atomic sub 2" - it's gnarly!

By daich on May 27, 2021

19  988  4

it's like a micromachines version of the tadpole!
GnarlyFPV sent me a stock notification and when I went to browse I saw they had a 2" version! Had to snag it.

Then the newbeedrone hive micro stack was on crazy clear out sale 20 usd for a truly all-inclusive stack -- unbelievable. Just add motors, frame and camera!
It fits PERFECTLY on the frame. Just have to remove the bottom M2 soft mounts and I took the sub-atomic's extra foam bits to pad the bottom board from the carbon.

The stack was being clearanced without support as it was extra stock of a prototype version so it is recommended to only run on 1s but it has been engineered for 2s. There were some issues in testing where certain motor combinations would get desyncs but it is unclear from my searches what the exact details are. Regardless, my fingers are crossed for the maiden.

These skystars are amazingly light and powerful...I've been recycling them on so many builds already... a couple of the holes are stripped and this frame unfortunately only has holes for two motors (on the 4 bolt battern 9mm motoors) so I had to play some musical chairs to figure out which ones should go where.

The pictures don't really do justice on the smallness of this build. I can only imagine how tiny v1 of the frame being 40mm props are.

I have a relatively recent build about the same weight and 1.9" props but with some junky happymodel motors, I think this will fly better...only the maiden will tell. Lets hope this prototype board can keep the smoke in!

Playlist of All Flights of this frame

newbeedrone's betaflight hex 3.5.4 -- non standard due to custom OSD, VTX and RX
(alternate host for 3.5.4 hex file)
CLI Dump of the original firmware

on initial indoors hover, there was a bad twitch. This was pretty disheartening as I thought I got a gimp stack. But I fiddled with the ESC settings and the twitch went away! Initially I was looking for a 48hz PWM update firmware for the YH-10 blheli_s ESCs on this stack but it seems all the 3rd party firmwares didn't have the YH-10 variant (I checked Joe Lucid's JESC and also Blue-Jay) So instead of going that route, I tried increasing demag compensation to High which helps with noise, as well as moved motor timing to Med/High (from Medium) as that also helps with noise. Woila, the twitch went a way! so excited for the maiden.

UPDATE 27 May 2021
maiden flight proved it to fly really well on stock pids. No sliders for betaflight 3.5.4 so I just left everything as is for the initial flight. Just had a bit of minor propwash to be tuned out. I started really enjoying the flight when I hit a wood fence, it was a solid hit but not that hard. It knocked 3 of the 4 motors off, stripping the weeny M1.6 bolts out of the soft skystars motor mount holes. It was a combination of the unconventional M1.6 bolts instead of M2 bolts and also the SubAtomic frame only using 2 bolts for 4 bolt motors that made it a weak point. Oh well, I have since taken some little self tapping screws and screwed all the motors back. Hopefully I'll be able to squeeze a few more flights in before I retire these motors.

UPDATE 28 May 2021
got a few packs in today. in the end, I had to flash the ESCs to a firmware that supports 48khz PWM update. This help reduce noise and the twitch in the yaw goes away. Even with default ESC settings. You'll need to load any firmware that supports 48khz pwm updating like Jesc, BlueJay or Jazz Maverick. I used Jesc which has a free version if you are just doing 48khz and not bidirectional. The original Y-H-10 needs to be replaced with S-H-40 - I learned this from Newbeedrone's documentation. Other than that, I raised my P's up a couple points and the rest is all default pids and default filtering. I also brought feedforward up to 90 but that is just personal preference.

UPDATE 29 May 2021
insta360 go mounting bits are only 3g more, not bad. the battery comically sticks out the back. it flies surprisingly props started slipping though...waiting for more 2" in the mail.

UPDATE 10 June 2021
noooo, stuck in a tree!

UPDATE 13 January 2023
I gave up trying to get it down with a rope. It was lassoed around the very branch it was on and shaken violently, only to prove how securely wedged it was. I visited that tree frequently just to see if it had fallen or moved. After a day of crazy winds in December I went to go check on it and to my surprise it had dropped from the tree. Unfortunately there was a very thick covering of leaves everywhere. I kicked around the leaves and branches for quite a while and came to a sad conclusion that it was a loss. I figured someone picked it up.
Another month passes and while passing by the park I noticed all the leaves were blown away from the last few windy days. With very little hope and expectation I decided to walk under the branch it was stuck in, just to have a look. Lo and behold, what is that orange thing in the tall grass? If it wasn’t for the bright orange cnhl lipo I wouldn’t have seen it! It was properly buried securely into the dirt...perhaps people had walked over it.
I'm still in the process of cleaning it up. THe motors are shot, seized up with rust. I've dismantled and soaked everything else in alcohol. The stack powers up and responds in betaflight!



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Qsmodshop   May 30, 2021  

Awesome build! I've been trying to get my stack to bind with my QX7, but had no luck, did you have a similar issue?

daich   May 30, 2021 

thanks man. I didnt have any issues binding with my multiprotocol module. make sure transmitter is in D8 mode. with FC plugged in to pc, in betaflight command line type "frsky_bind" and hit enter. then on TX hit the bind button. when the tx stops giving the binding beeps its done. power cycle everything and then you should see movement in the receiver tab on betaflight. the nice thing is that the RX is powered when FC is plugged into USB so you dont need to plug in a lipo and burn the VTX

Junnicutt   May 28, 2021  

I never would have thought the tadpole could be shrunk but that looks sick. I picked up one of the hive 16 sale stacks as well, is there anything else unusual about them or is there a good place to read up on them?

daich   May 28, 2021 

Well they are a bit finnicky as they are, after all, prototypes. Because of that, there is no support for them. The advice is 1s only but mine seems to be doing ok on 2s. I've flashed the ESCs to 48khz PWM to help with the noise and now it's flying pretty good.
As for as details, there are a few useful posts in Newbeedrone Hive group on facebook. I've started my thread there too and have logged my experience there as well

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