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A beginners guide to multirotors (written by a beginner)

Balu

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#1
The following posts are some thoughts and information about multirotors. Hopefully it will help lower the learning curve for other beginners. Don't let the length of this thread discourage you from starting a new and fascinating hobby. But you should also know that we are not talking about collecting beer coasters here. You will have to learn a bit before flying your first maiden and you will keep learning new things as you progress. This is why one of the Multirotor Top Tips says: Study Study Study.

Why a multirotor?

Flying is wonderful. There are so many great model planes (with wings) out there that show incredible details and the love their owner put into building them. But somehow I'm more interested in models that can hover like a helicopter. Since I was told they are difficult to fly and can be quite dangerous because of their big rotors I started in the multirotor category - which seems to be something that many people go for these days.

RTF (Ready To Fly), Kit or Scratch Build

There are many Ready To Fly (RTF) models out there or kits that include everything you need to start. Some even come completely built and test flown. It is also possible to build your own multirotor from scratch from your own design. Which one you choose depends on many things. Budget, previous experience, expectation and patience to name a few.

Expect to crash

And when you do, don't be afraid to start over. Knowing the model in detail will allow you to find what's broken and replace it more easily. You don't have to buy expensive replacement parts after all. If you don't like the setup anymore just take it apart and build something new (with more rotors, a different configuration or a kitchen blender).

So what do you need to start?

Every multirotor has a few basic elements. How they are put together defines the type of multirotor you build. Some of these elements will be described in detail in later posts.

  • Transmitter / Receiver
    This is RC, so you need a remote control . It should have at least 4 channels to control throttle, yaw, pitch and roll. Having more channels doesn't hurt, so you can enable and disable stabilization modes, turn on lights, etc..
  • Chassis
    The chassis defines the basic form and the size of the copter.
  • Flight Controller (FC)
    This is the "brain" of the multirotor. There are quite a lot to chose from in all price ranges you can imagine.
  • Electronic Speed Controllers (ESCs)
    Those are controlled by the - well - controller and in turn manage the speed of the motors.
  • Batteries / Chargers
    Motors and other electronics need power. Most people use the Lithium Polymer kind because compared to other batteries they have the highest charge density.
  • Motors
    Brushless motors are the ones that are used for multirotors. Combined with the propellers they are responsible for providing the lift to get the multirotor in the air and maneuver it.
  • Propellers
    These are the parts that seem to break quite often.
  • Additional stuff
    This will probably never end. There will always be things to add like First Person View (FPV) flying, Gimbals to get stable camera shots, lights, GPS and whatever you can imagine.
 
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Balu

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#2
Transmitters / Receivers

To be able to control your multirotor, you need a remote control (RC) link. The link is established between a - usually hand held - transmitter and a receiver in the multicopter.

Depending on the type of Transmitter you have more or less channels to send commands. To be able to maneuver a multicopter you need at least 4 channels for throttle (up/down), rudder (yaw), elevator (forward/backward) and aileron (left/right). Some flight controllers have optional settings like a flight mode that you can change in flight. For this you need an additional channel. You might even want to have even more channels to control the shutter of a camera, switch lights or drop something.

So even for a simple multicopter you probably want to go a little bigger and invest in a transmitter that has at least 6 channels - if not 9.

Transmitters are pre-programmed for a specific setup or mode. Mode 2 is a common one where the left stick controls the throttle and the yaw and the right stick sets elevator and aileron. Usually you can change the mode by opening the transmitter and switching the gimbals that hold the sticks - if you really have to.

Computer controlled transmitters allow you to program special settings. For example they can change the output of the sticks so you have less movement the closer you are to the center and making movements near the end of the stick more sensitive (and twitchy) to give you the full range of your control. This is called “Expo”, because the output is based on an exponential curve.

Also there is “mixing” of multiple channels. This allows you to give one input and the transmitter sends data to more than one channel. You won’t need this for a multirotor as the flight controller will do it all, but it might be handy if you also wish to fly a fixed wing plane or glider too.

The receiver on the other end of this wireless link passes the input on to the flight controller.

