Sohei MK2 - sub 250g 3" 4S

By jeffcd on Mar 26, 2022

13  258  0

This is my first frame from roninUAV.
The parts came impeccably packaged and well labelled with an actual paper assembly guide.
In addition, the website has an amazingly comprehensive build guide & tuning guide and also has links to download STL files for the frame.
If your looking for a great 3" freestyle frame, I highly recommend supporting this independant frame designer!

From an electronics perspective, the build didn't go exactly as planned...
I had an ImmersionRC Tramp Nano VTX and Atto Duo RX mounted on a whoop proton pack, which was removed from an old build.
It stacked neatly on top of the whoop board, but I was having issues with the receiver so I had to remove it and go with an individual VTX and RX mounted in the back.

The JHEMCU H7 AIO flight controller was another issue.
It doesn't have an official firmware target in Betaflight, so you have to either use the custom .hex file on their Github page or use the iFlight H7 AIO target in Betaflight (which is what I did).
After flashing it with BF 4.3 RC3, I found that bidirectional dshot doesn't work. It turns out there's currently a bug in Betaflight that is affecting some H7 boards and preventing the use of bdshot. So I am running with bidirectional dshot OFF. Check the open issues in the Betaflight Github to see if this problem has been solved before buying an H7 FC (if you want to use bdshot).
*** UPDATE: As of 2022-04-01 this Github issue is closed. Bidirectional DShot now works and there's an official Betaflight target for this AIO board!!

This thing is really fun to fly. I was worried the T-Motor F1404 3800's would be a little underpowered, but they feel super smooth and the throttle control is very predictable.

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