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Old 05-05-2014, 05:20 AM   #1
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Default Motor Brushed/Brushless Advantage/disadvantage

ok guys everyone explains how they work somewhat, but why is one better than the other? I buy a plane RTF it has a motor/esc/battery, why should I change it? Does is Battery life (run time) better with one over the other?

Now with my Car or Motor Home I buy the largest 12v battery I can make fit in the required Space. (Minnesota Winters require more Starting Ampe than Florida/Texas Winters)

Just bought a Super Cub S and after it fly's Ok, I plan on adding floats, some say prop change is needed others say larger motor, then others say it just flys a little slower.

So What should I plan on doing ?

Motor Size: 480-size brushed motor (installed)
Prop Size: 9 x 6
Battery: 11.1V 3S 1300mAh LiPo battery (included)
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Old 05-05-2014, 05:26 AM   #2
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a Brushless motor has more than twice the power of a Brush motor, the battery size depends a lot on the type of plane you have, motor size, etc and what the plane is able to carry in weight, its a Balancing Act, Brush motors are very very good for Paper Weights LOL

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Old 05-05-2014, 05:41 AM   #3
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Default Motor Brushed/Brushless Advantage/disadvantage

Right Chellie, This is all I get for a answer "Brushless is better"

WHY?

Plane type:Hobby Zone Super Cub S. Think they are the only ones with "SAFE" Tech thats what the "S" is.
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Old 05-05-2014, 05:52 AM   #4
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From what I understand, brushless achieves power equal to brushed in a smaller motor. Also brushless experiences little acceleration loss when going to a bigger prop or a higher pitch. Brushed has a major trade off and the more it has to turn or the higher the rpm, the longer it takes to achieve it. I gather this is what gear boxes are for in planes: to increase prop rpm on a higher turn motor. Furthermore, brushed has brushes a source of friction, which means heat and eventual loss of brush usage. Brushed, from what I know, is only inrunner, and unless you brushed can be removed, it won't be easy changing them. Due to the fact they are inrunners, I believe inrunners have less torque than out runners.
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Old 05-05-2014, 05:55 AM   #5
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Originally Posted by RVDriver View Post
WHY?
I'm no electronics expert but a few advantages of brushless would be:
  • No friction losses of in commutator.
  • No sparking and wear of the brushes and armature contacts.
  • No limitations on current and/or voltage caused by the commutator.
  • With brushless the timing of the motor can vary depending on load and RPM (making it more efficient) brushed timing is fixed for all conditions.


There is one advantage of the brushed motor over the typical sensorless brushless motor on RC models, and that's that the brushless can produce full torque right from stationary. A sensorless brushless has to initially spin up slowly at low torque until timing is established. This generally isn't a huge issue for airplanes but it's a problem for cars. the better cars have sensored brushless motors which gets around the problem.
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Old 05-05-2014, 06:08 AM   #6
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Originally Posted by JetPlaneFlyer View Post
I'm no electronics expert but a few advantages of brushless would be:
  • No friction losses of in commutator.
  • No sparking and wear of the brushes and armature contacts.
  • No limitations on current and/or voltage caused by the commutator.
  • With brushless the timing of the motor can vary depending on load and RPM (making it more efficient) brushed timing is fixed for all conditions.


There is one advantage of the brushed motor over the typical sensorless brushless motor on RC models, and that's that the brushless can produce full torque right from stationary. A sensorless brushless has to initially spin up slowly at low torque until timing is established. This generally isn't a huge issue for airplanes but it's a problem for cars. the better cars have sensored brushless motors which gets around the problem.
Cogging is what you speak of. Essentially, on a sensorless motor, the esc sends to find the closest pole, but doesn't know without sensors, so what takes place is random bits of current that move the motor slightly. If not enough, it will actually keep cogging, as the motor is not turning enough to allow progression. Planes have this too. When you first start the throttle on very low, you will hear a ratchet sound. Sensored motors are used on on or offroad racing models, such as used in ROAR championships. Another way to solve this cogging is simply: add more poles. My buggy has a 6 pole motor, cogging is essentially non-existent. Also, the higher the kV, the more cogging will be present, along, to some degree, with gearing, although kV is the biggest factor. Because a higher kV motor has less torque, it takes more current to get that pole to "turn over", and thus, usually more throttle, a lighter vehicle, wheels with less rolling resistance, and 2wd rather than 4wd. On planes, well, there is simply much less going on really, there is no gears, contact friction of wheels, only resistance of trying to get the prop to spin.
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Old 05-05-2014, 06:11 AM   #7
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Originally Posted by RVDriver View Post
Right Chellie, This is all I get for a answer "Brushless is better"

WHY?

