This is Link - The best 2.5" freestyle quad in the world.

By The Van on Mar 11, 2018

48  4,914  29

And I do mean the best.

Ever since the Split Mini came out, I'd been determined to fit it into a nice package. Reviews mentioned stack height being a setback, but they all used 4in1 ESC, stack VTX, etc.. If you go that route, then yes you're going to have a ridiculous stack and most likely a pretty dumb looking quad that may or may not fly all weird!

Enter the Nemesis X. Another product that, once I saw it, I knew it was the 2.5" frame for me. I'm a sucker for a low CG and it doesn't seem like many micro frames really give a damn about that. I've heard from a few people that 'CG doesn't matter on quads that size' - but I would argue the opposite, that it matters just as much if not more than on a 5" build. It's about easing the load on your components. Your FC, Motors, and ESC don't have to work as hard to make small adjustments rotating on an axis when they aren't pulling a bunch of weight from underneath. I've flown a lot of micros that - for lack of a better term - just feel WONKY and I attribute much of that to the fact that they're fighting weird weight distribution. Bottom mount batteries only make sense when they're balanced with significant weight at the top (i.e. an action cam in a typical mini quad). Most micros use a bottom mount and yada yada they all fly like weird little micros. (Spared some redundant lecturing here)

So, the goal was a low-CG micro that shoots decent HD footage and FLIES WELL.

Stack height being tricky, I had to choose a FC board that didn't need a separate PDB (or 4in1 ESC). DYS F4 has a nice layout and most importantly a built in PDB. I also like that I get to run an F4 chip and OSD at this size. This is mounted directly to the bottom plate on its soft-mounts with no standoffs. To achieve this I had to make some cuts in the base plate where the board's tallest components sit, in order to sink it down into the base plate. ! One more tip: Originally I soldered the battery lead straight upward from the board. This gave me nothing to secure it to AND blocked the SD card slot on the Split (think I actually broke the SD card slot on the first Split Mini I used.. replacement arrives today :/ ). I reoriented them to come out of the side (the way you'd normally do it) and from there it twists up and is secured to the front right standoff. Will update with photos.

Needed power. Hyperlite 1106 @7122kv on 3S delivers and then some. Met with a throttle curve for smoother control (for me this is a freestyle quad)

UPDATE: I've had a lot of people ask me about these motors heating up. They DO get hot, they're hard to tune, they're too notchy and I wouldn't recommend them - especially now with some much better choices out there (I'd have loved a 1404 or 1304 when I was building this). If you do run these motors, it's a good idea to start out with much lower P's than you normally might; AND to limit the throttle to 90% or lower to deal with that heat a little better.

Now, I could very well have used the 20a or maybe even the 15a bullet - BUT - those are the exact same size as the 30a and about the same price. Sold.

The VTX03 is the smallest VTX with at least 200mw output. That new TBS thing, the micro Unify or whatnot would have fit a lot more easily but only delivers 50mw max output. Not ideal for me as I want range enough to explore and fly around trees etc. The VTX03 fits just behind the camera with almost no room to spare. All wires and antenna are routed in between the Split Mini and DYS F4.

I almost always buy my FPV antennae as leaps of faith. New ones come out all the time and are seldom talked about at length. This Lumenier dipole looked interesting - lightweight, small, rather durable it seemed. Big surprise is just how fantastic reception is. I've used some pretty good antennae: AXII, VAS Ion, Triumph, some Pagodas (not a big fan), and this little dipole seems to be able to hang with all those. Much, much better than a dipole whip.

I've now doubled up on the Tattu 450mah 3S 45C packs. The cell size is just perfect for the Nemesis' top plate, it provides plenty of power and lasts a good 3min on this quad. I'm sure other packs will work great, you could probably get more flight time out of a 550 or 600mah pack, maybe squeeze a little bit more thrust out of a higher C rating but for me, these rock.

Still playing with prop choices and working on a tune. PID values are a good bit lower than stock in BF. Pictured are the Gemfan 2540 but I'm liking the HQ 2535 so far. The HQ seems more durable and trades just a tiny bit of smoothness for responsiveness when compared to the Gemfan.

UPDATE: This build inspired production of the 20mm hop-up kit. BRDM sent me one to try out and it's a much nicer fit! New photos added.

Photos

Discussion

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MakeitHappen   2 days ago  
1

Sweet build! How do you like the RunCam Split?
I'm putting together a list of parts for a build on KAIKEN 2.5" by tomoquads. I'm mostly freestyle no racing. This would be my very first build after a year of reading/researching. I'm hung up on the motors to use with 3S that would get me good flight time and power I need. Props would be Gemfan 2540.
So far I was thinking
Emax 1106 (but keep reading they get hot)
TMotor/Racerstar 1106 6000kv or TMotor F15 V2 1106 6000kv ( I think they are the same but branded different )
BROTHERHOBBY 1106 5100kv or 7100kv

Recommndations of any not amp hungry?

The Van   1 day ago 

So, I never actually flew this build much unfortunately.. and I blame the split. The latency is right at a point where it doesn't feel like it effects freestyle performance, but it still isn't as fun to fly because I'm always just slightly compensating (even if unconsciously) for that latency. As a result I'd pretty much only fly at spots I know really well. However my freestyle... style.. could be faster than yours; or maybe you fly more often in familiar areas, in such cases the latency would probably be less of a detractor.

