5" Rooster on Crossfire

By beeb on Jan 21, 2018

13  1,433  10

Trying something new with this one! It's my first true freestyle quad with a top mounted battery and dedicated place for a gopro. As such, it was kinda challenging to build since I'm not used to that kind of layout. I had to think about what to do with the battery pigtail, where to mount the vTX, etc etc.

I really wanted to try the Fortini F4 OSD as a flight controller because I think it's great that it supports 32kHz gyro (for BF 3.3) and it has a dedicated pin for camera control, amongst other cool features. But now I kinda regret this decision because I didn't anticipate that it had only 1 fully normal uart (uart1 has both TX and RX pins without inverter or anything). The other uarts either only provide a TX or RX pin, or have an inverter in the way. For a normal receiver this would not be such a problem, but in this case with the crossfire, I could not add the GPS module I had planned...
Another point of concern is that I had some nasty yaw twitching on the first hover test (the only flight so far). It seems strange because I have softmounting (built into the FC) and a capacitor on the mains, which are the two usual remedies to yaw twitching. Maybe a faulty gyro? I tried softmounting the motors too, we'll see if that helps.

I initially wanted to use the normal crossfire antenna (the flexible one) in an L shape to have some kind of polarization diversity, but it was a sketchy mount at the back with zip ties and heat shrink, and it would have been close to the video antenna, which could alter the tuning of both antennas. So I went for the immortal T which is super easy to mount on the back arm.

Quite happy with the "Race wire" as a solution to the annoying problem of having to swap a motor or an arm with a 4-in-1 ESC. Also it helps with propstrikes, although I never really had a motor wire cut by the props.

Not pictured here is the final solution I adopted to mount the crossfire RX and vTX. I put the RX right between the back arms and the back standoffs, on the bottom plate (the width is just perfect). The vTX is kinda held on top of that and the back arms with a zip tie that goes around the bottom plate.

UPDATE! I upgraded the flight controller and put a HelioRC Spring in there! I only did a couple of tests but I can tell this thing is amazing! The motors sound totally different that with other flight controllers, much smoother.


Part List


Rooster (140 builds)

Flight Controller

FORTINI F4 OSD 32Khz Flight Controller Rev.2SKU: FPV-FORTOSD (23 builds)


XRotor Micro 40A 4in1 BLHeli-S DShot600 for FPV Pilots - HOBBYWING North America (142 builds)


Xnova Lightning 2207-2600KV FPV Racing Combo (4pcs) (3 builds)


Gemfan WinDancer Durable 3 Blade 5042 - Blue (4 builds)

FPV Camera

RunCam Eagle 2 FPV Camera - 16:9 (98 builds)

FPV Transmitter

TBS Unify Pro 5G8 HV (SMA) (596 builds)


TBS Triumph 5.8GHz RHCP FPV Antenna Set (SMA Male) (191 builds)
See Site


TBS Crossfire Micro RX V2 (287 builds)


FrSky 2.4G ACCST System Taranis Q X7 16 Channels Transmitter Remote Controller White Battery and Battery Trays Not Include (263 builds)


Fat Shark Dominator HDO FPV Goggles (136 builds)

HD Camera

GoPro Hero7 Black — Waterproof Action Camera with Touch Screen 4K Ultra HD Video 12MP Photos 720p Live Streaming Stabilization (26 builds)

HD Camera

GoPro HERO Session Waterproof HD Action Camera (4 builds)

Misc Parts

WhitenoiseFPV Race Wire (Set of 6) (7 builds)

Misc Parts

TBS Crossfire Immortal T antenna (18 builds)

Video Receiver

ImmersionRC rapidFIRE w/ Analog PLUS Goggle Receiver Module (178 builds)

Radio Module

TBS Crossfire Transmitter

Battery Charger



Lowepro QuadGuard BP X2
Show stores (12)


Sign in to comment

Mofoe   Feb 05, 2018  

I'm planning to do a similar build. What are your thoughts on the Bardwell FC? Any tips on building?

beeb   Feb 11, 2018 

Hey! I have not used the Bardwell FC so I can't really speak for it. No particular tips on building, except make sure you get the new batch of screws from Armattan. The first batch from January had a problem where the hex hole would strip too easily because it was too shallow. One tip maybe, if you can, rotate your PDB or 4-in-1 ESC half a turn so you have the XT60 pigtail to the front. And route it between the gopro plate and the top plate. Or if your PDB / 4-in-1 has the XT60 on the side, then that's even better I think, you can then make it very short.

Mofoe   Feb 12, 2018 

Thanks for the reply. Sorry about the Bardwell FC I got the post mixed up with another. Lol

Zookzor   Jan 29, 2018  

Hey I just got the Fortini and am building an identical quad minus motors. Did you figure out your use twitches? Thanks

beeb   Jan 30, 2018 

Hey! No, nothing I did could fix it. I replaced the faulty board and the problem went away.

Hawki   Jan 22, 2018  

Hi beeb, your build sure came out nice ... sorry that your fighting the yaw issues. Hope your able to get them sorted out soon so that you can enjoy the build. I noticed in the fifth photo that your hd camera strap looks pretty stressed and I'm not sure I would trust it.
Anyway, have fun with her, she really is a beauty!!
Cheers ...

beeb   Jan 22, 2018 

Hey Hawki, thanks for the heads up. Yeah I noticed that but I figured most of the strength comes from the fabric underneath the "grippy" coating which is damaged. I'll def need to buy more straps that are long enough for this application (even more so when I use a TPU protection). Cheers!

Whiffles   Jan 21, 2018  

Nice build! Why not cover those ESCs with some shrink tube or tape though?

beeb   Jan 22, 2018 

Hey Whiffles! Those are not ESCs, those are "race wire" which is basically a PCB with 3 traces that acts as stiff wire and makes swapping a motor easier (as opposed to removing the top plate + FC and accessing the 4-in1). Since they are very light, I think the very strong sticky foam tape will hold them enough.

Whiffles   Jan 22, 2018 

Interesting. I was wondering why the chip and capacitors would be on the bottom. I guess I could have read the part list :)

Guides & Reviews

Jun 21, 2021

AirbladeUAV has done it again and this time they've brought long range to the 5" class! Based on the popular Transformer Mini, the new Transformer 5" Ultralight adopts a lot of the same design philosophies with larger props and more payload capacity. It can fly upwards of 20 minutes on a 4 cell Li-Ion battery pack and in ideal conditions it's got a range of over 4 to 5 miles. In this guide I'll walk..

Read more
Mar 04, 2021

With the release of the DJI FPV Drone cinematic FPV has become a lot more accessible, but you certainly don't want to crash a $750 drone! The QAV-CINE Freybott is a compact, lightweight cinematic FPV drone that can take a hit and keep going. It's a lot safer to fly indoors and around people. With a naked GoPro or the SMO 4k you can capture some great stabilized footage. In this guide I'll show you..

Read more