Plane type:Hobby Zone Super Cub S. Think they are the only ones with "SAFE" Tech thats what the "S" is.
Whats Needed is Specs when asking this type of Question. if this is the plane, a person can give a better Answer, Lots of Super Cubs out there.

Specs

Wingspan: 47.7 in (1212mm) Overall Length: 32.5 in (826mm) Flying Weight: 25.2 oz (714 g) Motor Size: 480-size brushed motor (installed) Radio: DX4e 4-channel transmitter (included) Servos: (2) SV80 servos (installed) Prop Size: 9 x 6 Recommended Motor Battery: 11.1V 3S 1300mAh LiPo battery (included) Flaps: No Retracts: No Charger: DC 3S LiPo balancing charger with AC power supply Is Assembly Required: Yes Assembly Time: Less than 1 Hour Plane Type: Scale Civilian Experience Level: Beginner Power Plant Size: 450-480 Electric Recommended Environment: Outdoor Fuel Type: Electric


This would be a great motor for the Plane listed above, you will need the extra power to fly off of water with Floats, this motor will give you a better than 1.5 to 1 Power ratio, use a 3 cell 2200 mah lipo of about 40C and a 10x6 prop, for max Thrust, use a 40 amp esc,

With a Brush motor you may or may not be able to get off of the water

http://www.headsuphobby.com/Firepowe...otor-E-640.htm

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Old 05-05-2014, 06:23 AM   #8
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Originally Posted by RVDriver View Post
ok guys everyone explains how they work somewhat, but why is one better than the other? I buy a plane RTF it has a motor/esc/battery, why should I change it? Does is Battery life (run time) better with one over the other?

Now with my Car or Motor Home I buy the largest 12v battery I can make fit in the required Space. (Minnesota Winters require more Starting Ampe than Florida/Texas Winters)

Just bought a Super Cub S and after it fly's Ok, I plan on adding floats, some say prop change is needed others say larger motor, then others say it just flys a little slower.

So What should I plan on doing ?

Motor Size: 480-size brushed motor (installed)
Prop Size: 9 x 6
Battery: 11.1V 3S 1300mAh LiPo battery (included)
You might be starting a can of worms here

From my perspective, having owned a number of $$$$ Astroflight brush type motors up to about 900 Watts, brushless is the way to go.

You've probably got a few battery powered tools like drills and so forth. These are all brush type units. Problem is with brushes, with the physical space available in a typical model motor, those brushes can't handle much more than about 30 Amps. Push them to hard, and they won't last more than a season of flying. Or maybe much less.

Going on to brushless motors, the required switching of the motors windings is done electronically. These motors are essentially a three phase AC motor with a variable frequency drive. These electronic switches can handle a surprising amount of power, far exceeding that of a brush setup. It's not hard to come up with a brushless motor that can handle over 1000 watts, or about 1.3 horsepower. For a lot more $$$$, brushless motors rated for over 3000 watts are readily available. How much more power than a brush type motor? Numbers vary, but double the watts on the propeller for the same weight of motor, brush vs brushless type would be reasonable. These brushless motors can usually swing bigger diameter propellers than a brush type unit. That's why brush type units often use a reduction gearbox.

I've had three different models that started out with a brush type motor, namely the top of the line Astroflight motors, back in the mid 1980's. These motors were upgraded with the $$$$Hacker motors, using the same battery pack, and same airplane. Performance immediately increased, and at the same time, flight times were longer.

For the real small, tiny models, a brush type motor works just nicely. Once you get to a wingspan of perhaps 20 inches or more, brushless motors start to make sense.

The circuitry behind those brushless motor controllers is extremely complex, along with even more complex computer software used to drive that circuitry. How does it work? "Very Well!".

