In this post, I will be reviewing and building the Ummagawd Acrobrat 3″ micro frame from Rotor Riot, with the latest Runcam split Mini V2 camera.
Don’t forget to check out my mini quad frame buyer’s guide :)
Where to Buy?
You can get the Acrobrat frame from the following vendors:
- GetFPV: http://bit.ly/2QDMy3F
- Amazon: https://amzn.to/2EdvIqP
A Closer Look at the Acrobrat Frame
At first glance, I was amazed by the top notch packaging, build quality, and the innovative design. You can tell how much effort Tommy (Ummagawd) put into developing this frame.
The Acrobrat is designed specifically for the Runcam Split Mini V1 camera. With the long frame body, it has more than enough room for three separate 20x20mm stacks! This means you can mount the Split Mini in the front away from the FC stack.
They reintroduced the “clean and dirty sections” which is supposed to mitigate jello in the footage. Basically the camera section is separated from the motors where the vibration is produced by some rubber grommets.
The frame comes with 4 sets of grommets of different stiffness. You can choose the one that gives you the best result depending on the condition you fly in (temperature, how much vibration your build has etc).
It also offers smaller grommets for soft-mounting your FC stack.
Some Acrobrat Frame Spec:
- Lipo top mounted
- Diagonal motor to motor 163mm
- front to back 115mm
- left to right 115mm
- Unibody bottom plate with arms 3mm
- motor mount pattern 11.5mm, 3 holes each motor
- top plate 1.5mm
It comes with high quality “Ummagrip” anti-slip battery bad, awesome stuff!
How’s the Acrobrat?
It’s one of the easiest 3″ frames I’ve ever built! It’s got so much room you can literally fit three triple-board stacks in there… It’s designed for the Split Mini, but it also seems to work with the Split Mini 2. I think it’s also compatible with the Cadex Turtle and Foxeer Mix since they all have 27x27mm boards?
Runcam changed the dual-board design into a single board in the Split Mini 2, as a result the board is made bigger in order to fit all the components. As you can see the Acrobrat can barely fit the Split Mini 2, the gap is less than 2mm. I don’t think that’s going to be a problem, but if you are unsure, just use a file to remove some carbon fibre.
Flight performance is really stable and smooth thanks to the “massive” motor layout. With the camera placed so far ahead in the frame, the propellers and light reflection won’t appear in the footage.
However it’s quite heavy for a 3″ frame, weighing in at 58g! If you compare side by side with other 3″ quad you are going to notice it’s considerably larger as well.
If you want to build an FPV drone for filming smooth videos using one of those “Split” style HD/FPV cameras, the Acrobrat is an awesome frame! But if your goal is racing or fast freestyle flying, then you might want to consider other lighter frames. 20 grams extra weight is HUGE to the flight performance of a 3″ quad.
Acrobrat Build Parts List
I tested these parts in the past and really like them so I decided to use them on the Acrobrat:
- Acrobrat 3″ Frame
- Runcam Split Mini 2: My Review | Banggood
- Mamba F405 Mini FC with 4in1 25A ESC: http://bit.ly/2NO4P14
- Diatone Edge 1408 4000KV Motors: http://bit.ly/2BYIZRk
- Unify Pro VTX V3: Amazon | GetFPV
- Frsky R-XSR Receiver – Banggood | Amazon | GetFPV
The Mamba F405 Mini Stack (previously known as Fury F4) has great form factor and capability.
A lot of 3″ motors are very “notchy” (not smooth when you spin the motors by hand), and the Diatone Edge Racing 1408 are one of the smoothest motors for 3″ I’ve found. I believe they are made by Sunnysky.
For VTX I am using the Unify Pro, it’s one of the smallest VTX that is capable of 800mW, so I can go a bit further if I want to :)
After soldering up the motors to the 4in1 ESC, and mounted the motors on the frame, it’s time to install the ESC.
I used some long M2 nylon screws (20mm) for the stack, the 4in1 ESC and FC will be separated by some nylon spacers.
Unfortunately, the widened PCB of the Split Mini 2 presses against the 4in1 ESC connector. Luckily the Mamba FC has its own rubber grommets and soft-mounting. If you are using other cameras with smaller PCB this shouldn’t happen.
I am mounting the VTX at the rear with some double sided foam tape.
I installed two capacitors for reducing noise in the power: the small silver one at 5V (47uF), and a bigger one (220uF) at the LiPo pads. Because I am powering the Split directly from LiPo, I am hoping this should minimize the noise I get in my FPV feed.
The AUW is around 253g with a 850mAh 3S. 300g with a 1000mAh 4S. 4S is preferred for this setup.
Some close up photos of the build.
The 4in1 ESC is BLHeli_S, so the optimal ESC protocol would be DShot600.
Here is my setup in the Ports tab. Note that I am not using soft serial for SmartPort as I am getting the “uninverted” signal directly from the R-XSR.
Current and Voltage meter settings.
I will upload some footage soon… with my PID tune.
do you already have your pids right to show us.
I’m struggeling with my build because I can’t get rid of some propwash and it does not feel very locked in more kind of like spongy in the air also.
Went for BF4 and started with the suggested pids for 3″ quads from George Hartmann but can’t get it “feel right” from there.
Hi Oscar, I wonder if this motor would be good with this frame – BrotherHobby Avenger 1507 3-4S Brushless Motor for RC FPV Racing Drone – 4100KV. (banggood.com/BrotherHobby-Returner-R3-BH15017-1507-2800KV-3600KV-4100KV-3-4S-Brushless-Motor-for-Racing-Drone-p-1225242.html
Thanks in advance
Looks like they might work.
What pads did you solder the caps to on the flight controller?
Oscar, how much experience do you have with those Diatone 1408’s? I’m asking because I went through 3 whole sets with the EXACT same results on all three: after one or two hours of more or less intense hovering (i.e., not racing or freestyle, 4.5min of flight on a 650mAh 3S), the bells are loose and able to tilt laterally, and the motors sounds like pure trash (starts with one or two more and eventually spreads to the others).
I went to the Tachyon 1408’s and they are far better than the Diatone, in this regard. The notchiness didn’t affect the tune either, although they seem to draw more current and be slightly more powerful.
Couldn’t find info on the bearing dimensions to replace them, either.
I have been flying the Diatone 1408 for over 30 flights and they are holding up. I also have the Tachyon 1408, you are right they are more powerful and notchy, but i prefer the smoothness from the Diatone. If you are happy with the Tachyon they are still great choice :)