June 5, 2026
Description
WARNING - THIS IS A WORK IN PROGRESS
Future changes:
Longer wing span
Taller rudder
Tail wheel
Movement of ailerons to outer edge of wings
Weight reductions using nylon screws instead of steel screws
This design provides the components to construct a modular RC airplane. The components are slid onto an 8mm carbon fiber backbone. The wing sections and ailerons are slid onto three 4mm carbon fiber rods. Except for wing end caps, no glue is used, instead everything is fastened using M2.5 and M3 bolts and screws. This allows you to easily do things like adjust wing size and slide components on the backbone rod to adjust the center of gravity.
I used PLA+ for printing, where it provides a better strength to weight ratio than lightweight PLA. The tires for the landing gear were printed using TPU. The total weight of the plane shown in the picture with all components, motor, servos and battery is 644 grams.
My implementation uses the popular 2.4GHz Express LRS (ELRS) for radio controls. This involves a 4 channel receiver, three servos and an electronic speed controller (ESC) , as well as an ELRS transmitter. I have chosen these components from Radiomaster.
The (non-printed) parts list includes:
Note that the battery mounts are sized for either a 2200mAh 2S (7.4v) battery or a 1400mAh 3S (11.1v) battery. A 3S battery will generate about 50% more thrust than a 2S battery due to the higher voltage. The battery mounts are also used to hold the 1.5mm rods used for the landing gear. Use of other sizes of batteries would require adjustments to the size of the battery mounts. The center of gravity of the plane is adjusted in part by the specific weight and placement of the battery.
The hardest part of construction is to properly bend the stainless steel rods used for landing gear and push rods for the ailerons. Need to be sure that the rods for the ailerons don't interfere with those for the rudder and elevator. Note the bends in the rods for the landing gear so that they attach to the wheel mounts securely and keep the wheels aimed straight ahead. Pictures are provided.
Amazon provides a low cost 'RC plane motor kit' with the brushless motor, ESC, propeller and servos. There is also a kit for push rods and connectors. All of the listed non-printed materials (except for the toggle switch) were purchased on Amazon.
The design uses four channels (which is why the ER4 receiver is a good choice) which are very/most common for RC planes:
Some of the design parameters realized using the provided STL files are:
This is marked as a WORK IN PROGRESS, as I am currently testing everything thoroughly before actual flight. I am using a Radiomaster transmitter. I strongly recommend getting familiar with your transmitter by connecting it to a flight simulator before you attempt actual flight. You will likely want to invert a couple outputs in your transmitter (as noted above) Also, with motor disconnected, make sure your control surfaces are operable and properly set with your transmitter. When connecting your brushless motor, you need to be sure it rotates in the correct direction. Do this before you attach the propeller. If it rotates in the wrong direction, you just need to reverse any two of the three wires to the motor. It's a good idea to mark the wires with colored tape so you can reattach properly in the future. Note that you will likely need to update the firmware and configuration on your receiver (i.e. the ER4) before it will connect to your transmitter.
The OpenSCAD file used to generate the STL files is provided. The OpenSCAD files for landing gear wheels and tires are from my other designs at https://www.thingiverse.com/thing:7316286 and https://www.thingiverse.com/thing:7317402.
Version History:
See my other RC projects at https://www.thingiverse.com/thing:7328990, https://www.thingiverse.com/thing:7326362 and https://www.thingiverse.com/thing:7073846.
License:
Creative Commons - Attribution - Share Alike
scottneumann
