The Highly Efficient Brushless Motor

Brushless motor technology is rapidly changing the face of the RC hobby, especially for airborne models because of the higher power to weight ratio. In fact, up till now, only gas or nitro engines could achieve the performance available from brushless motors.

Also, in the last year or so, more manufacturers have sprung up, especially in the Far East, providing an ever increasing variety while helping to drive the prices down too. I believe that in the very near future, all electric RC models will come equipped with them instead of old fashioned brushed motors.

A brushless motor avoids many of the drawbacks of a traditional brushed motor while being more efficient and MUCH more powerful. It also has the following advantages over glow powered gas motors:

• Cheaper - because only a charger and batteries are required
• Simpler - just connect the battery to the electronic speed controller
• Quieter - fly in your local park or ball field
• Cleaner - no spills or exhaust (fly indoors!)
• Maintenance free

Here's a short primer on RC brushless electric motors:

With the more traditional inline motors, current passing around the outside of the motor’s can causes magnets on the motor shaft to follow in a circle (imagine the passing current acting like one magnet, pulling the magnets on the motor shaft toward it).

With the outrunner type of brushless motor, the magnets rotate around the windings on the stationary motor shaft and the power curve has a very different "feel" to it. While brushless technology is more expensive, most converts will say its well worth it!

Since motor efficiency is largely dependent on the volume of copper (amount of wire inside) in the motor, and brushless motors can fit much more copper inside (thicker wires) than a brush motor of equivalent size, a brushless motor yields much better performance by lowering resistance, increasing efficiency, and increasing torque.

In engineering terms, this greater efficiency due to more copper and less resistance means more energy goes into kinetic and less into heat. This extra energy can either extend running time or increase power output.

TURNS are the number of times wire has been wrapped around the motor armature.

WINDS are the number of strands in the armature wire.

I should also mention that brushless ESC's (electronic speed controllers) must be used and they are completely different from brushed ESCs. A brushed ESC just pumps out current like a fire hose pumps out water, while a brushless ESC spreads current in a precise pattern to different places in the motor.

It also adjusts the timing automatically for peak power and since all the commutation of the motor is done electronically, the overall reliability of the brushless motor system is also much higher. In brushless, sensorless motors the electronic speed controller also adjusts the timing automatically for peak power which is a major benefit for us speed freaks!

To sum up the advantages of a brushless motor over a regular RC brushed motor...

• Increased efficiency resulting in 20% to 30% longer run times
• Higher performance optimized for increased acceleration and higher top speeds
• No brushes springs or commutator replacement or service required
• Less electrical radio interference
• Lower operating costs & virtually no maintenance!!

Below are the specs for the MTM RC brushless electric motors that I sell. These numbers are an estimation of the performance you might expect from the combos and your performance may vary depending on battery choice, altitude, prop, etc. Amp draws and thrust figures are for full throttle settings. The chart will give you a very good idea of what to expect from each combo, and will assist in the purchase of appropriate items.

PRICE LIST:

MTM motors:
300-DF
Weight = 25g/0.83oz
Price = USD$39

400-T
Weight = 49g/1.63oz
Price = USD$46

400-F
Weight = 49g/1.63oz
Price = USD$46

MTM 20amp ESC
Weight = 20g/0.6oz
Price = USD$53

Please use the form below to email me your questions or to place an order. All prices are in U.S. dollars and shipping is extra. I accept PayPal, International money orders and certified checks, thanks.