Ascent 3" Crossfire Caddx Tarsier

By wrong17 on Nov 21, 2018

13  677  9

Background Story:
I took me almost a year before starting this build. All the parts were sitting and waiting to be built but not enough time. So here it is, the FlexRC 3" Ascent long range with TBS Crossfire, Runcam Split Micro, and up to 800mw of VTX power using the TBS Unify v3. I waited so long that the frame and hardware has been outdated. They do not even make this frame anymore because they update the design to HD or Lite version. Even the Runcam released a Micro 2 and a new player named Caddx joined the fun with the Turtle (the Turtle v2 is out already too). And finially RotorX came out with a version 2 of the 1404 motors.
The main reason why I was not motivated to build this quad is because of the problems I hear and saw with the Runcam Split. When I first bought this frame, it was designed for the original Split (because the Split 2 and micro was not even out yet). I lost confidence with the Split when it froze midflight and it lost all FPV video. It also did the same (many times) for a friend. How can I trust something that does that on a long-range quad?
Recently I finished building an Airblade Eclair 3” Lite and I forgot how fun it was to fly a smaller quad. I also saw a few videos of people mounted HD cameras on a Tiny Whoop and I built one of those too. Now I wanted a small HD quad that can get long flight times. That is why the FlexRC Ascent project jump to the front of the building queue.

The Build:
I stated with the motors first. I was debating if I wanted to use the wire mesh covers like I did on the Eclair Lite build. I really liked how it turned out, so I did it again for this build, but this time I picked orange (I did not have a choice, orange is the only color I had). This frame supports bought 30.5 and 20mm stack but I want to keep this thing as light as possible, so I used whatever I have and that happens to be the HGLRC 428 stack.
I had a slight issue with the HGLRC 428 and RunCam Split mini stacking on each other because the 2 USB ports would touch, so I increased the space between the 2 boards by adding an extra nut. Because the 2 boards are further apart, I was able to stuff the TBS Nano RX in there. At the top of the stack is the TBS Unify VTX. I just double side taped the VTX to a 20x20 Carbon Fiber plate (I took it for my Armattan Bumper frame).
The TX antenna is standard one it came with and I ran it along some zip tie and heat shrunk it. I like using this method because it will be lighter than using and Immortal T. Plus, I would need some special mount if I wanted to use the Immortal T properly. Do not be fooled by the cheap price tag on the Realacc UXII Stubby antenna because it is awesome, and it only weighs 1.78g.
I was being weight conscious on this build, so I did not want to add any unnecessary weight. Unless I really needed it, I did not use any TPU motors dampeners, backpack, or arm guards.

Test Flight:
With no tuning and just stock Butterflight PIDs/Rates it flew great (but still needs some tuning to get rid of the prop wash). I tried using 3 different lipos and I am sad to admit that my favorite choice is the Tattu 650mah 75c 4s (69g). The other 2 lipos I tried are Tattu 850mah 75c 4s (103g) and RDQ 650mah 80c (80g).

Update: Jun 23, 2019 - Caddx Tarsier:
Swapped out the Runcam Split v1 for a Caddx Tarsier. I thought the Camera was defective because I was not able to get anything to work. The first problem is that is was not recording. Then I tired to use the phone app to check out the setting on the camera. I am able to connect to its WIFI but the app will not communicate with it. So, I end up using an iPad and that worked. When I was using the app, I notice that the SD was not working. I tried 6 different cards and formatted it differently.... none of them worked. According to Caddx’s website I need to format the card to FAT32 (64K) and it must have a U3 speed rating. Long story short, I used the Tarsier camera to format the card and it worked.


Part List


Ascent X 3" HD - FPV Racing Drone Frame (6 builds)

Flight Controller

6.5g 20x20mm HGLRC XJB F428 Micro F4 AIO OSD BEC Flight Controller & 28A Blhel_S BB2 2-4S 4 in 1 ESC (49 builds)


4 x RotorX RX1404 - 3600KV High Performance Micro Motor (5 builds)


RotorX Triblade RX 3044TX Props (3CW, 3CCW) (32 builds)

FPV Camera

Caddx Tarsier V2 4K HD FPV Camera (62 builds)

FPV Transmitter

TBS Unify Pro 5G8 V3 (SMA) (197 builds)
See Site


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


Team BlackSheep TBS Crossfire Nano RX - Heli-Nation (1484 builds)


Tattu 14.8V 4S 650mAh 75C LiPo Micro Battery - XT30 (26 builds)


Team BlackSheep TBS TANGO 2 V3 PRO RC RADIO (104 builds)


DJI Goggles 2 (7 builds)

HD Camera

GoPro Bones - HERO10 Black (FPV Lightweight Drone Camera) (3 builds)
See Site

Battery Charger

HOTA F6+ 1000W 60A 1-6S Quad Channel AC/DC Smart Charger - Grey

Battery Charger

HOTA D6 PRO Dual Charger 1-6S AC200W/DC650W 15A w/ Wireless Cellphone Charging - Black (14 builds)

Soldering Iron

TS100 Portable Programmable Smart Soldering Iron (264 builds)


Lowepro QuadGuard BP X3 - Drone Backpack for 4 FPV Quad Racing Drones and 15" Laptop w/Exterior Mounts (Black)


iFlight Crystal HD Patch and Stubby 5.8GHz RP-SMA Antenna Set for DJI - LHCP - Carbon
Show stores (9)


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pjquad   May 14, 2020  

What size is the frame motor to motor ? Doesnt say on the Flex website..

wrong17   May 14, 2020 


pjquad   May 14, 2020 

Thank you

mbilozub   Jan 27, 2020  

I have the same problem with the SD card. How did you fix it?

wrong17   Jan 29, 2020 

For some strange reason I had a lot of problems installing stuff with my Google Pixel Android phone, so I used an IPAD and I was able to connect to the Tarsier via Wifi. Then I used the Caddx APP on the iPad and formated the SD card through the Tarsier and then the it was able to read the SD card. I hope that helps.

sergetania   Nov 21, 2018  

A proof it's better late than never! 👍 Fun flier! That is a skyscraper stack! 🏗️
Why does the split have a microphone? It's worse than terrible

wrong17   Nov 21, 2018 

I am glad I followed though with this build because I was tempted to sell it. The Ascent frame can take a beating too because it seems to bounce off everything I have hit....maybe its because of the egg shape... or pure luck. The stack is a bit taller than I like but I can not do much about the 2 extra boards for the Runcam Split.

sergetania   Nov 21, 2018 

I think I have built a half of a dozen of FlexRCs. They are great fliers and sturdy but not indestructible. The new design is an enhancement

wrong17   Nov 21, 2018 

Nothing is indestructible, but good thing FlexRC frames have a lifetime warranty. :) So that is good as indestructible to me, lol. Too bad the electronics does not have that kind of warranty too.

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