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Quadcopter Will Not Lift Help!!! Using SunnySky 4108 380kv Motors Only 2.08652 kg

#1
Hi,

I have built a Hobby King X650F quadcopter. The total build weighs 2086.52 grams or 2.08652 kg or 4.6 lbs. I can't seem to get the quad off the ground. My parts are as follows:

HK x650f frame
4 x Sunnysky 4108s 380kv
Emax 40amp Ubec ESCs
5000 mah 3s 30c battery - I combined 2 of these battery for 22v 6s and still no lift, It wants to though
4000 mah 3s 60c battery - I wants to lift..........nothing
1045 props - no lift not sure on pitch
1245 props - no lift
SJ4000 w/gimbal
APM 2.6

So, I got the Sunnysky 4108 380kv to lift the quad b/c I knew I would be adding stuff on it they may add weight. I guess I was in a hurry to get the quad built and I thought I had did enough research, but I guess I was wrong. Based off of the above info..........to get in the air (not racing, just slow for videos) what do I need? After further research I'm leaning towards the Sunnysky 3508 kv700..........or, What props would you recommend for the 4108 380kv? Oh, I forgot to mention that this is my 2nd quad. The first quad was the knockoff qav250 so, I'm aware of the rotation and prop position.

Again, Can I get different props for the current motor and what pitch(not really clear on pitch) or do I need the Sunnysky 3508 with the higher 700kv?

YouTube Video

https://www.youtube.com/watch?v=wVYhVqoHBOk&feature=youtu.be


Thanks
 
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cranialrectosis

Faster than a speeding face plant!
Mentor
#3
You are wayyyy under powered for those motors.

Look at the chart at the bottom of this page:
http://www.buddyrc.com/sunnysky-v3508-29-380kv.html

To use 10" or 12" props on those motors you should be running 5S or 6S to get the voltage needed to spin those motors fast enough for that length of prop. You need to either use SIGNIFICANTLY longer props or SIGNIFICANTLY more voltage to get lift with those motors.

700kv motors will allow you to use these props on 3S per this chart, but really, once you are going this large and this advanced, why not be using 6S anyway for efficiency?
 
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Cyberdactyl

Misfit Multirotor Monkey
#4
Yea, as Cran said. And that's what "popped out" immediately to me as I read down your list. . . 380kv and 1045 props. Even 1245 are smallish for for 380kv, even for 6S.

Those are some heavy lift motors, built for hovering around and slow flight for stuff like nicer aerial photography.

The old analogy of driving down the interstate in second gear trying to match the flow of traffic fits here well.

All is not lost though. If you get something like 1650s and combine those 5000s in series for 6S, as you did for the smaller props, you'll see plenty of lift.

(by the way, your video is set to private)
 

SoFly

Junior Member
#5
Tiny props, I'm running 1045 props with my 980kv motors 3s 2x2200mah parallel. I'm not sure exactly but u should bule looking for props 13-15 my guess I'm not expert im a newbie.
 
#7
You are wayyyy under powered for those motors.

Look at the chart at the bottom of this page:
http://www.buddyrc.com/sunnysky-v3508-29-380kv.html

To use 10" or 12" props on those motors you should be running 5S or 6S to get the voltage needed to spin those motors fast enough for that length of prop. You need to either use SIGNIFICANTLY longer props or SIGNIFICANTLY more voltage to get lift with those motors.

700kv motors will allow you to use these props on 3S per this chart, but really, once you are going this large and this advanced, why not be using 6S anyway for efficiency?
Reread his post, he did try with 2 3S battery in series "I combined 2 of these battery for 22v 6s and still no lift".

Even with the 10x45 props, that should give >4Kg of lift.
 

cranialrectosis

Faster than a speeding face plant!
Mentor
#8
Reread his post, he did try with 2 3S battery in series "I combined 2 of these battery for 22v 6s and still no lift".

Even with the 10x45 props, that should give >4Kg of lift.
Yeah, I just noticed that in CyberD's post.

I would check to see if the props are blowing air up or down and without the video its a guessing game.
 

Cyberdactyl

Misfit Multirotor Monkey
#9
I wonder if it means truly "no lift", or more 'terrible lift'. I would think someone that has flown before would notice props mounted upside down.
 
#11
I want to thank all of you guys for your willingness to assist. Let me know what you think about these props:

http://www.ebay.com/itm/381129945695

If you think these may work I'll go ahead and try them............it's almost been a full 30 days since my quad "Betty Lou" has been supposedly finish. My head is beginning to spin like the props......lol. I thought I was building a quad for slow flights with accessories that's why I choose the sunnysky 4108 380kv. I'm now wanting to cut my loss and buy the higher kv........sunnysky 3108 900kv http://www.ebay.com/itm/Sunnysky-X3...648?pt=LH_DefaultDomain_0&hash=item3aa983d5e8 or the sunnysky 3508 700kv http://www.ebay.com/itm/SunnySky-X3...2703c75&pid=100005&rk=2&rkt=6&sd=231565569606

Then I'll have an excuse to build a cheap plastic reptile quad with the 4108 380kv. What do you guys think?
 
