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Technical questions for experts Turnigy Aerodrive SK3 - 3548- 1050kv
#1

Ok so I have a ]Turnigy Aerodrive SK3 - 3548- 1050kv The description says that the motor can run on 3s or 4s, its max load is 50A and its max power is 820 watts, HobbyKing also recommends a 70A ESC and props from 11 to 13 inches so I tried running on 4s using a 80A ESC and a 12x6 prop and the load was 100+Amps and 1500+ watts of power, of course the motor got hot really fast, using 3s with the same setup and the load was 70+Amps

Now I am running on 4s with a 10x5 prop and it is already reaching 57 Amps, my questions are:
does these numbers make sense? there is no way this motor is going to move a 12 inches prop without melting, why is my motor so out of specs? could it be my wattmeter, my ESC or the motor? 


I don't know where to go from here, thank you for your help  Thumbup
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#2

I used to just work in Watts and whether the plane needed to go fast or slow. The motor will happily swing a 12in low pitch prop on 3s. You'll get a nice slow flyer with lots of static thrust but not much top end. If you want to fly faster, then go a smaller diameter with a higher pitch. What is the target airframe and flying style for the power train?


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#3

(04-06-2021, 12:01 PM)kizza42 Wrote:  I used to just work in Watts and whether the plane needed to go fast or slow. The motor will happily swing a 12in low pitch prop on 3s. You'll get a nice slow flyer with lots of static thrust but not much top end. If you want to fly faster, then go a smaller diameter with a higher pitch. What is the target airframe and flying style for the power train?
I wanted something in between, sporty flyer with a good climb, I tried 12x6 on 3s but still getting 60+ Amps of load and getting hot
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#4

Keep in mind that your amp draw will drop slightly when in flight due to the prop unloading and you'll have airflow to keep things cooler. Depending on your self restraint, you could safely fly that 12x6 on 3S as long as you keep in the back of your mind to limit your full throttle flying. Its not like as soon as you go over the recommended amp draw the motor will pack it in. Generally it'll get hot to a point of the glue holding the magnets in losing its strength and letting go but its rarely ever an instant failure.
I used to fly a Hotliner with a Turnigy 3548 1100kv motor on 4s swinging a 13x8 prop! 1100Watts! But I always limited runs to 10 second bursts and it never let go in years of flying.

My other 3548 Powered plane was a Balsa Decathlon, I ended up running that on a 13x4 Prop on 3s, Was a hoot
https://www.youtube.com/watch?v=5WCiH6yqMx4


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#5

(04-06-2021, 05:15 PM)kizza42 Wrote:  Keep in mind that your amp draw will drop slightly when in flight due to the prop unloading and you'll have airflow to keep things cooler. Depending on your self restraint, you could safely fly that 12x6 on 3S as long as you keep in the back of your mind to limit your full throttle flying. Its not like as soon as you go over the recommended amp draw the motor will pack it in. Generally it'll get hot to a point of the glue holding the magnets in losing its strength and letting go but its rarely ever an instant failure.
I used to fly a Hotliner with a Turnigy 3548 1100kv motor on 4s swinging a 13x8 prop! 1100Watts! But I always limited runs to 10 second bursts and it never let go in years of flying.

My other 3548 Powered plane was a Balsa Decathlon, I ended up running that on a 13x4 Prop on 3s, Was a hoot
https://www.youtube.com/watch?v=5WCiH6yqMx4

I see, I am suspisious because this motor is pulling too much current even without a prop, around 10 amps unloaded and that doesn't seem normal.
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#6

That does seem high. Have you tried playing with esc timing? Maybe it got it wrong...
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#7

(04-06-2021, 07:17 PM)kizza42 Wrote:  That does seem high. Have you tried playing with esc timing? Maybe it got it wrong...
Yes I tried that, I think this motor is reving higher than suppose to
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#8

It could be mislabeled and has a higher winding. Just reduce your prop pitch to accommodate!


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Dynam Meteor
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HobbyKing Giant Stick Sport 90
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#9

(07-06-2021, 10:08 AM)kizza42 Wrote:  It could be mislabeled and has a higher winding. Just reduce your prop pitch to accommodate!
Yeah, I got a 9x8 for it, I think it will run ok but in another model hehe thank you for your help
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#10

Hi Gabino

I just did some full power current tests using my FRSky radios.
As you will see the 3 and 4S batteries were not fully charged and it is very cold!. When I next go flying I can put the Amp sensor aboard and log the real world results.
   
When doing something like this always have the model secure, stand from behind and have a think about what could go wrong.
   
First to test  is my balsa HobbyKing stick with a Bandgood  3536 1000kv motor, Prop is a Xoar 10x5.
https://www.banggood.com/Racerstar-BR3536-950KV-2-4S-Brushless-Motor-For-FPV-RC-Airplane-Model-p-1384217.html?cur_warehouse=CN&rmmds=search
   
First with 3S.
   
And 4S.
   

Hope this helps. I'll get some more planes out and test them.

srl
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#11

(10-06-2021, 02:54 PM)srl Wrote:  Hi Gabino

I just did some full power current tests using my FRSky radios.
As you will see the 3 and 4S batteries were not fully charged and it is very cold!. When I next go flying I can put the Amp sensor aboard and log the real world results.

When doing something like this always have the model secure, stand from behind and have a think about what could go wrong.

First to test  is my balsa HobbyKing stick with a Bandgood  3536 1000kv motor, Prop is a Xoar 10x5.
https://www.banggood.com/Racerstar-BR3536-950KV-2-4S-Brushless-Motor-For-FPV-RC-Airplane-Model-p-1384217.html?cur_warehouse=CN&rmmds=search

First with 3S.

And 4S.


Hope this helps. I'll get some more planes out and test them.

srl

Thank you for that, yeah I think my motor is mislabeled, I am getting 42 amps with a 9x8
 and it is really reving up that thing, I'll have to buy a more sporty model for this motor.

Thank you
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