Preparing the Geometry

The quality of the CAD model decides whether the aircraft can be meshed and how well the results represent it. Prepare the model in your CAD system before you upload it.

Requirements

A closed outer surface. The model must describe the outside of the whole aircraft as closed solids. Internal structure, such as ribs, spars, wiring and components, is not needed and should be removed.
One solid or an assembly of solids. Parts that overlap or touch are joined into one outer surface for meshing. A part that lies completely inside another is removed.
Propellers removed. Export the aircraft without propellers and spinners’ blades. Propellers are represented in the analysis as actuator disks, which are set up in the Aircraft step.
Control surfaces as separate solids. For a flight model, each moving surface (aileron, elevator, rudder, ruddervator, elevon, flap) must be its own solid, separated from the wing or tail by a physical hinge gap. A single solid cannot be deflected.
Hinge clearance. The surfaces must be able to rotate through the tested travel, at least ±10° (flaps 0 to 10°), without touching the wing.
Units. STEP files carry their own units. STL files do not; you choose the unit when you upload.
File size. Up to 100 MB per file.

Recommended practice

Export STEP where possible. STEP keeps the solids and their names, and lets Deneb Aero repair some faults.
Close every slot that is not a hinge gap. Slots narrower than the surface cells of the mesh are meshed closed or roughly. For the Raven, the hinge gaps are 1.0 mm.
Remove small details that do not matter to the flow, such as screw heads and antennas. A part smaller than the surface cells of the mesh is resolved only roughly.
Make sure no solid intersects itself. Self-intersecting solids are refused by the wall-resolved runs (the polar and the stall study).
Landing gear, booms, motors and pods may stay in the model. They are part of the airframe and add their drag.

Orientation

The model can be exported in any orientation. In the Geometry step you tell Deneb Aero which CAD axis the wind blows along and which axis is up. See Step 2: Geometry.