RC Rate, Expo, Super Rate Explained

by Oscar
Published: Last Updated on

This tutorial explains what RC Rate, Expo and Super Rate are, and how to tune them for optimal FPV drone flying. I will also touch on Throttle Expo, Throttle Mid and TPA and how these settings can affect the performance of a quadcopter.

You might be also interested in PID tuning.

Tl;dr

The combination of RC Rate and Super Rate determines “max angular velocity” – how fast the drone is allowed to rotate (measured in degrees per second). Expo changes the sensitivity in centre stick. Note that while Super Rate changes max velocity, it also has an effect on centre stick sensitivity too just like Expo.

Still don’t get it? No worries, let me explain in a bit more detail.

RC Rate

RC rate changes the sensitivity of your sticks. High rates makes your quad rotate more with less stick deflection.

High rate will make your quad more responsive but at the same time, twitchier. Small movement on the stick would produce big movement in the quad.

Increasing RC rate also makes the quad spins faster, as you can see an increase in deg/sec figure. This allows you to do faster flips and rolls as well, but usually we use “super rate” to control how fast we want our flips and rolls to be, we will talk about super rate shortly.

RC Expo

RC Expo is also known as Exponential, or simply Expo. It reduces the sensitivity near the centre of the stick where fine controls are needed (for Roll, Pitch and Yaw), while retaining the maximum rotation speed at the ends of the stick.

Expo is a percentage value. At 0% the increase in rotational speed between minimum and maximum stick input is linear, imagine the curve as a “V” shape with no stick input being the center. At 50% stick input, your quad will rotate around the given axis at exactly half of the maximum rotational speed.

As you increase Expo, the sensitivity around mid stick is reduced so you have to push the stick further to reach the same 50% of max rotational speed. Imagine that Expo changes the “V” shape to a  “U”, the higher the expo percentage, the flatter the “U” is around the middle.

Super Rate

Super Rate (aka Super Expo in other firmware) changes your full-stick-deflection rate as well as your centre stick precision. It’s like having the combined effects of RC Rate and RC Expo.

By increasing Super Rate, it allows you to have relatively moderate stick sensitivity around mid stick for “normal flying maneuvers”, and yet super fast roll and flip at the stick end points.

It gives you more flexibility over tuning and control. It must be adjusted together with RC Rate and RC Expo to achieve the desired curve and stick feel.

Actual Rate & Quick Rate in Betaflight

These are two other types of rate system in Betaflight.

With “Actual Rate”, you can enter exactly the max rotational speed, and center sensitivity value – it’s a lot more clear and less confusing for new comers to be honest than the old rate system.

And “Quick Rate” is the mix of the the traditional rate and Actual Rate. You still enter Rates and Expo but you can set the max rotational speed value directly.

If you are new to all these, I’d recommend using the default Betaflight rate system for now, until you know what is actually going on, then explore other rate system so you don’t get confused.

How to Tune Your Rates?

Rate values are really a personal preference, it’s all about finding what works for your particular setup and flying style.

To tune my rates, I always increase RC Rate first. Just cruise around (no flips or rolls), and make sure the quadcopter responds quickly and predictably to your sticks when doing turns. If it’s too sensitive to make precise movement then you need to turn it down.

Then I adjust Super Rate until I am happy with the max rotation speed when doing flips and rolls. A good test is to do some 180° or 360° rolls and see if you can get them perfectly. You can also check in the GUI what the rotation value is for each axis (deg/sec), personally for my freestyle rig, I usually aim for 700-800 degrees per second.

Note that Super Rate also affects your centre stick sensitivity (it acts like expo), meaning by increasing Super Rate too much, your center stick will actually feel softer, and so you might or might not want to slightly bump up your RC Rate to compensate.

How about Expo? Well, it’s not always needed, as you get the same effect from having Super Rate. But if you still find little movement around mid stick too sensitive, then increase RC Expo until you find a good balance between precision and responsiveness.

You will have to go back and forth a few times until it’s right. Note that your pitch, roll and yaw rates do not need to be identical. Many freestyle pilots actually prefer higher yaw rate and lower pitch rate, it’s all personal preference.

Different flight controller software has different ranges and scaling in PID, rates and expo, so the same numbers don’t necessarily give the same results in a different firmware.

