I had previously converted a small handful of older quads into a single X8 machine, and have really enjoyed the results. So I decided to do it all again, but this time do it 'properly'; 8" frame, decent 6S motors, AIO ESCs, F7 flight controller, and of course the DJI FPV gear.

And this time I came armed with a better understanding of how to build this sort of crime against aerodynamics. I spent a week or so printing bits and pieces, and took my time putting it all together (well, what else is there to do these days? May as well savour the experience, any experience really...) Astonishingly it was one of those builds that actually worked first time (well nearly, the gyro was 90 degrees off first test flight for some reason, always fun to be around, especially something of this scale)

I used 2 cheap iFlight XL8 frame clones as the basis, and I sandwiched the doubled-up rotor arms between the two bottom plates this gave me, printing a spacer for front or back. This resulted in a nice flat bottom to the quad, and that made securely mounting huge batteries much easier.

This go around I went with 2 AIO ESCs rather than 8 individual ESCs, which significantly reduced the wiring clutter. Even still, these X8 builds are a cabling horrorshow. I also went with an 8-input iFlight FC that I could plug into at least one of the ESCs, again to minimise the wiring, but disappointingly, like the HGLRC 8-input FC I used in the last build, only 6 of the inputs support DSHOT. So I am stuck with using Oneshot again; such a strange design flaw. Anyhow, it works, but it does mean that I can't attempt any, likely ill-advised with 8 motors, RPM filtering experiments.

In the end I went with a single XT60 as this is going to be a 5S cruiser with a nice steady draw rate, rather than something I am throwing around and spiking the power. So some huge 5S on a single plug will all be just fine. Well, that's the theory, we'll see how long before it bursts into flames.

I toyed with trying to get the Air Unit inside the frame, putting the ESCs side-by-side, but it didn't really make sense, and given that I have to bottom-mount the battery to give the lower props ground clearance, sticking it on top seemed reasonable. Especially given that this will not be an acro-machine; I don't intend on doing anything with it that is specifically likely to crash it. And it turns out having the video antennas all the way up there gives a nice, clear signal, so it all worked out.

What is more, it even flies. And flies quite well. I managed one test pack this evening. It has a nice, grippy, locked-in feel; definite somehow. It's faster than I had expected too, not a speed demon, but it barrels along. The Air Unit footage obviously has props in view, and is a bit rattly and bumpy; this was entirely default BF4.1.1 tune, so not entirely ideal for such a big machine. But of course the Hero7 footage was nice and silky.

And it sounds amazing again. Huge. Not a machine for wildlife photography.

UPDATE 2020-04-17
Pack 2 - After a preliminary tune. Still rattling at high throttle, but better at cruising speed. And cruising speed can be really quite fast. But the big surprise is that you can acro it, and it handles some flips, rolls, and swoops interestingly. It's a bit like doing acrobatics with a Lancaster Bomber, it certainly sounds like it, but there is definitely something about it. Plus it's fun to put its head down and crash along at speed.

So much for the non-acro 5S cruiser thing. Oh well, whatevs, this is rather splendid: