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ESC Development: BLHELI_S, Hardware PWM and 32BIT

BLHeli_S – New Firmware
BLHeli has released a new code geared for new hardware in ESC’s (electronic speed controllers). It uses the BLHeli 14.5 base firmware revision and improves upon it. It’s specifically designed for new ESC’s such as the Aikon SEFM 30A ESC. Here are a list of improvement from BlHeli_S.

·BLHeli_S delivers a throttle response that is smoother than previous BLHeli, thanks to the hardware PWM. Two MCU’s support this for BLHeli_S, namely the BusyBee1 at 24MHz and the BusyBee2 at 48MHz.

·It will have the same good sync holding properties as base BLHeli.

·BLHeli_S does damped light only.

·It has motor PWM that is Synchronous to the MCU master clock, as it is generated by hardware. This makes the motor run more silently.

·It has very small throttle steps. The resolution varies between hardware configurations (MCU clock speed and driver type), and is between a nominal 512 steps and 2048 steps.

·Supports very high motor Speed: BB1 MCU can support up to 350k eRPM, and currently the BB2 is set to 500k eRPM.

·Supports regular 1-2ms input signal, as well as Oneshot125, Oneshot42 and Multishot. Auto-detected when the ESC sees an input signal.

All these improvements look promising and when reached, definitely will change the way our multirotors fly!

You should also check out this guide about how to choose ESC. Check out this article to learn about ESC firmware.

Hardware Changes

The changes in programming are directly related to the ability of improved hardware that is being implemented. As SSKaug mentioned, this new line of ESCs are running the BusyBee1 (EFM8BB10F8) and the BusyBee2 (EFM8BB21F16) MCU’s (Microcontroller Units). These two MCU’s are different than the previous Silabs chips that many ESC’s have been using. The reason these MCUs are going to be better is because instead of using software PWM they will be using hardware PWM that is synced to duty cycle.

The great thing about using dedicated hardware to generate the PWM is that the speed at which the ESC writes the values to the motors is doubled! With old Blheli ESCs and software generated PWM signals, the ESCs write to the motors at a 16khz rate. With hardware generated PWM it’s bumped up to 36khz. These means that your motors are getting input even faster which allows for better response. KISS ESC’s are an example of this. They have hardware generated PWM and the smoothness and response you get with those is hard to beat.

Is 32 bit ESC better than 8 bit?

Currently the Aikon SEFM 30A ESC is the only ESC being tested with BlHeli_S on it. Of course, there will be many more ESCs to make the switch to BlHeli_S in the future. At the moment there are a few different options. Some of the best and most popular ESCs that will be competing with the Aikon ESC during its release are:

·KISS 24A RE ESCs

·DYS XM20A and 30A ESCs

·XRotor 30A and 40A (40A may also be BlHeli_S capable, unconfirmed)

·SEPM32 ESC

·VGood Firefly ESC

Three of these ESCs are actually using 32 bit processors on them. Being that they are 32 bit ESCs, they’re capable of much more processing and storage. These ESCs are the KISS24A RE ESCs, the SEPM32 ESCs, and the VGood Firefly ESCs. The other ESCs (pretty much all OTHER ESCs) use an 8 bit processor.

More processing power is generally better with every bit of technology. However, in this case there really isn’t a difference in actual performance. ESC’s are not even close to the 8 bit processing capacity at the moment. In the future 32 bits may become a requirement as coding gets more complex. Right now the only difference between the two is from a coding perspective. The 32 bit ESCs can be programmed in C++ because of the added bytes, but the 8 bit ESCs have to be programmed in assembly. Does it make a difference in practice? Only if you’re a programmer and only know C++ not assembly and cannot take the time to learn the syntax.

Personally, I’m very excited about the improvements BlHeli is going through. I’ve been flying BlHeli for a long time and even tried SimonK and others back in the day. It’s amazing how far ESCs have come and how much an improvement they have made to flight characteristics of multirotors. I look forward to testing these ESCs in the future and comparing them in real life situations to other ESCs. Keep your eyes out for them!

Original link from Oscarliang: https://oscarliang.com/blheli-s-hardware-pwm-32bit/
Using ESC Beacon as a lost model Alarm

Do you notice the start-up beeps the motor/ESC makes when you plug in the LiPo battery? It beeps even when there is no buzzer connected, and we can turn that feature into a lost model alarm.

It can be useful when you don’t have a buzzer installed, or in case your buzzer failed in a crash. Check here for more useful tips on quadcopter building/flying.

In this tutorial we will show you how to do this in ESC’s with BLHeli firmware. To set it up there are only 2 settings you need to configure in BLHeli Suite:

·Beacon Strength – How loud you want the beeper to sound (default 80, range from 1 to 255); 120 is a good value IMO, I suggest trying different values and check if the motors and ESC would get too hot. I don’t recommend setting this too high to prevent motors and ESC overheat

·Beacon Delay – After how long the beeper starts to activate being idle (default 10mins, IMO 5 or even 2 mins is a good idea for our purpose)

There is also Beep Strength. This setting might seem relevant but actually it’s not. It only controls the volume of the start-up beep, just leave it as it is.

A bit out of topics, if you ever wondered how ESC’s can make sound, they don’t. It’s actually the motors that makes the sound. The pitch and volume of the sound is controlled by signal from the ESC. It’s even possible to play a jingle with motors :)

Original link from Oscar Liang: https://oscarliang.com/esc-beacon-lost-model-alarm/
Travelling with Mini Quad and Lipo Batteries

Travelling with a drone includes some inherent inconveniences, but a little preparation can ensure friendlier skies. Here are some basic rules to follow on how to travel with mini quad and LiPo batteries on an air-plane.
Folks travelling with mini quads are most likely hoping for lots of blue skies and tons of fun. If you happen to be one of these lucky enthusiasts heading out on a trip, the last thing you want is to spend hours locked up in a stuffy back room – which is a distinct possibility if you don’t know “the rules.” As always, knowledge is power, so follow along for several quick tips you can use, to make sure your next dream drone vacation doesn’t turn into a drone-confiscation nightmare.

If you are not travelling on plane, check out a couple of backpacks we reviewed for quadcopters.

#0 – LiPo Restrictions in Airports

Every airline and airport has different regulations regarding LiPo batteries. Some are more strict than others. Large, well equipped airports seem to be fine usually, but smaller airports are more nervous about LiPos and to be sure it might be better to check with them before you go through.

There should be no limit on the number of <100Wh batteries, and only 2 over 100Wh are permitted with airline approval. These are the rules for FAA and some other countries, presumably the UK is the same. Although there is no limit on how many small LiPo batteries you can take, security will still get nervous when there are too many show up.

#1 – Understand it’s all in the delivery

Think of this tip as more of a cardinal rule for drone travel. All words have power, and the ones you use to describe your mini quad to travel officials have the power to ruin your trip.

That said, here’s what you do: avoid calling your drone a “drone”, a “quadcopter”, a “multirotor”, a “mini quad”, or anything else that sounds cool. It is, for the duration of your trip, a “toy RC helicopter“.

If you are using LiPo bag, try to remove or cover the words “explosion” and “fire” to avoid causing unnecessary panic at the check point :)

#2 – Be transparent

With everything you do, you want to give the impression that you have nothing to hide (after all, you don’t!). For example, if you plan to pack your mini quad as a carry-on, take it out of your bag and place it in its own bin at the Airport security checkpoint.

Expect suspicion; it’s their job. Do what you can to ensure your quadcopter will be easy to take out should the agents require it.

#3 – Remove propellers

Even if you have an awesome drone case or backpack that allows propeller-attached transport, you should still remove the props for your trip. If you’re asked to take your multirotor out of its case, there’s a possibility the security might want you to also power it on. Having the props already removed will be much more convenient and less time consuming for both you and the airport staff. The sharp blades might also injure someone.

#4 – How many LiPo can I take?

LiPo batteries for mini quads are small so you can actually take quite a few with you (check with airline how many exactly you can bring). Some have rules on how many Watt-Hours (total capacity mAh x voltage) you are allowed to bring on board.

Before you leave for the airport, remember the following:

·Discharge your LiPo batteries to storage charge, or below the level required by the airline (some require batteries do not exceed 30% of their rated design capacity)

·Tape up the terminal connectors with electrical tape

·Put LiPo in Lipo-safe bags

·Print out the airline’s regulation regarding LiPo batteries, put it somewhere with your batteries. If anything happens you can pull out the documentation and show them

·Batteries are only allowed as carry-on baggage

Once boarded the aircarft you can just leave your quad(s) / batteries on the overhead locker.

#5 – Separate your items

Avoid mixing your important stuff with your multirotor stuff.

