Introduction

The Titan Viper is a tiltrotor VTOL (Vertical Takeoff and Landing) designed by Titan Dynamics. In this post, I’ll share my experience setting up ArduPilot for the Viper’s first flight, focusing on a crucial issue I encountered and how to avoid it.

Essential Resources

The ArduPilot documentation for configuring tiltrotor VTOLs is excellent here are pointers to some of the parts I found most useful.

  • For a general overview of QuadPlanes start here
  • Jump into the QuadPlane setup here
  • Tilt Rotor specific setup for drones like the Viper starts here.
  • I found the tips for mechanical setup of the rotors here and here very helpful.

Even with the great documentation one can still run into issues. A proper setup can be the difference between a flop and flight. I’ll talk about the specific issue I ran into getting to my first flight.

Motor Ordering

The issue I ran into was with motor ordering. The flight controller thought power motor was being applied to the two front motors. However, it was actually being applied to one front motor and the tail motor. This caused my drone to flip over.

There are good diagrams here of various frames with motors and their motor ordering. When I first looked at these diagrams, it showed only the numeric reference system. The diagrams have since been updated to include the alphabetic reference system.

I initially connected my motors using the numeric reference system. When I tested the motors, the sliders were labeled A, B, C, D. I assumed A was the first motor and B was the second, etc. That is not the case as numeric system is a distinct reference system from alphabetic reference system.

You will need the use the numeric reference system when configuring the servo parameters. E.g. SERVO1_FUNCTION is configured using the numeric reference system.

However, don’t fly until you’ve tested your motors using the alphabetic reference system with the sliders in your Ground Control Station (GCS) software. A is always the front or front right motor depending on your frame orientation. From A the motors should activate sequentially in a clockwise direction as you go up in letters.

Flight Attempts

Here’s what happened during my first attempt:

After correcting the motor ordering issue, here’s a successful flight:

Conclusion

Setting up a tiltrotor VTOL drone, can be a challenging but rewarding experience. The key takeaways from my first flight experience are:

  1. Thoroughly review ArduPilot’s documentation, especially for QuadPlanes and tiltrotor setups.
  2. Pay close attention to motor ordering and understand the difference between numeric (1,2,3,4) and alphabetic (A,B,C,D) motor references.
  3. Always perform motor tests using the alphabetic reference system with your GCS software before attempting your first flight.

Remember, the difference between a successful first flight and a potential crash often comes down to these small but crucial details. Don’t get discouraged if you encounter setbacks. I hope sharing my experience helps you avoid similar pitfalls and gets you in the air faster.