kennydee

Electric or Glow, electric or glow, god, I'm in such a quandry. I love the neatess of the electrics. But I would have to rob a bank to buy a nice brushless motor and ESC. I need good basic information on good brushed systems that deliver decent power and flight times(8 to 10 minutes). I'm interested in the 300 to 600 sized motors. By the way, why does the brushless need a different ESC and why does it cost so much? Please, someone lead me to the reasonably priced Promised Land!!

goleith

http://www.hobby-lobby.com/brushless_mpjet.htm

I saw a post on here and a video of a guy running this in a switchback and it looked awesome

Dave Lilley

In any motor we use in our models, the force that turns the output shaft is magnetic repulsion between two or more permanent magnets and three or more electromagnets which are switched on and off in sequence in order to create a rotating magnetic field. In a conventional brushed motor, this switching is done by the brushes and the commutator. The motor's electromagnets are attached to the rotating output shaft. Timing is the relationship between the moment when the electromagnets on the armature are energized, and the fields of the permanent magnets. This is controlled by the physical angle between the brushes and the permanent magnets in the motor case. To change the timing, you rotate the motor end bell containing the brushes or the case containing the magnets relative to one another.

A brushless motor normally has the permanent magnets attached to the output shaft and the electromagnets fixed to the case, with the exception of the Köhler/Aeronaut Actro motors. Instead of a mechanical switch formed by the brushes and the commutator, the commutation function is performed by the electronic speed control in addition to the throttle function. With no mechanical linkage between the electromagnet switching and rotation of the rotor, there has to be some other means for the controller to "know" when to energize each of those three electromagnets to start the motor turning and keep it going in the right direction.

Brushless motors


The reason that brushless ESCs are more expensive is that they are significantly more complicated than brushless ESCs. However, I see many brushless ESCs that have dropped in price to what a good brushed ESC costs only three or so years ago.

kennydee

I appreciate the info. I can always depend on someone to help out on this site. I hear a lot of people raving about the "awesome" brushless motors(in fact, that word comes up a little too often here, along with the word "indestructible"), but I don't often see references to the cost. If I go to the expense of a 400 sized brushless motor and ESC(an investment of at least 100 dollars), will it last long enough to off-set some of the cost? Is the improvement in power and flight time really that dramatic?

Dave Lilley

Speed 400 motor.....$10 - $15
Cobalt 400 size........$35 - $70
Brushless 400 size...$50 - $140

I have had brushed 400 motors last as many as many as 100 flights and as few as 20, but all degraded over time.

I have a Neodym (similar to Cobalt) that lasted about 50 flights until I crashed the plane it was in. (The brushed were getting thin.)

I have brushless motors that have many good flights, and they could last for many, many years to come. (I didn't start buying brushless motors until they started coming down in price last year. ...plus, I already had a huge investment in brushed motors and controllers.)

The power, longer life, and longer flying times of brushless motors easily make every penny worthwhile, especially at the new lower prices.

kennydee

OK, I've weighed the current evidence and I will stick with Brushed for the time being. I can buy and burn up at least 5 or 6 brushed motors and still not spend as much as for one brushless with the extra cost ESC. I've learned the timing trick and have timed my GWS 300C's. I got a noticeable increase in power. I'm gonna wait for the Brushless stuff to come down in price a bit.