It’s important that transmitter and receiver use the same protocol as in “speak the same language”. Most manufacturers only support their very own protocol. If transmitter and receiver match, you still have to make them know each other. This is called binding. Check your manuals on how to do this.

To make things more difficult, expensive setups can have the receiver send data back to the transmitter. This is used to display or log telemetry data from sensors like battery voltage, GPS data, etc. on your transmitter.

Also the receiver output has to be compatible to the flight controller you want to use. There are various protocols like PPM, PCM, and SBus and most FC need a specific input protocol.

Also see the local forum on Radios, Transmitters and Receivers.
 
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Balu

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#3
Chassis

The Chassis is the basic structure of a multirotor where all other parts are connected to. Think of it as two parts: a "core" and the "arms" where the rotors are attached. The core houses most of the electronics and protects it from crashes. Also you usually find the center of gravity there.

What materials are used to build a Chassis?

A chassis can be build from a lot of different basic materials and is often constructed with a mix of wood, plastics, metal (Aluminum), fiberglass, carbon fiber and others. Then there are screws and zip-ties to hold everything together and often some kind of flexible foam or similar to dampen vibrations.

To a beginner wood seems to be a great choice. It's easy to work with and cheap. Many kits come with plastic parts. If you own a 3D-printer you can probably print those yourself. Glass fiber and carbon fiber are quite strong and light, but more difficult to work with.

What multirotor models are there?

The form of the multirotor is defined by the number of the rotors and the orientation of the arms.

  • 2 rotors
    Twincopters, Dualcopters or Bicopters have two rotors. They can be arranged on top of each other or side by side. Those are the simplest ones, but they are difficult to tune and fly and can not carry a lot of weight. If a motor stops the copter accelerates with about 9,81 m/s^2 in the general ground direction. Some people call that "landing". These types of multirotors are basically never used as they are too unstable.
  • 3 rotors
    Tricopters usually have two arms to the front and one to the back. So they look like a T or a Y. The rotor in the back is pivoted using a servo to make the copter rotate on its yaw axis. They can lift more than a twincopter, but not much. If a motor stops the copter crashes. But then these models are very agile.
  • 4 rotors
    Quadcopters once again can carry more than a tricopter and are easier to build because they don't need a pivoting servo. They are more stable and can have longer flight times because you can carry bigger batteries. Quadcopters yaw by reducing the speed of two motors so the torque of the other two makes the copter rotate on its yaw axis.
    • QuadX or Quad+ have arms that looks like an X or a +. They differ mainly in where the "front" is.
    • H-Quads look like a - well - H
    • Quad V-Tails are a mix between Tricopter and Quad. The back two rotors are closer together and are mounted in a 30-55° angle to the inside or outside. This allows for a much bigger yaw-authority.
    • There are other rarely used configurations with 4 rotors like a Y4 which looks like a Tricopter but instead of a pivoted motor in the back it has two motors above each other (coaxial), rotating in different directions.
  • 6 rotors and more
    Hexa-, Octo-, Hexadeca- or Hecatommyriacopters all are based on the same basic design pattern. The rotors are mounted around a central point - usually in a circle. Some models have motors that are mounted on top of each other. A Y6 is an example that looks like a Tricopter, but doesn’t have a tilting mechanism in the rotor. Instead the yaw is done by changing motor speeds just like in Quadcopter. In comparison the yaw feels “sluggish” compared to a mechanical yaw design.
    More rotors result in a bigger lifting capacity and more stability in flight. Those copters can - depending on the controller - survive one or more motor blackouts without losing the ability to fly. But of course the total weight adds up just as the complexity of the build and its price tag. A lot of motors also require a lot of power that needs to be carried in the form of batteries.

Deciding what kind of model to build depends mostly on what you want to do with it. You will probably not mount a camera that costs $ 3000 or more on a tricopter (if it lifts it at all). And you probably will not do acrobatics with an octocopter.


For a beginner quadcopters seem to be a great solution. They are easy to build and can be very stable. But when you are just starting, make sure you follow this tip: Keep it simple, keep it light.

