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Mid throttle oscillations brand new motors....

Roandb

New member
#1
Yo,
so I recently took the jump from 4s to 6s, and along with it got rid of my Lumenier 2206 and installed xing 2306. I have a noticeable sound just below mid throttle where it sounds like a harmonic and the quad is very jittery. I then ran a bench test with no props or nuts and I can hear the same sound. All motors are soft mounted and brand new I wouldn’t care but I can’t seem to tune them out of it either, any fixes or ideas?
Cheers,
Roan
 

FDS

Well-known member
#2
What Kv are the new motors? Was the ESC designed for 6s? What version of Betaflight are you running?
If you plug in a 4s does the vibration go away?
 

Roandb

New member
#3
What Kv are the new motors? Was the ESC designed for 6s? What version of Betaflight are you running?
If you plug in a 4s does the vibration go away?
1700 KV, kiss 32a for 6s, kiss FC v2 I’ll have a look but I assume once I hit the same particular rpm on the quad it will do the same
 

Roandb

New member
#6
Ahhh! - if it were betaflight, RPM filtering might have been a way through that. KISS....no idea!
Ye I’m running the filter in high which means the filter is just on the lowest setting. I don’t want to turn up the filter any more as it will compromise the feel of my quad, maybe soft mounting the fc could fix it
 

PsyBorg

Wake up! Time to fly!
#7
@Roandb How have you mounted the FC? did you just use the O rings supplied under the FC or do you have other soft mountings anywhere on the quad? KISS unlike Betaflight actually works better with no soft mounting other then those O rings.

For my Alien build I learned different props actually have different places for the "sweet spot" in tuning. What I do on my Kiss build is tune tight to get the crisp solid flips and rolls with no bounce back then work TPA to get rid of mid throttle issues. With good parts you dont need filtering or soft mounting at all. Specially if you have a good carbon frame and not a cheap banggood knock off.
 

Roandb

New member
#8
@Roandb How have you mounted the FC? did you just use the O rings supplied under the FC or do you have other soft mountings anywhere on the quad? KISS unlike Betaflight actually works better with no soft mounting other then those O rings.

For my Alien build I learned different props actually have different places for the "sweet spot" in tuning. What I do on my Kiss build is tune tight to get the crisp solid flips and rolls with no bounce back then work TPA to get rid of mid throttle issues. With good parts you dont need filtering or soft mounting at all. Specially if you have a good carbon frame and not a cheap banggood knock off.
Ye for sure I agree with your good parts point, I’ve ran tape under the motors then now tpu still junk. Got some rubber under the fc but it’s mostly hard mounted. Apart from the frame my build is high quality. However I don’t know how smooth these xing 2306s are, and maybe I should just save my time and get new motors. I did have a decent tune then tried TPA, I raised the break point up much more so it was much higher PID round the mid throttle range to help stop the mid throttle oscillations. I’ll give it another solid tune, but the motors have so much more noise than the old lumeniers
 

PsyBorg

Wake up! Time to fly!
#9
Higher battery voltages - Lower pids - lower TPA break point. Here are old screenies from my Alien on 4s and TAZ on 5s to give you an idea how I make it all work.

this was my alien on 4s. Am working on changing over to 5s for everything so I dont need to kepp so many different batteries.
TPA 10-28-19.jpg


This is Taz on 5s sorry for only the limited TPA info. But the curve is similar I just kick it in around 42% break point I think. If need be I can hook em all up and get current screenies. But these should give you an Idea.

TAZ pids_TPA.jpg


I originally was designing TAZ for a 6s build and found too much problems others were having with voltage spikes and all those related problems. I dont think the weight vs power gains are there either. Besides straight line Taz will do 145 ish mph straight line runs which is far faster then would be used on a track. The only advantage to 6s IMO would be lower amp draw to stretch out full throttle flight times in serious competitive racing. And I am not sure that I still have the filters set to high. I believe this screenie was when I was tuning for max straight line runs.

This was Taz when I was working on finding tighter race style rates to hug flags and gates tighter without a bajillion crashes.

 
#10
Higher battery voltages - Lower pids - lower TPA break point. Here are old screenies from my Alien on 4s and TAZ on 5s to give you an idea how I make it all work.

this was my alien on 4s. Am working on changing over to 5s for everything so I dont need to kepp so many different batteries.
View attachment 154765

This is Taz on 5s sorry for only the limited TPA info. But the curve is similar I just kick it in around 42% break point I think. If need be I can hook em all up and get current screenies. But these should give you an Idea.

View attachment 154769

I originally was designing TAZ for a 6s build and found too much problems others were having with voltage spikes and all those related problems. I dont think the weight vs power gains are there either. Besides straight line Taz will do 145 ish mph straight line runs which is far faster then would be used on a track. The only advantage to 6s IMO would be lower amp draw to stretch out full throttle flight times in serious competitive racing. And I am not sure that I still have the filters set to high. I believe this screenie was when I was tuning for max straight line runs.

This was Taz when I was working on finding tighter race style rates to hug flags and gates tighter without a bajillion crashes.

Yee I see, I guess your quad is quite light so you can get away with the low p gains, if I run a 3 p gain the ship feels very doughy. Also I wasn’t really after power when I upgraded, as I was on 2350 4s now 1700kv 6s, so that’s a theoretical max rpm of 38540 to 41820 RPM not much increase as I’m running the much lower KV motor.