Otherwise, the flight performance is awesome & has access to more power than I even really want out of a quad this size.

If I were building this again I'd go for a wider, shorter stator with a lower kv for 3S. Currently have my eye on the Spintech 1304 in 6500kv. RotorX also has a nice 1404. Both seem to be pretty good options for efficiency at this size & 3"

Good luck on the build!

mochichama   Sep 22, 2018  

how do you wiring the esc signal wire? my 4 in 1 esc gone bad, and want to switch to standard esc but i dont know how to wire the signal to dys mini f4

The Van   Sep 24, 2018 

Just gotta splice the signal wires from the 4-in-1 connector to the ESC signals 👍

I believe the FC has pads for power and ground

Philo777   Sep 03, 2018  

Is there room for adding a TBS Crossfire micro?

The Van   Sep 04, 2018 

The (nano) receiver itself is surely small enough - roughly the same size as the R-XSR I used. I'm sure you could figure out a way to mount an immortal T, otherwise the dipole antenna should work just fine!

Abonacci   Mar 30, 2018  
1

Could you elaborate on your throttle curve  adjustments? Interested!

Show 1 more comment
JonnyPhenomenon   Jun 21, 2018 

this can easily be configured in betaflight on the PID Tuning tab. the Throttle MID option tells the FC the percentage of throttle required to make the drone hover, and adjusts the response to throttle input so you are just hovering when the stick is in the center of travel. then, the Throttle EXPO setting determines how much the response to throttle input changes as you move the stick the rest of the way. these can be set in the CLI with
SET thr_mid = 20
SET thr_expo = 100
SAVE
(well, if you want them like mine)

you can even change it in the OSD if you want. or by a LUA script from the TX..

Abonacci   Jun 23, 2018 

That is such a good idea.  The goal of making a curve like this is to minimize the travel below a hover , so that you get more throttle travel and resolution the rest of the way? Makes sense to me !

The Van   Jun 27, 2018 

Yeah! It can be really useful, and completely change the 'feel' of a motor. I've done the opposite before as well - boosting the curve up so that there's more punch down low (throttle expo in BF might be better for this). Generally I prefer doing it in the Taranis as you have fine control over the points, rather than just using the two control parameters in BF.

JonnyPhenomenon   Jun 21, 2018  

dude, can you post your pids for this? I just finished building this exact same setup, and my motors are totally smoldering... I took a blackbox log of mny first flight and this thing is going totally nuts...

The Van   Jun 27, 2018 

Hey man! Sorry just saw this. These motors are HARD to keep cool, even with a good tune. I noticed that when I went from the standard 15mm to the 20mm standoffs, the motors started feeling a lot hotter. That being said, these will probably need a bit further tuning but here's where I am:

Still dealing with heat though so my next measure will be to adjust the throttle limit. I already have the curve set to top out at 90%, I think 80% will keep things much cooler without losing much top end power.

The Van   Mar 11, 2018  

Here are the cuts I had to make to lower the FC a bit further. I don't think any carbon contact is made, but I laid down some electrical tape to be sure.

Show 1 more comment
Whiffles   Mar 26, 2018 

Is there still carbon on the right side there? Seems like the structure might be affected by that cut.

The Van   Mar 27, 2018 
1

There's maybe 1mm of carbon left. I was really nervous about making that cut.. and like someone mentioned, I could very well have just removed the connector from the board instead.

That being said, with a 3mm base plate on something like this I don't think it's lost much in terms of durability!

The Van   Mar 27, 2018 

pazifist I used a dremel tool with a cutting bit. Marked the cuts with sharpie and using a tabletop vise to grip the base plate (Also I put a rag between the vise and the carbon), made the cuts carefully and incrementally. Keep the FC nearby (but probably away from carbon dust) so you can keep checking as you go. Good luck!

Burning North   Mar 12, 2018  
1

What a gem of a build! Would love to see the HD footage when you take it out for a spin. :)

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Pimpmykwad   Mar 23, 2018 

Can you give us your YT Channel please ??

The Van   Mar 23, 2018 

There are a couple more clips from this build since I last posted here. Though, it's proven difficult to get a really nice tune (I think it's because of these motors). Also, I've had some issues with the Split Mini not recognizing SD cards. Runcam's solution is to put tape on the card, essentially to press the contacts together.

Pimpmykwad   Mar 19, 2018  

Very nice build!! love it!!! can you give the weight of this wonder?? ;-)

The Van   Mar 23, 2018 

Thanks! All up is 147g with a Tattu 450mah 45C 3S, Dry weight is a little under 110 :)

Watsamatta   Mar 13, 2018  

Awesome build! If i may ask, why a JST connection on the battery lead and not an xt60 ?

The Van   Mar 13, 2018 
1

Not sure what you mean, that's an XT30. An XT60 would look pretty funny on this!

QuadStar Drones   Mar 11, 2018  

Really nice! I agree: battery on top makes the most sense, looks like it puts CG right at center of thrust :) I still need to try a micro - probably this summer.

UnderDawg   Mar 11, 2018  
1

Nice build!! I would love to see some flight footage.

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