[SonicScrub]

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.

[kingkongjaffa]

I used xfoil in my aerodynamics masters degree, it absolutely good enough for hobby applications

[SonicScrub]

The 2D model alone maybe be sufficient for OPs needs, but I'd advocate for going at least a little further with some form of 3D model. The wing tip effects are significant enough to warrant some form of "next step" after the initial 2D analysis. Although simple algebraic relationships are likely good enough to satisfy this end.

However, the 3D tools above give you a little bit more, that I feel warrant their consideration by the op. These models can yield performance of wing-tail-body configurations that include wake effects. They also can give stability analysis in both longitudinal/lateral axes. The stability effects being especially important if OP wants to design a flying-wing, which are a tad more challenging to get right than just slapping a "good-enough" sized tail on a classic config plane.