How Wings ACTUALLY Create Lift!
Summary
TLDRThis 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
🛫 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.
🔧 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.
Mindmap
Keywords
💡Wing
💡Aerofoil
💡Bernoulli Principle
💡Lift
💡Coanda Effect
💡Angle of Attack
💡Stall
💡Flaps
💡Leading Edge Slats
💡Spoilers
💡Atmospheric Pressure
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
make sure that you receive any new
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
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