Don't start with a fully equipped system. First of all it will hurt a lot more if you crash with expensive equipment. Second: A light system is easier to control and keep in the air. Third: you will not learn how to fly a multirotor if the controller (see next post) does all the work for you by self-leveling and staying at a programmed position. Learn how to handle a simple multirotor first, then proceed to the next level.
 
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Balu

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#4
Controllers

The controller is the brain of a multirotor. It takes input from the receiver and tells the speed controllers to translate that input into movement. The difficult part of its job is to keep the copter stable. To do that it needs all kinds of sensors to learn about its orientation and position.

The keyword here is "degrees of freedom" (DOF):

  • 3DOF
    A three axis accelerometer or gyroscope measures changes in speed or rotation.
  • 6DOF

    The combination of a three axis accelerometer and gyroscope allows to measure precise changes in a copters orientation. For a stable flight a multirotor requires at least 6DOF.
  • 9DOF
    In addition to the two acceleration and orientation sensors a compass (magnetometer) is used to determine the orientation of the multirotor.
  • 10DOF

    To maintain the height an additional sensor is required. Usually that's a barometer to measure air pressure, but sometimes ultrasound is used to measure the distance to the ground.
  • 11DOF
    Finally an additional GPS is used to find the exact position of the machine.

Simple (and cheap) controllers usually only support 6 DOF. Some can be extended using external modules.

More complete controllers have more complex software and provide a lot of additional features. This way they can support a lot of different flight modes. For example the Ardupilot Mega supports the following:

  • Manual
    Direct transfer of transmitter input to the multicopter. If you let go of the sticks the copter keeps flying in the direction you pointed it at.
  • Stabilized
    Let go of the sticks and the copter stops and maintains a stable position
  • Fly-By-Wire, Training

    Some flight-characteristics are maintained by the controller. You can define a min and max yaw, roll and pitch rate.
  • Automatic

    The multirotor flies a pre-programmed path. You can intervene by using your controls.
  • Return to Launch (RTL)
    The copter flies back to its starting position and tries to stay there at a programmed height. GPS is required for this feature.
  • Loiter

    As long as you don't give any control input the copter tries to maintain the current position.
  • Automated starting and landing
    Perhaps the best way to avoid horrific crashes when getting closer to the ground

Other FCs have different features or use other terms. What you need depends on the intended use.

What flight controllers are there?

A lot. Too much to get a good overview. It is best to distinguish commercial modify the complete programming of those - or at least make a feature request and hope someone in the community is able to program it.

Controllers around at the moment are:

  • HobbyKing KK2.1.5, KK2.1 or older KK2
    A very simple commercial 6DOF controller with integrated display and buttons that allow you to change all parameters directly. It's a very basic system but very popular and great to learn on. There are different firmwares out there which make setup easier and result in better flying characteristics. There is no way to to add more sensors, so you can not extend or upgrade the features. Even though it's considered large by todays standards it is a great controller for beginners.
  • Naze32
    A small lightweight board that has a very good reputation of flying small multi's very well. 32bit is a plus. The full version has a barometer, compass and can be hooked up to a GPS but the later is still experimental. The acro Naze does not have these extra features. These are not as easy to setup with no inbuilt screen and some computer knowledge is required.
  • MultiWii

    This has a lot of different versions from basic 6DOF to full GPS capability. The simpler acro boards like the flip boards can give great results for simple setups buts can be fiddly to setup. The fullhouse boards with GPS etc. require patience to setup and even then the results are mixed. These boards are cheap which is a plus and are good quality when bought through RTFQ who can make the initial setup for you.
  • ArduPilot
: APM 2.5 / APM 2.6 / Pixhawk
    Open-source project that has a huge amount of features with many add on features like GPS. They are very powerful boards that have the usual magnetometer, barometer and GPS functions plus a whole host of others giving you an amazing suite of options including full autonomous capabilities and control via computer. But this also means a complicated setup. A fair bit of work and knowledge is required to tune it. Also can be expensive but this is what commercial operators use.
  • HKPilot Mega

    A cheap ArduPilot Mega clone made by HobbyKing.
  • OpenPilot
 CC3D
    Another open-source based project. The hardware is difficult to get hold of because it's not manufactured commercially. Very similar to the acro Naze.
  • DJI Naza

    A commercial controller that is quite popular. Can have a full list of features but being a commercial system is more restrictive on what you can do. Easy to use and setup. Known for good GPS lock and stable hover but not much else. It is very expensive and limited on its capabilities especially considering the high purchase price.

