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Motor Chat: Cheetah vs Turnigy Motors

Old 05-19-2016, 02:37 PM
  #1  
Billyg
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Default Motor Chat: Cheetah vs Turnigy Motors

Hello, I am old in RC airplanes but NEW in Electric. Funny since I was an electrical engineer in college. So I am looking at converting a HOB FW190 which lends itself well to a 480 ish motor. I have looked at nice write ups by Forge and some other sites on how to convert. I have found the Eflite power
series (450 &480),

http://www.horizonhobby.com/park-480...020kv-eflm1505

the Cheetah on the BP site...
http://www.bphobbies.com/view.asp?id=V450327

And the Turnigy motors...
http://www.hobbyking.com/hobbyking/s...er_1020kv.html

I hope I am not starting a Thread which has been covered a lot, but I looked in the old ones a bit. I am just trying to start with something that is reliable. Thanks so much for any and ALL input. When I start my build I will post.

Bill
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Old 05-19-2016, 02:50 PM
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Rockin Robbins
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I can tell you that I've run a Turnigy 2217-20 motor on my Slow Stick for three years and the $13.00 motor has been a 200W beast. It has a quality finish that impresses, tons of power, 20 minutes of duration on a 3S 1350mAh battery. I could have spent three times as much money and not got a better motor.

I run a Turnigy NTM 35-30A 1400Kv motor on my Grim Reaper and it's been 560W of flawless performance for $18.00. That's a quarter the price of the name brands and you won't get four times better for spending the difference for a different name painted on the can. This is a proven motor, used on hundreds of combat flying wings with great success.

That being said, Turnigy sells both good and not so good motors. Check out threads here and elsewhere, read the customer feedback. A little research can save you major money over the "default" Eflite alternative, which is adequate, but not stellar, in quality.


Since this is a non-standard installation where you can't readily check to see what everybody else with the plane is using (a cheap way to engineer a power system provided the information is credible), I recommend you buy a wattmeter and then go one step further to buy a data logging ESC. The data logging ESC gives you real world, in flight performance data, which is often very different from test stand data. You get continuous graphs of battery voltage, amps drawn, rpm, throttle position and ESC temperature for an entire flight. It's the true gold standard. I bought my Turnigy Super Brain 40A data logging ESC for less than $30. It also has been stellar and is the ESC I use for maidening all airplanes. It's overkill for a 20A Slow Stick, but you can replace the ESC with another of a more appropriate size when you have the data you need. It's been the single best expenditure I've had in the hobby.

Here's a graph of a test stand run of the Turnigy 2217-20.


Last edited by Rockin Robbins; 05-19-2016 at 03:37 PM.
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Old 05-19-2016, 03:30 PM
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Nice analysis by RR. While looking at HK, also look at their SK series. Pretty darn good
Also, check out headsuprc.com. A nice selection. I really like their Powerup brand. Plus, they only charge $2.00 shipping on most orders.
Good luck !

Hawk
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Old 05-19-2016, 03:49 PM
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I think hobbyking has the best prices, I look at reviews and see why the bad ones are bad: is it the reviewer, a minor or major flaw, different specs, misuse. I think the NTM are pretty low on quality, but I cautiously use them. Many like the orange and silver turnigy motors. I've run one for a long time on my slow stick with not as nice of a mount as above, but instead of being rigid, my balsa mount is designed to easily break if the prop hits the ground to save the prop, shaft, and carbon stick. It glues back on in minutes with CA and activator after fitting together like a puzzle piece.

The colored hobbyking brand ESCs, not the red brick or the black and orange, but the others are the cheapest and work great, very simple with only braking as a programming option I think.
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Old 05-19-2016, 05:12 PM
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Billyg
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This is all great info, I was trying to understand the different Turnigy motors because there are a few. All this is great info. I am looking to get my son a trainer also but not sure what. So a turnigy may end up on the front.

I will see if I can contact the company to understand the differences. I will also read a bit on the electrical terms.

Thanks guys!!!
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Old 05-19-2016, 05:12 PM
  #6  
fhhuber
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I've got some Turnigy motors and some Cheetahs

I like the Cheetahs better.

Note that Cheetah uses a different number designation system a 2215 Cheetah is MUCH bigger than a 2215 Turnigy.
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Old 05-19-2016, 05:53 PM
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Rockin Robbins
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My Slow Stick with Rhino 1350Mah 3S battery, 40A Super Brain ESC, Turnigy 2217-20 motor and APC 11x4.7SF prop. It's just a bit overpowered.....


I can hold the plane by the wingtip, drop it, then hit the throttle. It just flies away like that's a normal way to launch.
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Old 05-19-2016, 06:27 PM
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Billyg
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WOW - that is great - yeah - electric motors allow for so much more torque that glow. Very cool. So I should just do that ESC you recommended or are their other middle of the road controllers for one of these motors?