Put what you think have a higher chance of getting checked or confiscated in one single bag (such as your batteries). So even if it does happen, your more important stuff don’t get taken away.

#6 – Tools – No knives or scissors

You can’t carry certain tools with you, such as wire cutters or scissors (anything that looks like can be used as weapon). Use common sense and check online if in doubt.

#7 – Be kind and polite

If you find yourself in a situation where someone has the power to make the call whether to confiscate your drone for good, your kind words and friendly demeanor might mean the difference between keeping or losing it. Expect that you will likely be hassled at the airport for traveling with a drone and lots of LiPo batteries, so be prepared. And remember that those hassles serve the purpose of keeping us all safer in the skies.

#8 – Make an battery inventory

Probably one of the most important off the list here, is to make an inventory of all your battery. All they look at is the Watt-hours of your battery:

·Work out the “Wh – watt hours” for each battery, stick that on the battery (Wh = capacity * nominal voltage)

·Write them down on a piece of paper, along with quantity

This is not compulsory (because security didn’t check mine every time), but I found it helped speed up my clearance in several occasions. This also helps you understand if you have any batteries larger than the limit.

Happy flying!

And one more thing. While these tips are great rules of thumb, you always want to check with your particular airline to make sure you’re aware of any specific rules they may have.

Original link from: https://oscarliang.com/travelling-mini-quad-lipo-batteries/
What is RSSI Transmitter Receiver– RC Quadcopter

RSSI is a measurement of how good radio signal is between RC transmitter and receiver, which stands for Received Signal Strength Indication. It’s an important safety feature to help avoid lost of radio signal, which could lead to unexpected quadcopter crashes and damage to properties.
Getting RSSI

RSSI is generated from the receiver, but not all RX can have this feature. You can connect the RSSI pin on the RX to the FC or OSD if supported. Some receivers don’t provide this pin for RSSI so DIY modification and additional components might be required. If the radio system is capable of telemetry, it’s also possible to obtain RSSI and display it on your TX. You can even do some more advanced hacks with this.

For example with the FrSky Taranis transmitter and D4R-II receiver. The combo provides 1.5 km of range and telemetry feature including RSSI. We can simply connect the RSSI pin to the OSD, and the RSSI value can be shown on the FPV screen.

Another good thing with telemetry that sends RSSI is that the TX alarm starts beeping when the signal is getting too weak (based on RSSI value). It gives me great peace of mind to know how the signal strength is while flying, and when I should turn back. With this feature I barely looked at RSSI value in my OSD and eventually I removed it.

How to use RSSI signal

Knowing the difference between digital and analog RSSI

The RSSI is normally an analogue value (a voltage level). But that is not always the case and it could exist as PWM signal (pulsed width modulated) with variable high-low ratio depending on signal strength. Therefore there could be incompatibility in the system when reading RSSI. (That’s why a lot of people’s RSSI in OSD is always 0, 50 or 100)

To solve that, we need to convert the PWM signal to a voltage easily using a “Digital to Analog converter”, or simply a low pass filter (Resistor-Capacitor filter).

Some OSD modules or flight controllers accept direct connection to the PWM RSSI output because they have a low pass filter built in.

What if OSD doesn’t support RSSI?

If your OSD doesn’t support RSSI input, you might still be able to display RSSI. Most OSD has dual battery inputs (BAT1 and BAT2), they were designed to display your primary and secondary battery voltage levels. But most of the times we would only use one and with the spare battery input we can use that for RSSI.

Normally the range of the RSSI value is 3.7V to 0V (100% to 0%) when converted from PWM. It might not be a percentage number but voltage, you still get a good idea what RSSI level is. I did this mod with my Hobbyking E-OSD, and it worked like a charm.

Understanding what RSSI is

Not something you need to know in order to use RSSI, but in case you are curious.

RSSI isn’t actually an linear measurement like voltage or temperature, but a ratio of the current signal to some initial “good” value. It’s in dB, same measuring system used for audio levels. dB is a logarithmic measure, and it’s not linear. What this means is that by increasing 6dB means the signal has doubled in strength. So a change of +12dB in the RSSI means the signal has increased in power by 4 times, by +18dB means the signal has increased in power by 8 times, and so on.

For instance, if the RSSI reads about 110 at 1m and every time you double the distance between the transmitter and receiver, the RSSI level should drop by 6. At about 100 meters you should get an RSSI value of about 70 in ideal conditions.

A good way to see this effect is to use Range Test mode on your radio transmitter. In range test mode the transmitter module operates at 1/30 of full power.

Original link from Oscarliang: https://oscarliang.com/what-rssi-transmitter-receiver-quadcopter/
How to Choose Lipo Battery Beginner Guide for Mini Quad, drones and quadcopters

Multirotors (aka drones) are fueled by LiPo battery, they are able to store and deliver large amount of power. In this guide you will learn how to read the spec of LiPo for your mini quadcopter, and how to choose and handle them safely.
The Basics about LiPo Batteries for Mini Quad

Lithium polymer batteries, more commonly known as LiPo, have high energy density, high discharge rate and light weight which make them a great candidate or RC applications.

By learning the basics about LiPo batteries, you will be able to read and understand their specifications.

Battery Voltage and Cell Count (S)

LiPo batteries used in RC are made up of individual cells connected in series. Each cell has a nominal voltage of 3.7V. Therefore battery voltage is often referred to as how many cells in the battery (aka “S”).

Voltage affects brushless motors RPM directly, therefore you could use higher cell count batteries to increase your quadcopter’s speed if your motor/ESC and other electroincs support higher voltage. (here is a discussion about the differences between 3S and 4S on a mini quad)

But a battery with more cells of the same capacity is heavier since it contains more cells. To make a 4S 1000mah battery, you could simply combine two 2S 1000mah, or one 3S 1000mah with an 1S 1000mah.

LiPo battery is designed to operate within a safe voltage range, from 3V to 4.2V. Discharging below 3V could cause irreversible performance lost and even damage to the battery. Over-charging above 4.2V could be dangerous and eventually cause fire.

However it’s advisable to stop discharging when it reaches 3.5V for battery health reasons. For example for a 3S Lipo, the max voltage is 12.6V, and you should land when the voltage reaches 10.5V (at 3.5V per cell).

LiPo Battery Capacity

The capacity of a LiPo battery is measured in mAh (milli-amp hours). “mAh” is basically an indication of how much current you can draw from the battery for an hour until it’s empty.

Increasing your battery capacity might give you longer flight time, but it will also get heavier in weight and larger in size. There is a trade-off between capacity and weight, that affects flight time and agility of the aircraft. I wrote a guide about building a simple mathematics model to find out optimal Lipo capacity for longer flight time, which you might find interesting.

Higher capacity could also give you higher discharge current as you will see in the next section.

C Rating (Discharge Rating)

All Lipo batteries for mini quads these days come with C ratings. By knowing the C rating and capacity of a battery, you can calculate the safe, continuous max discharge current of a LiPo battery.

Most batteries come with 2 C-ratings, Continuous and Burst ratings. The Burst rating is only applicable in short period of time (e.g. 10 seconds), where wide open throttle happens.

This article explains the significance of C rating. Although C rating could be a useful indication, it’s not an absolute performance indicator nowadays.

Connectors

Rule of thumb, the battery connector should match the one you are using on your copter. If you don’t own a quad yet, choose one, and stick with it.

All Lipo batteries come with 2 sets of wires/connectors: a balance lead and a main lead or discharge lead (Except for 1S batteries which only have a main lead). There are quite a few different connectors used in LiPo batteries. The main differences are shape, weight and current rating.

1S Battery Connectors

1S connectors are tiny and have very low current rating. They are commonly used in brushed micro quadcopters.

2S-6S Battery Connectors

You will find a lot more different types of battery connectors in this category, in fact not all are listed here. But majority of them are not used that often so you don’t need to ever worry about them. For mini quad, the most popular connector is probably the XT60.

However since XT60 is only rated at 60A, and mini quad are running at higher and higher current and voltage, we might soon see a change in the popular connector used.

Balance Lead

Balance lead is mainly used for balance charge to ensure all cell voltages are equal. It also allows you to monitor the voltage of each cell.

The number of wires in a balance lead starts at 3 for 2S LiPo, and for every increment in cell count, the number of wires also go up by 1.

Internal Resistance (IR)

Internal resistance exists in every battery cell, and IR could be different in each cell of the same LiPo battery. Higher internal resistance reduces the max current the LiPo pack can produce, that why as a LiPo battery gets older or overly used, you will find it losing the punch, or power.