A much bigger list can be found at Oddcopter.

Remember that simplicity is the key when starting out. Extra features like GPS may just get you into more trouble early on.

For a beginner you would be wise to get a KK board or risk a very steep learning curve.
 
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Balu

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#5
Electronic Speed Controllers (ESCs)

The electronic speed controllers (ESCs) drive the motors based on input of the controller. There are different types of ESCs for different types of motors. Brushless motors (also called outrunners or inrunners) are used for multirotors and require an ESC that works with brushless motors.

How a brushless ESC works is quite complicated. Basically they control three phases to generate magnetic fields in coils to attract the permanent magnets fixed on a runner. The speed in which those magnetic fields are changed determines the speed of the motor.

For this to work an ESC has to have it's own brain - a small CPU with an internal program. This programming can be quite different depending on the kind of model it's supposed to be used for. For example the ESC for a car needs to be able to turn the motor backwards and our multirotors require extremely fast speed changes to keep the copter stable.

Because of this a lot of ESCs need to be re-programmed (flashed) with an alternative firmware to work on a multirotor. The most common one is called "SimonK" written by Simon Kirby. There are different versions for different ESCs manufacturers. Some manufacturers or merchants even offer pre-flashed ESCs. If you don't want to fiddle with this yourself, it might be a good idea to get those.

The SimonK firmware increases the rate at which the ESC sends speed information to the motor and removes some features that are bad for multirotors. For example most ESCs have an averaging function to filter quick throttle moves to reduce spikes in current. But also make sure you use a SimonK flashed ESC only in multirotors. If you have a heavy rotor like on a helicopter it will probably break the gears because of the sudden speed changes. (also see PPM filtering)

The most important detail on an ESC is its current rating in ampere (e.g. 25 A). ESCs that can handle higher currents usually are larger and heavier. Because of this you want to get an ESC that can handle the current your motors generate plus a little headroom for spikes generated by fast speed changes, but not too big to keep the weight down - after all you need one ESC for each motor. If your ESC is too small for the current it will let you know - with little sparks and smoke.

Another thing to think about is the battery eliminator circuit (BEC). If you don't want to have an extra battery or external BEC to power your main controller, you should get ESCs that have a BEC on board. ESC’s called OPTO’s don’t have a BEC built in as sometimes it is not wanted or could harm your flight controller. It is best to find out which you need and that depends on your setup.

Non multirotor ESCs have a low-voltage-cutoff which senses a voltage drop if the battery charge is getting low. This is important as draining a Lipo battery too far can destroy the battery for good. There are two kinds of low-voltage-cutoffs: A "hard cutoff" where the ESC cuts the power to the motor completely so the steering servos can use the remaining power to maintain the control surfaces and allow for an emergency landing. This is a really bad idea on a multirotor for obvious reasons. A “soft cutoff” slowly reduces the power over a 8-15 second span to allow the aircraft to settle to the ground. Although better that is still not good for a multirotor. A true multirotor ESC has no cutoff at all and the pilot relies on a timer or a low voltage buzzer to tell them to land.
 
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Balu

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#6
Batteries / Chargers

There is a whole section on this forum on batteries and charging systems, so there is no need to go in detail here.

An important read is the sticky post about "Understanding Batteries 101".

Also there is an episode on batteries in the FliteTest Beginner Series.

Important keywords that you need to learn about are number of cells (S / Volts), capacity (mAh), C-rating and how to charge and discharge the most common type of battery correctly ("LiPo" - Lithium Polymer).

What kind of battery you need depends a lot of your multirotor model, how you want to fly and the motors you use. But a beginner should follow this little tip: 4S battery powered multirotors are for the experts. 3S battery setups are for everyone else.

4S batteries will result in a fast and really agile multirotor - too agile in fact for a beginner. Start slow and learn how to fly before trying to do more crazy stuff.
 
