How Wings ACTUALLY Create Lift!

Summary

This video delves into the science behind how planes achieve lift. It explains the common Bernoulli principle and the equal transit theory, then clarifies that lift is actually created by the wing's downward deflection of airflow, not pressure difference. The Coanda effect, angle of attack, and devices like flaps, slats, and spoilers are discussed to show how they influence lift and control the plane's flight dynamics, including stall prevention and safe landing.

Takeaways

• 🛫 Planes fly due to the lift generated by their wings, which is a result of the airflow being turned downwards.
• 📚 The script explains the incorrect common belief that lift is created by a pressure difference, clarifying that lift is actually due to the wing turning the airflow downwards.
• 🔍 The Bernoulli principle is mentioned, highlighting the role of airspeed differences over and under the wing, but also pointing out its limitations in explaining lift fully.
• 🌀 The Coanda effect is introduced, explaining how the airflow 'sticks' to the wing's upper surface and follows its curve, contributing to lift.
• ✈️ Lift can be increased by flying faster or by increasing the angle of attack, which is the angle of the wing relative to the airflow.
• 🚫 Warning about the risk of stalling an aircraft by increasing the angle of attack too much, causing the airflow to separate from the wing and stop producing lift.
• 📐 Flaps are used to increase lift by increasing the wing's surface area, allowing for slower takeoff and landing speeds.
• 💨 Flaps create drag, which is the aerodynamic resistance that opposes the motion of the aircraft through the air.
• 🔄 Slotted flaps are a specific type of flap that allows air to flow between the wing and the flap, helping to maintain airflow attachment at higher angles of attack.
• 🛬 Leading edge slats are devices that extend forward from the front of the wing to increase lift at slower speeds, similar to flaps but at the wing's leading edge.
• 🛑 Spoilers are used to reduce lift during landing and to create drag for slowing down the aircraft, but their use can cause turbulence and discomfort for passengers.

Q & A

What is the primary reason planes are able to fly according to the video?

Planes fly primarily because of the lift generated by their wings, which is caused by the turning of airflow downwards, not just a pressure difference as commonly misunderstood.

What is the Bernoulli principle mentioned in the video?

The Bernoulli principle, as mentioned, is a part of the explanation for lift, stating that as air flows over the top of the wing, it speeds up, creating an area of low air pressure above the wing.

What is the 'longer path or equal transit theory'?

The 'longer path or equal transit theory' is a common explanation for how wings generate lift, suggesting that the air flowing over the top of the wing has a further distance to cover and thus speeds up, creating lower pressure above the wing compared to the higher pressure below it.

What is the Coanda effect and how does it relate to lift?

The Coanda effect is the tendency of a fluid to follow the contour of a surface. In the context of wings, the airflow 'sticks' to the top of the wing and follows its curve, which contributes to the downward deflection of the airflow and the generation of lift.

How can you increase lift on an aircraft?

Lift can be increased by flying faster to increase the speed of airflow around the wing or by increasing the angle of attack, which is the angle of the wing relative to the airflow.

What is the danger of increasing the angle of attack too much?

Increasing the angle of attack too much can lead to a stall, where the airflow cannot follow the top of the wing and separates, causing the wing to stop producing lift and the plane to fall.

What are flaps and how do they help in generating lift?

Flaps are movable sections on the trailing edge of a wing designed to increase the wing's surface area, allowing the plane to produce more lift at slower speeds, which is useful for takeoff and landing.

What is a slotted flap and how does it function?

A slotted flap is a type of flap that, when extended, has a small gap between the wing and the flap itself, allowing air to pass from underneath the main wing over the flap, helping the airflow to stay attached at higher angles of attack.

What are leading edge slats and their purpose?

Leading edge slats are devices that sit over the front of the wing and can extend forward to increase the wing's surface area, producing more lift at slower speeds, which is beneficial for takeoff and landing.

What are spoilers and what is their function on an aircraft?

Spoilers are flat panels that extend from the top of a wing to disrupt the airflow and reduce lift. They are used during landing to ensure the aircraft touches down safely and to prevent it from taking off again.

What are the secondary effects of using spoilers?

The secondary effects of using spoilers include creating a lot of drag or wind resistance, which helps the plane slow down to a safe taxi speed, and causing turbulence and noise, which can be uncomfortable for passengers.

Outlines

00:00

🛫 Understanding Aircraft Lift

The first paragraph introduces the topic of how airplanes achieve lift. It debunks the common misconception of the 'equal transit theory' based on Bernoulli's principle and explains that lift is actually created by the wing or aerofoil turning the airflow downwards, not by a pressure difference. The Coanda effect, which causes the airflow to 'stick' to the wing and follow its curve, is mentioned as a key factor in this process. The paragraph also discusses how increasing the speed or the angle of attack can generate more lift, but warns of the risk of stalling if the angle of attack is too high, causing the airflow to separate from the wing.

