Introduction

Open source projects are a fantastic resource for learning, collaboration, and innovation. They provide a transparent window into real-world codebases and offer endless opportunities for customization. Aerosimulations.com hosts a growing library of open source simulation projects spanning aviation, aerospace, and more. Forking and modifying these projects allows you to tailor them to your own research, education, or hobbyist needs. This comprehensive guide will walk you through every step of the process—from creating your account to submitting your improvements back to the community. By the end, you will have the confidence to take any simulation project and make it truly your own.

Understanding Open Source and Forking

Open source software is built on the principles of transparency, collaboration, and shared improvement. When a project is hosted on a platform like GitHub or GitLab under an open source license, anyone can view the source code, suggest changes, and create their own derivative versions. Forking is the mechanism that enables this. A fork is a personal copy of another user’s repository that lives under your own account. You can experiment freely without affecting the original project. Once you have made improvements, you can offer them back via a pull request. This cycle of forking, modifying, and contributing fuels the open source ecosystem.

On Aerosimulations.com, most projects are hosted on GitHub and are licensed under permissive licenses (MIT, Apache 2.0, or GPL). Always check the license file before making modifications or distributing your version. Understanding the license ensures you respect the original author’s intentions while exercising your rights to modify and share.

Getting Started with Aerosimulations.com

Before you can fork any project, you need an account on Aerosimulations.com. Visit the site and click the Sign Up button. Complete the registration with your email and a strong password. Many projects also require a GitHub account because the underlying repositories live there. If you do not already have a GitHub account, create one at GitHub.com. Linking your Aerosimulations.com and GitHub accounts simplifies the forking process—you can directly fork repositories from the project pages.

Once logged in, browse the project repository. Use the search bar or browse categories such as “Flight Simulators,” “Aerodynamics,” “Navigation,” and “Vehicle Dynamics.” Each project page provides a README with an overview, installation instructions, dependencies, and usage examples. Take time to read the README thoroughly; it will save you many headaches later. Also check the issues tab to see known bugs or feature requests—these can be great starting points for your modifications.

Step 1: Forking a Project

After selecting a project you want to customize, locate the Fork button. On GitHub-hosted projects, this button sits at the top‑right corner of the repository page. On Aerosimulations.com, the button may be labeled “Fork this project” or simply “Fork”. Clicking it triggers a background process that copies the entire repository—code, history, branches, tags—into your personal namespace. You will be redirected to your new repository, typically at https://github.com/yourusername/projectname.

The fork is a full clone of the original project at the moment you forked it. It does not automatically receive updates from the original (upstream) repository. Later, you can add the original repository as a remote and merge upstream changes if you wish. For most customization work, the initial fork is all you need.

Step 2: Cloning the Repository

Now that you have your own fork, you need to bring the code to your local machine. Open a terminal (Command Prompt, PowerShell, or a Unix shell). Navigate to the directory where you want to store your projects. Use the git clone command followed by the URL of your fork. You can obtain the URL from the “Code” dropdown on your repository page—choose either HTTPS or SSH. For simplicity, HTTPS is recommended for beginners:

git clone https://github.com/yourusername/projectname.git

If you have set up SSH keys, you can use the SSH URL:

git clone [email protected]:yourusername/projectname.git

Cloning downloads all files and the entire commit history. Once the process finishes, enter the project directory:

cd projectname

You are now ready to start editing.

Step 3: Setting Up a Local Development Environment

Simulation projects often have specific dependencies—Python libraries, C++ compilers, or simulation frameworks such as Unreal Engine or Godot. The README or a requirements.txt file will list these. Install them according to the project’s instructions. For Python projects, it is wise to use a virtual environment:

python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate
pip install -r requirements.txt

For compiled languages like C++, ensure you have a compatible compiler (GCC, Clang, or MSVC) and any build tools (CMake, Make). Some projects provide a setup.py or Makefile that automates the build process. Run those as instructed.

Finally, run the simulation or test suite to confirm the project works out of the box before you modify anything. If it fails, troubleshoot the environment setup—common issues include missing system libraries, incompatible Python versions, or unset environment variables. Working with a known‑working baseline makes it easier to isolate your own changes later.

