Aircraft Longitudinal & Lateral/Directional Models & Modes (Phugoid, Short Period, Dutch Roll, etc.)

[@ChristopherLum]

In case it is helpful, all my Flight Mechanics videos in a single playlist are located at kzbin.info/aero/PLxdnSsBqCrrEx3A6W94sQGClk6Q4YCg-h. You can support this channel via Patreon at www.patreon.com/christopherwlum. Please let me know what you think in the comments. Thanks for watching!

[@milesrobertroane955]

AA516: Great explanation of the different modes! For my final, I am going to be doing the visualization. Can't wait to get it working to see them in real time!

[@hasanhorata8381]

AA 516 - No questions, just wanted to say how cool it is to see everything tie in together from what we have been doing the entire quarter!

[@ChristopherLum]

I know, isn't it cool how the math predicts all this real world behavior?

[@BenDurante]

As always, another very helpful video! I really appreciate how your videos can distill days worth of textbook reading and cross-referencing into a single video.

[@ChristopherLum]

Ben, thanks for the kinds words. It is always good to hear from you on KZbin. Thanks for watching!

[@reesetaylor3506]

AE512: Appreciate the visualization of the different longitudinal modes, helps to solidify what is actually going on in the state traces. Great video!

[@yaffetbedru6612]

AA516: I enjoyed the visuals that you pulled up to show how the different modes looked in the simulated environment. Thanks Professor!

[@sianhoan833]

AA516: Finally! This is my most awaited video of this course, and it's great to see everything comes together to help build an intuitive understanding of these modes.

[@ChristopherLum]

I'm glad it was satisfying, it has been a long journey and I agree that it is fun to see how we can leverage our past results to get to this stage.

[@aimeepak717]

AE512: I liked the extensive discussion on the modes. Thanks!

[@rwikrana]

AA516: Awesome explanation about phugoid and dutch roll modes!

[@Kumky605]

AA516: I really enjoyed the visuals! Glad to see everything we've been learning coming together

[@AlexandraSurprise]

AA516: Super cool how these modes can describe real life occurrences in the aircraft model!

[@milesbridges3547]

AA 516: Amazing to see all the class content come together. This video has been super fascinating to watch!

[@ChristopherLum]

I'm glad it was satisfying, it has been a long journey and I agree that it is fun to see how we can leverage our past results to get to this stage.

[@princekeoki4603]

AA516: Great visuals with the simulator for demonstraing the different kinds of modes

[@evaristoreyes3583]

Bro I love u, you help me with my flight mechanics exam!

[@zaneyosif]

AE512: Great to see the eigenvalues of the different modes and visualized on the real/imaginary plot to explain the behavior during the state traces.

[@Colin_Baxter_UW]

AA516: Enjoyed learning about the phugoid and dutch roll modes.

[@petermay6090]

AA516: So cool to see everything coming together!

[@AhmedSamir-lz6gr]

Super Interesting! I am waiting for a video explaining designing the corresponding controllers using cascaded successive loops. Great job, Prof!

[@ChristopherLum]

Hi Ahmed, Thanks for reaching out. If you have questions or would like to request a video, I hope you'll consider supporting the channel via Patreon at www.patreon.com/christopherwlum. I'd love to have you as a Patron as I'm able to talk/interact personally with Patrons. Thanks for watching! -Chris

[@dilmismain3709]

Very interesting course for basic flight mode and we would like to introduce the superior mode for the guidance and navigation

[@EomjiKim]

AA516: 26:54, in terms of A_long = A(1:4,1:4), is this same as Atilde(1:4,1:4)? I think A, here, is new matrix A(Atilde) because it has longitudinal states information in its(1:4,1:4). However, there are no tilde symbol in the video and lecture note(page 8), I'd like to confirm.

[@EomjiKim]

I got the answer from the past reply:) A_long = Atilde(1:4,1:4)

[@binyulong5995]

AA 516 This is such a cool lecture, you did a great job making such a complicated system intuitive for students. I have a canard pusher prop drone that I am designing in my free time and I was considering mounting the motor onto a 2-axis robot arm to make a "vector thrust propeller" to replace the rudder. However, because of the gyroscopic precession caused by rotating a spinning propeller, I wasn't sure about how to design the control algorithm to make it fly the airplane as I wanted. Your lecture shows me the way to analyze how it might affect the different states of the aircraft. Thank you!

[@ChristopherLum]

I'm glad they are helpful, keep me posted on your project, it sounds very interesting!

[@rileyjohnson1003]

AA 516 In using the modal similarity transformation to calculate a new initial condition to use for exciting the various modes, I've used x = Tz where T is the matrix of eigenvectors. However, this transformation results in a complex valued vector for me, and not a double, as expected. What is the process to get from z(0) to x(0) at 46:23?

[@ChristopherLum]

Riley, I just saw this. Did you get it worked out?

[@rileyjohnson1003]

​@@ChristopherLum Yep! It helps a lot to make sure you keep the latitudinal and longitudinal vectors in the right order.

[@edwardmau5877]

AE 512: The review in the beginning helps piece all the previous videos together to form the final picture.

[@Gholdoian]

AE 512: Sounds like you could use the eigenvector similarity transform on the B matrix to see what inputs excite which modes and use that as inputs to perform some system identification in flight/on orbit to verify the modes of the system? Instead of trying to put the vehicle in a specific state, like you said.

[@Gholdoian]

How do the eigenvalues of a fighter jet look? Are some on the RH side of a pole-zero as the instability would help with being very responsive?