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Balu

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#7
Motors

As you can imagine the motors are one of the more important elements of a multirotor, because - well - they are an the only parts that keep it in the air. Since it doesn't have a wing, you have no surface to glide after all...

Motors have different characteristics you have to look for. First of all, it should be a brushless one. Those are more efficient than brushed ones. Then of course the size is an important factor, because bigger motors will usually be heavier and since there's usually more than one (multirotors, remember? ;-)) the weight multiplies too.

For brushless motors you have two kinds: Inrunners where only the shaft moves (usually used for very high RPM motors) and outrunners where the whole bell moves around the stator (lower RPM motors).

From the electrical point of view there is one important number that everybody talks and asks about: The kv rating. It is measured in rpm/V (revolutions per minute per volt). So if you put 1 V on an 1000 KV motor it will spin with 1000 rpm, 2 V means 2000 rpm and so on. This is directly related to the battery you have in your model. Most common ones are 3 S (11,1 V) or 4 S (14,8 V), so the maximum revolutions per minute of our 1000 KV motor would be 11 100 rpm respectively 14 800 rpm.

How fast a motor has to be depends on what you want to do with your model and is directly related to the propeller size as well. For example - if you want to build an agile multicopter you need a fast motor and smaller props but if you want to lift a heavy weight like a camera it needs to be the other way around. What to choose here is a difficult decision and deserves it's own post.

Select a proven design and motor setup. For beginners it helps a lot to ask experienced guys, look for build videos and plans that are similar to what you want to create and go for a similar setup.

Important ratings for a motor are the maximum allowed Voltage (V), the maximum current in Ampere (A) and the amount of power it can provide in Watt (W). The maximum current is an important value, because the ESC has to be able to handle it - adding 20% for security is always a good idea.

A good quality motor has good bearings, equal spacing between the magnets and is well balanced, so it doesn't put vibration on your frame.
 
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Balu

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#8
Propellers

These things are evil and will hurt you if you don't take care. So make sure to never go near a rotating propeller with any body part you want to keep.

Specifications

A propeller has two important numbers that define the basic characteristics - the diameter and the pitch.

Most propellers are marked with these two numbers in a format like 8x4.5". This means the propeller has an 8" diameter and a 4.5" pitch.

The diameter quite obviously defines the length of the blades and the disc area in which air is moved. This determines the power of the pull and the torque that is generated, but not the speed.

This is what the pitch stands for. It is defined as how far the propeller would travel in one full rotation while being in a perfect fluid. You can visualize this by thinking of a screw. A higher pitch screw will go deeper into the wood than one with a lower pitch if you turn both exactly one revolution. Since air is not a perfect fluid, this number does not translate into the real world. But it still helps in determining the speed of the air transported by the propeller.

A high pitch propeller is used for speed, but takes longer to accelerate and has poor climbing abilities. Compared to a car it's like starting to drive in 5th gear. You will get fast, but it takes a while and you will probably not get up a hill. These are not good for a multirotor.

A low pitch propeller on the other hand is slower, but accelerates faster, has a better climbing rate and better speed control. As four our car comparison - it's like driving in a low gear: You will be slower, but can accelerate quicker and climb hills.

To make things more difficult there are variable pitch propellers. Usually those are reserved for helicopters, but there are multirotor models out there that use these - and can do crazy maneuvers like flying upside down...

Also important is the type of the propeller. You can have clockwise (CW / pusher) or counter clockwise (CCW / tractor) props. For a multirotor you usually have to use both kinds because the motors rotate in different directions to minimize torque that wants to turn the copter around. Always make sure you use the right type of propeller on each motor and have the numbers that are written on the blades point in the direction the motor is supposed to travel (that is "up" for multirotors).

There are discussions on the number of blades though. Two blades are more efficient than three, because more blades might disturb the air for the next blade. But if you want to build a smaller model and have to reduce the disc area, you can go for a three or four blade prop.

It's important that these numbers match the motors you use. Quite often the manufacturer of a motor mentions an "engine comfort zone" and suggest what propellers you should use. For low kv motors that usually means a bigger diameter, but flat pitch. High kv motors are used with smaller diameter props with a bigger pitch which results in higher speeds.

