R4 - X class

By MauiToast on Jan 29, 2020

37  857  9

I was fascinated with building an Xclass when I first saw one. Its been a little while and a journey to get this in the air but its easily the most rewarding drone I've built. The frame has gone through 4 major redesigns before I got to this one. I built 2 frames that were close to something like the Carolina XC's but wasn't happy with them. I really wanted to have fun and make something that tested out some of my ideas for 3D printing and also composites. I designed the frame in Autodesk Fusion360 and printed it mostly with an Ender2. I did use 2 other printers but all the parts did fit on the Ender2. The frame is a combo of 3D printed parts along with carbon rods and a carbon fiber skin. The end weight was more than I intended but I ended up dremeling out a lot of material before and during the build process. The batteries are centered in the frame as much as possible. The overall shape is a stretch X 1000mm mtm. I pre-ordered the polar 345 kv's and wish I had waited a bit since a lot of different options came out before I got to actually building the frame. The Radix FC has been my go to for awhile so when I found out it was the go to for Xclass I wasn't surprised. I have it running BF 3.5.7 and couldn't be happier with how she handles with only a few tweaks. Will tune a bit but happy with it already. Working on an actual race version next. Should easily get the weight chopped down now that I have this one flying. The battery door alone was around 420g and its not essential to fly with. The ESC's get good airflow through the vents and haven't had any heat issues (air temp was 80F). I've got a discord for sharing info on design and building, if anyone's interested let me know and I'll give out the link. If anyone's interested in a frame, feel free to send a message.

Normal AUW 4.55kg
With battery door 4.97kg


Part List

Flight Controller

radix fc - brainfpv (104 builds)


4 x APD 120a F-Series 120F3[X] 12s 50v ESC (3 builds)


4 x MAD Polar XC5000 345kV (8-14S)


4 x 3-Blade - 13x12 Propeller Rev./Pusher Black

FPV Camera

Foxeer Standard/Mini Predator 4 Super WDR 4mm latency FPV Racing Camera 2.5mm lens (2 builds)

FPV Transmitter

TBS Unify Pro 5G8 V3 (SMA) (168 builds)


Lumenier AXII 2 5.8GHz Long Range SMA Antenna - RHCP or LHCP (45 builds)


TBS Crossfire Diversity Nano RX - FPV Long Range Drone Receiver (45 builds)


2 x Turnigy Graphene Panther 3000mAh 6S 75C Battery Pack

Power Distribution

APD 500a PDB500[X] 12s 52v PDB (3 builds)


FrSky 2.4G 16CH Taranis X9D Plus Transmitter SPECIAL EDITION w/ M9 Gimbals (50 builds)


Fat Shark Dominator HD3 Core FPV Goggles (70 builds)

HD Camera

GoPro HERO7 Black Action Camera (74 builds)

Video Receiver

LaForge Main & Diversity Module Combo V4 For Fatshark Goggles (5 builds)

Radio Module

TBS Crossfire Micro TX V2 (109 builds)

Battery Charger

iSDT D2 Smart Balance Charger (11 builds)

Soldering Iron

TS100 Digital OLED Programmable Interface Mini Soldering Iron (162 builds)


Pillbox™ (29.5 L)
Show stores (9)


Sign in to comment

Unknown FPV   Mar 06, 2020  

Holy fuck!! Thats a beauty of a beast....!!!

quangdat   Feb 10, 2020  

Your design is very beautiful, could you please give me the 3d file?

MauiToast   Feb 10, 2020 

Thanks! I don't have plans to share the files on this one. I'll be releasing a frame design soon based off what I learned from this project.

Pairadime   Feb 01, 2020  

I love the way you did the paint finish.  Like a hardened battleship from the stars.

MauiToast   Feb 02, 2020 

I had a white/carbon tiger stripe pattern on there that looked pretty sick but I like the rough up look more. Shows off the carbon skin more. I wet sanded it to and gave it 3 light sprays of polyurethane clearcoat. I've had a few flights now and it moves fast pretty effortlessly. Such a blast to fly.

JimmyProton   Jan 30, 2020  

Gorgeous work.

thumbtwiddler   Jan 30, 2020  

This is the first build that's had me just... speechless

miromir237   Jan 30, 2020  

Wow. Just wow.

kwadkenstine   Jan 30, 2020  


Guides & Reviews

39 4,190  47
May 05, 2020

This guide will walk you through the process of building your first FPV quad. The goal with this design was to build a low-cost, lightweight quad, yet powerful enough to safely carry a GoPro in close proximity areas. I chose these parts to minimize the amount of soldering at no cost to the quality. A typical build requires around 30 solders while this only needs 25. It's not a huge difference, but..

Read more
28 7,929  38
Nov 30, 2019

In late 2019 DJI made inroads into the FPV scene with their remarkable low-latency digital system. It gave us a 720p video feed with latency on-par with the status quo, analog video. Traditionally we've used analog video systems for low-latency video, but the video quality is far from ideal. It's a trade-off we've been willing to accept for the control. Now we've got the best of both worlds and what..

Read more