Name brand Electronic Speed Controls along with quality brushless motors can easily outperform a glow engine in the same model. Only problem is, brushless motors are limited to perhaps 6-8 minute flying time, where a glow engine can double that flying time.

So, do you need to pull the brush motor out of your model, and upgrade to a brushless?? If you are happy with how your existing model flies, no reason to upgrade, at least IMHO. For your next model, just add brushless motor to its requirements.

Hope that helps.

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Old 05-05-2014, 06:26 AM   #9
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Originally Posted by kyleservicetech View Post
You might be starting a can of worms here

From my perspective, having owned a number of $$$$ Astroflight brush type motors up to about 900 Watts, brushless is the way to go.

You've probably got a few battery powered tools like drills and so forth. These are all brush type units. Problem is with brushes, with the physical space available in a typical model motor, those brushes can't handle much more than about 30 Amps. Push them to hard, and they won't last more than a season of flying. Or maybe much less.

Going on to brushless motors, the required switching of the motors windings is done electronically. These motors are essentially a three phase AC motor with a variable frequency drive. These electronic switches can handle a surprising amount of power, far exceeding that of a brush setup. It's not hard to come up with a brushless motor that can handle over 1000 watts, or about 1.3 horsepower.

I've had three different models that started out with a brush type motor, namely the top of the line Astroflight motors, back in the mid 1980's. These motors were upgraded with the $$$$Hacker motors, using the same battery pack, and same airplane. Performance immediately increased, and at the same time, flight times were longer.

For the real small, tiny models, a brush type motor works just nicely. Once you get to a wingspan of perhaps 20 inches or more, brushless motors start to make sense.

The circuitry behind those brushless motor controllers is extremely complex, along with even more complex computer software used to drive that circuitry. How does it work? "Very Well!".

Name brand Electronic Speed Controls along with quality brushless motors can easily outperform a glow engine in the same model. Only problem is, brushless motors are limited to perhaps 6-8 minute flying time, where a glow engine can double that flying time.

Hope that helps.
great general answer Denny

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Old 05-05-2014, 06:38 AM   #10
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If Just Starting out with RC and E Power, use Thrust as a means to get a power system, Its a heck of a lot Easier to find a power system using Thrust for the Beginner RCr, Watts can Be and Is Very Confusing, lost of Watts can be Pulled from a small motor with a high KV with a small prop on lots of lipo cells but not give very much thrust, and a large motor can give lots of thrust with few cells and a large prop and hardly draw any Watts, Using the Motor / Thrust specs on Heads up Rc motor pages will help a lot, if your planes weight is 20z and the power system generates 40 oz of thrust, you know you have a 2 to 1 power ratio and a ton of power, a 1 to 1 power ratio is great to have too
IMHO always shoot for a 1 to 1 power ratio or more, you will be happy you did you dont need to use all the power / thrust thats available, but its sure nice to have to get you out of a Jam

http://www.headsuphobby.com/Firepowe...otor-E-640.htm

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Old 05-05-2014, 06:42 AM   #11
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Originally Posted by CHELLIE View Post
If Just Starting out with RC and E Power, use Thrust as a means to get a power system, Its a heck of a lot Easier to find a power system using Thrust for the Beginner RCr, Watts can Be and Is Very Confusing, lost of Watts can be Pulled from a small motor with a high KV with a small prop on lots of lipo cells but not give very much thrust, and a large motor can give lots of thrust with few cells and a large prop and hardly draw any Watts, Using the Motor / Thrust specs on Heads up Rc motor pages will help a lot, if your planes weight is 20z and the power system generates 40 oz of thrust, you know you have a 2 to 1 power ratio and a ton of power, a 1 to 1 power ratio is great to have too
IMHO always shoot for a 1 to 1 power ratio or more, you will be happy you did you dont need to use all the power / thrust thats available, but its sure nice to have to get you out of a Jam

http://www.headsuphobby.com/Firepowe...otor-E-640.htm
Chellie
Another great response!

