Killbot Mk I

By ACROBORG on Jan 29, 2020

52  2,071  26

Still very much a work in progress. But it really seemed like it needed to happen. Put 4" toothpick-class hardware on a sturdy, minimalist freestyle body. Is this the future of FPV freestyle? How will you make every 249g count? Initially testing with a 3000mah 2s 18650 pack, what's lost in raw speed is regained in ENDURANCE. There's a reason the Mavic Mini uses the same configuration. Testing on 3" and now this 4" quad, flight times of 15-20 minutes are normal. ~235g as pictured with 18650 pack.



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dejavu   Feb 08, 2020  

Can you please talk more about the batt, like diagram? Can you share the Battery cover stl please?

ACROBORG   Feb 11, 2020 

Yeah! I'm working up a guide to how to build them, along with the STL files. I'll update here when they're available, as well as post in the brushless micros facebook group.

Shackmir   Mar 03, 2020 

how is the progress? I really like your project!

ACROBORG   Apr 26, 2020 

I need to get on top of my projects! testing has been slower, it's been harder to find space/time to fly with everything shut down. I've been putting a bunch of time into developing the LFH6, just uploaded it here on thingiverse :)

d'jazz.fpv   Apr 25, 2020  

Great build. Love the pinky mount.
Did ou shared it on Thingiverse ?

dtex   Mar 10, 2020  

Hi, is there a reason why you dont scare, not to use a bms to protect the li-ions? If something will go wrong, they will start to burn.

IceC0ld   Feb 05, 2020  

Is the frame available to purchase?

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ACROBORG   Feb 05, 2020 

I haven't decided if I'm just open-sourcing the plans, or free plans and also offering frames for sale, or what exactly. Either way, I'm just flying (and testing) it as much as life/weather allows. And I've already started playing around with a pod design for a nano-cam + naked H6 :)

IceC0ld   Feb 05, 2020 

That would be great. I also want to develop it, design a tpu prop guard for it. Much like the Cinerat frames tpu prop guard.

Want to move into Li-Ion cause Lipo batterys here cost so much.

Looking forward to your cinewhoop build in that frame

IceC0ld   Feb 18, 2020 

Can i ask whats the frames weight? without the tpu part

Samiel2d   Feb 08, 2020  

how are those 1404 motors working for ya? looks good with the matching braided motor wire cover.

ACROBORG   Feb 11, 2020 

Thanks! I'd say these 1404 7000kv are likely the perfect motor spc for this quad, or at least getting really close. I'm finally getting nice smooth prop control through most flight situations. I haven't flown it in intense wind yet though. Peak thrust is limited more by battery then the motor, so I can't imagine larger motors would be of much benefit. I still have some question as to the best KV... if 5000-6000kv would be sufficent, or if there would be any benefit from something 8000-9000kv.

Samiel2d   Feb 11, 2020 

i know that the 7500kv motors ive run didn't like anything more than 2s voltage on a 2.5" prop. i would assume that with the voltages you're using that the higher kv would be better performance than a 5000kv motor. im trying to decide if im going to get a whoop next (spring is coming and the rain here will be constant for the next month or so. or to build a mutant 4 with a set of 1204 5000kv motors

Samiel2d   Feb 05, 2020  

the 1108s don't have a problem swinging the 4" prop? what is the voltage of that 2s 18650 pack?

ACROBORG   Feb 05, 2020 

Funny you ask about the 1108 motors... They're actually doing suprisingly well, performance is totally adequate, temps are fine, and overall flying nicely. But I'm having trouble getting that last bit of smoothness I need in the footage. So I have some xing 1404 7000kv showing up tomorrow that are getting swapped on, I'll see how they work out. The 18650 pack is 8.4v fully charged, and I aim to have it back on the ground around 5.8v.

Samiel2d   Feb 06, 2020 

thanks for the insight. i saw your build the other day and i instantly thought about getting a racer x mutant 4 with these motors. probably will keep with lipo batteries as im not as concerned about endurance. just good to know those motors can handle the 4"

zsoltm   Feb 04, 2020  

Impressive! I was thinking about the same, 2S LiIon on 3-4" or maybe 3S on 5" with DJI FPV, so it's very nice to see it's working in practice. Also the cam mount design looks very solid, well done.

Jodie Froster   Jan 29, 2020  

This is SO good.
Love the cam mount, love the layout, love the weight!
Hit us with some footy!

ACROBORG   Jan 31, 2020 

It's coming along! The weather hasn't been so cooperative, but today's flight will get posted.

IVRZ   Jan 30, 2020  

15-20min?? thats pretty crazy! Does the battery just have lower discharge rate so theres less punch? I think this type of battery is good for cinebees and smooth flights. Nice Job!

ACROBORG   Jan 31, 2020 

Lithium Ion cells come in a wide variety of chemestries, so I'm only really talking about the ones best suited to our needs (most the rest just suck). LiIon (Lithium Ion) packs more energy into less space then Lithium Polimer (LiPo), but also has higher internal resistance. Basically it's a lower C rating. So to make it work, the quad just has to be designed around sucking fewer amps, and keeping up prop RPM at low voltages. Essentially, the same stuff that lets modern Toothpick-type racers have stupid-fast acceleration for a couple minutes, means that even at half the thrust-to-weight this thing still rips around plenty quick for a long time shooting 4k footage :-)

kfncolo   Jan 30, 2020  

Does that FC/Esc work in the 6-7 volt range, which would allow you to use more of the li-ion battery capacity?

ACROBORG   Jan 31, 2020 

Yup. I'm using a tiny LC filter supplying vbat to the camera. It will run 5-20v. The VTX and RX use 5v, and it all appears pretty tollerent of low voltage. I haven't actually found which component glitches first, I've had it in the air below 5.4v specificly testing to see what happens. I'm sure something was struggling, but nothing failed. With this quad, and other's I've flown with 18650, I aim to be back on the ground by 2.9v. At that voltage, everything seems to hum along fine.

miromir237   Jan 29, 2020  

Yep, this is probably the future. Nice design. It would be nice to get it working with DJI FPV.

ACROBORG   Jan 29, 2020 

Eventually I'm sure this size of quad will feature digital FPV. But right now, the Air Unit would dwarf this quad. It would have to be so much larger to fit it, it wouldn't be the same quad. However the Caddx Vista should fit ok directly over a Zeus AIO. When the frame goes open-source, if I don't design a camera pod for the Vista I hope/expet someone else will :)

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