Pro Tip: Applying Expo on the radio (TX) reduces your stick resolution, therefore ONLY set Expo in the flight controller software whenever possible!

To give you some examples, here are the Rates and Expos I have used:

Freestyle

  • RC Rate – 1.3
  • RC Expo – 0.25
  • Super Rate – 0.68

Smooth Cruiser:

  • RC Rate = 0.80
  • RC Expo = 0.00
  • Super Rate = 0.65

Expo is set to zero here on purpose, this is to avoid overreacting in close situations and actually gives you overall smoother result.

Aggressive Acro Quad:

  • RC Rate, Pitch/Roll = 1.80, Yaw = 2.00
  • Super Rate, All = 0.64
  • RC Expo, Pitch/Roll = 0.20, Yaw = 0.15

As your flying skill improves, and you become more comfortable performing aggressive maneuvers, you will probably increase your rates. As you do, you will also probably want to adjust (increase) the expo to maintain accurate fine control.

There is no right or wrong Expo and Rate values, as long as it suits you. For example, I have shaky fingers, so my expo might be a bit higher than others. :p

Consistency!

Having consistent rates on all your quads is actually very important because of muscle memory. Especially for yaw and roll, you can train yourself to control these movements instinctively with consistent rates.

When you change rates, it can take you longer to get used to the different feel depends on how experienced a pilot you are. So having consistent rates help you moving from quad to quad without surprises.

Throttle Mid and Expo

Lastly, next to RC Rate and Expo, we also have Throttle Mid and Throttle Expo.

Throttle Expo changes the shape of the throttle curve, it flattens out the curve around “Throttle Mid” and allows for softer throttle response and maximum stick resolution around this throttle level.

Throttle Mid changes where in the throttle curve you want to apply the Throttle Expo. By default it’s set to 50% throttle (0.50), but in my opinion this should be set to your normal cruising throttle. This is where you will need the most throttle resolution and it should make it easier to control your altitude.

Throttle Mid won’t do anything if you set Throttle Expo to 0, because your throttle curve will be a straight line regardless what throttle mid is set to.

I personally prefer to use a tiny bit of throttle expo (<0.10) to get a better resolution and smoother throttle control. It’s especially useful for proximity flying.

You can also setup throttle curve in your transmitter for more precise throttle control.

TPA & TPA Breakpoint

TPA lowers PID values by a certain percentage, the more you increase throttle, the lower PID becomes. It helps reduce vibration associated with high throttle.

TPA breakpoint determines where in the throttle PID should begin to be reduced. You should normally set this slightly below the throttle level where you start to get vibration.

See this article for a more detail explanation of TPA.

Edit History

  • Sep 2015 – Article created
  • Mar 2018 – Article updated
  • Mar 2021 – Added info about new feature in Betaflight: Actual Rate and Quick Rate

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44 comments

5li3ret 15th June 2021 - 6:45 pm

Hey Oscar; first of all – thank you so much for the effort you put in this site. It has helped me tremendously!! I have one question regarding the rates. I put my rates in Betaflight 4.2 and no problem with this but then i go flying and when i look into the rate options in the dji goggles and there are different rates then i set in BF4.2. It seems it makes no difference what i do in BF, the dji goggles always show the same standart rate … any idea? Thank you so much!

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Oscar 15th June 2021 - 11:41 pm

Make sure you’ve chosen the correct Rate profile in Betaflight? There are 3 profiles.

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Jorge Jesus 9th January 2021 - 9:46 am

Thank you Oscar

This has help me alot with the DCL game.

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Nmw01223 8th February 2020 - 5:05 pm

I have just belatedly found this useful post after trying to work out what the configurator settings mean.

However I cannot quite see the point of having three settings – rate, super rate and expo? It seems to me that everything necessary could be achieved by two – rate and expo? The rate being rotational deg/sec at full stick movement (linear), and expo ratio of centre stick position slope to max stick position slope (or vice versa)? In the end it is just one transfer function, so cannot see why it takes three settings to achieve that?

Also, I think it might be more accurate to say that applying expo in the FC rather than Tx increases stick resolution at the centre (at the expense of max deflection resolution) rather than doing it in the Tx reducing it. Doing it in the Tx just doesn’t increase it, but it doesn’t reduce it either.

