LITTLE CHUBBY

By kwadkenstine on Oct 27, 2020

13  307  5

Hi All .
The object of the excercise was to build a 2s 1300-1500 MHA capable rig , with what i had and make some batteries from damaged 4s.
Building the drone EASY.
Soldering the sells together , the welded ones KING HARD.
Result = I have no high c low mah 2s batteries...Yet
Conclusion , build battery tab welder.
Update, battery tab welder not needed , just use the correct flux and be hot and fast.
Replaced the 1102 1000kv motors with 1104 6000kv .
Also moved the sliders one notch to the right and then added more p term.
Adjusted the numbers up in the filter tab as recomended for 3 inch craft, and increased anti gravity to about 8.
So thats about it . Im happy with the tune . Prop wash has to be induced or flown in to .
It now moves out like a , i was going to say a five inch , but thats not right , It is some how quicker and slower at the same time.
Oh , It accelerates faster but isnt quite as fast . Just like drag raceing , 2 cars can start and finish at the same time but one can have a higher speed at the F line.
As expected i crashed many times.
Thankfully even after sheding 3 , yes 3 props !!! I flew it home , bit wobly but not as wild as i thought, I even spun off 2 props doing a split s and still recovered and landed no problem. Do that with a counter rotating x8 .
Cheers

Photos

Discussion

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kwadkenstine   Nov 16, 2020  

Had a little rebuild. replaced the bottom motors with something closer to the specs of the top motors.
Top motors are 1106 7600kv bottom are 1104 6000kv
previous were 1102 10000, they worked and lifted the craft and flew but only just.
Replacing the week motors with something better has saved this model .
I feel it is a keeper

Jodie Froster   Oct 27, 2020  
1

First of all, this is cool, and I have been waiting for a post from you for weeks!
How does she fly? Is she fast? Does she feel fat in the air, or does the powah overwhelm the girth?
I would love to hear that bad boi in the air!!!!
I had similar thoughts about wanting to use spare cells from 4 cell packs that just lost one or two of their cells, as a big battery for a 3".
I like your octo stack. I don't know much about it, but I see ppl counter-rotating the bottom set of props on rigs like this most of the time. They say it increases efficiency.

kwadkenstine   Oct 30, 2020 
1

Hi. I dont know about efficiency but if counter rotating and a motor stops it will fall out of the sky if you try and yaw too much because it tries to spin up one motor and down the other, if the fc commands a motor to spin up that isnt working and slow the other to do the yaw . And it doesnt like it.
But by just making a 8 motor quadcopter , loosing one prop of a pair only reduces maximum power to what the single prop can do.
And I still do not have a 8 x Dshot capable fc.
But i do have a 6 x Dshot f4 fc. Try try and guess what is next

Jayembee67   Oct 30, 2020 
1

Oo! Oo! Me! Can I guess! Gowon! I think it's going to be a hexacopter! That's what I think!! Captain Obvious, that's me. But I am looking forward to seeing that now!

So yes, I have read that contra-rotating props, which is what I built my X8s with just because I did have FCs with 8xDSHOT, can be more efficient - 6%-16% I read here. You are also canceling out the torque around each motor, but I imagine that's less important in a quad. And there is some effect where the 'twisted air' from the top prop gets 'un-twisted' by the lower props, which reduces rotational airflow, potentially smoothing flight.

But yes, lose a motor, and it's goodnight nurse with this setup...

Jayembee67   Oct 30, 2020  
1

This is another splendid engineering effort - I particularly like the double stack. At first glance I didn't understand why both sets of motor pointed up, but now I do, and that's a good idea. The Vista held in with a rubber band is just the cherry on top (literally)!

And you are a braver man than I, prizing apart battery cells and doing who knows what with them! ;-)

But again, and as always, excellent work.

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