motor stops while flying!

[flyingdragon]

Hi Guys,

I had problem last week when I was testing my final setup, the flying siteTemp was about 85F and the winds was about 6mph

the flight was about ~7 min before the motor stopped in the mid air! and I had to Autorotation - Landing a Helicopter without Engine Power!

I twisted the skids but no big damages !!

the motor was super hot
the ESC was cold
the batteries were cold and had 3.8-3.9V per cell so still got 3 more min to go for!

I flew it after 6 minuets and flew for 3 min just fine and landed it with motor cold to touch!



here is my setup

45c 5000Mah 2x 5s lipos total 10S 5000 mah
2s 45c 3000mah lipo for servos
Castel creation 120 HV

SK 720 Black with power bus
motor pinion 10T slant
main gair 118T slant
blades radix 713mm
motor align 440KV 10 magnets pols

Futaba R7008sb and 14sg
my radio setup : throttle curve :
Normal :
1- 0.0 2- 20.0 3- 88.0 4- 88.0 5-89.5
Idelup 1:
1- 70.0 2- 70.0 3- 70.0 4-70.0 5- 70.0
Idelup2 :
1- 100.0 2- 100.0 3- 100.0 4- 100.0 5- 100.0
my flight was all on Normal mode !

pitch curve:
Normal :
1- -67 2- -48 3- +0 4- +50 5- +100 this allow me to have -3 degrees and about +10 full stick pitch
same on both Idelup1 and 2
here are the logging data from my ESC I took screenshot of them

total wet weight 15.2

Note; I disabled the SK720 GOV and my white single CC wire connected to the IO-C
if anybody can read CC data or just know what is the wrong with my setup please let me know!

GOPR0323 (8 min 42 sec)

thank you
OZ

[Freeskiken]

The batteries after the flight were at 8.1 volts per cell after a 7 minute flight? The max is 4.2 volts per cell.

The motor being so hot sounds like its way undersized for a 15 lb. helicopter.

[flyingdragon]

sorry about my mistake it was 3.8 - 3.9 after 7min flight..

I see many scale 700 size helicopters with more than 16LB run that same motor with no problem!!

if the LB is more than what the motor will lift then that mean the heli will not lift up at that low rpm!

more LB more RPM require to lift up the Mass!

that motor Watt rated 4440W so if I divide the watts by the LB I have

each one pound need 250watt
so I am at 3750watt still not reached the 4440watt yet! BUT I run only 10S so that 37Vx100A = 3700Watt max


BUT notice at the time when the motor stopped I had more than 3.7V left so if I calculate it again will be 3.8x10 =38v x 100a= 3800watt so I had about 100watt left to recover add to that the peak that the motor can pull for 2 sec!!

I was thinking to lower the RPM more and get it around 1000 RPM and 1050 RPM max

that will put less load on motor!

thank you
oz

[acrow]

Originally Posted by flyingdragon

.....

it was 3.8 - 3.9 after 7min flight......

BUT notice at the time when the motor stopped I had more than 3.7V left ...........
thank you
oz

Hi

How are you measuring the voltage?

If you are just reading the voltage after the flight has ended, then it is a no-load voltage. The voltage under load would be even less.

Also, if you delay reading the voltage, it does tend to increase a little as well.

Please tell us more.

[ic-racer]

Sometimes one can avoid complex in-flight amperage measurement by making the very reasonable assumption that a hot motor drew too many amps.

I'd change the gear ratio and follow motor temps with a temp gun or telemetry until they are in a reasonable range.

However, if your gear setup is similar to what other people have already proven to work, maybe you have an ESC setup issue. Is the timing on the ESC set correctly? Too high timing could cause the motor to draw too many amps just like too high gearing.

[flyingdragon]

Thank you for helping me getting this thing flying right!

I do have small little Hobbyking voltages measurement devise with digits can plug it into the balancing cable and will give me how much voltage I have in each s,

I don’t believe the reason of the stop is because of the voltages dropped less than 3.7 because I Checked it right away and I re flew it again for 3 min with no problem!!

But What I think is that the motor is start pulling more AMPs to cover The heat loss and the whgite of the aircraft!

This will bring me back to the standard mathematic (watt per LB))
So after calculate 250watt needed per one LB I had 3700watt Maximum since I was running 10s (37v). 37x100A= 3700watt!
It’s on the edge of my flying LB which is 15.2lB. But With more flying time/ weather temp/ hovering style flight the motor start losing its quality resulting on less Wattege !!
Then it’s stoped !!

