Thin airfoil theory [Aerodynamics #12]

[@moroit1]

This is a goldmine for someone studying aerodynamics. Our professor's approach on these is to do almost exclusively math heavy theory without any kind of visual explanation / aid on what we are actually trying to do. It makes understand this kind of subject difficult at best. Your approach is the opposite with great visual aids and clear explanations on to the point.

[@prof.vanburen]

I'm glad you resonate with it and I felt a lot like you did during my first few aerodynamics courses!

[@byagnik]

Very few KZbin channels are dedicated towards Aerodynamics. Thanks for the initiative!

[@prof.vanburen]

Thanks! Hope you find it useful

[@maxalanchen7866]

This is the best thing I've ever seen, thank god I found this before my aerodynamics exam.

[@prof.vanburen]

I'm glad you found it! Good luck on the exam.

[@curtisgoldin]

HAH. Sup Max. I am also here watching this through tears before tomorrow morning.

[@maxalanchen7866]

@@curtisgoldin oh yeah, it's cry time. I'm shooting for any grade higher than an F.

[@msergejev]

That's all pretty sweet. I got a job related to flight mechanics which I have never done before in my life since I studied control system engineering, so here I am now watching these videos :D They are so darn good tho I kinda regret. not studying aerospace before

[@willm6598]

If it wasn't for these videos covering my book, I would not be able to pass this class, you are such a great teacher

[@prof.vanburen]

Aw thanks! Glad you liked them

[@alexanderpayne1410]

Thank you! These videos are so useful. I have watch the first 12 in this series today and have learned more about aerodynamics than I have in an entire semester from my aero 1 professor! Do you currently have any videos of you working any real world examples of these problems? I find your videos so good that I even watch them leisurely haha! Best of luck with the channel

[@prof.vanburen]

Thanks for the kind words and I'm glad you find them useful! Sometimes even just changing a learning format can help. Right now I am finishing the Fluid Mechanics series with a few more videos to go. After that, I will definitely consider something that connects these courses to real life engineering problems.

[@YitzharVered]

Thank you so much for making this series! I'm finishing my degree in physics this year, but I've always, for I believe obvious reasons, been drawn to the whole realm of aerodynamics. I've studied fluid dynamics from an old book I found in the library, but this is really what I want to be studying! The whole field seemed completetly unapproachable, but now it doesn't! Thank you again!

[@prof.vanburen]

Happy to do it!

[@CarlosAntonioMejiaMazuera]

Excellent. Although it involves advanced mathematics it is very well ordered for a full understanding. Congratilations.

[@prof.vanburen]

Thank you!

[@karldergrosse431]

Thank you a lot for this video! You have a great KZbin-career ahead of you :D

[@prof.vanburen]

Thanks!! I'm glad you find it useful!

[@bluemantle8269]

Hello Prof. I have a doubt, in the last video u said the strength of the vortex panels are constants but here in 3:27 u say they have varying strengths. Plz help

[@prof.vanburen]

Hi and sorry I am late to this! Where in the previous video are you referring to? The vortex panels can vary in strength distribution.

[@manoj_kr1457]

Bro what your doing is really great We can not get good videos in aero field that clear all doubts. I appreciate you for doing this, I don't what to comment but, I have to get more clear of our doubt. Your writing the letters and equations very small that we are not able to your explanation at your speed. Can please increase the size of the letters, this is just a suggestion.

[@prof.vanburen]

Thanks! Definitely, the writing can get small and fast, and I have horrible handwriting. If it helps, a PDF of the notes themselves are uploaded to my website: sites.udel.edu/vanburen/education/ those notes should be zoomable and may be a good reference for the older videos with small font

[@manoj_kr1457]

@@prof.vanburen oo thank you bro this is really nice of you , Thanks for replying.👏👏👏

[@msergejev]

@@prof.vanburen I dont find the handwriting so bad to read, in some lectures letters do get small (e.g. in previous lecture in integration it is hard to distinguish N/A and L/D). I think both writing and illustration is quite pleasant to watch and it is quite different from many other video lectures that just feel "dry". Also, even tho sometimes content is quite fast (you can always pause and ponder), there is a well structured and logical flow. Small improvements are always good, but overall - a very quality content. Reminds me on one of my favorite lecturers on control system theory: kzbin.info

[@prof.vanburen]

@@msergejev Thanks for the kind words! Brian Douglas at Control Systems Lectures is actually what inspired the format, their channel is awesome

[@Shakau24]

I found it very useful and yet simple. Thank you

[@prof.vanburen]

Thanks for the kind words!

[@msergejev]

I am a bit confused about equation (1). Shouldnt it be alpha PLUS Theta rather then MINUS? Wouldnt (for fixed AOA) increasing Theta increase "perpendicularity" between airfoil element and the free stream? Also if Theta = atan(dy/dx), and approximation is that tan(theta) ~ theta can we just replace atan(dy/dx) with dy/dx? Approximation is valid for tan, but does it mean it is valid for atan as well?

[@prof.vanburen]

Thanks for the keen eyes Amir!! I think you're right, there's a bit of a signage mix-up here. In this case, I think it would be a PLUS theta and the dx is technically negative so it would be tan^-1(-dy/dx). Ultimately, the next line has the correct signs. For your second part of the comment, it depends on your tolerance for small angle approximations, but atan(x) = x within 1% for angles up to 10 degrees. I think the line of equation (1) already has the small angle approximation you suggested.

[@msergejev]

Thanks for the reply! I was a bit confused since approximation was written for tan(X) = x and theta was define as atan(dy/dx) so I wasn't sure if we can just replace atan(dy/dx) with dy/dx. Somehow intuitively I expected an inverse which is dx/dy, but that is not how this works at all :) In fact, when I gave it a bit of thinking, I think if some function like tan(x) can be approximated faithfully with a linear function of unity slope, then per definition its inverse can as well be approximated by the linear function of the same slope, (for same range of small perturbations) since function y = f(x) = x is an inverse function of itself. Anyways, I've plotted in matlab both tan and atan around 0 and they look very much the same, so it all adds up :)

[@prof.vanburen]

@@msergejev Plotting it out always helps me! I plotted it out in Wolfram before replying just to make sure

[@Caleb-tk8hg]

I think it’s {(pi/2 for n=1),(-pi/4 for n=2),(0 for n=3)} so it’s necessary to have 3 A’s per angle of attack: A0, A1, A2 (I’m an AE student 😅)

[@prof.vanburen]

I hadn't seen that! Where are you referring to? I have only ever seen the derivation that considers the zeroth and first mode.

[@flth1040]

Yes, it must be 3 modes with A0, A1 and A2. A3 is zero. MIT website is a good reference on this

[@thomasdrezet5076]

really great lesson, thank you

[@prof.vanburen]

Glad you liked it!

[@johnjoseph6634]

Hello Prof. Van Buren, If it is possible could you show us how to read the data of NACA airfoils, (for CL, CD Velocity and etc.)

[@prof.vanburen]

Hi John, that's a great idea! I definitely think adding a video about how to read the basic performance plots of an airfoil, like you would see in "Theory of Wing Sections" for example, and noting important features of the plots would be really helpful. I will add that to the list of upcoming videos!

[@johnjoseph6634]

@@prof.vanburen Thank you much appreciated for your support

[@markly5400]

Aree kuch samaj nhi aa rha kya padha rha hai.

[@prof.vanburen]

I think this translates roughly to "I don't understand"? Happy to help if you have any specific questions!