Rate/Acro Mode VS Horizon/Self-Level Mode

When it comes to general multirotors flying, there are two main flight modes we use, one is rate mode (AKA manual mode or Acro mode), and the other is self level mode.

There are many flight modes depends on what flight controller and firmware you use, for example in Multiwii we have these flight modes.

What is Rate Mode and Self-Level Mode?

Self-level mode is an assisted flight mode that the flight controller would always attempt to put the quadcopter in its neutral position when the pilot let go of the transmitter sticks. On the other hand, rate mode, as known as manual mode, doesn’t level the aircraft automatically and requires manual control.

Rate mode uses only the Gyro sensor, while self-level mode uses both Gyro and Accelerometer.

Self-Level Modes: Angle and Horizon

Angle and Horizon modes are both assisted, self level flight modes, but there are some little differences between them.

Angle Mode

Your stick controls the tilt angle of your aircraft. When your stick reaches its max position the copter will stop and hold there as it has reached the max tilt angle allowed. If you release the stick back to centre, the aircraft would follow and back to horizontal level.

Horizon Mode

When the stick is near centre, it’s the same as being in angle mode, but when the stick is at full deflection, you are in rate mode. This allows you to have control like in Angle mode but it also allows you to do flips and rolls if you bang the stick all the way over.

What is Rate Mode?

Horizon and Angle modes (Self-level) are tempting for beginners: the pilot controls the pitch and roll angles of the multirotor with the stick (radio transmitter), but it returns to the neutral position when the pilot is not controlling it.

Acro mode (aka Rate mode) could be a bit more intimidating.

The pilot uses the stick to control the drone’s angular velocity of rotation, not the angle, In simple terms, your stick controls how fast your copter rotates. That means if you move your pitch stick forward and hold it, the copter will keep rotating at a constant rate, instead of just remain at an angle like it in self-level mode. If you let go off the stick now, the copter will maintain its current attitude (angle) and will not return to level, unless you move your pitch stick to the opposite direction.

Why Fly Rate Mode?

Self-level mode is recommended to beginners, because of the predictable behaviour: let go off the stick, and your drone would simply just level and stay there. But here is the truth, if you want to enjoy flying FPV even more, you should start learning rate mode as soon as you feel confident with angle mode. Here are some of the advantages of Acro mode.

  • Acro mode is useful for acrobatics such as flips or rolls, or FPV when smooth and fast control is desired
  • You have more control when flying FPV once you master rate mode, because you don’t have to fight with ACC sensor… and you only control the quad whenever needed, it reduces stick input over time, making flying more smooth and fluid
  • Control is intuitive as the craft flies much more natural like a glider (although could be hard at first)
  • Flight performance is more stable with less vibration due to the fact that ACC is not used, much better for aerial videos, especially when camera gimbal is not used
  • One fewer sensor is involved means fewer failing points, also frees up processsing power for something else if ACC can be disabled

Learning Rate Mode

Mastering rate mode doesn’t happen over night. For beginners, you should expect to crash a number of times before getting a hang of it.

If you could, practise in a simulator first. Then practise with a quad that is tough to break with some cheap/durable props. Go somewhere open and without too many obstacles and people. Stick with it, it might take hours, days even weeks, but it will start to click one day and it will feel great I promise.

Also, give it a bit of expo as well to start with, just to get the feel of how you have to correct for any movements. As you get more used to it then dial the expo down to where you feel comfortable.

Here is a great discussion of someone who was learning how to fly FPV in Rate mode.

Flying Rate Mode Line Of Sight

Here is the bad news :)

Even if you have mastered flying rate mode in FPV, flying rate mode in LOS is almost completely different. You will be like learning it from the beginning all over again. It’s useful to improve your LOS skills in case of emergency situations.

That’s why some people would setup 2 modes, Rate for FPV and Angle mode for LOS.

18 thoughts on “Rate/Acro Mode VS Horizon/Self-Level Mode

  1. Youri Rombouts

    How do you actually change modes on baseflight?

    I’m using a raspberry pi to talk to the naze32 through a USB connection but i’m having a problem which I believe is called the “bunny hop” for obvious reasons. I am wondering if there is a way to change to angle mode so my quadcopter can stay leveled without it slamming itself into the floor. I am a complete newbie in this area so please don’t assume I know anything.

    Thanks in advance

    Youri Rombouts

    Reply
  2. Byron

    Good day!

    I im learning to fly in a rate mode of toy grade quads . Din in preparation to a hobby grade quads from 120-130mm class. Is this same whem i shift to a hobby grade tx flying in acro mode?
    Thank you

    Reply
    1. Oscar Post author

      on some toy grade quads rate mode work slightly different, but regardless that shouldn’t stop you from upgrading and learn it on a hobby grade quad :) just make sure you practice on soft grass and get plenty of propellers, you should be fine.