I’m not entirely sure PIDs will fix it either, I’m running a bench test and the escs are just outputting power, they are not responding to any kind of movement etc. At the 1330 throttle mark these motors have a fair bit of noise, something that would still happen on 4s just higher up in the throttle range but it’s still the same RPM and therefore the same frequency making standing waves in the frame. I’ll check it on 4s and see if the same frequency happens, but theoretically will.

I can do lots of filtering etc on the kiss software, but what I really want is a clean source initially, and to kill the source of where it’s coming from; the motors. I can help the FC not see the source with rubber gromets and filter it out but I wonder if I can only do so much. It’s not like these escs are rubbish either, there kiss 32a good for 6s some of the best in the game. I know EMF noise is massively increased from 4s to 6s so maybe my next bet is some low ESR capacitors, as maybe the escs are causing issues too with these particular motors
 

PsyBorg

Wake up! Time to fly!
#11
KISS on their wiki states NO soft mounting other then those O rings that come with the FC. I agree that KISS is rock solid gear I love it.

As far as it being mushy on lower pids I agree to a point. I was told by guys racing you have to detune the higher the voltage goes. The caps will help a little with voltage spikes but so far I have not had to add caps on mine like I have with the betaflight builds. Kiss esc's have a fairly good sized cap bank on them just for that reason. I did it on Taz early in testing for the same exact things you are going thru now. They didnt solve anything other then cutting the loud pop when the battery arcs as you plug it in.

I found detuning yaw was the most helpful to clearing out that grindy noise. On 4s for freestyle I would tune 4,6,8 Pgain style for racing I am keeping them fairly even in the high 3.xx range with only pitch slightly higher as Taz is a stretch X frame. I think by now you have noticed the grindy noise when you arm and then it disappearing the higher in the throttle you go. It took a bit for me to believe De tuning would help but after thinking what TPA does it relaxes pids the higher the throttle so it only makes sense starting at lower pids would help more. I suppose you could engage TPA sooner and harder and see what that does for the grindy noises at higher gains tune. I would just keep serious eye on temps for extremely short test hops. You can smoke a motor in under 5 seconds if you go too far the wrong way

If you want tighter feel then you can fix that with rates. I dont run anything over 450 dps on Taz and I am getting closer to being able to hug flags at near full throttle then ever. I have at this point cut the RC rate in half and brought Rate up to match my DPS. Then over time I have continued to cut RC rate down and adjusting "tightness" with Rate.

EDIT: oh yeah.. Taz is somewhere between 535g and 550g AUW depending on what props I use so not the lightest of race builds by far.
 
#12
KISS on their wiki states NO soft mounting other then those O rings that come with the FC. I agree that KISS is rock solid gear I love it.

As far as it being mushy on lower pids I agree to a point. I was told by guys racing you have to detune the higher the voltage goes. The caps will help a little with voltage spikes but so far I have not had to add caps on mine like I have with the betaflight builds. Kiss esc's have a fairly good sized cap bank on them just for that reason. I did it on Taz early in testing for the same exact things you are going thru now. They didnt solve anything other then cutting the loud pop when the battery arcs as you plug it in.

I found detuning yaw was the most helpful to clearing out that grindy noise. On 4s for freestyle I would tune 4,6,8 Pgain style for racing I am keeping them fairly even in the high 3.xx range with only pitch slightly higher as Taz is a stretch X frame. I think by now you have noticed the grindy noise when you arm and then it disappearing the higher in the throttle you go. It took a bit for me to believe De tuning would help but after thinking what TPA does it relaxes pids the higher the throttle so it only makes sense starting at lower pids would help more. I suppose you could engage TPA sooner and harder and see what that does for the grindy noises at higher gains tune. I would just keep serious eye on temps for extremely short test hops. You can smoke a motor in under 5 seconds if you go too far the wrong way

If you want tighter feel then you can fix that with rates. I dont run anything over 450 dps on Taz and I am getting closer to being able to hug flags at near full throttle then ever. I have at this point cut the RC rate in half and brought Rate up to match my DPS. Then over time I have continued to cut RC rate down and adjusting "tightness" with Rate.

EDIT: oh yeah.. Taz is somewhere between 535g and 550g AUW depending on what props I use so not the lightest of race builds by far.
Sick of the game now, think I’m just gonna swap some lumeniers over from the xings, worked before when I had them for 4s. Even without PID loop I’m getting a lot of vibrations, telling me that surely the motors are the source of the problem, also I can’t get anywhere near the pids I want as I just get so many oscillations. When I just spoil the motors up I can literally feel the vibrations and it’s pretty bad
 
#13
Sick of the game now, think I’m just gonna swap some lumeniers over from the xings, worked before when I had them for 4s. Even without PID loop I’m getting a lot of vibrations, telling me that surely the motors are the source of the problem, also I can’t get anywhere near the pids I want as I just get so many oscillations. When I just spoil the motors up I can literally feel the vibrations when I put my finger on the FC and it’s pretty bad.
 
#14
Hi, you are not alone!

I can't for the life of me tune my new build, you guessed it XING 2306 1700 KV on 6s!

No crashes or even bumps new high quality frame (Kabab Glide 5), very clean build!

Finally took the props off to check, it vibrates pretty bad just off idle with some nasty harmonics when I move the sticks around. FC is soft mounted but still can't filter out the pitch gyro vibes without way more then stock filtering in BF4.1. I would have to set the RPM filter cut off freq down to 40hz to deal with it, and that's crazy.

I'm about to buy new motors as well....

Did new motors fix your problem?
IMG_20200208_205738.jpg
 
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