Bret1

I have found that selecting a brushless motor can get very confusing with all the choices available. I like the fact that there are many choices, but when you try to compare different manufacturer's motors, they all seem to "rate" their motors differently. Here are some examples I found...

Astro
010, 020

Axi
2208/20, 26, 34
2212/20, 26, 34
280816, 20, 24
281410, 12
282010, 12
412014, 18
413016, 20

Himax
Ha 2015-4100, 5400
Ha 2055-4200, 5300

Mega
16/15/3, 4, 5
16/25/3, 4, 5
22/10/5, 6
22/20/3, 4

Mini AC
1215/120 20 turn
1215/16 16 turn

Jet Phaser 30/3

PJS 1000, 550, 800E

Hacker
B20 - several options
B40 - several options

Wouldn't it be much simpler if all these manufacturers standardized the specs of the motors so it would be easier to compare "the same" motors from the different manufacturers? For example, the glow motor sizes have standardized sizes, such as .46.

Matt Kirsch

My Feedback: (21)

All you're comparing are the motors' marketing names, not their specifications. It's like trying to compare a Volkswagen Beetle to a Ford F-150. You only know "Volkswagen Beetle" and "Ford F-150." You've never seen a commercial or been to a dealer lot to know what the vehicles look like. You don't have any literature on either vehicle. Your Internet connection is down. How can you possibly know which one is suitable for your needs? The simple answer is, you can't...

All motors are rated by cell count and maximum current, and this is really all you need. The first thing you have to do with any electric airplane is determine cell count and current draw. In other words, build the battery. Many people mistakenly think the motor is where the power comes from because it's bolted to the nose of the airplane, when in fact the battery is the source of the airplane's power.

An airplane requires a certain amount of Horsepower to fly in a certain way. One Horsepower is 746 Watts, and Watts are what we use to measure electric power. Watts are Volts times Amps Figure out how much power the plane needs, and you can translate that into a cell count (Volts) and a current draw (Amps). With that cell count and current draw, you can now narrow down your motor choices by eliminating any motors that can't handle it. Final motor choice boils down to the same criteria you'd use to buy a glow engine, a car, or anything else:

1. Price
2. Brand recognition
3. Quality
4. Service

jbrundt

My Feedback: (2)

Matt,

All you said is true but it still doesn't alliviate the confusion a lot of us experience when all those different motor designations are thrown about. Most glow guys know what a .40 size glo engine is capable of and what it can fly (and how it relates powerwise to a .60 or 1.20 sized engine). And in some respects electric flyers know what a S300, S400, 500/600 etc. typical brushed can motor is capable of. However when it comes to brushless motors the designations are all over the map. Sure, once you look at the specs you can know what the motor is usable for but that's a lot of specs to memorize and/or calculate.

It is rather difficult to compare an AXI 2212/34 to a Mega 16/15/5 with out knowing each specific manufaturer's coding system. Unless you use these motors all the time and get to know the ins and outs it takes a lot of time to make sure you've got the right choice. It would be nice if there was a standard of some sort that could be applied to make it easier when comparing one brand of motor to another.

Jeff

Greg Covey

Perhaps some people are starting to standardize motor sizes...

[link=http://www2.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=kontronic&FVPROFIL=++&search3=Go]Kontronic Brushless Sets[/link]

Matt Kirsch

My Feedback: (21)

If you think for a second that the electric motor industry wouldn't jump on some standard that would make motor comparison and selection easy and simple, think again. The point here is to make it easy and attractive to sell as many motors as possible, not make it as troublesome and complicated as possible to drive people away. Even the people that design these motors for a living can't come up with any meaningful standard. Two motors with different diameter armatures, different gauges of wire, different amounts of wire, different strength magnets, and heck, two completely different designs altogether (conventional vs. outrunner) have completely different characteristics. They're like apples and oranges. What aspects of these two motors are you going to compare to arrive at a standard?

Electric is going to require more thought and analysis. There's no way around it. You're assembling an "engine" from components instead of buying it all prepackaged.

