4" Hardcore Ripper - 40r

By ghostface on Feb 17, 2019

17  923  6


So after smashing my old 4" into a tree I rebuild it with a new frame.
Karl just got the design of his new 4" frame ready, the 40r, so I ordered, with a 850 4s, a pre-production frame for testing (final version is the same however).

I am super satisfied with it - flies great on stock pids and 3.5-4 min of ripping on 850mah 4s.
Very agile, fast and sturdy. It's 166g dry (without battery) so with a 850 4s it has a power to weight ratio of about 15:1 :D
With a 650mah 4s it clocks in at 246g making it sub 250g.


Changes compared to my old br3 build

Please refer to my BR3 - 4" Splitmini Beast if you are interest in more details.

I used most of my old parts, as only the frame broke, however I did change this:

  • Used a HGLRC Elf camera (rebranded microswift with some slight changes that came with my f428 stack) instead of the split - I'll probably swap it for a predator 3 soon.
  • Wired up the cam to the LED pad and remapped it in order to be able to change cam settings via OSD (awesome btw, i'll add that to all my builds now).
  • Wired up the tx20 for smartaudio control
  • Used soft mount m2 standoffs instead of the steel screw with tpu printed slide on spacers.

Build & Challenges

I initially had the camera control ground wired to the fc - this caused lots of noise and some ground loop I believe. Wiring it to the same ground as the camera got rid of that.
Camera control only required a 220 Ohm Resistor resistor wired inline to the LED pad to make it work.

Apart from that I only had to resolder the rear motors from the underside to make clearing the rear standoffs easier.
They can work from the top too but you have to solder them at an proper 90° angle then.


Printing the canopy will be stronger if done vertically but then you get an ugly front. Printing horizontally will need lots of support.
I'll probably reprint it at some point to look nicer but its ok for now.
The tubes are only held by friction but did not came loose yet, I may glue them in just in case.
I have no idea where I got the tubes from - they were in my stash of antennas :)


Stock Betaflight 4.0 PIDs and filters worked really well. All I had todo was increase motor idle a few points to get rid of deathrolls when rolling.


Part List


Bando Racers 40R

Flight Controller

HGLRC XJB F428 TX20 V2 ELF Camera Set 600TVL Cam & F4 OSD BEC & 28A Blheli_S & 25/100/200/350mW VTX


4 x RCINPOWER G1506 3400KV 4100KV 3-4S Brushless Motor CW for RC FPV Racing Drone (7 builds)


HQ Prop 4x4.3x3 V1S Tri-Blade 4" Prop 4 Pack - Choose Your ColorOrange (29 builds)


Realacc UXII Stubby RHCP U.FL / IPEX IPX 5.8GHz 1.6dBi Super Mini Antenne für TX RX Fatshark Schutzbrillen R (24 builds)


FrSky R-XSR Ultra SBUS/CPPM D16 16CH Mini Redundancy Receiver 1.5g for RC Multirotor FPV Racing Drone (928 builds)


Gaoneng GNB 14.8V 850mAh 4s 80/160C Lipo Battery for RC Drone (11 builds)


FrSky ACCST Taranis Q X7 Transmitter 2.4G 16CH Mode 2 White Black International Version for RC Drone (253 builds)


Skyzone SKY02S V+ 3D 5.8G 48CH FPV Goggles With Head Tracking HD Port DVR Playback for RC Drone (23 builds)


Matek System 4 PCS M2*5+4 M2 Rubber Vibration Damping Fixing Screws for RC Drone Flight Controller (7 builds)

Misc Parts

25R 30R 40R canopy axii support by BandoRacers
See Site

Misc Parts

BR25R Bumper by FloydDawg
See Site

Radio Module

iRangeX IRX4 Plus 2.4G CC2500 NRF24L01 A7105 CYRF6936 4 IN 1 Multiprotocol STM32 TX Module With Case (5 builds)

Battery Charger

ISDT Q6 Pro BattGo 300W 14A Battery Balance Charger (47 builds)
See Site

Soldering Iron

MINI TS100 Digital OLED Programmable Interface DC5525 Soldering Iron Station Built-in STM32 Chip (258 builds)
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Mehul Shocker   Feb 22, 2019  

this would be a better build than a 5 inch with Xing motors, more thrust to weight ratio. battery would be cheaper.
any cons??
the antenna mount is awesome!!

Show 2 more comments
ghostface   Feb 23, 2019 

Compared to a 3" its soft and drifty yes, especially if you are low on throttle, but if you give it some throttle it will react instantly so very agile. Also it seems to hang forever you throw it around, you need to pay attention not to cross the whole field when doing a powerloop lol.

I got the stack and frame on a discount so overall the build was quite cheap for me :)

Mehul Shocker   Feb 23, 2019 

did you try four blades??

ghostface   Feb 23, 2019 

Nope - I am guessing 4" on those motors would be too heavy. The hq v1s are the only good 4" props I know off.
The gemfan flash for instance are nice but also not very suitable for lighter motors like this.
I love the way it flies however

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