05:02

🔧 Aircraft Wing Devices for Lift Control

The second paragraph delves into the various devices used on aircraft wings to control lift. Flaps, which are extensions from the wing that increase surface area and curvature to generate more lift at slower speeds, are described. The downside of increased drag due to flaps is acknowledged. Slotted flaps, which allow air to pass through a gap between the wing and flap, are also mentioned as they help maintain airflow at higher angles of attack. Leading edge slats, which extend forward to increase lift at slow speeds, are explained, along with their retraction to reduce drag for faster flight. Spoilers, which are used to reduce lift during landing and create drag for slowing down, are introduced, noting their potential to cause turbulence and discomfort for passengers. The paragraph concludes by inviting viewers to subscribe for more related content and hints at the next video's topic about the dangers of ice to aircraft.

Keywords

💡Wing

A wing is a crucial component of an aircraft that provides lift, allowing it to fly. In the video, the wing's shape, specifically the cross-section known as an aerofoil, is discussed as a key factor in how planes generate lift. The script mentions that the wing's design causes air to split and flow over and under it, which is central to the explanation of lift.

💡Aerofoil

An aerofoil is the cross-sectional shape of an aircraft wing. It is designed to generate lift by manipulating the flow of air over and under it. The video script explains that the aerofoil's shape is critical in the process of lift generation, with air flowing faster over the curved upper surface and slower underneath, creating a pressure difference.

💡Bernoulli Principle

The Bernoulli Principle is a fundamental concept in fluid dynamics that relates the pressure and velocity of a fluid. In the context of the video, it is initially used to explain how lift is generated by the difference in air pressure above and below the wing due to the airspeed changes. However, the video later corrects this, stating that lift is primarily due to the wing's ability to turn airflow downwards.

💡Lift

Lift is the upward force that opposes the weight of an aircraft and is generated by the flow of air around the wings. The video script clarifies that lift is created by the wing turning the airflow downwards, not merely by a pressure difference. This is a central concept in understanding how planes can fly.

💡Coanda Effect

The Coanda Effect is the tendency of a fluid to be attracted to a nearby surface. In the video, it is used to describe how air 'sticks' to the top of the wing and follows the curve, contributing to the generation of lift. This effect is crucial in explaining how the wing shape influences airflow and lift.

💡Angle of Attack

The angle of attack is the angle between the wing's chord line and the relative wind direction. The video script explains that increasing the angle of attack can increase lift by turning the airflow downwards at a sharper angle. However, there is a risk of stalling if the angle is too high.

💡Stall

A stall occurs when the airflow separates from the wing, typically due to an excessive angle of attack. The video script mentions that during a stall, the wing stops producing lift, and the aircraft begins to fall. This is a critical concept in understanding the limits of lift generation and aircraft control.

💡Flaps

Flaps are movable sections on the trailing edge of a wing that can be extended to increase lift, especially during takeoff and landing. The video script describes how flaps increase the wing's surface area and curvature, allowing for more lift at slower speeds, but also generating more drag.

💡Leading Edge Slats

Leading edge slats are devices on the front of the wing that can extend forward to increase the wing's surface area and generate more lift at slower speeds. The video script mentions that these slats can also have slots to help maintain airflow attachment, which is crucial for maintaining lift.

💡Spoilers

Spoilers are devices on the wing that can be extended to disrupt the airflow and reduce lift. The video script explains that spoilers are used during landing to help the aircraft touch down safely and to slow down the aircraft on the ground by increasing drag.

💡Atmospheric Pressure

Atmospheric pressure is the force exerted by the weight of air above a given area. While not explicitly detailed in the script, the concept is implied in the discussion of lift, as the pressure difference created by the wing's shape is a result of atmospheric pressure acting on the air flowing over and under the wing.

Highlights

Introduction to the basics of how planes fly.

Discussion on the importance of wings in enabling flight.

Introduction to the concept of lift and how it affects flight.

Clarification of common misconceptions, such as the equal transit theory based on the Bernoulli principle.

Explanation of how air flows over and under the wing, creating pressure differences.

Introduction to the correct explanation of lift: the wing turning the airflow downwards.

Description of the Coanda effect and its role in flight.

Explanation of how increasing the speed or angle of attack can increase lift.

Warning about the dangers of increasing the angle of attack too much, leading to a stall.

Introduction to devices like flaps that increase lift by increasing wing surface area.

Discussion on the drawbacks of flaps, such as increased drag.

Description of slotted flaps and their benefits in maintaining airflow.

Explanation of leading edge slats and their role in increasing lift at slower speeds.

Introduction to spoilers and their function in reducing lift and assisting with landing.

Conclusion on the importance of understanding lift and aerodynamic principles.

