RC Rate, Expo, Super Rate Explained

This tutorial explains the differences between RC Rate, Expo, Super Rate, as well as Throttle Expo and Throttle Mid, how these settings affect the performance of a quadcopter, and some tips on how to set them up.

You might be also interested in PID tuning.

RC Rate

RC rate is the setting that controls the speed at which your quad rotates on a given axis (pitch, roll or yaw) for the TX stick travel.

Think of RC rate as the stick sensitivity setting, if you increase RC rate, your quad will respond more aggressively to your stick inputs.

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.

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.

How to Tune RC Rate, Expo and Super Rate?

This is really a personal preference, it’s all about finding what suits you the best.

With any new quad, I always tune RC Rate first. Just cruise around (no flips or rolls), and make sure the quadcopter respond quickly enough to the sticks.

Then I increase or decrease Super Rate until I am happy with the speed of rotation for acrobatics. Note that Super Rate also affects your centre stick sensitivity, so you might need to fine tune your RC Rate afterwards… You might need to go back and forth a few times to get the right feel :)

You can aim for a max rotational rate desirable to your. For me it’s around 900 to 1000 deg/sec. If the sticks are still too twitchy, you are lower RC Rate and increase Super Rate to dame the response around mid stick, yet maintaining the same max rotation speed.

Finally, if you are looking for more precision around mid stick, you might want to add some RC Expo.

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

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 from two of my quads:

Smooth Cruiser:

  • RC Rate, Pitch/Roll = 0.82, Yaw = 0.86
  • Super Rate, All = 0.80
  • RC Expo, All = 0.03

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

34 thoughts on “RC Rate, Expo, Super Rate Explained

  1. Renato

    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

    Reply
    1. Oscar Post author

      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.

      Reply
  2. Martin

    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.

    Reply
  3. James Wallo

    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

    Reply
    1. Sarcoise

      @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.

      Reply
  4. supernull

    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!

    Reply
    1. Oscar Post author

      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!

      Reply
      1. Michael

        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.

  5. Dave

    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.

    Reply
    1. Chris

      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 :)

      Reply
    2. Brian

      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.

      Reply
  6. joe

    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?

    Reply
    1. Oscar Post author

      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…

      Reply
  7. James

    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.

    Reply
  8. Robin

    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

    Reply
    1. Oscar Post author

      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.

      Reply
      1. DeeHawk

        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!

  9. Spencer

    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

    Reply
    1. Oscar Post author

      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)

      Reply
  10. Newbie

    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!

    Reply
  11. Mike

    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

    Reply
  12. Paul

    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…

    Reply
  13. Antonio

    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.

    Reply
  14. Ondrej

    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?

    Reply
    1. Oscar Post author

      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…

      Reply
  15. Holger

    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.

    Reply
      1. Holger

        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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