QuadX (Pixhawk 2.4.8, 3S, 10x4.5) – struggling to get clean 2 ft vertical takeoff/landing (config review request)

ArduCopter
1

Hi all,

I’m trying to bring up a simple QuadX build and I’m stuck at what should be the basic behavior:

Throttle up → clean liftoff to ~2 ft → throttle down → clean descent and land.

Instead I’ve been fighting inconsistent behavior and I’d like experienced eyes on my configuration.

Video Link : https://www.youtube.com/watch?v=nfdWO3rw_Yw

from the video, is it possible to guess what might be going wrong with this ?

Below is my setup & current config (Mission Planner screenshots available).

  1. Hardware
  • Flight Controller: Pixhawk 2.4.8
  • Frame: 450–class style Quad X (Frame type in MP set to QuadX)
  • Motors: 2212 class (generic)
  • Props: 10 x 4.5 (matched CW/CCW)
  • ESCs: generic SimonK/BLHeli type (calibrated together via ESC Calibration in MP)
  • Battery: 3S 11.1 V LiPo, 2200 mAh
  • Power Module: 3DR-style analog PM (in-line via PCB distribution board)
  • RC TX/RX: FlySky FS-i6 + receiver (PPM/SBUS into Pixhawk)
  • Firmware: ArduCopter V4.6.2 (fmuv3) (as shown in MP title bar)
  • GPS: currently not used for indoor tests (initial hover tests are without GPS lock)
  1. Battery Monitor config

Mission Planner → Optional Hardware → Battery Monitor

  • Monitor: Analog Voltage and Current
  • Sensor: 4: 3DR Power Module
  • HW Ver: 4: The Cube or Pixhawk
  • Battery Capacity: 2200 mAh
  • Voltage Divider: ~11.5 (manually adjusted so “Battery voltage (Calced)” ≈ multimeter reading at about 10.7–10.8 V)
  • Amps per Volt: 18.0 (rough starting value)

(Goal: correct voltage for reliable low-battery failsafe; current accuracy not critical yet.)

  1. Radio & Failsafe

Radio Calibration (MP popup values):

  • CH1: min ~1009, max 2000
  • CH2: min ~999, max 1998
  • CH3 (Throttle): min ~1002, max 2000
  • CH4: min ~1021, max 2000
  • CH5/CH6: min ~999–1000, max 2000

Radio failsafe intention:

  • Using RX failsafe on CH3 (Throttle).

  • Target behavior: on signal loss, CH3 goes well below normal low (or no pulses), and ArduCopter triggers FS.

  • MP Failsafe page:

    • Radio FS: “Enabled always Land” (for indoor tests)
    • FS_Pwm (FS_THR_VALUE): around 975–1050 µs tested

  • I understand FS is based on RC3 only; not trying to use CH6 to trigger FS.

(If you see anything obviously wrong / unsafe here, please point it out.)

  1. Flight Modes

Mission Planner → Flight Modes

  • Flight Mode 1: (currently) Stabilize
  • Intention for test: use AltHold for simple 2 ft takeoff/land (self-level + altitude hold).
  • Simple/Super Simple: mostly off (I only enabled temporarily while experimenting).

(Advice welcome on the minimal, safe set of modes for early tuning.)

  1. Initial Tune / Basic Params

Mission Planner → Initial Tune Parameters

  • Airscrew size: 10 inch
  • Battery cellcount: 3
  • Chemistry: LiPo
  • Fully charged: 4.2 V/cell
  • Discharged: 3.5 V/cell
  • Used the “Calculate Initial Parameters” button & wrote values.
  1. Motor Order / Direction

  • Frame set to QuadX.

  • Used Motor Test in Mission Planner (props OFF) to verify:

    • Test A/B/C/D spin the correct arm positions.
    • Directions corrected by swapping any two motor wires where needed.

  • Props mounted with correct CW/CCW orientation and tight.

Would appreciate any configuration-level corrections or “this is obviously wrong” callouts before I move to deeper tuning.

Thanks!

2

Follow the configuration guidance on the wiki of using Ardupilot Methodic Configurator.

Tests with external constraints do not produce meaningful results.

Next time you build a vehicle you should consider Hardware To Avoid When Building Your First Multirotor

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