So What I did today is upgraded from 10S to 12S also upgraded the esc from 120A to 160A. Now my motor can generate 4440watt for my 16.5lb total

So 44.4x100A = 4440 watt / 16.5lb x 250lb per lb = 4125watt need to lift that mass!

Now regard the motor timing was 12khz but now I dropped down to 8khz

The rpm setup is now
Normal : 1100 73.5% esc
Ideal 1 : 1150 77% esc
Ideal 2: 1200

The wax on the normal rpm recommend to use 30% flat throttle curve but when I do that the esc will not intilize and start blinking red!!

So I had to drop the first value to 0 then 30 , 30 , 30, 30
So why castle recommend using 30% flat????

Thank you very much for the he help
Oz

[acrow]

Originally Posted by flyingdragon

.......
The wax on the normal rpm recommend to use 30% flat throttle curve but when I do that the esc will not intilize and start blinking red!!

So I had to drop the first value to 0 then 30 , 30 , 30, 30
So why castle recommend using 30% flat????
....

The 30% is if you are using Castle Governor. It activates governed speed number one.
Also Castle ESCs are not "armed" until they have seen zero throttle. The ESC give a tone when it is first armed.

[Freeskiken]

I don’t fly my batteries past 3.78 to 3.8 volts. If the motor is hot it’s either working too hard or the timing is not set correctly. Being it is not a light model at 15.2 pounds most likely you are over working the motor. Is it geared properly ? Maybe try a bigger motor.

[flyingdragon]

Originally Posted by Freeskiken

I don’t fly my batteries past 3.78 to 3.8 volts. If the motor is hot it’s either working too hard or the timing is not set correctly. Being it is not a light model at 15.2 pounds most likely you are over working the motor. Is it geared properly ? Maybe try a bigger motor.

I looked around and didn’t find motor bigger that can take 12s to generate more than 4440w of power !!

Yes there are a lot of 300kv or 400 kv with 10,000watt but those motors require more ESC and more lipo voltages 14s -28S and more extra LB +++ will end up 20lb ;:;;

My current gears are 118t main
And the pinion is 10t

Can’t find bigger main gear and can’t find smaller pinion ( slant)

I don’t want to use the stock 600 esp main straight T gear ; it’s all vibration + sound to load! Hated !!

So I upgraded my ESC to 160A so I can go lower rpm and I put 12s 65c to cover 16lb by generating 4440watt of power

Remember you need 250watt each pound .
Will do a test flight tomorrow and report the result !


No body read my looking pics that I uploaded !!??
No body read my motor timing ???
It was 12khz

And now I turned down to 8khz my that help !!! Who knows !! 🙂
Thank you
Ozy

[Xrayted]

You dont need any cutoff voltage at all assuming you are using a timer properly, so you can set that to disabled if you wish as you shouldn't be relying on the ESC to tell you when it's time to land. Its one less nanny for the ESC to try and intervene with and shut you down in error.

This is a scale ship running very low RPM, so your power requirements are very low despite you thinking you need more and bigger equipment. Your average current in the log is only 23A with a max of 40A, so you do not need any larger ESC or motor of any kind. Your largest power need in the log was only 1800 watts. Saying your motor is hot doesnt tell us much as its completely normal for our motors to get from 130-170F which is hot enough to burn you hand within a second or so. It doesnt mean anything is wrong unless you are seeing temps climb near 200F, so you would need to verify with a temp tool what the actual value is as human hands are no good for making this diagnosis

Your "motor power out" which is an indication of proper gearing is a little on the low side at 65%, however this should not be a big deal due to the low RPM and currents you are getting. Ideally you want the this value to be 70-80% or higher without hitting 100% all of the time for best gearing efficiency, but this would require a smaller pinion on your current setup which you say is not possible. All is fine as long as your ESC is not hot when landing, and your internal ESC FET temps are very low in the log so the ESC is not being temp stressed at all. The temp cutoff for a Castle ESC is 100C/212F and you were only at 120F

I'm confident your issues can be corrected with two simple changes to your Castle settings. If not then you should be looking at all of your solder joints and connections from the battery to the motor for a poor connection

1) Disable the voltage cutoff (or at the very least change it to a low value that you would never hit while flying) and use a timer or telemetry

2) Change the current limiting setting from "Normal" to "Insensitive" as this is required for helis. It's quite common to hear of Castle shutdowns on helis unless this change is made

All castle ESC's come defaulted with model airplane values. Airplanes do not typically have large transient current spikes in flight like helis do, so by changing the current limiting to insensitive you are making the ESC ignore these momentary spikes without shutting down.

