Understanding Aerodynamic Lift

Humanity has long been obsessed with heavier-than-air flight, and to this day it remains a topic that is shrouded in a bit of mystery. In this video we take a detailed look at lift, starting with how it is linked with the pressure distribution around airfoils. We also cover a few different explanations of lift, including the Bernoulli Principle and Newton's Third Law explanations. Circulation is a key aspect of lift that it is important to grasp to develop a more complete understanding of lift so that's covered too, as is the Kutta condition. Finally we explore how the lift force varies with the angle of attack of the airfoil (which explains why aerobatic aircraft use symmetrical airfoils), and how stalling can result in a dangerous loss of lift.

If you'd like to read more about lift I highly recommend the textbooks Introduction to Flight and Fundamentals of Aerodynamics by John D. Anderson Jr. The paper "Babinsky's Demonstration: The Theory of Flight and Its Historical Background" published by J. A. D. Ackroyd in the Journal of Aeronautical History also provides some interesting history around theories of lift.

---

This will allow me to create more high quality videos covering a range of engineering topics.

---

The Efficient Engineer is a channel aimed at mechanical and civil engineers. The mission is to simplify engineering concepts, one video at a time!

[astro_gabe]

As a fluid flows around the airfoil, it creates three different kinds of stresses: shear stresses, pressure stresses, and engineering student studying stresses.

[deprecated]

I've been studying Aeronautical engineering for the last 7 years and I've been playing with some Aerodynamics projects for the last 2 years and I have never found a better explanation of Lift in the entire Internet, amazing job, clean and intuitive speech, wonderful animations and a solid theoretical background. My biggest congratulations for you man! You're Top engineering content creator, keep going!

[pushingthrottles]

2 semesters of advanced aerodynamics and a 4 year aviation degree i learned about lift. This 15 minute video simplified such a complex subject in a way that is easily understood! Phenomenal video... thank you!

[MrDavids]

You always happen to upload the topics my uni projects are on at the time and i love it

[uiggukx]

Guys that you are making these videos...I am incredibly grateful for your work. I am doing my MSc on Advanced Mechanical Engineering in a great university of UK. Literally, the help that you have provided me is out of this world. I am telling that with all the reality that possesses me. A combination of studies and your videos on Engineering Field have launched my knowledge on many fields. Thank you so so much. Keep working! You are changing the process of studying and unfold the engineering complexity on many fields. Good job!!

[gerrykambita]

That subtle background music, please don't dump it. Dont ever stop using it. Makes the videos doper🥺
I love your videos and please keep it up!

[AhmedAtef-jhup]

one of the best videos about lift, often when they want to build an intuition they state the Bernoulli Principle or Newton's Third Law but Never the Circulation and Kutta theory these we studied only at university and they always focus more on the math and calculation than on understanding, your video has a nice balance between the two.

[egamez]

I'm an A&P mechanic and engineer and this is the BEST explanation of how lift works on an airfoil. Thank you for this video.

[centaureacyanus]

Amazing explanation as always. I loved that you touched on the circulation aspect, because it often is not explained or mentioned as a reason of the velocity increase. Super thankful and so happy to see the extended version on Nebula! Thanks mate!

[Jordanian]

والله انك زلمة كفو قعد المهندس ٤ محاضرات وهو بشرح فيه عالفاضي ما فهمتو بس بفيديو ربع ساعه فهمتو منيح
جد شكرا عالفيديو الرائع عراسي استمر😍

[AvWoN]

Probably the best video on this topic I have ever seen, and I have watched a few over there years because I come back for a refresher now and then. This one is top notch.

[spaceshuttle]

YES!! THANK YOU. Finally someone who knows what they’re talking about. Circulation is the correct explanation for lift

[adb]

Dear The Efficient Engineer, as an Aeronautical Engineer who used to teach Aerodynamics at the uni, and did so proudly, and usually get upset with the poor or directly wrong explanations usually found in youtube, I want to tell you one thing:
*CONGRATULATIONS*
For a video that scratches the surface and is intended to be accessible to the general public, this is *EXCELLENT*.
Yes, concepts were simplified, but all the explanations were CORRECT (unlike most of the videos on the subject).
Every time while watching this video that I said "uh-oh" you quickly eliminated any concern that was starting to appear in my head.
"Engineers still debate how lift is generated" That is much better than the usual "We still don't fully understand how lift is generated"
"Bernoulli and Newton" presented NOT as two contributions to lift, but as 2 ways to approach the explanation of the same phenomena.
"Pressure on the top is lower because the air flows faster than on the bottom" Uh-oh, I thought, here comes "equal transit times". Nope. It was so satisfying to see those fluid parcels on the top arrive to the trailing edge before the lines on the bottom.
And also, I thought, you were committing the same mistake than many by saying that the lower pressure was caused by the faster speed, when in fact we could also say the faster speed is caused by acceleration that can only be caused by the air parcels running along a path of a negative pressure gradient (or, in another words, the lower pressure causes the faster speed). But then you explained how the three things affect each other and act concurrently, not one causing the other.
You were one (or several) steps ahead of me all the time and you won on every thing that I forecasted you were going to say wrong.
I am so happy for having been wrong every single time I thought that.
It was simply *BRILLIANT*.

[BenDurante]

Taking an aerodynamics course currently and this summed up everything covered thus far perfectly!

[brianbeasley]

I have only one minor nitpick at the very end. Pilots generally do not want higher lift for takeoff and landing. They generally want the same lift capability (enough to lift the aircraft) at a lower airspeed. The reason we want a lower airspeed is usually to allow a takeoff in a shorter distance and land either in a shorter distance or minimize the energy at landing to minimize wear on the tires or in case there is an accident, a lower speed is less dangerous. With high winds, we may want to keep our speed up for better control so we often don't use as much flaps.

Other than that, I loved the video!

[jose]

Current aerospace senior, I have “learned”(the best a struggling engineering student can), and seeing your video helped me understand how all these concepts tie together. Learning everything in detail was a headache and stress inducer, but taking step back and seeing the broader picture has made me realized I actually learned a lot. Great job keep up the awesome work

[sepehrhosseinkhani]

Overall very great video! However, one thing that is important to mention is that the lower air pressure does not "suck" on the airfoil as is implied by your pressure distribution illustration, but rather that the lower pressure on the top surface is pushing less on the body than the higher pressure along the lower surface.

[diegohidalgogarrido]

Probably the best and only video online that actually explains this topic in an intelligent and complete way. This is pure gold!

[xTheUnderscorex]

Finally found a single youtube video on this which is actually correct about the basic mechanism of lift generation.
It's a little sad how unique that actually is, but for some reason it seems to be just about the single topic with the most pervasive misconceptions circulating about it.

[planettobi]

Im studying flight principles for my ATPL rn so this video came out at a pretty perfect time!