Birdbrain RC Polaris 5.5 "Snow Angel"

By CarbonRain on Oct 15, 2018

17  447  9

After flying the Mahou Shoujo prototypes for the best part of a year, I've come to love how they handle - they just feel really well balanced, clean and crisp on every axis even with stock PIDs. With the weather turning poor I decided to design one last frame before letting the CNC hibernate for the winter, and eventually decided to follow the Mahou Shoujo template, albeit with a more freestyle focus. This the result - the Polaris 5.5.


I started out with the Mahou Shoujo baseplate layout, then stretched it slightly in each direction to allow for bigger props, and a larger pod to give more room for electronics. The baseplate is a little beefier all round and has extra bracing to deal with freestyle abuse.

The pod has a fixed mount for a full size FPV cam with "GoPro style" 2.5mm lens. I thought I'd left loads of room for the stack, but in a genius move I'd checked clearance at the back but not the sides - the tapered sides of the pod look lovely but also leave very little clearance at the back corners with full size boards!


Most of the components are personal favourites - Omnibus F4 V5, Racerstar REV35A 4-in-1 ESC, and AMAXinno motors. Did up from 2305s to 2307s for this build though, with the extra weight and bigger props I figured the extra grunt wouldn't come in wrong. Whilst I was at it I decided to make the build long range ready, so it got an R9 Slim+ and I decided to cram in a HGLRC M8N GPS I had lying around from another project. Surprisingly it wasn't too bad a build once I got the ESC board low enough, even had room for soft mounts for the Omnibus. I did end up making a little G10 plate to hold the M8N and R9 in the stack and make it a bit neater.


Whilst this particular build hasn't flown yet, I put together a more conventional twin first (difference being no GPS and an XM+ rather than R9 Slim+) - took it to a woodland session with the local crew and it flew great, but still have yet to really see what it can do though. Tight and twisty flying isn't what it's designed for, high speed freestyle and carving smooth lines down mountains is more its true intention. Hopefully this winter I'll get the chance to really put the prototypes through their paces and get some quality footage out of it too!


Part List

Flight Controller

Airbot Omnibus F4 V5 Flight Controller


Anniversary Special Edition Racerstar REV35 35A BLheli_S 3-6S 4 In 1 ESC Built-in Current Sensor for RC Drone (84 builds)


4 x Motor 2307-2500KV (2-6S) AMAXinno (2 builds)
See Site


DAL T5544C Cyclone Propellers - Crystal Purple (2 builds)

FPV Camera

FOXEER Arrow V3 2.5mm 600TVL 4:3 HAD II CCD PAL/NTSC IR Block Mini FPV Camera Built-in OSD MIC (134 builds)

FPV Transmitter

ChaosFPV VTX[T] Video Transmitter (25-800mW, 7-24V, BetaFlight Telemetry) (8 builds)


Antenna Pro Pagoda 2.1 Long goggles edition


FrSky R9 Slim+ 868MHz Mini Receiver
See Site


Turnigy Graphene 2200mAh 5S1P 45C Lipo Battery (8 builds)


FrSky R9M 900MHz Long Range Transmitter Module (2 builds)


FrSky Taranis Q X7S Radio w/ Upgraded M7 Hall Sensor Gimbals (Carbon Fiber) (32 builds)


FrSky Taranis X-LITE 2.4GHz ACCST 16CH RC Transmitter Red Black for RC Racing Drone (50 builds)


FrSky R9M 868MHz Long Range Module
See Site


FatShark Dominator HD 2 Hydro-Dipped Urban Cam Grey and White FPV Goggle
See Site

HD Camera

Hawkeye Firefly 6S 4K WiFi Sport HD DV Camera - $75.31 |

HD Camera

Hawkeye Firefly 6S 4K Sport FHD DV 16M CMOS WiFi Waterproof Camera (Quick Time Player Required)

HD Camera

HawKeye Firefly Q6 4K 120 Degree Angle Action Camera - $59.14 | (2 builds)

HD Camera

GoPro HERO5 Session (202 builds)

HD Camera

GoPro HERO5 Session - Waterproof Digital Action Camera for Travel with 4K HD Video 10MP Photos (202 builds)

HD Camera

GoPro Protective Lens (GoPro Official Accessory)
See Site


Matek System 4 PCS M2*5+4 M2 Rubber Vibration Damping Fixing Screws for RC Drone Flight Controller (6 builds)

Misc Parts

HGLRC Tiny GPS and GLONASS Receiver Module For iNAV (4 builds)


TrueRC True-MOX 868MHz Antenna
Show stores (12)


Sign in to comment

d3c0de   Jan 17, 2019  

Love the build, but honestly my first thought was how much this looks like an attachment for a blender. "Hey guys let's rip some packs and then I'll make some smoothies!"

Jodie Froster   Oct 15, 2018  

Looks fantastic! I would love to bash it around to see how tough it is, looks like great reinforcements to the exterior (all the "spokes"). This looks like a great chapter in this project. I liked the last one, and I like this one too. How do your vTx's hold up to the heat fully enclosed like that? How many milliwatts can you run before they start to destroy things?

CarbonRain   Oct 18, 2018 

Well, it turns out even though the previous plus had next to ventilation and was fine, having absolutely no ventilation is a step too far! Test flights on the beater rig ended in overheating the stack, MCU temp warnings and reboots (of the 4-in-1 I think). Printed a new vented pod last night (bit rough but it's functional, got a nicer one going for the white long range build now). Onwards and upwards!

Jodie Froster   Oct 20, 2018 

I dig the black/grey/pink. I can't seethem, but I want you to use gold motor bolts for style

TeamWolfFPV   Oct 15, 2018  

Sweet slick setup, love everything being totally enclosed! Are the plans available to print? How heavy is the frame?

CarbonRain   Oct 15, 2018 

Thanks! It's not a light frame (personally I like the feel of a heavier quad so it suits my flying) - comes in around 130g for the baseplate and pod. As for the files, well, I'm planning on starting to sell my frames later in the year, so whilst some stuff might get released (accessories like session mounts etc) the majority won't be. Also, neglected to mention in the description, but it's not a 100% 3D printed frame either - the baseplate is milled out of 12mm UHMWPE on a CNC machine for strength :)

Jodie Froster   Oct 15, 2018 

I was wondering how the baseplate was so texture free, but still had spots that hadn't been "cleaned up"

Showusflight   Oct 15, 2018  

Any flight videos?

CarbonRain   Oct 15, 2018 

Weather here has been shocking for the past week, looks like Wednesday after work is good for a maiden though :) I'll update the build once I have something to show!

Guides & Reviews

17 1,476  18
6 days ago

This is the 4th installment to my popular "Wizard Killer" series, and is based on the popular Wizard X220HV 6S. As usual, the goal was to build a substantially better quad, yet come in below the retail price of the BNF kit. Here are some of the improvements: Higher quality EMAX ECO 2306 1700kv motors Foxeer's top-of-the-line Falkor mini camera Eachine 25mw-1000mw Leaf VTX with microphone Tools This..

Read more
Jan 15, 2019

The iFlight XL5 V3 is a fantastic freestyle frame for the price. It features chamfered edges on some very nice quality carbon fiber. My goal for this build was to use high quality components at a relatively low price. Not only that, but I managed to reduce the number of solder points to the bare minimum. I've never built such a plug-in-play quad! The flight controller has an integrated VTX and doesn't..

Read more