IR isn’t shown on the label, because they can change over time. Lipo internal resistance increases with:

·time/age

·crashes (physical damage)

·over-discharging

·over-heating

·other abusing usage

You can measure IR with dedicated tools, some LiPo charger even comes with IR measuring features.

We covered IR in more details in the C-Rating article.

LiHV

LiHV is a different type of LiPo battery, HV stands for “high voltage”. They are more energy dense than traditional LiPo battery, and allow to be charged up to 4.35V per cell. However there are mix reviews out there regarding the longevity of LiHV, as they might have decrease in performance sooner than normal LiPo’s.

Original Link from Oscar Liang: https://oscarliang.com/lipo-battery-guide/
ESC Firmware and Protocols Overview

For quadcopters there are several ESC protocols and firmware available, which could get confusing for beginners. In this summary we will explain the difference, a little bit of history and links to articles for more technical detail.
When I started in the hobby, connecting an ESC to the flight controller was straight-forward. But now there is so much to consider: ESC settings, protocols, firmware etc, it can be confusing and overwhelming for beginners. I hope this guide can help answer some of the questions.

Check out this guide about how to choose ESC for mini quad.

ESC Firmware

ESC firmware is the software running on every ESC, which determines the ESC’s performance, and what configuration interface can be used. The firmware you can use depends on the ESC’s hardware.

Here are a list of ESC firmware available to mini quad ESC:

·BLHeli

·BLHeli_S

·BLHeli_32

·SimonK

·KISS

·Other manufacturers’ own firmware

Before and around mid 2015, there used to be a choice between SimonK and BLHeli for majority of the ESC’s back then. They were also two of the earliest open source ESC firmware. But over the years BLHeli has taken over the market due to its better performance and more user-friendly interface. (differences between BLHeli and SimonK)

As ESC technology continues to evolve, newer BLHeli firmware was written specifically for the better and more advanced hardware. BLHeli_S was the 2nd generation firmware developed for the BusyBee processors in 2016, and the BLHeli_32 was the 3rd generation firmware for the 32-bit processors in 2017.

Nowadays, all ESC’s come with ESC firmware pre-installed, mostly BLHeli_S or BLHeli_32 depending on the hardware, which should be stated clearly in the specification. You don’t need to worry about changing firmware because basically you don’t really have a choice. However you do need to make sure the firmware is up to date for bug fixes and performance improvement.

For non-BLHeli ESC’s, they are most likely to come with (and locked to) their own factory firmware, such as the KISS ESC, Castle QuadPack, and the Gemfan Maverick ESC.

ESC Protocol

What are ESC protocols?

ESC Protocols are the “languages” that flight controllers use to communicate with ESC’s, basically telling them how fast the motors should be spinning. Here are all the ESC protocols available to mini quad depending which FC firmware, and their respective signal width (the time it takes to send one data packet), click the links for more detail:

·Standard PWM (1000us – 2000us)

·Oneshot125 (125us – 250us)

·Oneshot 42 (42us – 84us)

·Multishot (12.5us – 25us)

·Dshot

oDshot150 (106.8us)

oDshot300 (53.4us)

oDshot600 (26.7us)

oDShot1200 (13.4us)

Before 2015, there was only one ESC protocol, standard PWM. But as hardware was getting better, faster protocols became possible: Oneshot125, Oneshot42 and Multishot. These protocols are all analog signals similar to standard PWM, but much faster and hence reduce the latency of quadcopter response.

DShot is the latest ESC protocol which is a digital signal. It’s the future of ESC protocol in my opinion because of its better reliability and performance, and the ability of sending not only motor speed, but specific commands to the ESC’s.

Hardware released after mid 2017 should support all the ESC protocols, apart from DShot1200 which is relatively new and is only compatible with some 32-bit ESC’s. Make sure to double check the specification when planning a new build.

I hope this guide gave you an overview of all the ESC software and protocols. Please don’t hesitate to leave me a question or comment.

Original link from Oscarliang: https://oscarliang.com/esc-firmware-protocols/
Considerations in Choosing Mini Quad Props

Material
Propellers can be made of different materials, plastic composite, carbon fibre, wood etc. Each type of material gives unique features, for example carbon fiber and wooden props are really stiff and best known for their smooth performance. While certain plastic compound are extremely durable. Check out this post for more info.

In fact, majority of the pilots in this hobby are now using what we call “durable plastic” props. They last much much longer and could save you tons of money in the long run. However, because they don’t just snap in a crash, they bend. It’s not obvious from appearance but they can cause vibration to your quadcopter, potentially giving your flight controller a hard time and leads to motor overheat. Make sure to make attention to vibration and oscillations when using these props.

And don’t use props with “white crease lines“. After a prop is bent it might develop these white lines and it’s a sign of asking to be replaced. If you don’t you risk snapping the propeller mid air and crashing.

Weight

Lighter props tend to perform better than heavier ones for mini quad in my experience, because there is less moment of inertia. RPM changes faster so the multirotor would feel more responsive in theory. Lighter props also run better on a wider range of motors, because they require less torque to spin up.

Weight distribution of the blades also makes a difference. It again affects the moment of inertia. For the blade’s center of mass closer to the hub is better for a propeller. Although that means the end of the prop gets thinner and easier to break. The more further away from the hub, the more drag there is and makes the prop harder to speed up and slow down.

Rigidity

The least rigid propeller I have ever used is the Gemfan 5030. They are so soft they literally bend when the motor reaches top RPM. Not only it will lose thrust and stability, it makes that crazy loud, high pitch noise! So rigidity is very important for a good prop.

Rigidity is affected by the type of material and how much material is used.

What To Use on Mini Quad?

It depends on the size of your quad and your motors, mini quads normally use 4, 5 and 6 inch props. Roughly:

·150-180mm – 2700KV+ motor running 4″ props

·210mm – 2300KV-2700KV motor running 5″ props

·250mm – 1900KV-2300KV motor running 6″ props

To pick the right pitch, shape and number of blades, really depends on what sort of flying you want to do also.

You also need to verify if the propeller hub size (hole in the center) fits your motor propeller shaft. Nearly all 4″, 5″ and 6″ propellers are designed for 5mm shafts. However, double check with any bigger or smaller props.

Thrust and Speed

It’s important to look up motor thrust tests data, and see which props work best with the motor you plan to use. Same propeller can perform very differently on 2 different motors (because of the design, torque, power, etc).

However these bench tests are done in static environment, and therefore it doesn’t represent the motor/propellers true performance in real life – where air are dynamic when the propellers are moving through the air.

One of the most noticeable difference between static bench test and real flight is motor thrust, which is normally 5%-10% less in real flight than in static bench test. Also people like to talk about “smoothness” of a motor and propeller, which is not measurable quantitatively, and more of a pilot’s feel.

Another consideration is how propeller RPM affect your quadcopter’s overall top speed. It’s interesting to know that with a quad running heavy propellers that generate lots of thrust but at low RPM, is not necessary faster than one that generates less thrust but at a higher RPM.

Your aircraft’s theoretical speed can be calculated by

However in reality your quad will be much slower than this due to many reasons such as air resistance, power reservation from PID controller etc. (Perhaps <50%)

Original link from Oscarliang: https://oscarliang.com/choose-propellers-mini-quad/
Best Quadcopter Flight Simulator

In this article we will talk about some of the best flight simulators for quadcopter FPV. There are already many simulators for heli, fixed wing and glider, and we’ve begun to see more and more multirotor FPV Sim designed specifically for Drone Racing and FPV Free-style, some of which are even free!
FPV Simulators allows you to practice flying on a computer 24/7 under any weather condition, without damaging your quadcopter. Either you are still learning how not to crash, or getting the hang of a challenging acrobatic trick, simulators are perfect for beginners and advanced pilots alike.

Before Looking for Best Drone Flight Simulator

But before searching for your drone flight simulator, you need to make sure to have a radio transmitter that is compatible with the simulation software. Alternatively you might be able to use other means of control, such as a gaming console, or even just a keyboard! However, I strongly recommend using a proper TX, that’s how you get the most benefits from the training and build up muscle memory.

Connect your TX to Computer

Picking a transmitter that has an USB port for computer connection is a huge advantage with FPV sim’s. For example both the Frsky Taranis X9D and QX7 are “plug and play” solutions for many computer platforms. When connecting it to a computer with a mini USB cable, it would simply show up as a game Joystick in Device Manager.

Some TX such as the Turnigy 9X doesn’t have an USB port. They might require an USB simulator adapter. The USB end goes into your computer and the 1/8″ stereo/mono jack into the training port in the transmitter. Do your research for the particular transmitter you have.

FPV FreeRider

This is probably one of the earliest FPV simulators specifically designed for multicopter racing.