[@tonymcdaniel6878]

AA516: I was wondering how do you go about avoiding those dynamics modes, or if there are times you would even want to go into those modes?

[@bsgove]

AE512: I find the discussion of short period and phugoid a little bit confusing because it sounds to me like a phugoid mode has 2 requirements: minimal damping (short duration) and long sinusoidal period. But what if you have a phugoid with a small sinusoidal period that dies out slowly? Is it still a phugoid mode?

[@nathanlipshutz3140]

AE512: If something like a slightly positive divergence eigenvalue existed for an autonomous system, would the linear controller be able to deal with it, like a pilot would? We've never looked at a case of eigenvalues with positive real parts being acceptable.

[@ChristopherLum]

If it is slightly in the right half place or means that it slowly grows. As such a human pilot or slow controller can handle it

[@ramkrishna-zp1rn]

Hello Christopher, That was an excellent anatomy of different modes of an Aircraft and its behavior. However, I'm working on a TECS controller and I kindly request you discuss the Eigen structure assignment method on the same RCAM model to design a MIMO controller for both the directional modes which would be a great conclusion to your playlist :) Thanks and Regards Ram

[@ChristopherLum]

Hi Ram, Thanks for reaching out. If you have questions or would like to request a video, I hope you'll consider supporting the channel via Patreon at www.patreon.com/christopherwlum. I'd love to have you as a Patron as I'm able to talk/interact personally with Patrons. Thanks for watching! -Chris

[@davidtelgen8114]

AE512: (58:51) You should've been a speed skater!

[@jeevankarthik5017]

hi professor, can we apply the same concept for a fighter jet in steady level flight?

[@technontechwithsumitohdar932]

Hi professor....can i use different- different controller to study further, after linearized model of RCAM

[@kennethwilsey6260]

AA516 Should the longitudinal and lateral A & B matrices be derived from Atilde(1:4, 1:4) and Btilde(5:8,5:8), or is it actually plausible for us to take A(1:4,1:4) and B(5:8,5:8) [which was shown in the video]. Thanks for the great video

[@ChristopherLum]

Kenneth, slight correction, Along = Atildle(1:4,1:4), not A(1:4,1:4). Otherwise, that is all you need to do, no derivation necessary.

[@bsgove]

AE512: I should've watched this lecture before beginning hw9! I ended up coming to the same conclusions with some of this stuff but in a more round about way.

[@peter_b.1337]

It maybe a stupid question, but what matrix are those eigenvalues from? A, B or concatenated A and B?

[@scose]

A. If we had a linear feedback controller u = Kx then we would also want to look at the eigenvalues of A - BK. But here we are analyzing how the aircraft behaves with no control inputs.

[@marcosszmania5874]

AE 512 - Hi Professor Lum. Any idea why I get different eigenvalues if I use Mathematica in lieu of Matlab? Eigenvalues[A] is giving me different results than [V,D] = eig(A)

[@ChristopherLum]

Marcos, that sounds fishy, the eigenvalues should be the same. That being said, the ordering may be different. Can you show me at office hours?

[@rowellcastro2683]

AA516: 1:04:30 FAA has entered the chat lol. Control tower has a number ready for you to call haha.

[@ChristopherLum]

You sound like a pilot :)

[@rowellcastro2683]

@@ChristopherLum Currently a Part 107 remote pilot but the plan is to be a "real" pilot one day! But right now GNC is much more interesting than pilot training!

[@ChristopherLum]

@@rowellcastro2683Nice, I also went through the part 107 certification but as you observed, the engineering and design is much more interesting

[@txemagonz]

Thank very much for all this wonderful content, Mr Lum. As a supporting fact what is said around minute 32 when you talk about the eigenvalues in the longitudinal decoupled system, the imaginary part of the poles gets excited when performing a bad landing. So it is usually said that if you bounce while landing you better touch and go. Otherwise a second and bigger bounce follows and in the third one the crash would be a secure fact. Nonetheless I saw very experienced pilots adding a dash of gas changing the elevator configuration to perform a satisfactory landing. Here is an example for the shake of completion: kzbin.info/www/bejne/rma9q56qdqt9gZY . In 1:11:38 we can also see that delta u = -1.99 (decelariting) and delta w = 0.18 (going down), like in the landings if I'm grasping it clearly. Thanks again for the content!!!

[@ChristopherLum]

Hi, Thanks for the kind words, I'm glad you enjoyed the video. If you find these videos helpful, I hope you'll consider supporting the channel via Patreon at www.patreon.com/christopherwlum or via the 'Thanks' button underneath the video. Given your interest in this topic, I'd love to have you a as a Patron as I'm able to talk/interact personally with all Patrons. I can also answer any questions, provide code, notes, downloads, etc. on Patreon. Thanks for watching! -Chris

[@peter_b.1337]

isn't it a copypaste mistake in matrix A at 22.17?

[@ChristopherLum]

Hi, Thanks for reaching out. If you have questions or would like to request a video, I hope you'll consider supporting the channel via Patreon at www.patreon.com/christopherwlum. I'd love to have you as a Patron as I'm able to talk/interact personally with Patrons. Thanks for watching! -Chris

[@aisyramaz5071]

are u aerospace engineer?

[@chayweaver.2995]

AE512: Would be an interesting discussion to show why imaginary values yield oscillatory Reponses in this 'real world' engineering example

[@WalkingDeaDJ]

Jason-AE512: This video is a little bit more complicated than others lecture.

[@ojasvikamboj6083]

A A 516: Ojasvi Kamboj

[@shavykashyap]

AA516

[@Po-ChihHuang]

AA516: Po