Thanks
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Old 05-19-2016, 06:40 PM
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Assume the size numbers are either the size of the out side of the motor, or the stator size, 22xx is usually a stator size probably for a 28mm motor. The orange and silver turnigy motors are usually very good, the SK3 or whatever they are called are ok, NTM is usually low on quality, the red turnigy motors are usually pretty good. I wouldn't get too picky, just make sure you know the outside dimensions.

I'm using a 3536 910kv on my slow stick for tons of power. It will hover on a 2s with a little vertical climb and go 46mph with flutter on a 3s. I have fun hovering.

https://www.youtube.com/watch?v=f3AScVrXqEQ

Last edited by Nutball; 05-19-2016 at 07:35 PM.
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Old 05-19-2016, 07:05 PM
  #10  
Rockin Robbins
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Originally Posted by Billyg View Post
WOW - that is great - yeah - electric motors allow for so much more torque that glow. Very cool. So I should just do that ESC you recommended or are their other middle of the road controllers for one of these motors?

Thanks
You'll never have to worry about a Turnigy Plush. I generally give them at least 20% headroom. I've worked my Super Brain at its rated 40A with no problems whatever. But I generally think that giving some headroom is a great idea.

Just the same, whenever possible I'm giving my money to Heads Up RC lately. Those guys are just excellent, prices very nice, very knowledgable staff, quick and cheap shipping. Often their out the door price is better than Hobby King and I have it a day or two later.
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Old 05-19-2016, 07:10 PM
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Rockin Robbins
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Originally Posted by Billyg View Post
WOW - that is great - yeah - electric motors allow for so much more torque that glow.
Thanks
And that's the secret. Spin up time is not an issue and you have full torque instantly. In the blastoff video I wafted across at minimum flying speed, pulled up and then hit the throttle. Electic means no hesitation and space shuttle blastoffs.
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Old 05-19-2016, 07:33 PM
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I'll have to check out Heads Up RC. I'm using a blue hobbyking 30A, cost $8-9, it takes all I throw at it, but yes, always go bigger on the ESC because if it is rated for 30A likely that is 30A at full throttle, and that number usually goes down quickly under full throttle. A bigger ESC will give a little more power too with the lower resistance.
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Old 05-19-2016, 08:56 PM
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JetPlaneFlyer
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Many of these motors are made in the same place and just anodised different colours and get different stickers according to the brand label that gets put on them.
Neither Turnigy no Cheetah actually make their motors themselves, they are just a brands so there is a very good chance that under the stickers these are the exact same motors . They certainly look remarkably similar both visually and in specification.

i'd buy the cheapest.

Last edited by JetPlaneFlyer; 05-19-2016 at 11:58 PM.
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Old 05-19-2016, 09:26 PM
  #14  
Billyg
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I was thinking the SAME thing. Thanks - I have found Suppa which looks just like cheetah and looks a LOT like the turnigy.

thanks
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Old 05-20-2016, 02:55 AM
  #15  
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Originally Posted by Billyg View Post
Hello, I am old in RC airplanes but NEW in Electric. ...
Some reading and handy e-tools for rainy/windy days. Will save you, and us , a lot of questions.
Will also prevent you from burning up several controllers and/or motors and/or battery:
E-flight primer and tools

Don't forget to buy a watt-meter, will pay for itself, several times over.
E.g. watt-meter: Hyperion E-meter II sale


Originally Posted by Billyg View Post
... Funny since I was an electrical engineer in college. ...
That could be a real problem
  • Motor/battery-current is proportional to voltage squared and proportional to Kv cubed! Way more than one would expect. (Worst case, ignoring voltage losses/sag due to the higher current ).
    Whether motor can handle those current- and powerlevels is a different story.
  • A motor's Kv constant says nothing about ... max.current and max. power a motor can handle, it is no indiction for efficiency, rpm, quality, torque, propsize etc.
  • Simple instructive table giving the extra current when you add one extra cell to a pack
    (a.k.a. "why did my motor and/or controller and/or battery go up in smoke ???")
  • The Kv motorconstant is not a rating, not a figure of merit, in that higher or lower is better, it's just a characteristic. More windings will give lower Kv, less windings will give higher Kv, that's all there is to it. No big deal, anyone can rewind a motor with more (thicker) copperwire. Will give you a more efficient (Pout/Pin), more powerful and cooler running motor.
  • Motors have just one Kv, not e.g. 1400Kv's.The motor Kv constant is a physical quantity (length, weight, time, current, ...) measured/expressed in rpm/volt. It is not a physical unit (meter, kg, s, ampère, ... ). Therefore, Kv=1400rpm/volt.
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Old 05-20-2016, 03:05 AM
  #16  
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Originally Posted by Rockin Robbins View Post
You'll never have to worry about a Turnigy Plush..... I'm giving my money to Heads Up RC lately.....quick and cheap shipping. Often their out the door price is better than Hobby King and I have it a day or two later.

