Tricopter VTOL Tilts Forward During Hover Test — Suspected Inverted Pitch?

ArduPlane VTOL Plane
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Hi everyone,

We’re a student team developing a VTOL aircraft in a Tricopter configuration. We’re reaching out for help after running into an issue during our first hover test. Here’s some details on the VTOL’s setup:

Our setup consists of two front tilting motors and a single fixed rear motor, with yaw control provided through vectored thrust by tilting the front motors. The flight controller we’re using is the Cube Orange, running ArduPilot firmware. Our motors are iFlight XING X4214 660KV (2–8S) class, paired with Sequre SQESC 28120 ESCs, all powered by a 6S 16000mAh Tattu LiPo battery. The power distribution is managed by a 200A PDB. While each motor is rated for 98A, we originally intended to use a 400A PDB , but it was out of stock. As a workaround, we used our existing 200A PDB to power the front motors, and powered the third motor (rear) separately using a Y-splitter from the battery, allowing the ESC to regulate voltage directly. For RC communication, we use a Radiomaster TX16S with an ELRS Micro TX module and a Radiomaster RP3 ELRS receiver that also has telemetry capability. GPS is provided by the DroneCAN M8N Module. I’ve attached a picture of the wiring diagram in this post.

We recently attempted our first vertical hover test. We did a basic motor test beforehand to check if all motors were spinning in the correct direction, and that was successful. During this hover attempt, the VTOL kept pitching forwards as throttle was increased. When we talked to the pilot, he said that it felt like the pitch was behaving inversely — pushing nose-up led to more nose-down movement, suggesting that pitch control may perhaps be reversed or misconfigured? I’ve attached a youtube link of a video showing the forward tilt during testing, and also have the flight log (.bin file is in the google drive link as it was too big for this forum) and parameters from the Cube Orange if anyone is able to take a look and help diagnose the problem. Any advice on what might be wrong or what might be good to check would be extremely helpful. Thanks!

Video of hover test:

Flight Log:

Project Vectair Circuit Sketch 2025
Project Vectair Circuit Sketch 20251280×720 191 KB

VTOL_Term2.param (22.6 KB)

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Hi Christopher,

It is not a good idea to make the first hover attempt in QLoiter. It’s better to try again in QStabilize first, then you can slowly apply more throttle and judge whether the VTOL wants to lift off correctly (or whether the directions of rotation are wrong or other careless errors in the setup) and the roll/pitch control works correctly in the right direction. (Check how the VTOL behaves when you try to lift it slightly with full left or right or front or back on the stick. Does it want to “tilt” in the right direction or does it behave incorrectly? )

If this does not work, please show a log file with QStabilze at the start attempt.

Many successes

Rolf

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Check the RC calibration page. When you push the pitch stick away from you the pitch graph should go to a lower number. If it doesn’t there’s a reverse check-box in mission planner beside pitch, or you can use RC2_REVERSE,1 (assuming pitch is on channel 2) to switch it.

Just note you might need to check your elevator servo and FBWA corrections to make sure they are going in the right direction after you make this kind of change.

And yeah, initial tests should be done in QStabilized. Don’t try to get to Qloiter or fixed wing transitions too soon or you’ll end up with a bin full of broken parts.

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