17
votes
Accepted
How can I reverse the direction of a brushless motor?
Swapping any two of the wires connecting a brushless DC motor to its ESC will reverse the direction it spins.
Despite the name BLDC which implies that the motor runs on DC power, each of the three ...
- 6,063
15
votes
Accepted
Why do the motors on my drone keep spinning up and max out when I run up the throttle on my radio on the bench?
TL;DR;
This is a result of I term windup from the PID controller. It's completely expected and normal with props off, and will be fine when you put props on and go fly! Almost everyone new to RC ...
- 1,220
15
votes
Why do brushless motors have 3 wires compared to 2 wires on a brushed motor?
A standard brushed motor has a positive, negative and a commutator that switches the polarity of the rotor.
Conversely, a brushless motor has a multiple of three sets of coils. These coils are ...
- 4,432
14
votes
Accepted
Why does a brushless drone fly longer?
Brushless motors (aka BLDC) are typically[*] more efficient than brushed DC motors. Higher efficiency equates to longer flight times for a same battery pack.
Amongst other reasons:
The inrush ...
- 1,892
14
votes
Accepted
What does KV mean on motors?
Ok, so this could turn into a very long answer!
The short version is, Kv stands for the velocity constant, and it has to do with the rotational velocity it takes to generate one volt of back EMF. ...
- 1,220
13
votes
Accepted
How does one hold the motor bell still when tightening prop nuts?
You know those rubber wristbands that are given out at lots of events?
You can wrap one of those around the motor bell to get better purchase on it, and then torque down the prop nut.
There are also ...
- 4,432
11
votes
What does KV mean on motors?
KV, often stylized as kV, is a rating for how quickly the motor will rotate for every volt supplied to it. (units of rpm/volt).
However, this is only exactly true ...
- 6,063
9
votes
Accepted
Why do higher voltage batteries need lower KV motors?
They don't necessarily, however a given amount of power will be required to rotate a motor at a certain RPM with a given propeller.
kV, the voltage constant of a motor, is the maximum RPM it can turn ...
- 1,049
9
votes
Accepted
Why do brushless motors have 3 wires compared to 2 wires on a brushed motor?
TL;DR:
Brushed DC motors have two wires because they require DC current (+VCC and Ground), while brushless motors require more complex driving circuitry which controls the AC current required to ...
- 6,063
9
votes
Accepted
How do you figure out which motors to use for your UAV?
N.B.: This applies particularly to drones, and to a lesser extent to helicopters. Airplanes are a totally different field and would require a separate answer.
Obviously the more power per weight... ...
- 1,053
8
votes
Accepted
What process should I use to ensure my motors are spinning the correct direction when using Betaflight
Checking Direction
In Betaflight you can have your motors spinning either props out or props in. The default is props in (towards the body of the quad from the front and back). Be aware other flight ...
- 1,220
8
votes
How can I reverse the direction of a brushless motor?
Swap any two of the wires between the ESC and the motor. Alternatively, use the configurator on your computer for whatever firmware your ESC runs and switch the direction via the software.
For ...
- 4,432
7
votes
How do you figure out which motors to use for your UAV?
Choosing the right motor can be a challenge. Unfortunately, the short answer to your question is no, there is not a simple formula for choosing a motor for a UAV. It's going to take some research ...
- 1,220
7
votes
Accepted
How to identify and address multirotor motor overheating
Assuming that you've spec'ed a good propeller-motor match and the heat isn't generated by a tiny motor being forced to drive a giant propeller, the heat generation is likely due to a physical issue ...
- 6,063
7
votes
Accepted
Can motors be "too big" for any reason?
Power systems should be balanced. If you fit motors that can handle more power than the battery can provide, you're just adding unnecessary weight. That weight will reduce performance in all areas.
...
- 7,418
6
votes
Accepted
One motor on quadcopter broken
So this method will vary based on whether they are brushed or brushless motors.
For brushed:
Spin the propeller with your fingers - is anything actively resisting the motion?
If yes, remove the ...
- 4,432
6
votes
Accepted
Differences between brushed and brushless motors - advantanges and disadvantages of each
They are very different.
Brushed motors
Brushed motors are good for toy grade drones for a couple of reasons: they are cheaper and don’t require ESCs, which would add extra cost and complexity.
...
- 4,432
6
votes
Accepted
What affects the total flight time for a drone?
I'd watch out for several factors:
1. Weight
Drop any additional weight that you don't absolutely need for functioning. This may mean downsizing to smaller motors, which obviously means that you have ...
- 1,053
6
votes
Motor output limiting
I don't think that you can edit the throttle limit directly in the goggles, but you can change rateprofile in the betaflight OSD.
So what you can do is to set up a few different (up to six) ...
- 2,674
6
votes
Accepted
How to keep my prop from flying off my motor?
It looks like you are missing a piece of the prop adapter.
There should be three pieces, the nut, the central shaft with a thread for the nut on one end and a taper on the other, and a collar that ...
- 7,418
6
votes
Accepted
How do I attach a propeller to this motor?
You use one of the provided rubber rings to attach the propeller to the motor. The 2 protruding screws with their heads are the anchor points for the rubber before it is wrapped over the prop to the ...
- 106
6
votes
Accepted
Help with finding a motor to rotate the plane of a propeller
I think what you are looking for is a servo. At least, that's what it's called in the hobby, officially it's a servomotor. Each unit consists of a motor, gears, a sensor to measure the position of the ...
- 7,418
5
votes
Accepted
How hot is too hot when it comes to multirotor motors?
Temperature is a killer of motors over time. If motors are exposed to prolonged heat, the magnets in the rotor lose their magnetic field strength over time and consequently reduce the lifespan of the ...
- 5,802
5
votes
How does one hold the motor bell still when tightening prop nuts?
There are commercially-available tools that are designed to grab around the bell using a rubber band, like this one:
However I felt that it's a fair bit too expensive for what it is.
So I made my ...
- 2,997
5
votes
How does one hold the motor bell still when tightening prop nuts?
You don't need to hold it with a tool, it's enough to pinch it with your fingers. Using a tool to hold it increases the risk of damaging the threads if you are not careful.
But I can understand if ...
- 2,674
5
votes
Accepted
Estimate safe ESC curerent for 4108 600kv motors?
Myriad factors contribute to the current draw of a drone motor including supply voltage, motor kV, the propeller geometry (i.e. diameter, number of blades, pitch), ambient atmospheric conditions, etc.
...
- 6,063
5
votes
Proper rotor fastening (Nyloc nut)
@JacobB's answer that you just need to tighten the nut more is correct, but I just want to explain why it (feels like it) is stuck when it is flush with the top of the motor shaft.
Nyloc nuts, or ...
- 2,674
4
votes
How to tell if you have a brushed or brushless motor?
Good question.
Brushed motors are generally thin silver cylinders with a shaft that look like this:
Photo source: https://oscarliang.com/fpv-micro-quad-beef-board/
Brushless motors, however, will ...
- 4,432
4
votes
Accepted
How to tell if you have a brushed or brushless motor?
As a general rule-of-thumb, brushed motors usually have two wires, while brushless motors generally have three.
Image source
- 6,081
4
votes
What affects the total flight time for a drone?
All of the things you mentioned will affect flight time.
Here is a synopsis:
Batteries
The batteries you use will have a very large impact.
Firstly, your battery chemistry. Li-ion generally has a ...
- 4,432
Only top scored, non community-wiki answers of a minimum length are eligible