Funny, I just outfitted a new plane exactly as you mentioned! Turnigy Plush and a Firepower 15!
Nothing but good experiences with the Plush line, and the Firepower? Well, it's another run of the mill, budget motor with a sticker on it.
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Old 05-20-2016, 11:01 AM
  #17  
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A lot of the Gold Turnigy motors are made by DYS so you can buy them other places like
Banggood. Just a different badge on them.
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Old 05-20-2016, 03:54 PM
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Billyg
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Ok- So I am going do do my reading. I understand the matching of battery to esc to motor then prop importance. What I am trying to get is where to start. So I have a plane... about 30 oz. Where do we start? I am reading a lot and understand adding a lipo cell increases voltage which will push up amperage to motor. So you have to change the prop and make sure ESC handles it. But what is the biginning question to answer to start to solve the equation of "what to put on the plane"?

Thanks
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Old 05-20-2016, 05:15 PM
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The easiest way to select components is to find another plane very similar or identical to the one you have that flies well and copy the spec of the components.

Most RTF, kit or plan built planes have a recommended power setup that you can use which makes things even easier. Or tell us exactly what plane you have and the members will give you recommendations based on their experience.
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Old 05-20-2016, 05:23 PM
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Increasing battery voltage doesn't necessarily increase motor amps as long as you use the same motor rpm on the high voltage lipo as you would on the lower voltage one. This involves not using as high of throttle. Actually if you use the same rpm on both a 3s lipo and 4s lipo you will get lower amps on the 4s because the motor is using the same power, but more voltage. Full throttle will result in more rpm than with the lower voltage battery, so the motor will likely draw more amps, if not it will definitely still draw more power (watts) which will run the motor hotter.

My slow stick hovers well on a 2s (8v), it rockets up on a 3s (12v) and I'll fly it on a 4s with limited throttle to get a 20 minute flight of 3s performance. Full throttle on 4s would likely break my slow stick.

If you look through the item description and discussion and reviews of motors on hobbyking you can usually find motor/ESC/prop/lipo combos that produce a certain amount of thrust and go from there. Online motor calculators can help too.

If I know the exact airplane I can usually come up with some good suggestions for what to use as I'm sure many of us are. Just by the weight and what I remember about my slow stick weight, I'll guess a 3536 1100kv motor with a 40A ESC and 3s lipo and a 10x7 prop is probably not a bad place to start. I tend to try to overpower all of my things, but my slow stick is lighter than 30oz
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Old 05-20-2016, 05:34 PM
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mid-range throttle is harder on the ESCs than full throttle.
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Old 05-20-2016, 05:35 PM
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Billyg
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It is a house of balsa FW190.
SPECIFICATIONS:
Wing area: 216 sq. in.
Wing span: 36 in.
Length: 28.5 in.
Weight: 28-32 oz.
Engine: TD .061 to.10
Wing loading: 14.6 - 18.6 oz./sq. ft.


:-)
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Old 05-20-2016, 05:47 PM
  #23  
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Originally Posted by Nutball View Post
Increasing battery voltage doesn't necessarily increase motor amps as long as you use the same motor rpm on the high voltage lipo as you would on the lower voltage one. This involves not using as high of throttle. Actually if you use the same rpm on both a 3s lipo and 4s lipo you will get lower amps on the 4s because the motor is using the same power, but more voltage. ...
If the current at wide-open-throttle is too high then reducing throttle on an overpropped motor to keep current below ESC max.current is not a good idea. Itis even harder on ESC than to keep overamping at full throttle. Better to prop down a bit to reduce current.
See:
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Old 05-20-2016, 06:29 PM
  #24  
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My explanation was considering you are using a big enough ESC, and keep the throttle low enough to not have problems, and the higher voltage at lower throttle will keep the amps down even more. Don't forget about active freewheeling ESCs
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Old 05-20-2016, 08:01 PM
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Originally Posted by Nutball View Post
My explanation was considering you are using a big enough ESC, and keep the throttle low enough to not have problems, and the higher voltage at lower throttle will keep the amps down even more. Don't forget about active freewheeling ESCs
The ESC would have to be 'big enough' for the wide open throttle amps with the higher voltage battery. Reducing throttle does not actually reduce peak amps. The peak amps are similar but reducing throttle decreases the duty cycle (the proportion of time when the current flows).
Bear in mind that a switching regulator (which is what an ESC is) is a fast acting switch that turns the power on and off very quickly. The throttle adjusts the proportion of time that the 'switch' is on.

Most ESC's dont have active freewheeling.
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