It took me much more time to put my Scarab Knife 200 4" from CarbonBird.com into the air and actually fly it. First try that happened 2 weeks ago failed due to beginner mistake: too long motor screw caused one of the motors to overheat. I had to order shorter M2 screws and redo some other things: add 1000uF 36V low-ESR capacitor to power rail, relocate VTX and X4RSB RX. Nothing super fancy. Final effect looks like this:

Scarab Knife 200 racing quad

Scarab Knife 200 racing quad

Scarab Knife 200 racing quad

There are a few problems that I hope proper tuning will solve. One of them, is strange wobble, or low frequency oscillation, on full throttle. I'm not sure what is the source of it. It might be from quite soft props. I will try replacing stock HQProp 4x4.5" with DAL T4045. But second problem is that probably 4" props do not match my flying style. Those small props just do not gip so much air as 5-inchers and do not keep flying path as good as I'm used to. I had similar feelings when testing JJPro P175, so that might be the case.

Next tries in 2 weeks...