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Quentin 24th December 2019 - 2:59 pm

Hi Oscar
Thanks for your valuable blogs.
I’ve been coming back to this article quite a few times over time. Nice reference to have.
Just one thing. Is there a typo in your Smooth cruiser settings?
You have RC Expo, All = 0.03
Shouldn’t that be 0.3? Can’t see how such a low expo will give you smooth cruising?

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Oscar 3rd January 2020 - 2:30 pm

For me, expo is to accommodate rate, if rate is low you don’t need much expo otherwise it will make your centre stick way too insensitive. Also Super rate also acts as expo, setting it higher gives you some expo effect.

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Rajeev Gopal 10th September 2019 - 6:28 pm

Hi to get a 700Deg which combination RC and Super rates should be given for freestyle flying? And do do smooth flips and rolls. Iam flying 2in micros.

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Oscar 10th September 2019 - 6:50 pm

There are endless combination… but This is what I’d use, RC Rate 1.3 with Super Rate 0.65-0.67?

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roberto 26th March 2019 - 10:35 am

Oscar, is there any excel file that generates the Rate chart as in BF based on inpunt Parameters: Rate, SuperRate, RCExpo? I’d like to create one but it is difficult to find the correct formulas

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Oscar 1st April 2019 - 12:56 pm

Best to adjust this on the actual quad, sometimes the actual response from the quad is slightly different that the numbers suggest in the GUI, because it’s largely dictated by the performance of motors, props, ESC and battery

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Renato 28th September 2018 - 10:36 pm

Thank yoi. Why in some quad, the Max Vel Deg/s of yaw is smaller or bigger, despite the rates of pitch, roll and yaw are equal? Thanks

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Oscar 1st October 2018 - 4:58 pm

It’s just an estimation, the actual rates of rotation depends on your props and motor, and how good the battery is providing the power.

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Martin 10th August 2018 - 7:57 pm

Hello.
I’m new to this hobby, and i’ve just bought a Taranis qx7, but the throttle stick doesn’t give throttle before its in 50% travel (in the middle).. Do you know how to change that?

Best regards Martin.

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Oscar 11th August 2018 - 4:33 pm

Doesn’t sound like a straight forward question, please join our forum for further troubleshooting. (http://intoFPV.com)

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James Wallo 20th March 2018 - 2:22 pm

Hello…I would like to know if transmitter DUEL RATE is the same thing as FC RC RATE? Should I have both my DUEL RATE in my transmitter and RC RATE in my betaflight set at 100? Thanks. Jim

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Sarcoise 25th April 2018 - 5:36 am

@James Wallo

As he stated in the article, you should NOT use any rates or expo settings on your TX, let the flight controller read your actual stick inputs and set all expo/rates using the configurator. TX expo settings were necessary when using servos and control surfaces as with a fixed wing or heli – but are not needed with the use of a FC that allows you to program them internally. The FC’s gyros are able to detect the rate at which the model is rolling or flipping in degrees per second and uses the rate/expo settings to provide a consistent roll rate.

Besides, it would be difficult to set a desired rate if both the FC and TX were performing expo calculations. Ideally you would have rate/expo numbers that you are comfortable with and you’d be able to punch in those numbers on any new build as a starting point. That way, you would have a set rotational rate and you would be used to flipping 360 degrees in x time, allowing you to “feel” when a roll or flip is complete and not have to use visual confirmation.

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supernull 15th March 2017 - 8:05 pm

Now it’s march of 2017 and some things seem to be different. Like when you write “I personally use no expo or just a little expo (<10)", the throttle expo now goes from 0 to 1, so <10 would be <0.1 today, right? Also when you write about throttle mid, "You need to use this with some throttle expo, otherwise it won’t do anything." is this statement still true today? So if I want to make use of throttle mid, I have to set expo to something like 0.05? Thanks!

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Oscar 24th March 2017 - 12:16 am

Yes you are right, these firmware keep changing stuff it’s impossible to keep track of and update all the articles :D
But I will try when I have time! thank you for the comment!

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Michael 15th February 2018 - 10:56 pm

You cover the broad strokes which is the important part. People can get educated on the specifics with tutorials.