What we need to do is get away from this notion of "How does motor X compare to motor Y," and start looking at the motor/airplane relationship. Is the motor suitable for the plane? Is the motor of good quality? Does the motor fit my budget? These are all questions to ask. Asking, "Will motor X turn prop Y faster than motor Z?" like you do when comparing glow engines is useless, because you can MAKE either motor turn that prop at any RPM you want by using different voltages and gear ratios...

I must contend with your notion that people know what a .XX glow engine or a Speed XXX motor is capable of. In fact, the only reason we know a particular plane needs a .40-size engine, for example, is because it's written on the side of the box the plane came in. Nothing about "OS .46FX" says, "I'm suitable for a 4-6 pound plane with a 48-60 inch wingspan." The same goes for the smaller park flyers that use Speed XXX motors, except that they go one step further and include the motor with the plane in most cases.

Bret1

I understand what you are saying about all the different variables each brushless motor can have. However, when looking at glow engines. Each .46 engine may handle alot differently from other brands, but it is still a .46 engine. At least that is a good starting point. The .46 designation makes it easier to then look into the different manufacturers and compare the characteristics of THEIR .46 verses others, like weight, max RPM, quality, price. I think if the brushless manufacturers wanted to, they could "group" their different motors into catagories also. They could be based on size, weight, max amps, prop size, or something. I think that by having all the different spec ratings, they are hoping that once you use their motor, it will be easier for you to just go with them again instead of doing the research comparison. If I am used to running an Astro 020, the only way I can find out which Mega compares is to it is to ask around at the field (research).

Alan W

Bret - I switched to Electric almost 6 years ago and I thought very similarly then to how you feel now, but the fact is, its just not that simple.

Electric motor types are of such varied designs that simple comparisons - FOR NAMES SAKE - is pointless.

Does a cheapo chinese bushed .46 swing the same prop at the same rpm as a Rossi or Jett ??

Does a Ferrari 3.0 Litre engine produce the same horsepower / Tq. as a Hundai 3.0 Litre engine ??

You need to break away from that line of thinking and concentrate on learning

There are tools Electric flyers use to evaluate how a certain motor performs with a certain amount of power given to it, under a particular load.

There are certain parameeters that are "known" about an electric motor and computer modeling can then take these known values, apply power loading and evaluate performance based on efficiency

Such porgrams are called Motorcalc, Ecalc, and P-Calc, and Aveox's Virtual motor test stand. You can select the motor, number and type of cells, prop diameter, pitch, and type (manufacturer) and you get......more numbers [&:]

What you actually get is an approximation - a starting point- as to what the performance should be in terms of static thrust, Amp draw , pitch speed, and a few other valuable tidbits. You can then change the parameters, such as prop size or number of cells and see what happens.....then take that and change motors from say, a Mega 3 turn to a 4 turn......and compare those data sets to what Axi's and Hackers give.

.......buy the LARGE bottle of Bayer Aspirins, BTW

What you have to understand is that Electric power systems of this magnitude, i.e. capable of flying a pattern plane effectively and efficently - is just coming off of the bleeding edge, Therefore it may be the case that its best to copy people like Kyle, Jason, and Tony who have already done the experimenting to see what works best......for now

......or you can start your own nice collection of motors that you've tested, been unimpressed with, and put in "That Drawer" along with speed controllers that have let the smoke out.

I dont mean to sound derogatory in any way - its just that you're asking for it to be over-simplified.....and as in the case of the two analogies I gave above, sometimes that just silly once you look at it in the proper light

Have fun.....burn electrons

Matt Kirsch

My Feedback: (21)

I think the main sticking point is that people are used to comparing a single glow engine with another, even though if they stepped back and really thought about it for a second, they're comparing BRANDS of engines against each other. Does it really matter what the displacement is if you're comparing an OS .46FX against a GMS .47? If you go right down the line, from the .91 to the .25, displacement for displacement, any OS FX engine will have the same advantages and disadvantages over its GMS counterpart.

Electric "scales" even better! Because the mechanism and design of a motor is much simpler, all the motors in a particular line are exact miniaturizations or enlargements of some base design. They'll all have the same advantages and disadvantages over another line of motors. Because electric motors scale so well, there's little to no chance of there being a hidden dog or standout in a line of motors, as there can be in glow engines.