It’s a cheap simulator and it allows free trial. You are able to change the physics in the game, such as gravity, drag, quadcopter power etc. You can also change camera tilt angle, and FOV. In the free version you can’t change any settings, and only limited to one map.

FPV Freerider used to be one of my favorite quadcopter simulators. The physics is acceptably realistic and it’s good for beginner practicing. However, the rate system has always seem a bit slow to my taste. It doesn’t have “super rate” which I feel the quad always spins too slow in acro flying. Also the lack of support for multiplayer lets a lot of people down.

Furthermore I always feel like there is more delay in the stick input with Free-rider. It’s not a massive problem, but I can just feel it.

LiftOff

Liftoff is backed by ImmersionRC, and it’s designed specifically for mini quad FPV. Liftoff is the first to come up with the “parts system” that allows you to change components and settings just like in the real world.

They have also made the rate/expo behave so much like a real quad does. Liftoff also tried to implement the PID system like the one in Cleanflight or Betaflight. It’s a good idea but it’s a fail because it just doesn’t work like the real one and they seem to have unexpected results. In the end you are better off to just leave them at default.

It has improved significantly in terms of physics over the years. But still, I found it to be really “floaty”, and I can’t say it’s most realistic sim out there. You cannot change any of the physics in the game. Also it doesn’t detect crashes very well, most of the times I have to lean over to the keyboard and reset the game manually.

Liftoff is also the most graphically intense sim in the list. Many people complain about the performance to be “choppy” and “slow”.

Lastly I found Liftoff to have the most frequent updates in all FPV sims. When I wanted to have my weekly 20-min practice, and there was a new update and had to wait 10 mins for it.

VelociDrones

In VelociDrone there are many known real-life drone models you can choose to fly. You are able to change the physics of the game, such as gravity, drag, quadcopter power etc.

I got to say this sim feels very realistic to me, probably one of the best in that aspect. (Apparently it uses Betaflight codes)

The fact that you can make adjustments to your PIDs and rate just like in Betaflight, changeable FOV and camera angle, and that it uses your TX’s full range of motion without having to use offsets speaks volumes in my opinion. Great track editor too, tracks load fast, in multiplayer you can jump between races and freestyle in one session, have voice chats, even changes courses.

DRL Racing Simulator

DRL is free and allows multiplayer. But physics is probably the worse in all the Sim’s we have mentioned. Way too much drag and under-power. It feels like flying a quad that weighs 1kg with tiny motors on. (Edit: apparently they based their simulator model on the real quads used in the DRL events, which indeed weigh 1KG each, which I think is a mistake)

Anyway, the maps and scenery is probably the best out of all Sim’s I have tried. You get tall buildings, shipyard, abandon factories etc all in one single map! It allows you to reset the quad’s position, or race with your TX switches and it’s really handy.

Not the best sim, but It’s a fun game… Definitely give it a try since it’s free :)

Here I am having fun diving buildings, and trying one of the race tracks…

RotorRush

Previously known as FPV Event, is another known FPV simulator. I’ve heard it’s a great sim, and has some of the tracks in past racing events. Originally they were selling it for £40, later on they changed the pricing to the £4 monthly subscription model which makes it even more expensive IMO. I haven’t tried it due to this reason.

Heli-X Simulator

The graphics is not the best, and I often get lost in orientation easily after a roll, because the landscape is over simplified.

It offers self-level mode and acro mode. The only available quadcopter model is a Phantom in the free version. But it’s all good, you can do FPV and practice with it. It’s not that realistic, but I still prefer the physics in this game over the Phoenix. The Phantom in Heli-X feels powerless, doesn’t have the punch like the mini quad in real life.

This software is built specifically with multicopters in mind. But I still finding it lacking basic functionality, such as PID tuning etc.

AeroSim RC

Graphics looks quite good, however like most of other Sim’s, you can’t use full resolution on your TX as it only takes 0 to 127 as range (where the Taranis uses -127 to 127).

pros:

1.Big variety of models.

2.Allow FPV

3.Ability to create FPV tracks/scene based on satellite image and geo-referenced it by two sets of coordinates. Also the ability to load terrain elevation data from .hgt file.

4.Training mode for beginners with progress tracking and nice exercises.

5.OSD plugins for FPV mode with the ability to load external OSD plugins and to change OSD settings as they are in the real OSD system that’s being modelled in the plugin.

6.amazing control over model characteristics in a way that imo enables u to get real close to your real model behaviour including flight time based on weight and battery capacity.

7.Big variety of flight modes available including ALT hold, heading hold, course lock, auto stable and more.

8.Control over wind settings.

9.Realistic Physics

Original link from Oscarliang: https://oscarliang.com/free-quadcopter-simulator-drone-multirotor-trainer/
Looking For A Quadcopter Motor, Where to Start?

If you are new to mini quad and FPV, you should understand the relationship between motor thrust, and weight of your copter. This is useful to building any sizes multirotors.However if you are just building a mini quad, feel free to move on to the “Motor Size” section.
Total Weight

First, of all, estimate the total weight of your quadcopter. Don’t worry if you can’t get the total weight precisely the first time, it can just be your best guess. It should include everything you plan to take on-board: frame, FC, PDB, motors, propellers, ESC’s, LiPo battery, payload (such as HD camera), and so on.

Frame Size

Second thing you need to know is the size of the frame, from which you can then understand what the propeller sizes can/should be used in your quadcopter.

Thrust Requirement

Once you’ve worked out quadcopter weight and frame size, you can now calculate roughly how much thrust the motors need to deliver in order to lift the aircraft, by using propellers of certain sizes.

Read this article about how to choose propellers for mini quad.

Thrust to Weight Ratio

A general rule is that you should AT LEAST be able to provide twice as much thrust than the weight of the quad. Remember this is the bare minimum to ensure you have a stable copter that is easy to control during hovering. If the thrust provided by the motors are too little, the copter would not respond well to your control, it might even have difficulties to take off.

For faster flying like drone racing, you should expect the ratio to go much higher than this. It’s not uncommon to see someone build a mini quad that can achieve 8:1, even 10:1 thrust to weight ratio. The quad’s performance would be much more agile and dynamic, it would accelerate much faster and corner better. But when you have excessively high thrust to weight ratio, the quad would become very hard to control, because a little increase in throttle is enough to “shoot the quad in to orbit like a rocket”. :D

My recommendation is, even if you only just plan to fly a slow aerial photography platform, you should aim at somewhere between 3:1 and 4:1. Not only it gives you better control-ability, but also the room for adding extra payload in the future (like heavier cameras, or maybe extra batteries to extend flight time). But if you are into racing, then there is no limit :D Go as high as you feel comfortable with!

Motor Size

The Size of brushless motors in RC is normally indicated by a 4-digit number – AABB. “AA” is the stator width, while “BB” is the stator height or stator diameter, both in mm (millimeter). Basically, the taller stator the more power at higher RPM, while the wider stator the more torque at lower RPM.

The size of propellers the motor is designed for determines the prop shaft size. Motors for 4″, 5″ and 6″ propellers have M5 motor shaft. Modern motors has the prop shaft integrated into the motor bell. Older generation motors might have separate prop adapters.

KV

“KV” means velocity constant. It’s an important parameter of brushless motors, which indicates the theoretical increase of motor RPM (rotation per minute) when voltage goes up by 1 volt without load (i.e. propeller). For example, when powering a 2300KV motors with a 3S LiPo battery (12.6V), the motor would spin at about 28980 RPM without props on (2300*12.6). Typically this just an estimation, or round-up number specified by manufacturer.

Once you mounted a propeller on the motor, the RPM decreases due to air resistance. Higher KV motors would attempt to spin the propeller faster, but lower KV motors normally generate higher torque. That’s why we tend to see larger props paired with low KV motors, and smaller props with high KV motors.

Frame Size => Prop Size => Motor Size

Most of the times by knowing frame size, we can estimate what motor size we should use. This is because frame size limits props size, and each propeller size requires a different motor RPM to generate thrust efficiently.

This is where the KV of your motor comes into play. Then you’ve got to make sure that you’ve got enough torque to spin the propeller, this is where your stator size comes into play. The mathematics involved to determine the exact KV and stator size you should use is a lot more complex than most pilots care to worry about.

To make things simple, you can always check motor thrust data to verify the current draw does not exceed safety rating, when pairing the propellers you want to run.

Voltage and Current Draw

It’s important to understand that voltage has a large impact on your motor and propeller choice too. Your motor will try to spin much harder when a higher voltage is applied, and thus drawing a higher current. Always check thrust data first.

Now you have got a good understanding of what motors you want to run and estimated current draw, you can select ESC of the required current rating.

