YoungRC XL8-X8 Octocopter

By Jayembee67 on Apr 16, 2020

27  3,693  11

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:



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SPeCTRuM_TMD   Feb 04, 2024  

Very impressive. :) I like builds out of the ordinary. I will build an x8 as well. Your build and pictures helps me a lot.
Keep up the good work !

mrechte   Jun 30, 2022  

Hello. Thanks for all these pictures. Could you please explain what you did with the ESC current sensor wire, considering the FC has only one input ?

Jayembee67   Jun 30, 2022 

So I actually didn't do anything - I don't generally use the current sensor in my builds as I am not a racer, and don't really worry about pushing my machines to the extremes. Apologies, I'm afraid that I can't help you here.

nerdCopter   Aug 07, 2020  

This is friggen awesome!! you use a spare plate as Lipo protection?
I dont think i'll be building an octo, but it's awesome how you are doing this and now i know it's possible this way. :)

Jayembee67   Aug 07, 2020 

Thank you! Yes, I cannot deny that it came out better than expected, and it is kind of epic in the air - so noisy! :-D

And no, I actually used dedicated lipo protection plates that I picked up from Banggood for a couple of dollars - they were a good investment, and a hangover from the Old Days way back when I was building bottom-mounted 3S machines!

volitant   Apr 19, 2020  

I wanna see/hear some ground footage of that thing haha

kwadkenstine   Apr 17, 2020  

Yes we are working outside the comfort range of beta flight.
So what fc will support d shot and rpm filtering on 8 motors? im due for some new gear and would like to try the traditional way of counter rotating props and the way i have been doing it by 8 motors off 4 outputs.
You really got into this one deep.

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MaddiRC   Apr 17, 2020 

F7 should work, else try a H7 based FC. The SP Racing H7 Extreme has 8 dedicated motor outputs.

Jayembee67   Apr 17, 2020 

Oh, thank you for this. I might invest in that crazy-looking H7 and see if I can get DSHOT out of 8 pads!

MaddiRC   Apr 18, 2020 

Ask Dominik Clifton, he answers by email pretty quickly:
shop @ seriouslypro . com" (remove spaces)

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