We are presented with a brushless and a coreless option for every RC servo. The brushless servo always costs more than its coreless counterpart. What extra perks can you expect to enjoy in a brushless servo? Are you making too big of a compromise by settling for a coreless servo? These are the questions we will try to address in our brushless vs coreless servo debate.
Brushless vs Coreless Servo: Side By Side Comparison
Criteria | Brushless Servo | Coreless Servo |
| Commutation System | Electronic | Mechanical |
| Maintenance Frequency | Once In Every 3 or 4 Years | Once In Every 1 Or 2 Years |
| Electronic Noise | No Noise Can Be Heard | Produces Audible Noise |
| Size | Larger | Smaller |
| Price | Pricier | Lower Priced |
Brushless vs Coreless Servo: What Makes Them Different?
1. Mechanism
Brushless Servo
Brushless servos are state-of-the-art servos that feature fixed rotating magnets and armature. The stator draws power from a solid-state circuit and enables the magnets to move back and forth. Since the magnets are closely located in the stator, the presence of electricity in the stator creates an electromagnetic field.
This electromagnetic field keeps the rotor moving. The rotation of the rotor leads to energy generation. Because of their unique design, brushless servos deliver a higher torque ratio than other servos. Since the rotor is 100% winding-free, centrifugal force can’t affect it. Therefore, it can produce energy with better efficiency.
Coreless Servo
In a coreless servo, there is no iron core inside the rotor. Traditionally, the winding rests on a metal core inside the servo rotor. But, in a coreless stereo, you will see a mesh of wires inside the rotor instead of a metal core. Therefore, it’s more lightweight and compact. It also happens to be more responsive.
Once the stator gets electrically charged, it rotates the rotor, which ultimately leads to energy creation. A ball bearing keeps the coil in place. We must point out that all coreless servos are not essentially brushed. There are brushless servos that are also coreless. But in the RC world, coreless servos are often brushed.
2. Commutation System
Brushless Servos
The electricity in the windings causes the armature to move; that’s how engines as a whole work. To ensure the armature movement is focused toward a single direction, there has to be switching between the phases. In brushless servos, this switching is done through a dedicated switching device.
Now, what does this particular detail mean to the user? On the plus side, you won’t have to worry about sparking since the commentator does not come in contact with anything else. It also allows for less maintenance and a longer lifespan. But the reliability is solely dependent on the switching device.
What happens when your servo fails to communicate properly? It means that it will fail to direct the current flowing through the coil in the same direction. Without a steady, one-directional flow of current, the rotor rotation will keep getting interrupted. As a result, the energy output will be substantially hampered.
Coreless Servos
The commutation happens through a mechanical process in a coreless servo since the winding is on the rotor itself. There are both downsides and upsides to this. It’s way more reliable and likely to maintain ideal engine operation. On the other hand, this takes a toll on the servo’s durability since there is high friction between the brushes and the commutator.
3. Durability
Brushless Servos
Brushless servos are more durable because the commutator never has any physical contact with other objects. So, on average, they will function without any sort of servicing for three to four years. The added durability comes from the brushless design rather than the use of sturdier materials.
Coreless Servos
Coreless servos cannot match the lifespan of their brushless counterparts because of their operating mechanism. The brush and the commutator regularly rub against each other to maintain a unidirectional flow of current through the windings. So, they wear out faster than brushless servos.
4. Performance
Brushless Servos
In what particular areas do brushless servos excel? Brushless motors will give you better torque to weight performance. They take up less current, which makes them more energy efficient. They are more durable, and if you are willing to splash the cash, you can also make them waterproof, which is a pretty big deal for all-weather RC lovers.
This might not be seen as an advantage by many, but the brushless servo provides 100% silent RC operation. You won’t even get to notice that you are operating an RC vehicle or an aircraft. In a coreless servo, you can definitely hear the sound. However, many consider that to be a vital part of their RC experience. So, it’s a matter of taste, we must say.
Coreless Servos
We already know that coreless servos cost less to produce, so they are cheaper than brushless motors. But is that all they have to offer? Not at all! Coreless servos are better suited for speed control since they transmit signals faster. This happens because of the superior commutation stability coreless servos earn through mechanical commutation.
5. Size
Brushless Servos
Brushless servos are not gigantic by any means, but in comparison to coreless servos, they are larger. Since the rotor and the coil are located separately, it requires a larger housing. So, it’s challenging to fit a brushless servo in a tiny RC unit. Sometimes, size restraints might compel you not to use brushless servos.
Coreless Servos
Coreless servos are as compact as servos come. There is no metal chore involved. The rotor and the coil are essentially the same things. So, coreless servos take up far less space. For the smallest RC units, coreless servos would be more convenient.
Final Words
We don’t believe this brushless vs coreless servo debate establishes one to be universally superior to the other. Both have their perks, and they would prove valuable to different user classes in different situations. Overall, brushless servos are considered to be more premium, but coreless servos offer far more than saving a few bucks.
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