Original link from Oscarliang: https://oscarliang.com/quadcopter-motor-propeller/

ESC Development: BLHELI_S, Hardware PWM and 32BIT

BLHeli_S – New Firmware
BLHeli has released a new code geared for new hardware in ESC’s (electronic speed controllers). It uses the BLHeli 14.5 base firmware revision and improves upon it. It’s specifically designed for new ESC’s such as the Aikon SEFM 30A ESC. Here are a list of improvement from BlHeli_S.

·BLHeli_S delivers a throttle response that is smoother than previous BLHeli, thanks to the hardware PWM. Two MCU’s support this for BLHeli_S, namely the BusyBee1 at 24MHz and the BusyBee2 at 48MHz.

·It will have the same good sync holding properties as base BLHeli.

·BLHeli_S does damped light only.

·It has motor PWM that is Synchronous to the MCU master clock, as it is generated by hardware. This makes the motor run more silently.

·It has very small throttle steps. The resolution varies between hardware configurations (MCU clock speed and driver type), and is between a nominal 512 steps and 2048 steps.

·Supports very high motor Speed: BB1 MCU can support up to 350k eRPM, and currently the BB2 is set to 500k eRPM.

·Supports regular 1-2ms input signal, as well as Oneshot125, Oneshot42 and Multishot. Auto-detected when the ESC sees an input signal.

All these improvements look promising and when reached, definitely will change the way our multirotors fly!

You should also check out this guide about how to choose ESC. Check out this article to learn about ESC firmware.

Hardware Changes

The changes in programming are directly related to the ability of improved hardware that is being implemented. As SSKaug mentioned, this new line of ESCs are running the BusyBee1 (EFM8BB10F8) and the BusyBee2 (EFM8BB21F16) MCU’s (Microcontroller Units). These two MCU’s are different than the previous Silabs chips that many ESC’s have been using. The reason these MCUs are going to be better is because instead of using software PWM they will be using hardware PWM that is synced to duty cycle.

The great thing about using dedicated hardware to generate the PWM is that the speed at which the ESC writes the values to the motors is doubled! With old Blheli ESCs and software generated PWM signals, the ESCs write to the motors at a 16khz rate. With hardware generated PWM it’s bumped up to 36khz. These means that your motors are getting input even faster which allows for better response. KISS ESC’s are an example of this. They have hardware generated PWM and the smoothness and response you get with those is hard to beat.

Is 32 bit ESC better than 8 bit?

Currently the Aikon SEFM 30A ESC is the only ESC being tested with BlHeli_S on it. Of course, there will be many more ESCs to make the switch to BlHeli_S in the future. At the moment there are a few different options. Some of the best and most popular ESCs that will be competing with the Aikon ESC during its release are:

·KISS 24A RE ESCs

·DYS XM20A and 30A ESCs

·XRotor 30A and 40A (40A may also be BlHeli_S capable, unconfirmed)

·SEPM32 ESC

·VGood Firefly ESC

Three of these ESCs are actually using 32 bit processors on them. Being that they are 32 bit ESCs, they’re capable of much more processing and storage. These ESCs are the KISS24A RE ESCs, the SEPM32 ESCs, and the VGood Firefly ESCs. The other ESCs (pretty much all OTHER ESCs) use an 8 bit processor.

More processing power is generally better with every bit of technology. However, in this case there really isn’t a difference in actual performance. ESC’s are not even close to the 8 bit processing capacity at the moment. In the future 32 bits may become a requirement as coding gets more complex. Right now the only difference between the two is from a coding perspective. The 32 bit ESCs can be programmed in C++ because of the added bytes, but the 8 bit ESCs have to be programmed in assembly. Does it make a difference in practice? Only if you’re a programmer and only know C++ not assembly and cannot take the time to learn the syntax.

Personally, I’m very excited about the improvements BlHeli is going through. I’ve been flying BlHeli for a long time and even tried SimonK and others back in the day. It’s amazing how far ESCs have come and how much an improvement they have made to flight characteristics of multirotors. I look forward to testing these ESCs in the future and comparing them in real life situations to other ESCs. Keep your eyes out for them!

Original link from Oscarliang: https://oscarliang.com/blheli-s-hardware-pwm-32bit/
Using ESC Beacon as a lost model Alarm

Do you notice the start-up beeps the motor/ESC makes when you plug in the LiPo battery? It beeps even when there is no buzzer connected, and we can turn that feature into a lost model alarm.

It can be useful when you don’t have a buzzer installed, or in case your buzzer failed in a crash. Check here for more useful tips on quadcopter building/flying.

In this tutorial we will show you how to do this in ESC’s with BLHeli firmware. To set it up there are only 2 settings you need to configure in BLHeli Suite:

·Beacon Strength – How loud you want the beeper to sound (default 80, range from 1 to 255); 120 is a good value IMO, I suggest trying different values and check if the motors and ESC would get too hot. I don’t recommend setting this too high to prevent motors and ESC overheat

·Beacon Delay – After how long the beeper starts to activate being idle (default 10mins, IMO 5 or even 2 mins is a good idea for our purpose)

There is also Beep Strength. This setting might seem relevant but actually it’s not. It only controls the volume of the start-up beep, just leave it as it is.

A bit out of topics, if you ever wondered how ESC’s can make sound, they don’t. It’s actually the motors that makes the sound. The pitch and volume of the sound is controlled by signal from the ESC. It’s even possible to play a jingle with motors :)

Original link from Oscar Liang: https://oscarliang.com/esc-beacon-lost-model-alarm/
Travelling with Mini Quad and Lipo Batteries

Travelling with a drone includes some inherent inconveniences, but a little preparation can ensure friendlier skies. Here are some basic rules to follow on how to travel with mini quad and LiPo batteries on an air-plane.
Folks travelling with mini quads are most likely hoping for lots of blue skies and tons of fun. If you happen to be one of these lucky enthusiasts heading out on a trip, the last thing you want is to spend hours locked up in a stuffy back room – which is a distinct possibility if you don’t know “the rules.” As always, knowledge is power, so follow along for several quick tips you can use, to make sure your next dream drone vacation doesn’t turn into a drone-confiscation nightmare.

If you are not travelling on plane, check out a couple of backpacks we reviewed for quadcopters.

#0 – LiPo Restrictions in Airports

Every airline and airport has different regulations regarding LiPo batteries. Some are more strict than others. Large, well equipped airports seem to be fine usually, but smaller airports are more nervous about LiPos and to be sure it might be better to check with them before you go through.

There should be no limit on the number of <100Wh batteries, and only 2 over 100Wh are permitted with airline approval. These are the rules for FAA and some other countries, presumably the UK is the same. Although there is no limit on how many small LiPo batteries you can take, security will still get nervous when there are too many show up.

#1 – Understand it’s all in the delivery

Think of this tip as more of a cardinal rule for drone travel. All words have power, and the ones you use to describe your mini quad to travel officials have the power to ruin your trip.

That said, here’s what you do: avoid calling your drone a “drone”, a “quadcopter”, a “multirotor”, a “mini quad”, or anything else that sounds cool. It is, for the duration of your trip, a “toy RC helicopter“.

If you are using LiPo bag, try to remove or cover the words “explosion” and “fire” to avoid causing unnecessary panic at the check point :)

#2 – Be transparent

With everything you do, you want to give the impression that you have nothing to hide (after all, you don’t!). For example, if you plan to pack your mini quad as a carry-on, take it out of your bag and place it in its own bin at the Airport security checkpoint.

Expect suspicion; it’s their job. Do what you can to ensure your quadcopter will be easy to take out should the agents require it.

#3 – Remove propellers

Even if you have an awesome drone case or backpack that allows propeller-attached transport, you should still remove the props for your trip. If you’re asked to take your multirotor out of its case, there’s a possibility the security might want you to also power it on. Having the props already removed will be much more convenient and less time consuming for both you and the airport staff. The sharp blades might also injure someone.

#4 – How many LiPo can I take?

LiPo batteries for mini quads are small so you can actually take quite a few with you (check with airline how many exactly you can bring). Some have rules on how many Watt-Hours (total capacity mAh x voltage) you are allowed to bring on board.

Before you leave for the airport, remember the following:

·Discharge your LiPo batteries to storage charge, or below the level required by the airline (some require batteries do not exceed 30% of their rated design capacity)

·Tape up the terminal connectors with electrical tape

·Put LiPo in Lipo-safe bags

·Print out the airline’s regulation regarding LiPo batteries, put it somewhere with your batteries. If anything happens you can pull out the documentation and show them

·Batteries are only allowed as carry-on baggage

Once boarded the aircarft you can just leave your quad(s) / batteries on the overhead locker.

#5 – Separate your items

Avoid mixing your important stuff with your multirotor stuff.

