FlexRC Ascent 3" with DJI FPV System

By wrong17 on May 02, 2020

11  437  5

I looking to build a 3-inch quad with prop guards but did not want to buy a new frame. I was digging through all the old frames that I have stashed away but not many have the space to accommodate the DJI Air Unit. I am not a fan of the Caddx Vista because it does not have a DVR.

Before I moved over to digital, I was in a middle of another project that most likely will not get developed any further. It is like the FlexRC Ascent build I am working on now, but the main difference is that I will not be able to fit an DJI air system in it. Here is a link to the other project, it will most likely stay as a “mockup” and never be published: https://rotorbuilds.com/build/21892

3D Printing

I was hoping to find something on thingiverse that someone created so it will be an easy conversion for me, but I did not find anything. But I did find a few things that was useful, and I will remix. It took some time cutting and hacking away on the computer to come up with the mount for the DJI Air Unit. Overall, I think it turned out okay. I hung the DJI Air Unit upside down by using modified mount that was intended for the FlexRC Nija HD. Then I created a bracket that would secure it from the top 2 standoff screws.

I am not sure if I want prop guards or not, but I will create one anyways. I really like the Ethix Cinerat props guards and it practically indestructible when printed in TPU. I remixed the original 3D model and made it fit the Ascent frame.

If this quad is intended for cinematic shots, I needed to make sure the prop guards are NOT in view. In order to do that, I have to put the camera out further. I took the 3D printed camera mount from the Shendrone Squirt v2 that was created by M490fpv and remixed it so it will mount on the Ascent frame. I might need to do some more work on it because it is kind of difficult to make something appealing from the ugly egg shape frame the Ascent has.


For this build I plan to use a BetaFPV 20a v3 AIO board because it gives me a lot of room to work with. My other option would be the HGLRC F4 Zeus AIO 15a 20x20, but it is not rated for 4s. It claims that it can handle 4s, but I need to make sure not to go over 13a. That is why I went with the BetaFPV 20a instead. I do not think a standard 20x20 4in1 and esc stack would fit so I did not even try. I think that a 12a AIO Tiny Whoop board will be able to handle the load because I am only 1404 3850kv motors with 3” props and 4s Lipo. I already use those electronics on the toothpick builds but the major difference is the weight. So, the safest bet would be the 20a AIO. Another reason why I did not even try using a 12a AIO board is because it does not have 2 open UART I need for the Crossfire RX and DJI Air Unit. The only 12a AIO that has 2 open UART is the Pyrodrone version, but I do not have that one. I only have the GEPRC and BetaFPV version on hand. If I have to buy something new, I rather get a setup that will work for sure.

Updates (May 06 2020) - 3D Printed Parts

After finishing the build, I noticed that the prop guard is designed for taller motors like 1407 because the props are better position where the guard can provide protection. I am assuming the horizontal part of the prop guard should be the same height of the prop. But right now, when I am using 1404 motors the props are sitting too low and the guards is not doing its job because it is slipping through when it bumps into something.

When I remixed the Cinerat’s prop guard I covered up the recessed area on the bottom of the motor mounts because I do not have the carbon fiber inserts that was usually provided with the frame. As we all know what happens when you try to tighten a screw on a TPU printed arm protector. The screw will sink in to the TPU and it might not be very tight. Now I added the recessed hole and created a 3D printed insert.

Recently I crashed the quad straight into the ground and scratched the camera lens. The camera mount that I originally created from remixed parts did not protect the lens. Now I took another DJI camera mount that was for a Floss 2.0 frame and remixed it to fit the Ascent. Unfortunately, the 3D files were purchased so I am not sure how that works in terms of sharing. For now, I am NOT going to be uploading the new camera mount to thingiverse.



Sign in to comment

yallauthority   Jan 07, 2022  

do you keep tabs on your ESC readings? just wondering what amperages you've seen on this setup because i was thinking about doing a Cinerat frame with JHEMCU ghf411aio pro (newer 35a version) and i have both 4s and 6s batteries

wrong17   Jan 08, 2022 

I used to have DVR footage from my OSD for all might flights when I was using analog. But since I moved to Digital, I have no way to record the OSD anymore. All I have is the telemtry SRT that DJI created with the DVR. So, I do not have any amp reading. But if you plan to use 1404 motors, the amp reading is usually pretty low with a 3" quad. I am guessing under 10amp total for all 4 motors when cruising. BUT that is with no HD camera, like a GoPro. So, a 35a ESC should be more than enough for 1404, 1407, 1507, and 2004 motors. If you are heavy on your throttle and using larger motors like 2004, and carrying a heavy load, they you might use a 40 or 45a ESC. Just make sure you have Capacitor on it too.

sac14sav   Jul 17, 2020  

omg i love this amazing bud.

RZFPV   May 08, 2020  

auwm with battery? any flight footage

wrong17   May 08, 2020 

I do not like putting AUW for the quad because it depends on the Lipo you use. In my case I have a few different lipos:
Tattu 650mah 4s 75c - 70g
Tattu 850mah 4s 75c - 102g
GNB 520mah HV 4s - 55g
CNHL Ministar 850mah - 106g

That is why I like to show the dry weight of the quad, 200g and you can add the weight of which ever lipo you want to use.

As for the flight footage, here is the footage of the crash where I scratched the front lens. For some odd reason the DJI Air Unit was not recording and all I have is the DVR from the goggle:

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