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Arknabbit vs. EMAX Magnum Tower System

The Tower

The EMAX Magnum Tower System F4 All-In-One (AIO) is exactly as described, an all-in-one solution that will make your build process as simple as possible. It features the following:

  • EMAX Bullet 30A 4-in-1 ESC that is DSHOT ready
  • F4 Flight Controller (FC) supports Omnibus F4 firmware
    • STM32F405 MCU and MPU6000 gyro
    • Power Distribution Board with built-in LC filter
    • Built-in 16MB RAM for Blackbox logging
  • Video Transmitter (VTx) that is 25-200mw switchable
    • Whip antenna and SMA cable included
  • FrSky XM+ 16-Channel SBus receiver
  • Betaflight OSD

Does it stack up? *grin*

I was surprised, it's not a single board but multiple boards retrofitted into a single stack.  I suppose it's good in the sense that if you crash and destroy a component you can swap it out.  However, I'm unsure if you can purchase the components separately at this time, with the exception of the FrSky XM+.

The pin-headers on the FC and ESC are pre-soldered so you just align and gently press them together.  The VTx is already soldered on top of the FC and supported with foam.  The XM+ comes separate in an anti-static bag so you simply align the holes with the pins on top of the FC and solder into place.

The Parts


The Build

Disclaimer - This isn't a detailed build log showing the assembly from A to Z, it's to show you the major build points of the Magnum Tower.

First, mount the ESC to the frame and solder the motor wires to the pads.  You don't have to cross wires to reverse motor direction, use the BL-Heli Configurator software via USB cable to do it.  I used a rubber o-ring at each corner to provide enough space between the frame and ESC components.  Every little bit of vibration dampening helps and it's provides enough space for the battery strap too.

Next, solder the provided XT-60 battery harness to the ESC.

Next, join the FC to the ESC.  Use 6mm m3 standoffs in between the boards to keep it secure.  I used o-rings on top of the stack for extra vibration dampening.

Line up the holes on the XM+ with the pins sticking out of the FC and gently press it on.  Solder the pins to the board

Solder your camera cable wires to the Video In, +5v, and Ground pads located at the front of the board.

I do a lot of night flying and it’s important to have a quad that’s lit up with the ability to change colors.  Having a bright quad makes it easier for the Race Director, spectators, and other pilots to keep track of you during a race.  The FC has a 3-pin wiring harness on it but my Magnum kit didn’t include the harness.  To make it work, I removed the connector from the board and soldered the LED wires directly to the pads.

Before you start configuration in Betaflight, it would be a good idea to do the following:

  1. Connect one of the supplied antennas to the VTx.  You don't want to damage it by accidentally plugging-in without an antenna connected.
  2. Bind the XM+ to your FrSky radio
  3. Update FC with the latest Omnibus F4 firmware
  4. Update ESC with the latest M-H-30 Target firmware

Now, lets dig into BF

  • Set UART1 to Serial RX

  • Set the ESC/Motor to DSHOT600

  • Receiver is Serial-based receiver, Serial Receiver Provider is SBUS
  • Enable VBAT

  • Enable LED_STRIP
  • Enable BLACKBOX
  • Enable OSD
  • Type in your call-sign in the Craft Name field

Don't forget to configure the following to finish this build up:

  • Go to the Receiver tab and set your endpoints for Throttle/Yaw/Pitch/Roll to 1000-1500-2000
  • Set your Modes
  • Configure your OSD
  • Configure the Blackbox
  • Configure the LED Strip
  • VBAT calibration

Final Thoughts

You have to solder 18 points ONLY, 12 of them the motor wires!  This has been the easiest build I've done by far and it meets my expectations for use in a high-performance race system.  I do have some recommendations though:

  • Apply hot glue or some kind of firm glue to the VTx and XM+'s U.FL connectors to keep them from popping off in a crash.
  • The XM+ is supported by the header pins only so it would be good to put a small piece of foam underneath the board for support.


Here is the system with BF3.2

Here is flight video after a few tuning packs on BF3.1.7


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