[flyingdragon]

Finally somebody read my esc logs

Thank you very much sir,

I already changed my castle to 160A and put 12s instead of the 10s

But I can always go back to 120a and 10s

I will make these changes on my 160A and test fly it at low RPM 12s at 80% throttle

If there is a better in flying time and no problem will keep the 12s and the 160a otherwise will go back to my 10s setup


What telemetry unit you recommend? I AM VERY NEW to the telemetry system

My reciever is futaba with sbus
I HAVE sk720 with power bus
And the radio is 14sg

Thanks again for your help

Oz

[Xrayted]

Originally Posted by flyingdragon

Finally somebody read my esc logs

Thank you very much sir,

I already changed my castle to 160A and put 12s instead of the 10s

But I can always go back to 120a and 10s

I will make these changes on my 160A and test fly it at low RPM 12s at 80% throttle

If there is a better in flying time and no problem will keep the 12s and the 160a otherwise will go back to my 10s setup


What telemetry unit you recommend? I AM VERY NEW to the telemetry system

My reciever is futaba with sbus
I HAVE sk720 with power bus
And the radio is 14sg

Thanks again for your help

Oz

I'm not familiar with Futaba or what if any telemetry your TX supports. The Skookum has no telemetry support at all like many of The more common FBL units do like V control, Spirit and MSH Brain, so it would require an external device such as a jLog assuming your TX is even capable. Bottom line is it might be doable with your current setup, but it will be a little messy requiring third party devices since you are not using a FBL unit that is capable of handling the telemetry for you

[flyingdragon]

Tony,
That is why I been thinking about buying pixhawk 2.4.8 with GPS and dive into the programing just to have a good telemetry and solid flight mission if I want to add camera stuff like that!
Oz

[flyingdragon]

In fact I just paid $212 for 2.4.8 pixhawk complete with GPS, telemetry 915mhz and OSD hope I can swim good in this complicated world !!!

[mattbeau]

Originally Posted by flyingdragon

I looked around and didn’t find motor bigger that can take 12s to generate more than 4440w of power !!

Yes there are a lot of 300kv or 400 kv with 10,000watt but those motors require more ESC and more lipo voltages 14s -28S and more extra LB +++ will end up 20lb ;:;;

My current gears are 118t main
And the pinion is 10t

Can’t find bigger main gear and can’t find smaller pinion ( slant)

I don’t want to use the stock 600 esp main straight T gear ; it’s all vibration + sound to load! Hated !!

So I upgraded my ESC to 160A so I can go lower rpm and I put 12s 65c to cover 16lb by generating 4440watt of power

Remember you need 250watt each pound .
Will do a test flight tomorrow and report the result !


No body read my looking pics that I uploaded !!??
No body read my motor timing ???
It was 12khz

And now I turned down to 8khz my that help !!! Who knows !! 🙂
Thank you
Ozy

If you can find a KDE 700xf-395, that would be pretty much what your looking for I think. I have one on my way for my XLP. It can run on 12s, 5500 mA continuous, 12000 mA max. There are some retailers still selling them new.

[flyingdragon]

It's look like a good motor!! But it only gives 5500watt if its run on 14s (51v)

So that will require more lipos = more LB !!

Tony surprised me when he said you don't need more than 1800watt! If that the case why the rules saying for each 1lb you need 150 - 200 watt in order to carry the mass..
Thanks
Oz

[Xrayted]

Originally Posted by flyingdragon

It's look like a good motor!! But it only gives 5500watt if its run on 14s (51v)

So that will require more lipos = more LB !!

Tony surprised me when he said you don't need more than 1800watt! If that the case why the rules saying for each 1lb you need 150 - 200 watt in order to carry the mass..
Thanks
Oz

Just look at your flight logs. That will show you exactly what your specific values are while in flight. It takes more power to just sit and hover than it does to fly. Forward flight at the rotor is much more efficient than hovering due to translational lift, so you cannot base your assumptions on any specific value that does not define the specific model setup or how it's being flown.

There are many guys that run heavy scale ships with 6S 5000 mAh packs and low rated ESCs because the current draw is so low. Low head speed models do not need high power setups, even if heavier than a standard model as there is a massive decrease in current draw that more than compensates for the added weight vs. running a much lighter model and much higher RPM. You certainly dont need a 14S setup!

