Someone please explain Brushless motor numbers etc - RC Groups
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Jan 09, 2005, 11:31 AM
Come get me if you can
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Someone please explain Brushless motor numbers etc

Can someone explain what this all means?????? I know very little about brushless motors and what allt he numbers mean in the motor title.

How do you know which part number is which

What does the kv rating mean

Any other info would be great also.

I tried to do a search but the search is down.
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Jan 09, 2005, 12:06 PM
6 planes 2 jets 2 helis
Pacoson71's Avatar
KV is revolutions per Volt

IE: 9.6v (8cell battery) X a 4200kv motor= 40320 rpm.

different manufactors use different descriptions for their motors.

Himax uses 2015 X xxKV, 2025 (same diameter but longer and heavier can)

Hacker has the B20 B20L (longer can)
Mega has the 16-15-x (the x is the number of strands for the wind)

Hope this diden't confuse you more

Jan 09, 2005, 12:17 PM
Registered User
HET have just introduced some new motors......
e.g the 2912/10.......29 = stator diameter, 12= stator stack length and the 10 denotes the number of poles.....(how that works beats me for a 3ph motor!)
Last edited by Chippie; Jan 09, 2005 at 01:47 PM. Reason: incorrect model number
Jan 09, 2005, 01:03 PM
I don't want to "Switch Now"
pmackenzie's Avatar
Originally Posted by Chippie
HET have just introduced some new motors......
e.g the 2814/10.......28 = stator diameter, 14= stator stack length and the 10 denotes the number of poles.....(how that works beats me for a 3ph motor!)
The /10 is the number of turns of wire on each pole.
The number of poles on a permanent magnet motor generally refers to the number of permanent magnet poles, not the number of winding "pairs".
Hacker motors for instance are two pole motors, but obviously wound 3 phase.
Some manufacturers use the number of turns to describe their motors, others use Kv. Lower turns = Higher Kv
It can all be very confusing.
Pat MacKenzie
Jan 09, 2005, 01:10 PM
Registered User
I'm sure the article I read in one of the modelling mags that featured the motors, that the text did specify that 10 referred to the pole count, hence my inability to comprehend how the motor would work......

I'm lead to believe that the numer of poles needs to be a factor of 3 in order for it to be a 3 ph brushless motor?
Jan 09, 2005, 01:23 PM
I don't want to "Switch Now"
pmackenzie's Avatar
A 2 pole brushless is analogous to a 3 phase AC synchronous motor that runs at 3600 rpm.
The mechanical and electrical rotations match . You can also have 3 phase AC motors that run at 1800 or 1200 or 900 rpm, ie 3600/n where n is an integer. 2n is the number of poles.
AXI motors have 14 magnets, so 14 poles, and 12 "slots" that the winds are made in. The number of slots must be divisible by 3.
Whoever wrote (or edited) the article was mistaken.
Pat MacKenzie
Last edited by pmackenzie; Jan 09, 2005 at 01:33 PM. Reason: Correct brain fade error: 14 magnets=14poles!
Jan 09, 2005, 07:20 PM
Megans Servant
Offtom's Avatar
Clear as mud..........
Jan 09, 2005, 10:08 PM
Good Better Best quest.
olmod's Avatar
But that covers a lot of ground.;-)
Jan 09, 2005, 10:21 PM
Registered User
hhhhaaaaaaaaaaaaaaaahhhhhhhhhhhhhhaaaaaaaaaaaaaaaa aaaaaaahaaaa electric motor numbers will drive you crazy!!!!!!!!! They make absolutely no sense!!!!!!!!!! hhhhhhhhhhhhhhhhaaaaaaaaaaaaaaaaaaaaaaaaaahhhhhhhh hhaaaaaaaaaaaahhhhhaaaaaaaaaaaa.

Too much rain!

Jan 10, 2005, 04:12 AM
Registered User
I have had no recourse except to keep buying magazines and trolling this forum to educate myself (and making mental notes on what fits on my planes and gearboxes). There's not a good shortcut to this unfortunately....

A good guide is to follow Balsa Products brushless (non-outrunner) selection to swap GWS power units. Brushless motors come in same diameters but different lengths for different 'hotness' in the winds -- the lower KV winds are slower as a rule.

The Feigao smaller 120 motors -- (IPS replacements) come in two lengths but same diameter as the IPS motor, the shorter one fits LPS and longer one fits IPS (hotter). The IPS sized brushless is good for airplanes about 10~12 ounce at the upper end.

Next step up is Feigao 130 motor and can be swapped for 20~22mm dia cans/gearboxes (your favourite 280/350 size motors) for the GWS 350 c size gearbox (5.33 ratio). This is the popular power combo up one step up from the IPS-sized brushless motor (known as the GWS EPS 350 size). These Feigao 130's are similar to most 20mm dia brushless motors (very common such as the Hacker 20).

Then you get onto larger diameter motors that follow size dias matching speed 400 motors/gearboxes, and then speed 600/700.

Please point out any mistakes I've made here.

Yeah talking about rain --- I'm right in the middle of it. Been raining every night for the last week ??!!?? Can't even put the garbage out without getting soaked. I'm in South Mission Viejo (Orange County -- the OC -- just like the previous poster)...

Whoever said it doesn't rain in SoCal is full of it

(Sorry about the OT post -- couldn't resist.)
Last edited by Fearofheights; Jan 10, 2005 at 04:29 AM.
Jan 10, 2005, 07:29 AM
Come get me if you can
Rat's Avatar
Still kinda lost but will work on it.

Fearofhieghts, are these the most common constants with brushless motors?????