Your site is my favourite for technical FPV knowledge. Particularly your articles on noise filtering.

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Dave 13th February 2017 - 8:04 pm

Hey man, I’ve recently taken an interest in flying quadcopters, I got a JJRC1000A to start off with and just learning how to get the damn thing to hover was a nightmare, it took me several weeks of playing around with it before I could fly it around my livingroom comfortably without constantly banging off walls and doors!!

Then I went out and bought the Syma X5C which I find a whole lot easier to fly, I’m able to cruise around outdoors with the Syma no problem at all.

But now I wanted to move onto something a bit bigger and better, also my dad has the Phantom 4 Pro which I’ve had the chance to fly it several times and it was an amazing experience, however, one thing that has me scratching my head with the Phantom, I thought with these high end drones like the DJI ones that the right stick that controls the left and right roll would always remain left and right regardless of the drones orientation, so you could just look at your display that’s connected to your controller and you’d be using that to know the drones orientation, I always thought this was how it’d be for flying FPV, or am I completely missing something?

I’ve searched all over the net to try and find an answer to this but I can’t seem to find anything at all, so I am hoping you could enlighten me here.

I mean surely people who fly in FPV through buildings around trees etc aren’t having to be thinking when and where those controls will be reversed, I figured you could use the display on the P4 controller for FPV instead of goggles??

Hope you get back to me, thanks in advance.

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Chris 26th March 2017 - 11:03 am

If I understand you right, you’re saying the phantom’s orientation with regards to the pilot is what controls what direction the pitch, roll controls move the quad? If so, this is called headless mode. Usually it’s only used for line-of-sight flying, because as you said, it makes fpv confusing. I’ve flown a Phantom 3 pro (iirc), and it didn’t do this, I suspect it is a setting that could be turned on or off somewhere in the labyrinth of the dji app. Don’t ask me how though, I don’t have a clue how those things work :)

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Brian 2nd May 2018 - 7:09 pm

It’s called headless mode. where no matter the orientation of the drone it will always move back if you move the stick in that direction. It is a setting.

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joe 29th January 2017 - 2:41 am

Hey thanks for the help, i have a question though. i changed my rates. but i cant figure out how to get my “roll” to move only the quad right or left without adding in pitch. Right now as it stands my roll and pitch move simultaneously causing a front ward tilt when trying to “roll right”. is there a way to tune the quad so roll and pitch dont work together at the same time?

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Oscar 4th February 2017 - 10:47 am

no they shouldn’t move the same time if you are only controlling pitch or roll :D
are you taking into account your camera tilt angle? with the tilt the quad will feel like it’s pitching and rolling the same time when you are doing a roll…

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James 30th December 2016 - 8:46 am

Yes im using the open source cx20 and i have an issue with the battery getting drained real quick like few seconds on giving it throttle. Just need to know what i can do to make it quit draining the battery and its fully charged.

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David 10th September 2016 - 12:10 am

Great article! Thanks for the help!

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Robin 25th April 2016 - 10:33 am

I am new to rate mode and have 3 modes setup (selected using a 3 way switch on the TX)
Angle and horizon “feel” fine but when I go into acro I do feel it needs a little expo
-possibly a mixture of me being new to flying acro and deadband being set at 6 because of jitter…mainly me being a ‘newbie’ thing though :)
I can fly helis so am kind of surprised I’m struggling a little- but my 250 quad seems more reactive/skittish than my Trex250 heli!

I have added some expo on the TX for AIL and ELE (15%) , but only when acro is selected and it does seem to be helping massively and I could possibly afford to lower it slightly – I can’t see how to only apply expo on the ‘acro’ mode in Cleanflight and leave angle and horizon without, so I guess I’m going to go with this method for now and slowly reduce till I have the skill speed and accuracy of BanniUK..(In my dreams!)
Weaning myself off horizon is the goal :D

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Oscar 28th April 2016 - 12:05 pm

Only way i can see is to have separate profile for different modes… but really you should get used to rate mode and completely forget about self-level mode :) All top pilots only fly rate mode.

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DeeHawk 14th June 2016 - 9:01 am

I’ll challenge anyone who thinks they can LOS better through a proximity track without gyro. :D
It’s horrible for FPV tho :)
Nice compilation of tuning tips yet again!

