Using a computational fluids model like OpenFOAM is overkill for reasonable estimates of aerodynamic performance and stability, provided you stick to normal-ish designs. The term you want to Google is "vortex lattice" and/or "potential flow" solvers, of which there are many open source softwares available specifically geared towards typical aircraft configurations, with simple, easy to use interfaces.

Some good ones to look at to get started with nice guis

- VSP Aero

- XFOIL (for 2D airfoil analysis only, also generates inputs for 3D VLM solvers)

- AVL

And some others if you want perhaps a little higher fidelity, and don't mind text/code interfaces:

-FreeWake

- Datcom (not technically a potential flow models, but a database)

To get the most value out of these softwares, you will need some background in aeronautics. You need to have an understanding of what a potential flow models can and cannot accurately model. It also helps to have knowledge about what forms aircraft stability/control and performance data is typically communicated in, as these softwares will use that terminology.