Put what you think have a higher chance of getting checked or confiscated in one single bag (such as your batteries). So even if it does happen, your more important stuff don’t get taken away.

#6 – Tools – No knives or scissors

You can’t carry certain tools with you, such as wire cutters or scissors (anything that looks like can be used as weapon). Use common sense and check online if in doubt.

#7 – Be kind and polite

If you find yourself in a situation where someone has the power to make the call whether to confiscate your drone for good, your kind words and friendly demeanor might mean the difference between keeping or losing it. Expect that you will likely be hassled at the airport for traveling with a drone and lots of LiPo batteries, so be prepared. And remember that those hassles serve the purpose of keeping us all safer in the skies.

#8 – Make an battery inventory

Probably one of the most important off the list here, is to make an inventory of all your battery. All they look at is the Watt-hours of your battery:

·Work out the “Wh – watt hours” for each battery, stick that on the battery (Wh = capacity * nominal voltage)

·Write them down on a piece of paper, along with quantity

This is not compulsory (because security didn’t check mine every time), but I found it helped speed up my clearance in several occasions. This also helps you understand if you have any batteries larger than the limit.

Happy flying!

And one more thing. While these tips are great rules of thumb, you always want to check with your particular airline to make sure you’re aware of any specific rules they may have.

Original link from: https://oscarliang.com/travelling-mini-quad-lipo-batteries/
What is RSSI Transmitter Receiver– RC Quadcopter

RSSI is a measurement of how good radio signal is between RC transmitter and receiver, which stands for Received Signal Strength Indication. It’s an important safety feature to help avoid lost of radio signal, which could lead to unexpected quadcopter crashes and damage to properties.
Getting RSSI

RSSI is generated from the receiver, but not all RX can have this feature. You can connect the RSSI pin on the RX to the FC or OSD if supported. Some receivers don’t provide this pin for RSSI so DIY modification and additional components might be required. If the radio system is capable of telemetry, it’s also possible to obtain RSSI and display it on your TX. You can even do some more advanced hacks with this.

For example with the FrSky Taranis transmitter and D4R-II receiver. The combo provides 1.5 km of range and telemetry feature including RSSI. We can simply connect the RSSI pin to the OSD, and the RSSI value can be shown on the FPV screen.

Another good thing with telemetry that sends RSSI is that the TX alarm starts beeping when the signal is getting too weak (based on RSSI value). It gives me great peace of mind to know how the signal strength is while flying, and when I should turn back. With this feature I barely looked at RSSI value in my OSD and eventually I removed it.

How to use RSSI signal

Knowing the difference between digital and analog RSSI

The RSSI is normally an analogue value (a voltage level). But that is not always the case and it could exist as PWM signal (pulsed width modulated) with variable high-low ratio depending on signal strength. Therefore there could be incompatibility in the system when reading RSSI. (That’s why a lot of people’s RSSI in OSD is always 0, 50 or 100)

To solve that, we need to convert the PWM signal to a voltage easily using a “Digital to Analog converter”, or simply a low pass filter (Resistor-Capacitor filter).

Some OSD modules or flight controllers accept direct connection to the PWM RSSI output because they have a low pass filter built in.

What if OSD doesn’t support RSSI?

If your OSD doesn’t support RSSI input, you might still be able to display RSSI. Most OSD has dual battery inputs (BAT1 and BAT2), they were designed to display your primary and secondary battery voltage levels. But most of the times we would only use one and with the spare battery input we can use that for RSSI.

Normally the range of the RSSI value is 3.7V to 0V (100% to 0%) when converted from PWM. It might not be a percentage number but voltage, you still get a good idea what RSSI level is. I did this mod with my Hobbyking E-OSD, and it worked like a charm.

Understanding what RSSI is

Not something you need to know in order to use RSSI, but in case you are curious.

RSSI isn’t actually an linear measurement like voltage or temperature, but a ratio of the current signal to some initial “good” value. It’s in dB, same measuring system used for audio levels. dB is a logarithmic measure, and it’s not linear. What this means is that by increasing 6dB means the signal has doubled in strength. So a change of +12dB in the RSSI means the signal has increased in power by 4 times, by +18dB means the signal has increased in power by 8 times, and so on.

For instance, if the RSSI reads about 110 at 1m and every time you double the distance between the transmitter and receiver, the RSSI level should drop by 6. At about 100 meters you should get an RSSI value of about 70 in ideal conditions.

A good way to see this effect is to use Range Test mode on your radio transmitter. In range test mode the transmitter module operates at 1/30 of full power.

Original link from Oscarliang: https://oscarliang.com/what-rssi-transmitter-receiver-quadcopter/
How to Choose Lipo Battery Beginner Guide...

Multirotors (aka drones) are fueled by LiPo battery, they are able to store and deliver large amount of power. In this guide you will learn how to read the spec of LiPo for your mini quadcopter, and how to choose and handle them safely.
The Basics about LiPo Batteries for Mini Quad

Lithium polymer batteries, more commonly known as LiPo, have high energy density, high discharge rate and light weight which make them a great candidate or RC applications.

By learning the basics about LiPo batteries, you will be able to read and understand their specifications.

Battery Voltage and Cell Count (S)

LiPo batteries used in RC are made up of individual cells connected in series. Each cell has a nominal voltage of 3.7V. Therefore battery voltage is often referred to as how many cells in the battery (aka “S”).

Voltage affects brushless motors RPM directly, therefore you could use higher cell count batteries to increase your quadcopter’s speed if your motor/ESC and other electroincs support higher voltage. (here is a discussion about the differences between 3S and 4S on a mini quad)

But a battery with more cells of the same capacity is heavier since it contains more cells. To make a 4S 1000mah battery, you could simply combine two 2S 1000mah, or one 3S 1000mah with an 1S 1000mah.

LiPo battery is designed to operate within a safe voltage range, from 3V to 4.2V. Discharging below 3V could cause irreversible performance lost and even damage to the battery. Over-charging above 4.2V could be dangerous and eventually cause fire.

However it’s advisable to stop discharging when it reaches 3.5V for battery health reasons. For example for a 3S Lipo, the max voltage is 12.6V, and you should land when the voltage reaches 10.5V (at 3.5V per cell).

LiPo Battery Capacity

The capacity of a LiPo battery is measured in mAh (milli-amp hours). “mAh” is basically an indication of how much current you can draw from the battery for an hour until it’s empty.

Increasing your battery capacity might give you longer flight time, but it will also get heavier in weight and larger in size. There is a trade-off between capacity and weight, that affects flight time and agility of the aircraft. I wrote a guide about building a simple mathematics model to find out optimal Lipo capacity for longer flight time, which you might find interesting.

Higher capacity could also give you higher discharge current as you will see in the next section.

C Rating (Discharge Rating)

All Lipo batteries for mini quads these days come with C ratings. By knowing the C rating and capacity of a battery, you can calculate the safe, continuous max discharge current of a LiPo battery.

Most batteries come with 2 C-ratings, Continuous and Burst ratings. The Burst rating is only applicable in short period of time (e.g. 10 seconds), where wide open throttle happens.

This article explains the significance of C rating. Although C rating could be a useful indication, it’s not an absolute performance indicator nowadays.

Connectors

Rule of thumb, the battery connector should match the one you are using on your copter. If you don’t own a quad yet, choose one, and stick with it.

All Lipo batteries come with 2 sets of wires/connectors: a balance lead and a main lead or discharge lead (Except for 1S batteries which only have a main lead). There are quite a few different connectors used in LiPo batteries. The main differences are shape, weight and current rating.

1S Battery Connectors

1S connectors are tiny and have very low current rating. They are commonly used in brushed micro quadcopters.

2S-6S Battery Connectors

You will find a lot more different types of battery connectors in this category, in fact not all are listed here. But majority of them are not used that often so you don’t need to ever worry about them. For mini quad, the most popular connector is probably the XT60.

However since XT60 is only rated at 60A, and mini quad are running at higher and higher current and voltage, we might soon see a change in the popular connector used.

Balance Lead

Balance lead is mainly used for balance charge to ensure all cell voltages are equal. It also allows you to monitor the voltage of each cell.

The number of wires in a balance lead starts at 3 for 2S LiPo, and for every increment in cell count, the number of wires also go up by 1.

Internal Resistance (IR)

Internal resistance exists in every battery cell, and IR could be different in each cell of the same LiPo battery. Higher internal resistance reduces the max current the LiPo pack can produce, that why as a LiPo battery gets older or overly used, you will find it losing the punch, or power.

IR isn’t shown on the label, because they can change over time. Lipo internal resistance increases with:

·time/age

·crashes (physical damage)

·over-discharging

·over-heating

·other abusing usage

You can measure IR with dedicated tools, some LiPo charger even comes with IR measuring features.

