ArduPilot flying on the CL84 TiltWing VTOL Aircraft

We did the first test flights of the Unique Models CL84 TiltWing VTOL with ArduPilot today. Support for tilt-wing aircraft is in the 3.7.1 stable release, with enhancements to support the tilt mechanism of the CL84 added for the upcoming 3.8.0 release.

This CL84 model operates as a tricopter in VTOL flight, and as a normal aileron/elevator plane in forward flight. The unusual thing from the point of view of ArduPilot is that the tilt mechanism uses a retract style servo, which means it can be commanded to be fully up or fully down, but you can’t ask it to hold any angle in between. That makes for some interesting challenges in the VTOL transition code.

For the 3.8.0 release there is a new parameter Q_TILT_TYPE that controls whether the tilt mechanism for tiltrotors and tiltwings is a continuous servo or a binary (retract style) servo. In either case the Q_TILT_RATE parameter sets the rate at which the servo changes angle (in degrees/second).

This aircraft has been previously tested in hover by Greg Covey (see but has not previously been tested with automatic transitions.
Many thanks to Grant, Peter, James and Jack from CanberraUAV for their assistance with testing the CL84 today and the videos and photos!


Really excellent! Great video!

@Tridge @grantmorphett @peterbarker with the CL84 prior to test flying. Users of SITL may recognize the salmon runway of the Canberra Model Aero Club


A few more videos of the transitions:

My aerial cinematography skills need some work…


I am impressed, especially with the speed at which the aircraft moved when the motors were tilted.
A few questions.

Q1. what advantages would the twisting rotor system, give over a conventional fixed position quad copter?
From the top of my head, I would imagine that flight times will be longer, but have you done any flight time tests?

Q2. Is the arduplane code you are using standard or have you made some changes for it to work with your particular air craft?

This aircraft is designed to be a scale model, not to be an efficient airframe. The wing loading is quite high, which means it isn’t efficient. That isn’t a reflection on tiltwings in general though, just this particular aircraft.

it is the standard ArduPilot 3.8.0beta2.

Hi Peterbarker,
I would like to ask:

  1. How much capacity of the battery?
  2. what is the total weight of your CL-84 (including battery and pixhawk and all accessories)?
  3. how long can fly?
    Thank you!

@mrcsh Sorry, this isn’t my aircraft. I just uploaded some film I took of it working.

@tridge can answer some of your questions. But I don’t think we know the answer to “how long” yet, regardless.

the battery is a 4Ah multistar:

the weight without battery is 1.7kg. The battery weighs 433g.
I don’t know exactly how long it will fly for. I would guess about 25 minutes if mostly in fixed wing mode, but so far I have been doing short flights.

Thank you for your reply.

Thank you for your reply, this information is useful for me.

Hi tridge.
First of all - congrats on all Your successes.
My CL84 is waiting in the box… Could You tell me - is there any point to try original flight controller, before using Pixhawk? I plan to use Pixhawk. And second question - Will Pixhawk with AP3.8.0 work include GPS? I mean waypoints missions, loiter etc. Thanks

I didn’t fly it with the original controller. I’m sure it does work, my aim was for ArduPilot though.

yes, it includes all the same navigation capabilities as ArduPilot normally has. The demo video included a full auto mission with waypoints and automated landing.


I have a tandem tilt wing VTOL similar to the Airbus Vahana design (8 rotors). I’ve been using KK board and Open AeroVTOL successfully but would really like full autopilot capability. Is the Arduplane VTOL tiltwing code far enough along in development to fly this configuration? Is there capability to do custom mixing and trimming during transition like OpenAeroVTOL?

Many Thanks,
Dave North
NASA Langley Research Center

It will be able to fly such a configuration, I think, there will probably be less flexibility than OpenAeroVTOL (i have never used it myself). There are no custom mixing or trimming functionality. There are several parameters to specify how fast to transition, tilt the wing ect.

It might be worth setting a model up in Realflight8 SITL to get a real feel for how it would handle and what all the parameters do.

OK. I have also wanted to learn how to set up a Realflight sim, so I guess now is a good time. Thanks!