Aircraft Design 2 – Stability calculation with AVL - ITLiMS

The Faculty of Power and Aeronautical Engineering of Warsw Uniwersity of Technology – Aircraft Design Department
Project 6 – Longitudinal static stability and control
Program AVL for aerodynamic and aircraft dynamic stability, originaly written by Mr.
Mark Drela and Mr. Harold Youngren, is available free on GPL license on web page:
http://web.mit.edu/drela/Public/web/avl/. Although, the program has text user interface and
simple graphics, it demonstrated it’s usefulness and is still improved and updated. Model
sailplanes designed with use of AVL can be seen on:
http://www.charlesriverrc.org/articles.htm.
Students should download from the page:
- Binary version of the program appropriate for the system they use, example:
avl327.zip (name of the downloaded file may change with the versions). After
unpacking the program is ready to use without any installation.
- Text documentation for AVL avl_doc.txt, which contains detailed description of AVL
functionality.
- Short tutorials session1.txt and session2.txt. It is strongly recommended to go through
this tutorial to get familiar with the software.
- Files with run cases runs/ directory, which contain example geometry of planes, mass
distributions, flight conditions (run files) and other.
Unpack AVL in desired work directory. Get familiar with the software by going
through tutorials using example geometry and mass files. Modify example files to suite
geometry and mass distribution of your airplane and save it under new name. Make
aerodynamic and dynamic flight analyses for cruise conditions. Show computed dynamic
stability eigenvalues. If plane is unstable, modify geometry or mass distribution to stabilize it.
Tips & Trics:
- Reading manual is unavoidable, but it is possible to use AVL efficiently after one day
of learning.
- If you start AVL from script or shell you will be able to read why it crashed even if it
crashed.
- Read what is displayed on screen, it might tell you about your mistakes.
- After opening program “LOAD” some geometry otherwise AVL won’t let you do
anything else.
- Type “?” to get list of available commands.
- Modifying example files is butter than building your own from the beginning. This
let’s you avoid mistakes in the text files.
- Make small changes in the text files and control many times if you are still able to load
them. Make backup of files from time to time.
- Pay attention to units. It is advised to use SI units: meters and kilograms.
Jacek Mieloszyk – Project Guide: Longitudinal static stability and control 1/2

The Faculty of Power and Aeronautical Engineering of Warsw Uniwersity of Technology – Aircraft Design Department
Requirements:
Aerodynamic analysis (OPER)
o Plot of geometry with pressure loads
o List of aerodynamic derivatives
o Neutral point in percents of MAC
Jacek Mieloszyk – Project Guide: Longitudinal static stability and control 2/2