#12
I haven't gotten to see your video. It is coming up as private.

The kids at my school built a hex using Tarot motors rated at 340 KV. They are running 5s and currently 13 X 6.5 props. Given how it flies, I would think that would be about the smallest props they could get away with. It may also be a tuning problem. They had to really crank up the gains other wise the whole thing was incredibly sluggish.

Hope this helps.

DB
 
#13
I haven't gotten to see your video. It is coming up as private.

The kids at my school built a hex using Tarot motors rated at 340 KV. They are running 5s and currently 13 X 6.5 props. Given how it flies, I would think that would be about the smallest props they could get away with. It may also be a tuning problem. They had to really crank up the gains other wise the whole thing was incredibly sluggish.

Hope this helps.

DB
Thanks DB, I'll have to look into the tuning part of the APM 2.6.
 
#14
Yea, as Cran said. And that's what "popped out" immediately to me as I read down your list. . . 380kv and 1045 props. Even 1245 are smallish for for 380kv, even for 6S.

Those are some heavy lift motors, built for hovering around and slow flight for stuff like nicer aerial photography.

The old analogy of driving down the interstate in second gear trying to match the flow of traffic fits here well.

All is not lost though. If you get something like 1650s and combine those 5000s in series for 6S, as you did for the smaller props, you'll see plenty of lift.

(by the way, your video is set to private)
Yes, I can try 13" props b/c I don't have room for the 14".
 
#15
I'm new here and more of a mini-quad guy, so take my advice with a grain of salt.

I am assuming your AUW is based around a 3S pack. So when you did a 6S test you added an additional pack, so your weight went up 300g or so? I think that may explain why boosting the voltage, didn't have as great an effect as you might have thought.

370kV on 3S with 1045 props @ 2kg will not produce enough lift to get the craft to hover.
370kV on 6S with 1045 props @ 2.3kg will not produce enough lift to get the craft to hover.
370kV on 6S with 1245 props @ 2.3kg should get the craft to hover, though you would requires 70% throttle which leaves little room for control.

If you are going to try 13" props you should also up your pitch to 5.5" ie. 1355 propellers.

370kV on 6S with 1355 props @ 2.3kg will get the craft to hover at 58% throttle which is more ideal and provide 2kg of lift capacity.


If you haven't tried http://ecalc.ch before you should... it is really handy to simulate builds before you spend your hard earned cash!

Cheers,
Hubert

PS: I am not affiliated with ecalc.ch I have just been using it and think it is a great resource.
 

Cyberdactyl

Misfit Multirotor Monkey
#17
Someone has to ask: are you sure you wired those batteries in series, and not parallel?
That certainly could be, and would make the above discussion make more sense.

But I still insist, providing there's no added mass being added to the list given in the first post, 1245s are simply the ragged edge of useful even with 6S, although the specs sheets include 1238 performance numbers.

If you're truly limited to a 6.5" prop radius, then you're going to have to do what Stoichiometric suggests and get a rather deep pitched 13". The negative aspects of that, is if you wanted higher efficiency (longer flight time) while hovering or slow translation flight, a deep pitched prop is not the best choice. It appears from the pics that you could use 14" and have the props pass over the frame slightly.

That would also impact the efficiency ever-so-slightly, but would allow you to use a slightly shallower pitch. Of course wiring tidiness and management becomes more important.
 
#18
I'm new here and more of a mini-quad guy, so take my advice with a grain of salt.

I am assuming your AUW is based around a 3S pack. So when you did a 6S test you added an additional pack, so your weight went up 300g or so? I think that may explain why boosting the voltage, didn't have as great an effect as you might have thought.

370kV on 3S with 1045 props @ 2kg will not produce enough lift to get the craft to hover.
370kV on 6S with 1045 props @ 2.3kg will not produce enough lift to get the craft to hover.
370kV on 6S with 1245 props @ 2.3kg should get the craft to hover, though you would requires 70% throttle which leaves little room for control.

If you are going to try 13" props you should also up your pitch to 5.5" ie. 1355 propellers.

370kV on 6S with 1355 props @ 2.3kg will get the craft to hover at 58% throttle which is more ideal and provide 2kg of lift capacity.


If you haven't tried http://ecalc.ch before you should... it is really handy to simulate builds before you spend your hard earned cash!

Cheers,
Hubert

PS: I am not affiliated with ecalc.ch I have just been using it and think it is a great resource.
Thanks Hubert! Hopefully I'll be flying by next Saturday. I'm ordering these 1355s from ebay: http://www.ebay.com/itm/4x-1355-135...Y680-FY690S-/271537282308?hash=item3f38e21d04
 
#19
Someone has to ask: are you sure you wired those batteries in series, and not parallel?
WHERE DO I SEND THE CHECK TO DOCTOR??!!!!!!!!!!!......................I skipped school that day so I missed that portion of the class. I was using parallel with more amps. My youtube instructor reminded me of the difference and I made a series cable. That was the difference like day and night. She wanted to lift at 42%...........;););););)

Thanks again!!!!