Materials

As the frame itself, propellers come in a big variety of materials.

  • Wood
    These can be lighter than other materials if they get bigger and can tolerate higher RPMs, but they break easily. They are not common on multirotors.
  • Fiberglass
  • Carbon Fiber
    These are the most rigid ones. They give you the best performance, but are really expensive and don’t handle crashes well.
  • Nylon
    These are the cheapest and come with quite a list of negative properties. They are flexible and might deform at higher speeds which will change the pitch and make them loose power. They are good for beginners though, because they will not break that easily.
  • Fiberglass-reinforced Nylon
    These are the heavier ones, but also the most durable. They are less efficient than fiberglass or carbon fiber props, but still pretty good for a beginner.

No matter what material your props are made of - if they show any sign of damage or cracks, throw them away and get new ones. Because they will mutate into high speed projectiles if they break at high speeds.


Choosing props, motors and ESCs

Besides using a proven setup you might want to choose your own power train for a built. When you're just getting started it can be quite daunting to pick the right props, motors, ESCs, and batteries. The best way to choose your gear is to start with the props and work your way back to the battery. For example, if you know you want to run 6 inch props, choose a motor that will swing them. Then you should know how much current that motor will draw with that prop, so you can get an appropriate ESC and a battery capable of supplying your ESCs. Of course, if you're considering 3S vs. 4S, you need to keep that in mind from the start.


Balancing Props

When you buy new props the first thing you should do is balance them. Because of the way they are manufactured they are more or less out of balance. If you don't fix this you will have vibrations as a result. These not only rob power from the engines, but might even destroy your frame or the electronics as well as reeking havoc on your flight controllers gyros.

Repeat after me: Vibrations are bad!

Balance your props and motors. Well balanced propellers will give you a better flying experience and are more efficient.

Finally, check out the Flite Test Beginner Series episode on power systems which includes information on props and motors.
 
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Balu

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#9
What now?

Try to learn from other people. Look at their setups and try to understand why and how they built it the way it is. When you have your first multirotor in the air, start slow. Move it from front to back and side to side before swooshing around like a maniac. You have to get used to keeping the copter stable first, then rotate it around and fly figures.

The maiden flight

Before you start for your first flight, check your receiver inputs and calibrate all ESCs - without props. How to do that depends on your flight controller. Some controllers calibrate the ESCs automatically, some require manual work. Your ESCs manual should describe how to do that. Also make sure the motors are spinning the right way. Depending on your model you have clockwise and counterclockwise rotating motors and props.

After you've added your props make sure you have enough space, preferably on a softer surface like low grass.

For the next step be prepared to chop the throttle off. If you've got something backwards, there's a good chance the multirotor will flip instantly, as soon as one of the skids leaves the ground. The flight controller is registering a wrong attitude and tries to correct that, making it worse. If it starts to do that you want the motors off in an instant.

Arm and throttle up slowly until the multirotor get's light on the skids. Gently move through the controls. Pitch forward and the rear skids should start to lift, pitch left to lift the right, etc.

Now find a smooth surface and repeat for the yaw.

After all the directions check out and you've not flipped your multirotor, it's time to go airborne. Throttle up slowly to get it light on the skids, build up your courage, prepare for a crash and in one fluid motion, punch to 3/4 and back to near 1/2, to try to catch it in a hover in a low height. Now try to hold it there for 10-30s to see if you register any weird vibes or shakes.

If you're stll learning and your flight controller supports it, turn on self level in the maiden hover, but be advised, it can make for poor flight characteristics until it's tuned - and you have to turn it off to tune it...

After you've hovered for a few moments, gently bump the controls to see it respond - if acro is on, you'll need to bump it back to get it back to level. Hovering the first battery pack with only little touches on the controls isn't a bad idea. Treat it gently for the first few packs, and when you start tuning, tune a pack, fly a pack (to take a break and see if you really need to tune further).
 
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Cyberdactyl

Misfit Multirotor Monkey
#10
Most excellent researched thread/posts Balu. :) An awesome one-stop shop for anyone new to the hobby.

