AVL Tutorial (1) - Basics, Program Structure

This AVL Tutorial - Part 1 - will teach you the basics and program structure of the Athena Vortex Lattice Code, which is very useful for quick and reliable Aerodynamic Analysis, Trim Calculation, Dynamic Stability Calculation.
I used it extensively in my Bachelor Thesis and further works on the battery-electric touring motorglider FVA 30 (www.fva.rwth-aachen.de/), as a research assistant at the Flight Systems Dynamics Institute of RWTH university (www.fsd.rwth-aachen.de/) and for personal UAV and model aircraft design.
AVL was written by Mark Drela and Harold Youngren (Massachusetts Institute of Technology).
"AVL is a program for the aerodynamic and flight-dynamic analysis of rigid aircraft
of arbitrary configuration. It employs an extended vortex lattice model for
the lifting surfaces, together with a slender-body model for fuselages and nacelles.
General nonlinear flight states can be specified. The flight dynamic analysis
combines a full linearization of the aerodynamic model about any flight state,
together with specified mass properties."
More information on web.mit.edu/drela/Public/web/avl/

[@fabioli96]

Nice Video, thanks! I hope to see new AVL video tutorial in future :)

[@BenjaminKelm]

Thank you! I'm currently uploading the next one ;)

[@ricokonratt]

Great video, thx for the work.

[@BenjaminKelm]

Always Rico ;) Looking forward to see your wing take off!

[@razorx6472]

15:30 Giving Elevator Deflection 16:45 Saving Stability Derivatives to .txt file 17:45 Saving the Plots

[@ronaldpandolfi1264]

Great Video. I would like to see one on using AVL for Blended Wing Body aircraft.

[@BenjaminKelm]

Thank you. Try it out yourself, should be possible with what you'll learn in this series

[@ishitmehta3057]

Such an amzing tutorial! It's the only one that actually shows how to run and navigate your way throught the program. Just one thing - Once i open the geometry plot, I am not able to change any angles or views if i want to look at the model differently. Any I enter the K command for keystroke, but then i get a message saying the window size has changed and neither the plot window nor the cmnd prompt accept any commands.

[@nawfhou9223]

I am having the same problems, i can follow the video except for when it comes to the geometry window. Once its opened, I cant use any command regardless of what AVL window i click on. The program essentially freezes and I have to close and re open.

[@nawfhou9223]

actually, the issue occurs once i press K, If i dont press K, i can still make adjustments and ad load, but once i try to move the geo, it freezes

[@danieleaccomazzo2796]

@@nawfhou9223 I had the same problem, then I tried with an older version (AVL 3.36 executable for Windows) and that works properly. Hope it helps!

[@captainlambo3443]

@@nawfhou9223 HI, have you solved the problem? i'm haveing the same. and i could not fix it even have tried an older version.

[@1125MG]

I solved this problem. If you compile directly according to the manual of the zip file, you can use the keystroke mode

[@alialemi9574]

Thank you Benjamin for your nice video, I watched them and they are really useful, I have a question about loading distribution, is it possible to export loading distribution?I mean exporting pressure distribution on the wing or body for all coordinate points, depending on x, y and z. I tried FS or FE but I thinks they are not what I want. Thanks a lot. Ali

[@BenjaminKelm]

Hi Ali, if you use FE, AVL will spit out the element forces, including the dCp (Pressure coefficient) for every single calculation point on the lattice.

[@ragingcanadian8987]

Hello Benjamin! I have thoroughly been enjoying watching your tutorial videos as they have been extremely straight forward and informative. I was curious if i wanted to save .ps files in a specific folder, what would i type in AVL so it directs the .ps download into that folder on windows?

[@BenjaminKelm]

In windows you just do relative paths... where you execute your .exe, there it will also spit the output

[@Chloe-o8j]

Thanks for the video, it’s very helpful! I am wondering why is it the case that my Oswald efficiency is sometimes larger than 1 and sometimes it is negative? And as I increase the aspect ratio, the Oswald efficiency somehow decreases, which doesn’t make much sense. On the other hand, for a rectangular wing, avl somehow predicts the Oswald efficiency to be 0.9933 and it seems too high, I am wondering how accurate is the avl Oswald prediction or if I potentially did something wrong? Thank you so much!

