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15

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 energized in a particular order to create a series of electromagnetic forces that ‘pull’ the bell (which contains permanent magnets) around. As there are three sets ...


15

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 wires (connected to one of the three phases in the motor) is driven by the ESC with a phase-shifted AC waveform. Each wire's waveform is shifted by 120 degrees ...


14

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 current at the moment of commutation can involve sparks (which is an inefficient waste of energy), and in any case is a free-running operation without the possibility ...


14

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 multirotors asks this question on their first build, so don't feel bad! Detailed Answer The detailed answer to this question is related to how multirotors ...


13

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. Contrary to a lot of popular belief, it actually isn't a direct measurement of the RPMs at any given input voltage. There is an ancillary relationship between the ...


13

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 specialised tools to hold motor bells, such as the one pictured below which can be found here, on Thingiverse.


11

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 when there is zero load on the motor, thus making the rotation rate with no load applied the so-called "free-speed" of a motor. Adding a load to the motor, such as a propeller, will result in the ...


9

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 at per volt of power supplied. Example: A 4S (15V to make math easy) battery will turn a 2000kV motor at 30,000RPM (with no load, inefficiencies, etc) a 6S (...


8

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 drive them. Despite sometimes looking similar on the outside, the functional principles of brushed DC motors and brushless DC motors (aka. BLDC motors) are quite ...


8

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... the better. But basically you want to be able to get enough energy out of the motor to be able to hover at around half throttle. There's a good tutorial here ...


8

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 control software such as FlightOne and Kiss have different defaults. Default Direction Reversed Direction If you are running props out, make sure you flip ...


8

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 example, if it is a BLHeli_32 ESC, you can go to the BLHeli_32 Suite and reverse the motor direction from there.


7

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 with the drone, mistaken filter settings, or a tight PID tune. First of all, it's a good idea to determine whether your motors are actually hot enough to matter. ...


7

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. With electric power systems the battery is the source of the power, and everything else is little more than the transmission. If you want a 3 minute flight from a ...


6

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 regardless. This question is fairly open-ended, so I'll try to cover a few approaches. Identify Your Goals The first thing you need to identify is the purpose of ...


6

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 to balance weight vs. power; you may be able to get your flight time much longer but at the expense of speed. 2. Battery Obviously the more juice you got, the ...


6

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 prop and check for something not immediately visible, like a hair or carpet fibres caught around the motor shaft. Remove anything you find and try the prop again. ...


6

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. Brushless motors However, in almost every way brushless motors are better: they produce much more power, are more efficient, produce more torque and, my favourite ...


6

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) rateprofiles in betaflight, and then change between those in the OSD. It won't be as granular as changing the limit directly, but it should be enough if you just want to ...


6

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 matches the taper. You're missing the collar. The nut forces the collar onto the taper, which squeezes the slots together, gripping the shaft. They're normally ...


6

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 other screw. The propeller motor connection is not rigid but has a little give and comes loose on impact, hopefully saving the propeller and the motor that way.


6

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 output shaft, and a comparator circuit. The electronics compares the requested angle to the actual angle, and drives the motor as required to minimise the ...


5

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 own, molded specifically for my motors' size: It grabs the motor well (especially thanks to the teeth), but it's quite bulky and motor-specific, so I'm still in ...


5

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 you want to use a tool to simplify things, and in that case the other answers are good. Just remember to be careful. Some examples of how I like to hold:


5

@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 nylon lock nuts has, as the name implies, a ring of nylon at the top (the white part in the image below). When tightening the nut the nylon has to deform, since it ...


4

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 generally have visible copper windings and, most often, have the outside or ‘bell’ rotate: Photo source: https://www.hobby-wing.com/emax-lite-spec-ls2207-2400kv-...


4

As a general rule-of-thumb, brushed motors usually have two wires, while brushless motors generally have three. Image source


4

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 larger capacity for the same weight but can provide a lower current. This means that if you are doing slow or cinematic flying, it is worth looking at lithium ion ...


4

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 motor. Generally, a well-tuned drone should not have extremely hot motors after flying (with a few exceptions). It depends on the motor, but you should avoid ...


4

The primary answer has to do with the fact that the torque constant (Kt) is proportional to the velocity constant (Kv) of the motor. That means the amount of power it costs to generate torque increase as Kv increases. A low torque constant means that less power is used to create torque, and a high torque constant means more power is used. For more ...


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