of these plays a key role in keeping an aircraft in the air and moving forward.

Why can't planes fly over the ocean? ›

Hazardous weather conditions and larger weather systems can occur over bodies of water. These include thunderstorms, which are extremely hazardous to flights. So, there can be cases in which airlines may look to spend as little time as possible flying over water or apply ETOPS.

Why can't planes land during a storm? ›

The main risk with landing during a storm, just like with taking off, is microbursts. A microburst is a small but strong column of air in a storm which can affect a plane's direction, making it hard for pilots to keep the plane under control.

How do planes not tip over when landing? ›

In the horizontal plane, thrust drives the aircraft backwards and drag slows the aircraft down. In the vertical plane, weight forces the aircraft towards the earth and lift directs the aircraft into the air.

What are the two forces that work against flight? ›

Each force has an opposite force that works against it. Lift works opposite of weight. Thrust works opposite of drag. When the forces are balanced, a plane flies in a level direction.

What are the 2 natural forces acting on an airplane? ›

Drag and gravity are forces that act on anything lifted from the earth and moved through the air. Thrust and lift are artificially created forces used to overcome the forces of nature and enable an airplane to fly. Airplane engine and propeller combination is designed to produce thrust to overcome drag.

How does Newton's laws apply to flight? ›

The first law shows us that the plane will keep flying at the same speed unless something makes it accelerate. The second law shows that we must add up the forces of lift, weight, drag and thrust and take into account the mass of the airplane to determine which direction and how fast the plane is accelerating.

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