I almost hate to post and ruin the stream, but I believe you will edit the posts above to keep it tight. Mine can be the first 'comment' at the end of the blog. :cool:
 

eXsoR

Junior Member
#11
Great Beginners Guide Balu!

I've been watch tons of videos because I would like to get in to the hobby and you basically summed it all up in one page witch is very informative. I'm going to continue to following to see the end results. I'm currently saving the money to build my own.
 

Cyberdactyl

Misfit Multirotor Monkey
#13
Nice resource. Also a bit to add do NOT go under around $50 for a control board, the i86 I got is HORRIBLE.
I have to disagree. The KK2.0 is under $30, and is like night and day from the i86. The KK2 and most likely the KK2.1 (I haven't used it yet) are extreme bargains.
 

Balu

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#14
I've just edited the post about ESCs. I'd be happy if someone experienced could proofread it and let me know if I forgot something or included wrong information.

As for a cheap control board, the KK2(.1) seems to be great. I've seen a lot builds using that controller for simple copters that don't require higher end features. I'm currently thinking about using it for my first build, because it allows me to change parameters without an extra computer. But then - I have no comparison to anything else yet =).

Bau
 

Cyberdactyl

Misfit Multirotor Monkey
#15
Most excellent, as usual. :)

The only tiny thing I would mention considering the low voltage cutoff is the "hard cutoff" which is the one you're referring to, where the motor abruptly stops as opposed to a "soft cutoff" programmed into the ESC for a multirotor, which slowly cuts power over a 8-15 second span to allow the MR to settle to the ground, if the flyer ignores the lowV buzzer or simply has no low voltage indication on board.
 

eXsoR

Junior Member
#16
Newbie question.

Is flashing ESC's still relevant? I would think that ESC's would be made for Multi-Rotor Copters and not have to be flashed..

or Is it for to be able to get the most out of the ESC's??
 

Cyberdactyl

Misfit Multirotor Monkey
#17
There are many ESCs now made specifically for multirotors.

But most are not and come with heavy PPM filtering.

Reflashing for MR specific flight provides a smoother, higher fidelity motor control. Rcexplorer (David Windestål) turned me on to the ultra cheap HobbyKing F-20 20A ESC. It comes with generic programmed settings and is flashed for a broad spectrum of uses, but are only $8... an amazing bargain for an ESC that will tolerate heavy abuse. But you WILL need to program some basic settings like soft cutoff and turn off motor breaking, etc. And once you move past merely hovering and lazily flying around, you'll probably want to flash them with MR specific firmware.
 

eXsoR

Junior Member
#18
Oh ok kool by any chance to you know if there are a 15A ESC that is flashable ??
I'm a noob at the hobby but I'm a Computer modder for over 5 years and if I can hack it and it will be hacked.!!!!

Only reason why I say 15 A is because I plan to use the recomemed one that flite test post on the H-Quad from form there site.


There are many ESCs now made specifically for multirotors.

But most are not and come with heavy PPM filtering.

Reflashing for MR specific flight provides a smoother, higher fidelity motor control. Rcexplorer (David Windestål) turned me on to the ultra cheap HobbyKing F-20 20A ESC. It comes with generic programmed settings and is flashed for a broad spectrum of uses, but are only $8... an amazing bargain for an ESC that will tolerate heavy abuse. But you WILL need to program some basic settings like soft cutoff and turn off motor breaking, etc. And once you move past merely hovering and lazily flying around, you'll probably want to flash them with MR specific firmware.
 

xuzme720

Dedicated foam bender
Mentor
#19
Oh ok kool by any chance to you know if there are a 15A ESC that is flashable ??
I'm a noob at the hobby but I'm a Computer modder for over 5 years and if I can hack it and it will be hacked.!!!!

Only reason why I say 15 A is because I plan to use the recomemed one that flite test post on the H-Quad from form there site.
Just go with the 20A if you haven't ordered yet. The weight difference is almost nothing and it will also give you more room for expansion later.
 

Balu

Moderator
Staff member
Admin
Moderator
#20
Thanks for the input, Cyberdactyl.

I've added the hard and soft cutoffs, added the link to PPM filtering and mentioned programming as opposed to flashing.