Servers by jDrones

Drone wobbles a lot in Loiter mode

(Paran) #9

It hovers at right above half throttle. Thanks for your help!!

(Paran) #10

Also, how can I balance the motors? Thanks!

(Dave) #11

It’s mid-throttle on the stick because it has learned a relatively high MOT_THRUST_HOVER of .685. And at that throttle command the motors are bouncing off of max output as Mr. Boland noted. It’s overloaded/underpowered. Assuming you are using 3S battery power (don’t know your voltage is not calibrated) the easiest solution would be to switch to 4S. Assuming your components are 4S capable. You could try larger props if they fit the frame.

(Paran) #12

Thanks for your response! Luckily my components are compatible with a 4s battery :slight_smile: so I’ll go ahead and buy one of those and do that larger props!
Also, you mentioned that my voltage isn’t calibrated, how can I go about doing that?

(Paran) #13

I’m looking for batteries on amazon and there is a variety of batteries with different discharge rates. My existing 3s is a 50C battery. Could I go with another 50C battery or should I go for something more?
Thanks!

(Dave) #14

In Mission Planner on the Battery Monitor page. Measure the battery voltage and input it in thr “measured battery voltage” box.

You don’t even need a 50C battery. 20-30C would be fine. Be careful of the battery weight. What you want is greater thrust/weight ratio so you will have to drop capacity from the 3S.

(Paran) #15

Sounds good! Thanks! I’ve gone ahead and ordered a new 4s battery. Unfortunately the only battery I could find in a reasonable price is 50C and I dropped the capacity slightly which unfortunately keeps the same weight.
But, based on ecalc, this spec seems that it should work with hover at 50% throttle. I’ll keep you updated on how it looks once I get the parts in a few days :slight_smile:
Thank you so much for your help!!

(Jeff) #16

@mango_apps

Paran -
You might also want to sign up for e-calc, which will help you estimate what combination of weight, props, and power you need for your drone to fly correctly. In your original 3s configuration with 9" props your drones thrust to weight ratio was only 1.2 to 1 (seriously underpowered) as a good thrust to weight rato is 2 to 1. This is exactly confirmed by what @mboland saw in the data log. note also that all motors have a maximum power limit, exceeding that can result in burned up motors or in-flight fires!

Good luck!

https://www.ecalc.ch/index.htm

(Paran) #17

I just purchased the ecalc membership and after plugging in my numbers, the electric power is at 280W whereas the maximum for the motor is 250W. Any suggestions on how to fix this?
The thrust to weight ratio though is at 2.7

(Paran) #18

Actually, I think that the real issue is that I can’t find what is the max power rating of this motor: Readytosky 2212 920KV Brushless Motors CW CCW for F330 X525 F450 F500 F550 DJI Phantom Quadcopter(4PCS) https://www.amazon.com/dp/B075DD16LK/ref=cm_sw_r_cp_tai_BbEtDbJARFRXA

I can’t find it anywhere. And I think it resembles a DJI 2212 920kV motor, but that also has different power ratings everywhere I look. Some places say 370W which would be perfect, but I have no idea.

After plugging it in as if it is 370W, I actually got better performance with 9 inch dji props compared to gemfan 10 inch props. Any ideas why this is?

(Jeff) #19

reducing weight on the quad reduces load on the motors (fewer watts), and smalller props will do the same

(Jeff) #20

@mango_apps

yes, this is a problem that plagues the industry. I do known highly regarded people who have used 4S on the DJI motorss without problems (possible “some” overheating), 370w sounds way too high Try replacing the RTS with the DJI in ecalc and assume that you will probaby get something less.

Also - you can run some tests for yourself. Tie the drone to something solid, and run the motors (or only one motor if you want to be safe), run the motors with 9" prop at various levels of throttle, and see if it gets hot. - and then do the same with 10" props and/or 4S, etc. start at low throttle and dont go to 100% until youre sure it wont burn up.

good luck! Ive always found the testing part the most fun part.

(Paran) #21

Sounds great, I’ll try that, thanks!!

(Paran) #23

So, I gave it a shot. The 4s battery definitely produces a ton of power! But, at just 50% power the motors get too hot to touch. Luckily it was taped down. But I have no idea where to go from here. Any ideas?
Thanks!

(Dave) #24

That’s odd. I have run 4S on 2212 920kv motors for countless flight hrs. What ESC’s are you using? I suppose you could try 8" props but I ran 9" and even 10" props.

(Paran) #25

I’m using these escs: nidici BLHeli-32 30A ESC 32bit Brushless Electric Speed 2-4s Controller for DShot1200 FPV Racing Drone(Pack of 4) https://www.amazon.com/dp/B07FD4G32J/ref=cm_sw_r_cp_api_i_ufyvDbR1H3W30

Could it be that your 920kV motors are able to handle this higher voltage and mine can’t? If so, may I ask what motors you are using? Thanks!

(Dave) #26

One one quad I was using these motors. They are very cheap but rated to 4S:
http://www.valuehobby.com/gforce-2212-920kv-regular.html
On another quad I used motors taken off an RTF quad that I know was only rated to 3S. I ran those until the bearings failed.

You might try using Dshot protocol instead of PWM. You have the ESC’s for it why not? It may provide better efficiency. Depending on what flight controller you have there are some considerations on outputs used. Info here:
http://ardupilot.org/copter/docs/common-dshot.html

(...) #27

I am pushing the Sunnysky X2212 980kv motors with 4S and 10x4.5 props without fail. Took a while to get the tune right. I think it came down to the crappy props I originally bought. I bought Xoar precision pair props and it flys great!

(Jeff) #28

@ekliptiko
I’ve been looking at those motors myself, it’s good to hear that they are working well for you. I also liked that according to ecalc they will also accomodate 12" props in 3S, for a price that is quite reasonable.

(Paran) #29

Thanks! Seems like those motors are out of stock, but I’ve found a few others that are rated up to 4s batteries. I’m thinking of returning these motors and purchasing 4s motors. They should also last longer.
Still haven’t had a chance to fly the drone with this battery. I heard that if the drone actually flies there is less strain on the motors and there is air flowing through the motors which could cool it down. I’ll try to give that a shot soon and the Dshot protocol and see what happens.
Thanks for your help!