Xilo-Phreakstyle Digital 7" - The Upgrade from Hell...

By Jayembee67 on Jun 20, 2022

11  415  0

I got a GoPro Bones camera and have been mounting it on various machines to see what it can do. And after watching some of that excellent ReelSteady footage, I got to thinking that this might work well on a big, fast cruiser... and so started to have thoughts about 7" machines.

I had an old analogue Super G Plus that had never got the stick time the build deserved, I switched over to digital soon after building it and we all kind of know how that goes. It had sat in the basement for a couple of years, so this seemed a perfect time to resurrect it, and make good on that investment. Oh dear, how naive I was...
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So I dug out the Super G Plus, spent some time with the printer, made suitable Air Unit mounts, reprinted other parts to make it less garish, and with fairly minimal effort converted the machine to a digital set up - upgrading all the firmwares to get RPM filtering and all the latest and greatest 1s and 0s. And then I took it out to fly. And it was absolutely terrible. It flew, but it was rattly and unstable, and had a tendency to tip over in the corners. I did some basic field tuning, but to no avail. It was so bad.
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I initially put this down to the geometry. I'm not a big fan of deadcat, I find the handling is strange, and as this was ultra-deadcat I felt that maybe this was a problem. So as an experiment, I ordered two more Super G Plus arms to replace the front arms with the hope that this new geometry would stabilise the machine some. But, as you can see, this resulted in an ultra stretch-X. Which looked kind of cool, I liked my Hyperlow Vert builds back in the day, but again when I took it out it flew horribly - very, very unstable. And tuning didn't help that much. So again, this geometry wasn't working out.
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At that point I threw up my hands, and looked around for a cheap-ish, Sensible-X 7" frame. And ended up going with a Xilo Phreakstyle, which seemed to fit the bill. I took all the electronics out of the Super G Plus, put them into the Phreakstyle, reprinted a whole bunch of parts, and tried again. And this time... it flew juast as horribly. A little better than the Super G Plus frame perhaps, but still rattly, and with poor authority. I did further tuning, and found I could slide the BF sliders all the way up into the red zone and my motors were not even getting warm. But I still had no authority. Hrm...
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I concluded that perhaps my motors were just too small and slow for those big old props. Maybe. I was getting desperate. And so swapped out the 2508 1200KV Racerstars for 2807 1500KV EMAX motors, a simple thing to do - but the cost of this cheap upgrade was definitely ramping up at this point. And again, I took it out to discover it flew horribly. Rattly, no authority, and again, I could slide the PID sliders into the danger zone and nothing took off for the moon and burst into flames on the way. This was definitely wrong.

And so, as a final act, I replaced the individual BLHeli_32 ESCs for a 4-in-1, and whilst I was as it, I replaced the Holybro Kakute with a Kakute HDV I had in the spares box, because the JSTs make it all a bit easier and definitely tidier. At this point the only original parts in the build were the Crossfire RX and the GPS module. So much for a cheap upgrade - the Ship of Theseus comes to mind...

I did some very basic backyard hover tuning, and already I could tell that things were different, the motors were spinning way faster, everything was much crisper, and the Blackbox logs looked much better than then every had. I certainly didn't need to slider the sliders up into the red zone, quite the converse in fact.

When I took it out... it did this:

And this, at long last, made me happy. It was big, and smooth, and fast. Obviously the ReelSteady makes it look fantasticly buttery, but even without stabilisation, the footage looks good. And the thing is powerful. Far too big a machine for the confines of the Flying Field - I was hitting the boundaries far too quickly. This is a beast for the open range, where it can run free and fly high. Although I might need some bigger batteries before trying that - I got through a 1300mAh 5S in under 4 mins, so not exactly the most efficient of machines. Fast though, nice and fast. But I will try some bi-blades, see if it make is less thirsty.

So it was the individual ESCs all along. I feel kind of stupid, really. Who knows, I may have got the original Super G Plus flying just fine with an ESC upgrade. TBH, I have no idea what the actual problem was - the firmware upgrade seemed ok, looking at the BLHeli_32 settings they were fine, there was nothing in the BB logs that made me go "Oh, ESC problems", BetaFlight configurator seemed to think everything was fine. But those ESCs were not spinning the motors anywhere near fast enough. And because I am not very familiar with big, slow motor machines, it seemed fine - it was hovering at 45% throttle. But the power was not getting through the ESCs to the motors in the right way somehow.

Oh well, maybe I'll put all the original parts back into the Super G Plus, replace the ESCs and have a spare 7"... sigh.

I have included a link to the a Thingiverse posting of all the TPU parts.



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