We covered IR in more details in the C-Rating article.

LiHV

LiHV is a different type of LiPo battery, HV stands for “high voltage”. They are more energy dense than traditional LiPo battery, and allow to be charged up to 4.35V per cell. However there are mix reviews out there regarding the longevity of LiHV, as they might have decrease in performance sooner than normal LiPo’s.

Original Link from Oscar Liang: https://oscarliang.com/lipo-battery-guide/
ESC Firmware and Protocols Overview

For quadcopters there are several ESC protocols and firmware available, which could get confusing for beginners. In this summary we will explain the difference, a little bit of history and links to articles for more technical detail.
When I started in the hobby, connecting an ESC to the flight controller was straight-forward. But now there is so much to consider: ESC settings, protocols, firmware etc, it can be confusing and overwhelming for beginners. I hope this guide can help answer some of the questions.

Check out this guide about how to choose ESC for mini quad.

ESC Firmware

ESC firmware is the software running on every ESC, which determines the ESC’s performance, and what configuration interface can be used. The firmware you can use depends on the ESC’s hardware.

Here are a list of ESC firmware available to mini quad ESC:

·BLHeli

·BLHeli_S

·BLHeli_32

·SimonK

·KISS

·Other manufacturers’ own firmware

Before and around mid 2015, there used to be a choice between SimonK and BLHeli for majority of the ESC’s back then. They were also two of the earliest open source ESC firmware. But over the years BLHeli has taken over the market due to its better performance and more user-friendly interface. (differences between BLHeli and SimonK)

As ESC technology continues to evolve, newer BLHeli firmware was written specifically for the better and more advanced hardware. BLHeli_S was the 2nd generation firmware developed for the BusyBee processors in 2016, and the BLHeli_32 was the 3rd generation firmware for the 32-bit processors in 2017.

Nowadays, all ESC’s come with ESC firmware pre-installed, mostly BLHeli_S or BLHeli_32 depending on the hardware, which should be stated clearly in the specification. You don’t need to worry about changing firmware because basically you don’t really have a choice. However you do need to make sure the firmware is up to date for bug fixes and performance improvement.

For non-BLHeli ESC’s, they are most likely to come with (and locked to) their own factory firmware, such as the KISS ESC, Castle QuadPack, and the Gemfan Maverick ESC.

ESC Protocol

What are ESC protocols?

ESC Protocols are the “languages” that flight controllers use to communicate with ESC’s, basically telling them how fast the motors should be spinning. Here are all the ESC protocols available to mini quad depending which FC firmware, and their respective signal width (the time it takes to send one data packet), click the links for more detail:

·Standard PWM (1000us – 2000us)

·Oneshot125 (125us – 250us)

·Oneshot 42 (42us – 84us)

·Multishot (12.5us – 25us)

·Dshot

oDshot150 (106.8us)

oDshot300 (53.4us)

oDshot600 (26.7us)

oDShot1200 (13.4us)

Before 2015, there was only one ESC protocol, standard PWM. But as hardware was getting better, faster protocols became possible: Oneshot125, Oneshot42 and Multishot. These protocols are all analog signals similar to standard PWM, but much faster and hence reduce the latency of quadcopter response.

DShot is the latest ESC protocol which is a digital signal. It’s the future of ESC protocol in my opinion because of its better reliability and performance, and the ability of sending not only motor speed, but specific commands to the ESC’s.

Hardware released after mid 2017 should support all the ESC protocols, apart from DShot1200 which is relatively new and is only compatible with some 32-bit ESC’s. Make sure to double check the specification when planning a new build.

I hope this guide gave you an overview of all the ESC software and protocols. Please don’t hesitate to leave me a question or comment.

Original link from Oscarliang: https://oscarliang.com/esc-firmware-protocols/
Considerations in Choosing Mini Quad Props

Material
Propellers can be made of different materials, plastic composite, carbon fibre, wood etc. Each type of material gives unique features, for example carbon fiber and wooden props are really stiff and best known for their smooth performance. While certain plastic compound are extremely durable. Check out this post for more info.

In fact, majority of the pilots in this hobby are now using what we call “durable plastic” props. They last much much longer and could save you tons of money in the long run. However, because they don’t just snap in a crash, they bend. It’s not obvious from appearance but they can cause vibration to your quadcopter, potentially giving your flight controller a hard time and leads to motor overheat. Make sure to make attention to vibration and oscillations when using these props.

And don’t use props with “white crease lines“. After a prop is bent it might develop these white lines and it’s a sign of asking to be replaced. If you don’t you risk snapping the propeller mid air and crashing.

Weight

Lighter props tend to perform better than heavier ones for mini quad in my experience, because there is less moment of inertia. RPM changes faster so the multirotor would feel more responsive in theory. Lighter props also run better on a wider range of motors, because they require less torque to spin up.

Weight distribution of the blades also makes a difference. It again affects the moment of inertia. For the blade’s center of mass closer to the hub is better for a propeller. Although that means the end of the prop gets thinner and easier to break. The more further away from the hub, the more drag there is and makes the prop harder to speed up and slow down.

Rigidity

The least rigid propeller I have ever used is the Gemfan 5030. They are so soft they literally bend when the motor reaches top RPM. Not only it will lose thrust and stability, it makes that crazy loud, high pitch noise! So rigidity is very important for a good prop.

Rigidity is affected by the type of material and how much material is used.

What To Use on Mini Quad?

It depends on the size of your quad and your motors, mini quads normally use 4, 5 and 6 inch props. Roughly:

·150-180mm – 2700KV+ motor running 4″ props

·210mm – 2300KV-2700KV motor running 5″ props

·250mm – 1900KV-2300KV motor running 6″ props

To pick the right pitch, shape and number of blades, really depends on what sort of flying you want to do also.

You also need to verify if the propeller hub size (hole in the center) fits your motor propeller shaft. Nearly all 4″, 5″ and 6″ propellers are designed for 5mm shafts. However, double check with any bigger or smaller props.

Thrust and Speed

It’s important to look up motor thrust tests data, and see which props work best with the motor you plan to use. Same propeller can perform very differently on 2 different motors (because of the design, torque, power, etc).

However these bench tests are done in static environment, and therefore it doesn’t represent the motor/propellers true performance in real life – where air are dynamic when the propellers are moving through the air.

One of the most noticeable difference between static bench test and real flight is motor thrust, which is normally 5%-10% less in real flight than in static bench test. Also people like to talk about “smoothness” of a motor and propeller, which is not measurable quantitatively, and more of a pilot’s feel.

Another consideration is how propeller RPM affect your quadcopter’s overall top speed. It’s interesting to know that with a quad running heavy propellers that generate lots of thrust but at low RPM, is not necessary faster than one that generates less thrust but at a higher RPM.

Your aircraft’s theoretical speed can be calculated by

However in reality your quad will be much slower than this due to many reasons such as air resistance, power reservation from PID controller etc. (Perhaps <50%)

Original link from Oscarliang: https://oscarliang.com/choose-propellers-mini-quad/
Best Quadcopter Flight Simulator

In this article we will talk about some of the best flight simulators for quadcopter FPV. There are already many simulators for heli, fixed wing and glider, and we’ve begun to see more and more multirotor FPV Sim designed specifically for Drone Racing and FPV Free-style, some of which are even free!
FPV Simulators allows you to practice flying on a computer 24/7 under any weather condition, without damaging your quadcopter. Either you are still learning how not to crash, or getting the hang of a challenging acrobatic trick, simulators are perfect for beginners and advanced pilots alike.

Before Looking for Best Drone Flight Simulator

But before searching for your drone flight simulator, you need to make sure to have a radio transmitter that is compatible with the simulation software. Alternatively you might be able to use other means of control, such as a gaming console, or even just a keyboard! However, I strongly recommend using a proper TX, that’s how you get the most benefits from the training and build up muscle memory.

Connect your TX to Computer

Picking a transmitter that has an USB port for computer connection is a huge advantage with FPV sim’s. For example both the Frsky Taranis X9D and QX7 are “plug and play” solutions for many computer platforms. When connecting it to a computer with a mini USB cable, it would simply show up as a game Joystick in Device Manager.

Some TX such as the Turnigy 9X doesn’t have an USB port. They might require an USB simulator adapter. The USB end goes into your computer and the 1/8″ stereo/mono jack into the training port in the transmitter. Do your research for the particular transmitter you have.

FPV FreeRider

This is probably one of the earliest FPV simulators specifically designed for multicopter racing.

