View Full Version : Motor Designation Confusion...

11-28-2005, 02:37 PM
Is there any correlation at all in the designation of brushed versus brushless motors? Looking at brushless motors has me totally confused...

I fly my E-Starter with a brushed 400, and my Corsair with a brushed 350. Looking to switch to brushless, I'm clueless what motor will replace what I am currently using.

For example, I ordered an Esskay 400XT Outrunner that was on sale. Thinking that since it was a "400XT", it could be used in place of my brushed 400. But I really have no clue.


Matt Kirsch
11-28-2005, 05:37 PM
Join the club. :)

Because electric motors are totally dependent on battery and prop to determine power output, and the motor's power output varies widely with changes in either, there's no single number that can be used to designate an electric motor like there is with glow engines, where displacement can be used.

Each motor manufacturer has their own numbering system, and truthfully, the numbers are useless for figuring out if the motor is suitable for a particular application. It complicates things, sure, but electric is more complicated by nature. The motor is but one piece of the "engine," the equivalent of the crankshaft.

I recommend you treat the numbers like the names car manufacturers give to their vehicles. Does "Chevy Silverado" tell you if it's a compact car, or a full size pickup? No, you only know that because of the accompanying specifications :)

Starting out, you're going to need a lot of help, so don't be bashful about asking questions. The Esskay 400XT does have about the same useful power output as a geared 400 can motor, so it would give roughly the same performance on either of the planes you have. It is much lighter, though, and allows you to use much lighter batteries, so there is an advantage if the plane balance will allow it.

11-28-2005, 05:53 PM
To answer your question, we would need to know WHICH Speed 400 you are using. As you may know, there are many variarions. They may all look the same, have the same weight and physical dimensions, but they are different inside. Most important difference is the windings, or more specifically: how many turns. This in turn determines the torque and speed characteristics of the motor: some are comfortable spinning a relatively large prop at slower speed, while other are better suited for smaller props at higher RPM. They generally have roughly the same power, just that some are better suited for specific prop ranges. And remember here: I'm talking about the spped 400s. But it is the same with nearly ALL R/C electric motors. So finding a brushless '400' size motor to replace a brushed '400' is indeed a little challenging. Best to take a close look at recommended prop sizes (and voltages) for both motors before deciding, that should at least get you close.

11-28-2005, 06:37 PM

The good news is the 400XT will handily replace either motor you have. The bad news was hidden in the first answer (assuming you already know you need a brushless speed control): I'm fairly certain you're talking about GWS planes, and they're notoriously designed to balance with a battery/motor combination that weighs approx. the same as your old Loadmaster. So you'll get better performance, but it won't be easy to get the plane to balance.

Many of the models still on the market were designed in the bad old days of NiCd power through brushed brick motors. The newer designs generally take the weight of LiPo/Brushless combos into mind.

Dave North

11-28-2005, 07:21 PM
Thanks guys...I appreciate your help and will not hesitate to ask questions in the future.

11-28-2005, 10:10 PM
It may be hard to get your E Starter to balance with the 400XT if its a lot lighter then your stock setup. The battery hatch on the E Starter is pretty much on the CG, without much room to move it back further without some modding.