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Spencer 15th March 2016 - 11:54 pm

Hey Oscar,

You have helped me countless times in the past, but in this case your post was detrimental.

mmix is now zero based instead of 1 based. If you define motor mixes starting from 1 it will not acknowledge them until you specify a motor 0 mmix. This can be very confusing based on your tutorial. Also: these settings are very helpful to know:

mixer custom
mmix reset

And finally, this website helped me figure out the issue I was having… so credit due: iforce2d.net/mixercalc/

Spencer

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Oscar 16th March 2016 - 1:04 am

are you commenting on the right post? I don’t think I talked about mixer in this article?
I am assuming you are referring to the “custom motor mixer” post… that was written back in early 2015… cleanflight decided to keep changing things around (including the name of the function), being a part time blogger, i tried my best to amend it and keep it up to day… but there are times I just can’t keep up with things… so if there was any confusion caused I apologise.

I would also really appreciate it if you could point out which part of the article isn’t correct or clear… I don’t use mmix for a very long time and I start to forget about some of the details. (and that’s why I like to document/blog things)

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Newbie 23rd February 2016 - 6:24 pm

Hi Oscar !

I dont speak well english and i am new with cf and naze32.
Your explanation of these are very easy to understand than cf docs.

THANK YOU!

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Mike 13th December 2015 - 10:56 pm

Hi Oscar
New to quads. Just built 280 with scorpion motors, BL Heli 20 amp esc, Naze 32 ver6, dx8 tx, Orange 615x using ppm and Clean Flight set up. On throttle up the quad noses over. I rechecked setup and same results. In motors tab in cleanflight the motors do not come up even when using transmitter but come up even with master motor tab.
Where do I start looking for problem.
Thanks
Mike

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Todd Brown 5th August 2016 - 2:28 am

Start with the simple things. Have you done a throttle calibration?

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Paul 19th September 2015 - 7:32 pm

Hi Oscar,
Are your certain that throttle mid has an effect if the expo is off?

My mini quad is 7:1 power to weight and I have the crash on landing problem :) I tried throttle mid at both 20% and 80% and it didn’t seem to have any effect at all. I’m using luxfloat…

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Oscar 21st September 2015 - 3:00 pm

sorry yes, i should have mentioned throttle mid is only effective when you give it a bit of throttle expo :)

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Antonio 15th September 2015 - 3:22 pm

Congratulations for the excellent tutorials and articles técnicos.Qual would be quieter fee for “exponential” more suitable for one who never flew and will learn for the first time.

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Daz 15th September 2015 - 2:01 pm

Exactly what I needed to read to fix my flight problems from last weekend. Thanks.

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Ondrej 15th September 2015 - 9:26 am

Hi Oscar,
I was playing with the Y/P/R rate lately. I was looking for the meaning of the numbers and still was not able to figure it out. In the CF forum, i found repeatedly, that the Y/P/R rate is multiplier. Well, i doubt that, because the default value is 0, as far as i can remember. Do you know, how these rates are processed in the PIDs?

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Oscar 16th September 2015 - 4:01 pm

Hi Ondrej, like i mentioned in the post, it depends on PID controllers, these rates don’t necessary affect PID.
for PID C 1 and 2, they only affect your stick sensitivity, saying they are multipliers so it’s easier to understand for people, it’s not like you really multiply the stick values with the Rate Number… no! :)
Not sure what you are trying to do… just turn it up or down to where you see fit :) for normal users like myself… i see there is no need to dig deeper than that unless you are a developer, or you have having massive problems with it…

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Holger 14th September 2015 - 9:14 pm

I always tought it’s recommended to set Expo in the Tx and not the FC? Most pro pilots don’t seem to touch the Expo settings in Cleanflight at all.

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Oscar 16th September 2015 - 3:34 pm

HI Holger, everyone has their own way of doing things, end result is similar anyway wherever you are setting it…

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Holger 16th September 2015 - 8:43 pm

I was curious about this topic and got an detailed explanation from joshuabardwell on why to prefer FC expo over Tx expo: rcgroups.com/forums/showpost.php?p=32705942&postcount=999

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Oscar 21st September 2015 - 12:40 pm

that’s a good theory and sounds legit to me :) thanks for sharing!

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