Transcripts

hello hello so today we're going to be

taking a look at how planes actually fly

so basically it planes fly because they

have wings so thank you all very much

for watching no seriously this video is

going to take a look at what the wings

are actually doing which causes a plane

to fly now I'm no physicist so please

forgive me if I say something out of

turn during this video so firstly we'll

need a wing this shape here represents

the cross-section of an aircraft wing

also called an aerofoil this view is if

you were looking at it from sidon ie

from the wingtip looking towards the

plane so one of the most common bits in

correct theories which is taught is

something called the longer path or

equal transit theory which is based on

the Bernoulli principle so the

explanation that this theory gives is

that the air flow the air which is

hitting the wing splits as it hits the

front of the wing the air passes over

and under the wing and rejoins at the

back of the wing at the same time so for

this to happen the air flowing over the

top of the wing has a further distance

to cover over the curved surface

therefore it speeds up as the air speeds

up it causes an area of low air pressure

above the wing the air which passes

underneath the wing slows down because

it has a shorter distance to travel and

this causes high air pressure below the

wing the end results this theory states

is that it's this pressure difference

above and below the wing which causes

the wing to move upwards and this

upwards force is more commonly called

lift now there are a few aspects of this

theory which are correct but it doesn't

tell the full story so I'm going to give

you the correct answer first and then

try and explain what's going on after so

the correct answer is that lift is

created because a wing or an aerofoil is

turning the airflow and directing it

downwards it's not a pressure difference

which creates lift so here comes my

attempt at explaining it and again

physicists please be gentle with me so

the airflow hits the front of the wing

and splits the same as before

also Bernoulli was correct when he

talked about the difference in

pressure above and below the wing and he

was also correct in saying that the air

which flows over the top of the wing

speeds up now the air which passes over

the wing it kind of sticks to the top of

the wing and follows the curve of the

upper surface this sticking phenomenon

is known as the Coanda effect as the

airflow leaves the wing at the back it

leaves a slight downward angle because

of that curve that downward deflection

also affects the air which passes under

the wing and also turns it in a downward

direction it's this turning of the

airflow which causes lift you can

generate more lift in two ways the first

is by increasing the speed at which the

air passes around the wing this is

generally attained by simply flying

faster you can also increase something

called the angle of attack this is the

angle of the wing relative to the

airflow so in this example you can see

that the wing is pretty much pointed

directly into the airflow however if we

increase the angle of attack you can see

that the wing is tilted backwards this

creates more lift because the airflow is

turned downwards at a sharper angle now

there is a danger to increasing the

angle of attack if you increase that

angle too much there will come a point

where the airflow cannot turn and follow

the top of the wing when this happens

the airflow will separate from the top

of the wing this is what happens when an

aircraft stalls there is no steady flow

of air over the wing therefore the wing

stops producing lift and the plane

begins to literally fall out of the sky

now there are a couple of devices used

on aircraft which help increase the

amount of lift that a wing can generate

the main one you have are flaps the

flaps on any aircraft are designed to

increase the amount of lift that a wing

can produce by increasing the surface

area of the wing this allows a plane to

take off and land at slower speeds yet

still produce enough lift for safe

flight

the downside to flaps is that they

create a lot of aerodynamic drag or you

could think of it as wind resistance

normally flaps are constructed and

integrate

into the overall shape of the wing then

they extend downwards at the back of the

wing

this increases the curvature for airflow

around the wing on modern aircraft you

will likely see something called a

slotted flap when extended these have a

small gap between the wing and the flap

itself where air can pass from

underneath the main wing through a small

slots and over the flap this helps the

air flow over the main wing stay

attached at higher angles of attack now

if you really want to solidify your

understanding of flaps I'd recommend

looking at some pictures of aircraft

flaps on line you'll notice that the

flaps are essentially mini wings they

have a similar shape and structure to

the main wing now another device which

is most commonly found on commercial

jets is the leading edge slats this

device sits over the leading edge or the

front of the wing and can extend forward

to increase the surface area of a wing

again causing the wing to produce more

lift at slower speeds these can also

have a slots where air passes underneath

the leading edge slats and then flow

over the main wing as with flaps these

can be retracted to reduce the amount of

drag or wind resistance allowing a plane

to fly faster now there is one more

device which is normally integrated into

a wing however its purpose is to reduce

the amount of lift that wing produces

these are the spoilers so these are

normally flats panels which extends up

from the top of a wing they are called

spoilers because they spoil the airflow

over the top of the wing and reduce the

amount of lift it produces these are

most often used on landing to ensure

that an aircraft touches down safely and

to prevent it from taking off again they

also have a secondary effect that they

creates a lot of drag or wind resistance

assisting the plane with slowing down to

a safe taxi speed on the ground it may

also be used in flights to help a plane

descend faster however they will only be

partially extended the main issue with

this is that they creates a lots of

turbulence error which causes the wings

and the plane to vibrate

you also get a sort of a rushing wind

noise so both of these effects can be

uncomfortable for passengers so I hope

that explains the basics of how a wing

produces lift now of course there is a

lot more to it

you know understanding how atmospheric

pressure plays its parts in keeping the

air flow connected to the surface of the

wing understanding things like lift

coefficients but honestly the physics

behind it all gives me a headache anyway

if you enjoyed this video and would like

to see more ABS and related videos in

the future hit that subscribe button to

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videos as soon as they're released

speaking of new videos the next one will

be very appropriate for this time of

year it's going to be all about ice and

the dangers that it poses to aircraft so

for now or thank you all very much for

watching it take care out there and I

will catch you all later