3D printed RC trainer DIY

The first airplane one flies is … a trainer.
In this tutorial you get to design a trainer main wing and empennages in your terms.

A trainer airplane has a high lift (thick) forgiving airfoil, straight wing with a bit of washout and dihedral.
The dihedral makes it fly in a stable equilibrium, straightening the fly path and allowing turna using the rudder.
A bit of washout at the wing tips ensures that a stall does not install sharply but first at the root chord and later at the tips, giving you time to react and making for a forgiving model.

We will design, print and cover with shrink wrap.

Building the wing

To build the wing we set a NACA thick profile 7321, a wing span of 1 meter (65in), a root chord of 12cm (6in) and select the build mode to 3D print with inner structure from the general settings tab. Set the rib count to 8 or larger or smaller depending on how sturdy / heavy you want the wing to be!

We go and add a dihedral at 10% on the X-axis of 3 degrees to get a nice dihedral to give out wing stability.

We go in the washout tab, click add and select the last cue point in the list (tip) and add a -4 percent washout

Our trainer wing is ready! Download the STL!

Download here a pre-made trainer 3D wing STL file

In order to prepare the wing for servos, in the slicer, we will do two things:
1. Add a rectangular solid negative along the wing for the wires to pass trough
2. Add another rectangular piece for the servo to be glued to and a rectangular negative to create space within the wing’s comb lattice

The empennage

Horizontal:
In general settings we select a symmetrical NACA profile 0015, wing span of 30cm and root chord length of 4cm. Set number of ribs to 5.

Download here a pre-made horizontal empennage STL file

Vertical:
The same model as for the vertical empennage but add 15mm at the tip for the trailing edge and wing thickness 50% at tip(100%) We’ll only print one half.

Download here a pre-made vertical empennage STL file

To get a full vertical and horizontal combo we’ll combine the full span horizontal model with 1/2 90 rotated vertical model

Once printed, a flat piece of material will be hinged on to the empennage and all surfaces covered with head shrink wrap