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Old 05-07-2014, 05:14 AM   #12
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Default Thanks Chellie

This is the answer I have been looking for Yes that is the plane:

This would be a great motor for the Plane listed above, you will need the extra power to fly off of water with Floats, this motor will give you a better than 1.5 to 1 Power ratio, use a 3 cell 2200 mah lipo of about 40C and a 10x6 prop, for max Thrust, use a 40 amp esc,

With a Brush motor you may or may not be able to get off of the water

http://www.headsuphobby.com/Firepowe...otor-E-640.htm
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Old 05-07-2014, 03:16 PM   #13
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Some of the 'power' thing is silly. The Cub has been around a loooooong time with EXACTLY the same motor, AND it used to fly off floats using a 7-cell NiMh battery (heavier with less power)
Now, I'm not saying it did a good job of it, but people did fly it that way. Without floats it flew just fine. ACT sucked, but the plane was OK. I think the new SAFE is maybe a big improvement.

The problem NOW, is the motor is the SAME (exactly), the ESC has NOT been improved, and the suggestion for the larger prop (the SAME OLD FAT 10x8 specified for the 7-cell Nimh) puts the ESC WELL into 'fry' zone. LOTS of people burn it out, a pain at $50. It pulls close to 19-20A on that prop with 3S and is maybe good for 13A. HZ won't tell....ever.
The current stock system pulls ~ 12A. They down sized the prop to a 9x6 to keep from having to replace burned out ESC and deal with pissed off customers on a routine basis.

Now, folks want their Cub to go straight up and go 50+mph or they think it's woefully underpowered. Newbies that can't even fly start plotting their power-motor mod before they've figured out how to repair the inevitable crashes.

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Old 05-07-2014, 03:44 PM   #14
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The motor, ESC, Battery and PROP make up the power system.

Change one and it affects all.

More diameter or pitch and you load the motor more that makes it draw more current through the ESC from the battery. More heat in the motor, more heat in the ESC and shorter run time at the same throttle setting.
Excess prop load will burn something up and its often the ESC.
Sometimes the ESC and motor go at virtually the same time and that usually means the motor burned up and took the ESC with it.
The prop is the easiest and cheapest (usually) part to experiment with, but just randomly sticking props on can burn the motor and/or ESC up very quickly.

Change the voltage and you change the rpm the motor wants to turn the prop. Increased voltage means the motor WANTS to turn faster. Prop load is proportional to rpm squared. A small increase in voltage can mean a huge increase on load on the motor. The motor will demand current to meet that load.
This is another "good way" to burn up motors and ESCs... Any time you increase voltage you need to verify that you are not overloading the motor.

***********

Gear drives: Electric motors are more efficient at relatively high rpm, but props are more efficient at relatively low RPM... so turn the motor fast, gear it down and turn the prop slower. appx 3 revolutions of the motor for one revolution of the prop is common when doing a gear drive.

Full scale aircraft also use gear drives because the engines are more efficient at high rpm relative to where the props work best.

***************

The number one advantage of brushless vs brushed is weight. Part of this advantage is due to use of better magnets in the brushless motors. Better magnets mean stronger magnetic field and a higher power + potentially more efficient motor.

Motor efficiency is highly dependant on how you load the motor. If you load either a brushed or brushless motor too much you will rapidly reduce efficiency. Excess current just goes to heating the motor instead of turning the prop.

If your motor is getting excessively hot you either have it overloaded or you are not providing adequate cooling. Hot motors will have their winding insulation damaged and/or have the magnets "demagnetized" Either will eventually lead to motor destruction. As the magnets get weaker the motor will become even less efficient and get hotter.
If you smell burned insulation its already too late... the motor is cooked.
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Old 05-07-2014, 04:12 PM   #15
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If you want to mod it....mod it.

If you just want floats and fly it, put on the 10x8 prop but DO NOT exceed 15-30 seconds of full power or risk ESC burn out and attendant loss of control > crash.
It'll get off the water OK with the stock setup if you haven't loaded it up with a ton of 'reinforcements' and cameras, also very common.

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Old 05-07-2014, 04:51 PM   #16
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Originally Posted by fhhuber View Post
The motor, ESC, Battery and PROP make up the power system.

Change one and it affects all.

