Flying R2-D2 or SpaceX Falcon 9? Both – RC coaxial dualcopter

The second generation of my 3D printed coaxial dualcopter is here! And this time it works almost as I wanted.

3d printed RC coaxial dualcopter

Just watch the video

On the more technical details:

  1. It runs INAV 2.0 with a custom mixer
  2. Thrust and yaw control is provided by 2 counter rotating propellers
  3. Upper motor is 2205 2300KV with 5×4.5×3 propeller rotation in CW direction
  4. Lower motor is 2205 2600KV with 4×4.5×3 propellers rotating CCW
  5. Control surfaces are rotated 45 degrees from the long axis to fit servos
    flight controller is also 45 degrees rotated
  6. Any 9g servos will do
  7. runs on the 4S battery that has to be on the top of the device
  8. All 3D printed parts can be downloaded from Thingiverse

Required parts:

  1. 2205 2300KV brushless motor
  2. 2205 2600KV brushless motor (2300 also will do but will have less yaw authority)
  3. 5×54.5×3 propeller
  4. 4×4.5×3 propeller
  5. 2 14mm carbon pipes (12mm internal diameter), each around 270mm long
  6. 2 2g servos
  7. 3M bolts to secure the motors
  8. good adhesive tape to make control surface hinges
  9. pushrods
  10. hot glue
  11. flight controller compatible with INAV
  12. radio receiver

3d printed RC coaxial dualcopter

It’s time to start to think about INAV 2.1 – DSHOT and braking mode

It's time to start thinking about INAV 2.1. No, I will not give you any timeline, but I can point two features that are very likely to go into the upcoming INAV release.

The first one is Braking Mode for multirotors. I already made a video about it, so you might want to watch it first. Right now there is an open test phase for this feature made as part of my fork of INAV. If you want to test Braking Mode, please visit this page and download the hex file for your board.

On top of that, it's very probable that DSHOT will finally make it to INAV too! DigitalEntity started to tackle with the DSHOT implementation so yes, this is finally happening for INAV!

INAV Airmode and Motor Stop on Multirotors and Fixed Wings

What are Motor Stop and Airmode features in INAV and how they differ from each other when used on multirotors and fixed-wing airplnes? Should you use Motor Stop on multirotor? Should you use Airmode on a fixed wing? Long story short:

  • On multirotors, Motor Stop not recommended to use while Airmode is recommended to use. More than that, you can not use them both at the same time, since they exclude each other!
  • On fixed wing aircrafts Motor Stop and Airmode are highly advised to use together.

Just flying: INAV 2.0 on a 7 inch long range cruiser quadcopter

I like my 7-inch endurance FPV drone. Maybe it does not flies super smooth yet, but slowly I'm getting there. The best move was probably to replace HQProp 7×3.5×3 V1S propellers with Gemfan 7×4.2. Fantastic propellers those Gemfans…

The common cranes (Grus grus) in a middle of the video really could not decide if they are scared of my drone or nor. In the end, I've decided to leave them alone… Storks are usually more friendly. They tend to ignore drones at all. The locals call this place The Carpathia. Why? Perhaps because those are the only "hills" on a completely flat area around.

Full 7-inch endurance drone specification is available here

INAV Wind Estimator

INAV 2.0: Wind estimator. What does it do? Tries to estimate the speed of the wind (obviously) as well as wind direction. Let's be honest, it's experimental and relays only on the difference of predicted and actual flight path. So do not even try to think it will give accurate measures. But my tries says that wind estimator results are plausible as long as an airplane is stable in the air.

How to use INAV Autotune

Autotune (or Auto Tune) that is present in INAV for quite a long time is a working solution for tuning PID (or rather PIFF) controller used by INAV on fixed wings (all airplanes, flying wings). Not like all the attempts designed for multirotors, this one actually works.

INAV Autotune can be used on any airplane and is fairly simple to use as long as you follow a few simple steps: