StabVSP

Python script for evaluate stablity using OpenVSP's stab file. Current version: v0.1.

Scripts' Description

There are two scripts and can be launched separately.

The first script Inertia.py calculates the moment of inertias. It reads input file Mass_Inertia_imp.txt and outputs the total moment of inertia into Mass_Inertia_out.txt. Each line includes CGx CGy CGz m(mass) Ixx Iyy Izz Ixz in SI units. Ixy and Iyz are not calculated because the aircraft is considered to be symmetrical in these two directions when analysing the stability.

The second script StabVSP.ipynb reads .stab file and inertia file in the specified dirs (corresponding with each configuration), saves these data in a python class, and evaluates both static and dynamic stability of the aircraft.

For static stability, the inertia file is not needed. Just comment lines for reading inertia, and plot the aerodynamic coefficients or derivatives, such as Cm or Cnbeta.

For dynamic stability, the eigenvalues and eigenvectors of small pertubration equations in body axes are calculated, in both lonitudinal and lateral directions. Note that this program needs the aircraft's pitch angle $\theta$ (the angle between x axis in body axes and the ground) and climbing angle $\gamma$ (the angle between velocity and the ground) as inputs. the pitch angle is used in lateral dynamic stability's calculation, and the climbing angle is used in longitudinal dynamic stability's calculation. You can set them as zero in the initial analysis.

Usage, Examples and Standard Models

Firstly, calculate aerodynamic derivatives in OpenVSP, and inertia using Inertia.py(optional if you only evaluate static stability). Then drop the .stab file and inertia file into one directory, and write the path into the variables in StabVSP.ipynb. Then run the .ipynb script. Skip the parts about inertia files if you only evaluate static stability.

See Examples directory which includes a flying wing aircraft Progress 6. Please refer to .vsp3 and .vspaero file for the settings for stablity analysis settings in OpenVSP.

A standard model in NASA report TM-4640 will be added in the future to. The comparison result of the aerodynamic derivatives between OpenVSP's VLM methods, VLM513's VLM methods and windtunnel test results are needed to be added. VLM513 is a MATLAB program developed by SONG Lei in BUAA which is more precise in calculating lateral aerodynamic derivatives.

Reference & Cite

This script is used in the paper “李志锴,魏莎,丁虎,等.平直翼飞翼布局飞机的操稳特性[J].上海大学学报(自然科学版),2024,30(05):925-937. ”

The small pertubration equations, the meaning of each aerodynamic derivatives and state derivatives can be found in "方振平, 陈万春, 张曙光 编著. 航空飞行器飞行动力学[M]. 北京: 北京航空航天大学出版社, 2005." The calculation of moment of inertia is based on "郭茂政. 论惯性积的平移变换和旋转变换[J]. 大学物理, 2004, 23(6): 23."

If you need to cite this program, please cite this GitHub page or cite the paper above.

@misc{StabVSP,
  author = {LI Zhikai},
  title = {{StabVSP}: Python script for evaluate stablity using VSPAero's aerodynamic derivatives result. },
  year = {2025},
  publisher = {GitHub},
  journal = {GitHub repository},
  howpublished = {\url{https://github.com/Kai2510/StabVSP}},
}