Why is it that all motors can not be classified with some kind of constant motor while using a constant type of part number. I could do a 10 min scan and would more then likely comeup with 5 dif motors from dif manufactures that would probly all perform the same and the only constant is that they are brushless. No common numbers between them????? Is this correct?????
Jan 10, 2005, 10:11 AM
Which way is up?
There's been lot's of comments in various threads to the effect of why can't the manufacturers settle on a naming system etc. and might happen when pig's fly etc.... I'm not holding my breath for any consensus in the industry!

Probably your best bet is to home in on the plane you want to outfit / refit with a power system. Get on the zone and read up on other members successful systems for that or similar weight and style of model. Then duplicate the system that looks best.

After a while, you'll get a feel for how things are working. KV, amps consumed at full rating etc will start to make more sense when you have experience using the systems in your models. Throw in the battery and prop choices only increases the learning curve, hence gain that experience by using known system configurations.

The members here are very helpful and can keep you from cooking motors, controllers and battery packs if you do your homework.

Jan 10, 2005, 02:26 PM
Registered User

Brushless motor numbers

Since Brushed motors themselves don't have a standard size and naming convention yet (after about ten years of being around at least) -- Brushless motors will still need at least another couple of years to settle on standard names and sizes.

Graupner twenty to thirty years ago came up with the speed 400, 500, 600 and 700 names based on Mabuchi motors for use in their new electric sailplanes. Illustration of Speed 400 motor (some call it a Speed 380)

Here's the brushless FEIGAO equivalent (fits into GWS speed 400 gearbox),

Later we saw Speed 300, 280 names added for smaller motors, as parkflyers grew in popularity. Illustration...

GWS 280 motor

Feigao Brushless 280 equivalent--one of many types of winds in this category and size(fits into GWS speed 280 gearbox)

Even later we're seeing Speed 180 (Actual designation Mabuchi FF-180 PH [3v] and Mabuchi FK-180SH [9v] ) designs. The Hobby people Clancy baby bee ARF uses this with a geared powerplant. There is currently no brushless equivalent to this motor AFAIK.

GWS IPS motors are informally called Speed 120 motors [because of the 12mm dia casing perhaps?]. Smaller than IPS size gets even more confusing but you have few if any brushless in that small a size.

Brushed GWS IPS (speed 120) motor

Brushless FEIGAO IPS equivalent (fits in same IPS gearbox),

Note that the brushless motor depending on the winds can have 'hot' , 'medium' or 'cool' (slowflyer) performance. The 'hot' winds will pull more amps and may tax the LiPo batteries and the ESC's. Typically in a specific size range (say the speed 280 or Feigao 130 size) shorter cans will have 'cool' winds and longer cans will have 'hotter' winds. It is definitely true of larger (speed 400 and above) brushless motors...

But yes -- the fact remains it is heavily confusing for any newbie to understand motor sizing just by name alone. The guys/gals at your LHS (if they are into E-planes esp. parkflyers) will be a great help. Support them!

I know that as most brushless motors are now being sourced from China (Some are from the Czech republic and Germany as well)-- the home market designations on the label are what is being advertised by mail-order distributors. IMHO -- the major distributors like HOBBY LOBBY, BALSA PRODUCTS and also HOBBY People should get together to decide on standard motor names for a size range so our hobby is less of a guessing game for newcomers. They need to describe motors with weight classes explicitly so there is less confusion. I understand there are business reasons why this is not happening (no one wants prices to come down where they have to compete on price alone for equivalent products a la the computer industry) but I think with enough new entrants the hobby will flourish anyway. OK off the soapbox for now!

Brushless motors come in two different designs primarily. One is a rotating core design (FEIGAO 120, 130 and Hacker B20 etc.) and the other is the rotating body design (Outrunners such as AXI 2808, HIMAXX 2025, PJS, NIPPY etc.). Outrunners typically do not need gearing because their torque is quite high without the need for separate gearing. This is not the case with non-outrunner designs so you need gearing to increase torque.

A few things to remember to make it easy to choose brushless motors (Non outrunner wise)--

1. Decide on what size airplane (weightwise) you need to power
2. Decide on the GWS equivalent powerplant with gearbox.
3. Find the brushless equivalent motor that'll replace the standard GWS brushed motor in that gearbox. Websites most often will say this clearly.
4. Find a brushless ESC to match the AMPERE rating for that brushless motor.

This will suffice for most common parkflyer applications. If you have an LHS nearby -- it's better to pay their premium (10% increase in prices) so you get the advice for each type of motors used in airplanes of different weight classes.

You can replace most common geared powerplants with a non-geared outrunner of various sizes. Outrunners are very quiet (no gear-teeth whine). But matching an outrunner to standard GWS sizes is a little more confusing.

To find out more -- please visit Hobby Lobby's website (their outrunner motors are described beautifully and they have a large selection of all types of brushless)

Here's a new type outrunner equivalent to a geared speed 400...

There's no shortcuts here. Keep browsing the E-Zone, keep talking with the LHS Guys/Gals.

The Fog will clear in time! Best of luck.....

If I've made any mistakes please point them out. Thanks.
Last edited by Fearofheights; Jan 10, 2005 at 03:35 PM.
Jan 10, 2005, 05:13 PM
Registered User

What a great post! You obviously took time in compiling all that info, much appreciated.

I guess, as with many other technical innovations we have had in the past, it will take time before there is some standardisation in brushless motors......Lets hope its not too far away.
Jan 10, 2005, 06:01 PM
Suspended Account
willhaney's Avatar

Thanks Fearofheights

I learned more about electric motors in your one post than the 11 months I've stalked this site. Thanks.

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