By Jayembee67 on Dec 05, 2019

25  1,743  25

I saw this frame, and even though I had emphatically claimed that I had no intention of expanding the HD fleet, I had to have it. To be fair I wanted a DJI-enabled 3-inch machine at some stage, and had been eyeing a couple of possibilities, but this thing leapt to the front of the queue, and had to be possessed at once.

It was a tight build, there really is only room for the FC and ESC under the middle plate, so that means the RX can only be mounted on top of the middle plate. And then there is a need for leads to be passed through the channels in the carbon, which is fine for the Air Unit's plugged connection, but is why I used pin headers on the Crossfire Nano; I can take everything apart without a soldering iron (and yes, I know, the leads are reversed, I spotted that before I powered up...) Tedious and a bit messy though, and as such I suppose that this frame is best used with the full DJI stack and no external RX.

Still, it seems to work; it makes beepy noises, hovers around the basement, sends and records HD video, all that good stuff, and looks rather splendid and unsettlingly insectile / xenomorphic whilst doing so. But I shall need to wait out the rains to properly test fly and see what it really does. More on that later, I imagine.

UPDATE 2019-12-07
I managed to squeeze in a maiden flight this morning before the storms started, and early returns are encouraging if not amazing. It flies quickly and nimbly but it obviously needs some tuning; currently all BF 4.1.0 defaults and it works, but there is too much rattle and shake coming through.

SECOND UPDATE 2019-12-15
I have now managed to get a firmware together that support BF4.1.1 and so have enabled RPM filtering. And whilst it hasn't fully eliminated the strange large scale oscillations, RPM filtering has done an impressive job of smoothing out a lot of that other issues. Still work to do, but this is now flying a lot better than it was.



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HyDrone_FPV   Jun 26, 2020  

what's your flight time with the 4s 850s?

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HyDrone_FPV   Jun 26, 2020 

thanks! I've got some 4s 850s that I picked up for a build but they were too heavy and killed the flight time so they have just been sitting at storage charge for months. But now I know what I'm doing with them and my extra air unit!

Jayembee67   Jun 26, 2020 

Haha! Very good! :-) Yes, I've had the same happen, some smaller machines top out at the 650mAh packs, but the slightly bigger motors on this build like the 850s. I look forward to seeing your build photos!

HyDrone_FPV   Jun 26, 2020 

thanks for the quick response, I just finished a mockup for it! Happy flying!

Rickard   May 22, 2020  

Really nice build. This one gave much inspiration to my latest build.

HushThatPanda   Mar 29, 2020  

Did you ever figure out a better tune for this?

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kwadkenstine   Apr 09, 2020 

HI, funny thing , props out uses a different strategy to do yaw , some say its better ,but who knows, I know little about 3in rigs , but as a general rule if i have issues with p wash i prop down a little, , the 3052s may be a little too much for the motors to handle. . Cute little rig .

HushThatPanda   Apr 10, 2020 

Glad to hear it's back in action. I've only used 650mah R-line 4S on it. I need to find a longer strap to try the 850mah out. 3min run itmes are too short. I'll give props out a shot – doing that with my 3" Gecko and it's working well. I was able to reduce my propwash quite a bit with turning Vbat Compensation on, bumping up the I term a bit, and increasing D-gain by about 5. That and with the filter sliders pretty far to the right. Also running 4.2 on it and it's muuch smoother.

Jayembee67   Apr 11, 2020 

Yes, reverseing the props definitely did something helpful. I see a lot of 3" and 2.5" pre-built machines with reversed props, so I suppose that there is something about prop direction and small machines? Dunno. But happy it helped. And yes, I did put on less agressive props, but that was before the motor reverse thing and so I was still having other issue. I should do more tests now!

kirkdis   Dec 09, 2019  

what is the weight of the setup without battery? Looks nice so far.

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Jayembee67   Dec 10, 2019 

Yes, trying to squeeze this tech into a 3" machine is asking for a bit much, to be honest... :-) I competely agree with your prediction, I absolutely expect the release of an Air Unit v2.0, and that it will be much smaller, hopefully a 30x30 footprint to better squeeze into more standard frames. And thank you,it came out nicely, and just today I set it up for RPM filtering, and that has made a lot of difference, it was flying so much better this morning. RPM filtering, unexpectedly impressive!

Jayembee67   Dec 12, 2019 

Well, THAT didn't take as long as I was expecting: http://www.multirotorguide.com/news/caddx-vista-vtx-for-dji-digital-fpv-system/ And DJI licensing this tech too? That's very interesting.

kirkdis   Dec 12, 2019 

nice finding! but from a business point of view this is the next step how to collect the customers money. Thanks for sharing...

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