Step 4: Making Modifications

Now the fun begins. Open the project in your code editor (VS Code, PyCharm, Vim, etc.). Familiarize yourself with the project structure: configuration files (.json, .yaml, .cfg), source code (.py, .cpp, .js), assets (3D models, textures, sound files), and documentation. Start with small, well‑defined changes. For example:

  • Adjust simulation parameters such as gravity, air density, or frame rate.
  • Modify the user interface text or color scheme.
  • Add a simple new feature like a log output or a new key binding.

Best practices while editing:

  • Keep your changes focused. One logical change per commit makes it easier to track and revert mistakes.
  • Write comments where necessary, especially in complex sections. Future you will thank you.
  • Follow the existing coding style (indentation, naming conventions). Consistency reduces merge conflicts.
  • Do not commit generated files (e.g., .pyc, __pycache__, compiled binaries). Ensure your .gitignore is set up properly.

Step 5: Testing Your Changes

After making modifications, run the simulation again. Test the specific features you changed as well as existing functionality to ensure you have not introduced regressions. Many projects include automated tests—use them:

pytest tests/          # Python example
ctest                   # CMake example
npm test                # Node.js example

If the project does not have a test suite, adopt a manual testing checklist: launch the simulation, verify all UI elements, run through common scenarios, and monitor error logs. For simulation projects, pay special attention to physics correctness, frame rates, and resource usage. Fix any issues before proceeding.

Step 6: Committing and Pushing Changes

Once you are satisfied with your modifications, commit them to your local repository. First, stage the changed files:

git add .

This stages all changed files. If you want to stage only specific files, use git add filename. Then create a commit with a descriptive message:

git commit -m "Increase maximum throttle to 1.5 in turbine simulation"

Good commit messages explain why a change was made, not just what changed. Use the present tense and be concise. After committing, push the changes to your GitHub fork:

git push origin main

If the default branch is named master, use that instead. Your fork on GitHub now contains your new commits, visible under the “Code” tab.

Step 7: Creating a Pull Request

If you believe your modifications would benefit the original project, consider submitting a pull request (PR). Navigate to your fork on GitHub and click the Contribute button, then Open Pull Request. GitHub will compare your branch with the original project’s default branch. Write a clear description of your changes, referencing any related issues. Include screenshots or logs if applicable.

PR etiquette:

  • Be respectful and patient. Maintainers review contributions on their own time.
  • Be open to feedback. You may be asked to adjust your code or add documentation.
  • Keep the scope of a PR narrow. One PR per feature or fix.
  • Ensure your changes are tested and documented.

Once submitted, the maintainers will review your code. After approval, your changes will be merged into the upstream repository. You have now contributed to open source!

Beyond the Basics: Advanced Tips

Proficient fork modification involves more than just editing files. Here are several advanced practices:

Syncing Your Fork with Upstream

Over time, the original project evolves. To keep your fork up to date, add the original repository as a remote:

git remote add upstream https://github.com/originalauthor/originalrepo.git

Fetch the upstream changes and merge them into your local main branch:

git fetch upstream
git checkout main
git merge upstream/main

If conflicts arise, resolve them manually and commit. Then push the updated code to your fork.

Using Feature Branches

Instead of working directly on main, create a separate branch for each feature or fix:

git checkout -b new-throttle-limit

This keeps main clean and makes it easier to work on multiple changes simultaneously. When ready, merge the feature branch into main, or push it to your fork and open a PR from that branch.

Leveraging Continuous Integration

Many open source projects include CI pipelines (GitHub Actions, Travis CI, CircleCI) that automatically build and test your code when you push to your fork. Check the CI status after pushing. A green checkmark means your changes pass the project’s standards; a red X indicates something is broken. Fix the issues before opening a PR.

Contributing to Documentation

Documentation improvements are highly valuable. You can fork a project solely to fix typos, rewrite unclear sections, or add tutorials. The process is identical—fork, edit, commit, push, PR.

Conclusion

Forking and modifying open source simulation projects on Aerosimulations.com is one of the most effective ways to learn simulation development, customize tools for your own projects, and give back to the community. The workflow—fork, clone, edit, test, commit, push, PR—is universal across open source platforms. With the detailed steps outlined in this guide, you have everything you need to start your journey. Remember to read the project’s documentation, respect its license, and engage with maintainers collegially. The open source world thrives on contributions like yours. Now go make something amazing.

For further reading, see Pro Git by Scott Chacon and Ben Straub, and the First Contributions guide for additional practice exercises.