More diameter or pitch and you load the motor more that makes it draw more current through the ESC from the battery. More heat in the motor, more heat in the ESC and shorter run time at the same throttle setting.
Excess prop load will burn something up and its often the ESC.
Sometimes the ESC and motor go at virtually the same time and that usually means the motor burned up and took the ESC with it.
The prop is the easiest and cheapest (usually) part to experiment with, but just randomly sticking props on can burn the motor and/or ESC up very quickly.

Change the voltage and you change the rpm the motor wants to turn the prop. Increased voltage means the motor WANTS to turn faster. Prop load is proportional to rpm squared. A small increase in voltage can mean a huge increase on load on the motor. The motor will demand current to meet that load.
This is another "good way" to burn up motors and ESCs... Any time you increase voltage you need to verify that you are not overloading the motor.

***********

Gear drives: Electric motors are more efficient at relatively high rpm, but props are more efficient at relatively low RPM... so turn the motor fast, gear it down and turn the prop slower. appx 3 revolutions of the motor for one revolution of the prop is common when doing a gear drive.

Full scale aircraft also use gear drives because the engines are more efficient at high rpm relative to where the props work best.

***************

The number one advantage of brushless vs brushed is weight. Part of this advantage is due to use of better magnets in the brushless motors. Better magnets mean stronger magnetic field and a higher power + potentially more efficient motor.

Motor efficiency is highly dependant on how you load the motor. If you load either a brushed or brushless motor too much you will rapidly reduce efficiency. Excess current just goes to heating the motor instead of turning the prop.

If your motor is getting excessively hot you either have it overloaded or you are not providing adequate cooling. Hot motors will have their winding insulation damaged and/or have the magnets "demagnetized" Either will eventually lead to motor destruction. As the magnets get weaker the motor will become even less efficient and get hotter.
If you smell burned insulation its already too late... the motor is cooked.

Could you add one more thing?

Don't go messing with prop size or cell count ON an existing power system without checking results with a WATTMETER!!!

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Old 05-07-2014, 05:00 PM   #17
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Originally Posted by kyleservicetech View Post
Could you add one more thing?

Don't go messing with prop size or cell count ON an existing power system without checking results with a WATTMETER!!!
Agree fully with that sentiment. In this case some of the work has been done. The issues about modding the Cub have spawned a separate forum and a 1000+ pages of chatter.
I collected this data for the SuperCub forum.
Stock motor/prop/thread - Lets get it straight

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Old 05-07-2014, 10:06 PM   #18
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You can verify you aren't overloading by simple use of an IR thermometer...
I avoid ever getting a motor above 150F. (flying in up to 115F "ambient" air) I keep the ESCs below 130F. My batteries get no hotter than 120F.
These are all a bit on the paranoid side... But you won't ruin anything by being paranoid.

If something is hotter I fix it with more cooling or upgrading to accept the load or reducing the load.
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Old 05-07-2014, 10:50 PM   #19
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Originally Posted by fhhuber View Post
You can verify you aren't overloading by simple use of an IR thermometer...
I avoid ever getting a motor above 150F. (flying in up to 115F "ambient" air) I keep the ESCs below 130F. My batteries get no hotter than 120F.
These are all a bit on the paranoid side... But you won't ruin anything by being paranoid.

If something is hotter I fix it with more cooling or upgrading to accept the load or reducing the load.
Thanks, I have an IR Thermometer that I check tire temps on my Motorhome with.

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Old 05-07-2014, 11:01 PM   #20
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Originally Posted by RVDriver View Post
Thanks, I have an IR Thermometer that I check tire temps on my Motorhome with.

RVDriver
Just make certain to aim the IR thermometer at a dark color on your motor/esc/battery pack. Bright shiny surfaces can result in errors. Those IR thermometers work real nice when they are aimed at the motor windings through the motor housing.

Kind of crude, but I just put my fingers on the motor for 15 seconds. If you have the motor mfg name branded on your finger tips, its to hot.

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Old 05-07-2014, 11:06 PM   #21
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Originally Posted by fhhuber View Post
(flying in up to 115F "ambient" air) I keep the ESCs below 130F. .
The heck with the motor, at 115F ambient temp, I'd worry about the pilot (We Northerners can't handle that stuff up in Wisconsin!)

Good point though. If you want a surprise, on a real hot sunny day, aim your IR thermometer at a black LiPo battery pack, after it's been in the sun for a few hours.

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