That’s the point. This is not a very refined design, it is a quick-and-dirty, “good enough” approach to get it out of the door as quickly as possible while still fulfilling the requirements. Which is why I found it surprising that forward sweep was deemed the best option, despite its aerodynamic and structural challenges (which usually outweigh any benefits). And as I said, fuel efficiency was not foremost on the designers’ minds. Case in point: small turbojets are notoriously inefficient (only pulsejets and rockets are worse), and many small details could be improved cheaply. But having a large unobstructed payload bay is a very good reason for forward-swept wings on such a small design and can greatly simplify operation. I will not recommend any computational fluid dynamics package, because it takes many years of study and experience to apply it to real-world problems meaningfully. And if the design team includes aerodynamicists, they will know what software to use anyway, and don’t need my recommendation. Surprisingly, if you have good data on the airfoil cross-section performance, X-Plane is not the worst tool to get a good idea of performance and stability. It was used for Solar Impulse in that way (also for pilot training).