[@hedleyfurio]

do you know where i can find 'carbon dragon.avl' as used by drela in his mit aerodynamics youtube course

[@BenjaminKelm]

Not sure where this is file can be found. Try searching it in the example folders of the AVL program

[@turddisturb]

Hi. I am using a mac too but the problem is that I can't open the file avl3.35. It says that there is no application set to open the file. How do you open it?

[@BenjaminKelm]

There's a ready built mac version of AVL - avl335_MacOSX.zip Just be sure to install X11 (see also XWindows or XQuartz)

[@MrWANTED44]

Thank you, Ben! How can I use it for a free-to-rotate wing airplane?

[@BenjaminKelm]

Well, principally yes, but you would have to calculate all of the operation points yourself. You can't add "free rotating" bodies

[@mariopegani]

Very useful content. How can I store the surface force results of more than one case in the same text file?

[@BenjaminKelm]

I would't know - Why not just have multiple files in a specific folder?

[@aluminiumjay9271]

Hi Benjamin. Are you the Benjamin who used to participate in some rcgroups discussions on airfoil design. ? (Hand launch and DS) . If so I'd love to see some videos from you on airfoil design. Thanks heaps anyway for the great job you have done here and your consideration.

[@BenjaminKelm]

Hey Jay, thanks for the comment. That have must been another Benjamin. But I'd love to do something on airfoils soon (I'm actually planning to do a "Drela-Program" video line, including XFOIL, QPROP or XROTOR etc. What would you like to learn on airfoil design?

[@aluminiumjay9271]

@@BenjaminKelm Hi Ben, thanks for the reply. A few cases on inverse design would be great. Ideally along with proper analysis behind the moves, meaning, with small explanation on the trend we are anticipating before the move. Also if you have access to it, a couple of videos on MSES will be priceless because there are non in the public domain. Thanks

[@xcvb2347]

How can i save just my CL distribution? I mean the values of CL in function of y

[@farehebahrami]

How can i have Dutch roll, short phugiod and poles in trim condition???

[@BenjaminKelm]

Just go into the .MODE menue and do your calculation there.

[@cvarun9055]

AVL isn't giving me the loading and the trefftz plane after I put in all the commands, any idea where it might be going wrong?

[@BenjaminKelm]

You would have to specify your setup. Generally, try to work on either windows or Unix based systems supported for the application

[@arnavketkar2104]

What did you use to open the plot.ps file?

[@BenjaminKelm]

In Mac you can just use the Preview Application to view these *Postscript* files On Windows there are other programs you need to install to view these - GIMP for example

[@arnavketkar2104]

@@BenjaminKelm thanks a lot

[@arnavketkar2104]

@@BenjaminKelm also can you make a video on how to do dynamic stability analysis using AVL please?

[@shibaowang5016]

Hi, could you share the Flight vehicle dynamics, Thanks!

[@BenjaminKelm]

No, sorry, please purchase that yourself

[@SpaceCowboy1301]

can i use that for a formula 1 car? thanks for the video

[@BenjaminKelm]

Not really made for that. In F1 DRAG is your main concern - where here you want to know the lift distribution.

[@akarshshetty9262]

What application do you use to start the AVl application.... I'm unable to find it😅

[@travelvlogs0511]

Do you find any software to start avl

[@Fabian-is3uf]

same! what did you do to solve the problem?

[@kiliang49]

since the file is named avl3.35 it can be that your computer interprets the .35 as a file extension. Rename it to "avl335" and try again :)

[@BenjaminKelm]

Sorry for the late reply. Depending on your system (here, Mac) you might need to compile it beforehand into machine code. Then launch it over the Command Line Tool (Shell). For windows and Mac there are pre-compiled versions available on the MIT AVL site.

[@enzo_wl]

no para today?????

[@BenjaminKelm]

Not today, but I have a lot of material. I hope I can find the time soon ;)