Just look at your own logs. The max amps you pulled was 40 and average only 26. That is nothing! A standard RPM 700 model will use more than 26A just to hover. My small Synergy 516 which weighs about 7 lbs or so averages over 50A for its flight and will hit 150-170A several times during flight. I routinely flew my big 716 Protos at 1200 rpm using only 1 7S pack.

Your problem is going to be in your ESC settings or some sort or poor connections somewhere. I had a 700 once that would spool up fine but then shut down as soon as I tried to lift. It turns out there was a poor solder connection on one specific battery plug. It was ok until a certain power threshold was crossed and would then fail. Reflow all solder joints everywhere if the problem persist after making the ESC changes.

It has nothing to do with you needing more powerful equipment as you already have waaay more than what you need now based on your logs. Don't get lost in a numbers assumption game. You have the exact info you need right there in the logs

[flyingdragon]

I appreciate your help! I feel better now when I posted this problem, I almost get lost and thinking very negative about my heli..

but now after you clear everything to me its making me thinking to go back to 10s and bring my 120A ESC back to the duty!!

I am waiting for the weather to get little better to do test flight and shot another video !

thank you Tony I am glad you replied to this topic!

oz

[flyingdragon]

Hey !!!
just flew it today for 5 min and I had to land it to check the temp and the voltage...

the Temp of the motor was very hot, burn to touch for one second!!

ESC 160A 12S 5000 mah 65C
the ESC was hotter than the old one too!!

but all the flight logs showing different than what my hand feel!!

I had ~ 4.00V per S after 5 min!! so that will not get me near to 10 min!!
but it was only hover !!! that my be the issue with to much heat!

here are the flight logs

thank you
Oz

[Xrayted]

Originally Posted by flyingdragon

Hey !!!
just flew it today for 5 min and I had to land it to check the temp and the voltage...

the Temp of the motor was very hot, burn to touch for one second!!

ESC 160A 12S 5000 mah 65C
the ESC was hotter than the old one too!!

but all the flight logs showing different than what my hand feel!!

I had ~ 4.00V per S after 5 min!! so that will not get me near to 10 min!!
but it was only hover !!! that my be the issue with to much heat!

here are the flight logs

thank you
Oz

Your ESC is cold at only 117F. That is barely above ambient temps where you live. Your max amp draw was less than 20 with an average of only 12 amps, so you are not stressing the electronics at all.

The only thing I see if your motor power out is at 50% which is the worst place to be. Battery ripple which is bad for electronics is at its highest at 50% and means that your motor is really seeing half the input voltage and twice the current that is being shown in your logs due to how the PWM in our ESCs work. The low power out is an indication that you are way over geared for how you are flying. You want the motor power out to ideally average 70-80% leaving a bit of headroom for harder moves up to 100%, but you dont have any other gearing options other than a lower KV motor or reducing the number of lipo cells. You are getting away with this poor gearing setup because your current draw is so low.

Once again, just because the motor or ESC is hot to your touch is meaningless. The normal temp for a motor is 140-150F and can get up to 175F+ in a warm climate. This is too hot for humans to touch for more than a second, but it does not mean anything is wrong and is completely normal! Too hot is 200F or higher, so you need to check with a proper IR temp tool to verify the actual values if you suspect its too hot. You cannot do this using your hand. The same applies to the Castle ESC which does not go into thermal shutdown until 212F.

Hovering is also the worst thing you can do. There is no airflow over the motor or ESC and as stated before it takes more effort for the electronics to hover than to fly so it doesnt surprise me at all that your electronics are warm after only hovering, especially at 50% power out (PWM).

You can try and lower the motor timing in the ESC settings if you haven't already as this may help lower the motor temps a bit, but I dont expect much change as long as your gearing setup has you using only 50% power out

You have plenty of battery left if you were at 4V after five minutes flight. 4V is only about 20% capacity reduced from fully charged, so you should easily get 10 minutes or more with the 60% you have left.

You have three choices here. Try and resolve the gearing issue with a lower kv motor or use less battery voltage and see if you can get a more efficient setup. Raise the RPM up to better match your current gearing setup and get the motor power out values up where they need to be, or fly it as is because your demands on the electronics are very low, so there should not be any serious issues with the electronics despite the less than ideal setup.

Its the combination of low power out and high current demands that are ESC and motor killers