It’s a cheap simulator and it allows free trial. You are able to change the physics in the game, such as gravity, drag, quadcopter power etc. You can also change camera tilt angle, and FOV. In the free version you can’t change any settings, and only limited to one map.

FPV Freerider used to be one of my favorite quadcopter simulators. The physics is acceptably realistic and it’s good for beginner practicing. However, the rate system has always seem a bit slow to my taste. It doesn’t have “super rate” which I feel the quad always spins too slow in acro flying. Also the lack of support for multiplayer lets a lot of people down.

Furthermore I always feel like there is more delay in the stick input with Free-rider. It’s not a massive problem, but I can just feel it.

LiftOff

Liftoff is backed by ImmersionRC, and it’s designed specifically for mini quad FPV. Liftoff is the first to come up with the “parts system” that allows you to change components and settings just like in the real world.

They have also made the rate/expo behave so much like a real quad does. Liftoff also tried to implement the PID system like the one in Cleanflight or Betaflight. It’s a good idea but it’s a fail because it just doesn’t work like the real one and they seem to have unexpected results. In the end you are better off to just leave them at default.

It has improved significantly in terms of physics over the years. But still, I found it to be really “floaty”, and I can’t say it’s most realistic sim out there. You cannot change any of the physics in the game. Also it doesn’t detect crashes very well, most of the times I have to lean over to the keyboard and reset the game manually.

Liftoff is also the most graphically intense sim in the list. Many people complain about the performance to be “choppy” and “slow”.

Lastly I found Liftoff to have the most frequent updates in all FPV sims. When I wanted to have my weekly 20-min practice, and there was a new update and had to wait 10 mins for it.

VelociDrones

In VelociDrone there are many known real-life drone models you can choose to fly. You are able to change the physics of the game, such as gravity, drag, quadcopter power etc.

I got to say this sim feels very realistic to me, probably one of the best in that aspect. (Apparently it uses Betaflight codes)

The fact that you can make adjustments to your PIDs and rate just like in Betaflight, changeable FOV and camera angle, and that it uses your TX’s full range of motion without having to use offsets speaks volumes in my opinion. Great track editor too, tracks load fast, in multiplayer you can jump between races and freestyle in one session, have voice chats, even changes courses.

DRL Racing Simulator

DRL is free and allows multiplayer. But physics is probably the worse in all the Sim’s we have mentioned. Way too much drag and under-power. It feels like flying a quad that weighs 1kg with tiny motors on. (Edit: apparently they based their simulator model on the real quads used in the DRL events, which indeed weigh 1KG each, which I think is a mistake)

Anyway, the maps and scenery is probably the best out of all Sim’s I have tried. You get tall buildings, shipyard, abandon factories etc all in one single map! It allows you to reset the quad’s position, or race with your TX switches and it’s really handy.

Not the best sim, but It’s a fun game… Definitely give it a try since it’s free :)

Here I am having fun diving buildings, and trying one of the race tracks…

RotorRush

Previously known as FPV Event, is another known FPV simulator. I’ve heard it’s a great sim, and has some of the tracks in past racing events. Originally they were selling it for £40, later on they changed the pricing to the £4 monthly subscription model which makes it even more expensive IMO. I haven’t tried it due to this reason.

Heli-X Simulator

The graphics is not the best, and I often get lost in orientation easily after a roll, because the landscape is over simplified.

It offers self-level mode and acro mode. The only available quadcopter model is a Phantom in the free version. But it’s all good, you can do FPV and practice with it. It’s not that realistic, but I still prefer the physics in this game over the Phoenix. The Phantom in Heli-X feels powerless, doesn’t have the punch like the mini quad in real life.

This software is built specifically with multicopters in mind. But I still finding it lacking basic functionality, such as PID tuning etc.

AeroSim RC

Graphics looks quite good, however like most of other Sim’s, you can’t use full resolution on your TX as it only takes 0 to 127 as range (where the Taranis uses -127 to 127).

pros:

1.Big variety of models.

2.Allow FPV

3.Ability to create FPV tracks/scene based on satellite image and geo-referenced it by two sets of coordinates. Also the ability to load terrain elevation data from .hgt file.

4.Training mode for beginners with progress tracking and nice exercises.

5.OSD plugins for FPV mode with the ability to load external OSD plugins and to change OSD settings as they are in the real OSD system that’s being modelled in the plugin.

6.amazing control over model characteristics in a way that imo enables u to get real close to your real model behaviour including flight time based on weight and battery capacity.

7.Big variety of flight modes available including ALT hold, heading hold, course lock, auto stable and more.

8.Control over wind settings.

9.Realistic Physics

Original link from Oscarliang: https://oscarliang.com/free-quadcopter-simulator-drone-multirotor-trainer/
Looking For A Quadcopter Motor, Where to Start?

If you are new to mini quad and FPV, you should understand the relationship between motor thrust, and weight of your copter. This is useful to building any sizes multirotors.However if you are just building a mini quad, feel free to move on to the “Motor Size” section.
Total Weight

First, of all, estimate the total weight of your quadcopter. Don’t worry if you can’t get the total weight precisely the first time, it can just be your best guess. It should include everything you plan to take on-board: frame, FC, PDB, motors, propellers, ESC’s, LiPo battery, payload (such as HD camera), and so on.

Frame Size

Second thing you need to know is the size of the frame, from which you can then understand what the propeller sizes can/should be used in your quadcopter.

Thrust Requirement

Once you’ve worked out quadcopter weight and frame size, you can now calculate roughly how much thrust the motors need to deliver in order to lift the aircraft, by using propellers of certain sizes.

Read this article about how to choose propellers for mini quad.

Thrust to Weight Ratio

A general rule is that you should AT LEAST be able to provide twice as much thrust than the weight of the quad. Remember this is the bare minimum to ensure you have a stable copter that is easy to control during hovering. If the thrust provided by the motors are too little, the copter would not respond well to your control, it might even have difficulties to take off.

For faster flying like drone racing, you should expect the ratio to go much higher than this. It’s not uncommon to see someone build a mini quad that can achieve 8:1, even 10:1 thrust to weight ratio. The quad’s performance would be much more agile and dynamic, it would accelerate much faster and corner better. But when you have excessively high thrust to weight ratio, the quad would become very hard to control, because a little increase in throttle is enough to “shoot the quad in to orbit like a rocket”. :D

My recommendation is, even if you only just plan to fly a slow aerial photography platform, you should aim at somewhere between 3:1 and 4:1. Not only it gives you better control-ability, but also the room for adding extra payload in the future (like heavier cameras, or maybe extra batteries to extend flight time). But if you are into racing, then there is no limit :D Go as high as you feel comfortable with!

Motor Size

The Size of brushless motors in RC is normally indicated by a 4-digit number – AABB. “AA” is the stator width, while “BB” is the stator height or stator diameter, both in mm (millimeter). Basically, the taller stator the more power at higher RPM, while the wider stator the more torque at lower RPM.

The size of propellers the motor is designed for determines the prop shaft size. Motors for 4″, 5″ and 6″ propellers have M5 motor shaft. Modern motors has the prop shaft integrated into the motor bell. Older generation motors might have separate prop adapters.

KV

“KV” means velocity constant. It’s an important parameter of brushless motors, which indicates the theoretical increase of motor RPM (rotation per minute) when voltage goes up by 1 volt without load (i.e. propeller). For example, when powering a 2300KV motors with a 3S LiPo battery (12.6V), the motor would spin at about 28980 RPM without props on (2300*12.6). Typically this just an estimation, or round-up number specified by manufacturer.

Once you mounted a propeller on the motor, the RPM decreases due to air resistance. Higher KV motors would attempt to spin the propeller faster, but lower KV motors normally generate higher torque. That’s why we tend to see larger props paired with low KV motors, and smaller props with high KV motors.

Frame Size => Prop Size => Motor Size

Most of the times by knowing frame size, we can estimate what motor size we should use. This is because frame size limits props size, and each propeller size requires a different motor RPM to generate thrust efficiently.

This is where the KV of your motor comes into play. Then you’ve got to make sure that you’ve got enough torque to spin the propeller, this is where your stator size comes into play. The mathematics involved to determine the exact KV and stator size you should use is a lot more complex than most pilots care to worry about.

To make things simple, you can always check motor thrust data to verify the current draw does not exceed safety rating, when pairing the propellers you want to run.

Voltage and Current Draw

It’s important to understand that voltage has a large impact on your motor and propeller choice too. Your motor will try to spin much harder when a higher voltage is applied, and thus drawing a higher current. Always check thrust data first.

Now you have got a good understanding of what motors you want to run and estimated current draw, you can select ESC of the required current rating.

Original link from Oscarliang: https://oscarliang.com/quadcopter-motor-propeller/

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