      Reply
  3. Frank Owen

    Ok, I am getting the idea that rate mode has a lot to offer, but it is hard at first. And quite a bit different than auto-level. So my question is: once you switch, does it become nearly impossible to switch back to auto-level, because it feels “too weird”? If I learn rate-mode, will I have a hard time flying toy-grade quads that don’t have rate-mode?

    Reply
    1. Oscar Post author

      not really :) it’s like learning riding a bike then learn swimming, you won’t forget one or the other :)

      Reply
  4. Jonathan Roung

    Oscar, I’ve been following your posts and I LOVE the insights you share. Here’s one for you:

    I want to fly acro/rate mode for pitch, but auto-level mode for roll.

    I’m assuming Betaflight’s ‘Horizon mode’ would accomplish this, by setting pitch stick deflection to 0° (essentially putting pitch in rate mode all the time) and setting roll stick deflection to, say, 70° (so that barrel rolls can still be completed during extreme stick deflections).

    What are the odds you have explored this and could comment?

    Reply
    1. Oscar Post author

      Hi Jonathan,
      As far as I know you can’t mix flight modes.
      but what do you want to do this?
      thanks
      Oscar

      Reply
  5. soli_sal

    Hi, I am building a quadrotor for first time and I implemented rate mode successfully on that…
    The problem is I can’t implement angle mode over the rate mode!
    Rate mode works great, but when I enable angle mode, quadrotor is too slow to stabilize with some overshoot. It takes a few second to go to desired angle and when I release the stick, it returned in same way…
    This is what I did in code:

    rate_needed = PIDcalculate(&pid_roll_stab, desired_angle, current_angle);
    pwm_for_roll = PIDcalculate(&pid_roll_rate, -rate_needed , current_rate_gyro);

    Rate PID has P,I coefficents and Angle PID has P for now…
    Thank you

    Reply
  6. E.L.K.

    Hi Oscar!

    I finished a build of 250 quad recently: https://dl.dropboxusercontent.com/u/54741704//Other/copter/el%20el/assembled-for-first-flight.jpg

    After some doings with the settings and radio and so on I finally got it to fly ok in autolevel. But in rate mode there is slight angle drift on pitch (it increases incline to back).

    The trick here is that quad actually not balanced – it’s center of gravity is ~2.5 cm to back from the center. I know that it possibly will fly better if balanced, but I just want to understand where this angle drift comes from so I experiment with unbalanced quad. As far as I understand, the “rate” mode is something like “angle lock” mode – sticks control the speed of angle change, and when sticks are not touched it should maintain the set angle. But it does not. What confuses me a lot is that the speed of drift is different over time. At the flight start (battery full) – the quad maintains angle ok, but as closer it gets to empy battery, the significanlty it starts to change angle by itself (up to about a degree per sec or even more).

    Why it can behave like that? Can you, please, recommend me a direction to continue investigation?

    Reply
    1. E.L.K.

      It seems that the problem was “I ” in PID too low for pitch, so it wasn’t able to stabilize. I increased I (almost twice, actually) and now it locks it’s angle almost pefrectly.

      Reply
    2. Oscar Post author

      does it drift to different direction or always that direction? i think it might be I gain too low?
      are you using 5030 props? it could also be that your quad is under powered…
      lastly… i would really appreciate it if you could post your questions on the forum: http://intofpv.com … I only check my blog comments once a week, but I use the forum everyday!

      Reply
  7. moosestang

    Is there a way to limit the angle in rate mode or even horizon mode? My biggest problem is giving it to much pitch and slamming into the ground. I’m going to try lowering the level pid’s in angle mode until i can get some smooth fpv video like rate mode. I want to learn to fly rate, but flying fpv i like to give it full pitch without flipping over.

    Reply
    1. Oscar Post author

      yes, use angle mode, it won’t allow you to go over 45 degree by default, you can change this angle limit in CLI i think. I don’t think it’s possible though in rate / horizon mode.

      Reply
      1. Jonathan Roung

        In Cleanflight configuration software, this is done through CLI command “set max_inclination_angle = XX” (or “max_angle_inclination” in Betaflight). You might also want to adjust your expo to account for the changes this would make to your corresponding stick deflections.

  8. Chiggz

    I’d highly recommend people grab themselves a simulator that supports FPV or quadcopters, like RealFlight 7.5

    I use to fly auto level modes and assisted flying modes all the time, but I spent a couple of hours on the sim, and the next time I went flying at the park, I had to turn auto leveling mode off as it felt too weird :P

    Now I’m an avid flyer of rate/acro mode and highly recommend it to others. Its much easier to be smoother around corners and generally push a bit harder.

    Reply
    1. Jonathan Roung

      LiftOff is a great new software program – joint venture between FPV gurus FatShark and gaming wizards Steam. It reads my Taranix X9D perfectly, has settings for customizing a quad to match your real-life setup (lipo size, PID settings, FPV cam angle, etc), and even offers a multiplayer simulator.

      Reply

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