Rates in Betaflight

Rates are a strange thing. People talk about their rates, other's rates and famous people's rates.

Rates are a very personal thing, there's not a direct answer to what's right or wrong for your rates.  I've talked with other race pilots, some say they never touch their rates, others say they change their rates based on the track they are flying on.

Before I jump off into explaining rates and how they translate to your quad, we should start with your transmitter.  Quads will come and go, quads will get crashed, quads will get slammed in to trees, into posts and whatever else you can imagine.  Your transmitter will be there side by side with you.

You might be wondering at this point why I would start with talking about your transmitter.  Its because your transmitter is a physical item that will effect your rates.  Your sticks can make your quad feel different.  I recently discovered this when changing transmitters.  My quad felt sluggish.  I didn't change my rates, just receiver and the transmitter.

Turns out after having both radios side by side, my new radio had much higher spring tension on the gimbals.  The feel of your sticks can really impact how your rates feel when you're flying.  But I was flying better, I have shaky hands and the higher spring tension made it less apparent when I was flying.

So why would I lead a conversation about rates with the spring tension on a transmitter? Because they will alter how you perceive your rates.  If you're fighting a spring and you want your quad to be more snappy, maybe you need to soften the springs on the sticks, not a harder stick feel in your rates.  But if you're really happy with exactly how your sticks feel, then maybe its time to look at your rates.

So rates in Betaflight are kind of a butt dyno, there are guys I know who fly really low rates, and guys who fly ridiculously, unflyable (for me) high rates.  Both are right, but not right for me.

Lets look at the cool screen Betaflight has, and kind of break it down to what they mean, and how I understand how they impact quad handling.


You may have seen this screen a time, or two.  Usually every quad I build, tweak or even plug into, I end up on this page.  But lets look closer at this page I have circled some things in blue, those are the numbers that add up to being your rates.

You might be wondering why I labeled the columns in the rates screen.  Its because that's helped me comprehend what those numbers do when I was playing with my rates early on.

The RC Rate is a straight line, it directly correlates your stick movement.  Its a constant rate.

Then the Super Rate begins to curve your line at the end of your stick travel, its predictable and reliable

The last is RC Expo, this is a dangerous setting to mess with, in my opinion.  It messes with the 'curved' part of the curve.  It can be unpredictable, because of how that portion of the stick is calculated by the flight controller.

The Max Vel [deg/s] is the theoretical speed of rotation measured in degrees per second your quad will rotate on a given axis.  That is an important number to pay attention to, most racers I know usually have that number between 300 and 500 degrees/sec.  Keep in mind that's a theoretical number and while it is close, it isn't always accurate.

The Graph on the right is a visual representation of what your theoretical speeds of rotation are with the rates you set in Betaflight.  

So lets talk about RC Rate and Super Rate.  In my opinion, those are the only two settings anyone who flies should adjust at all.  RC Rate of 1 is about 200 deg/s.  Super Rate begins to make a curve and give you a higher rate the further away from center you are.


Now that you have a rough idea of what those numbers mean, I am going to see if I can explain how they influence your stick feel.  If you look at the previous and the next pictures, you see they both have a yellow outline and a red outline.  Its not accurate or to scale but they help you get an idea of what each of them do when you're in the air.

Your RC Rate really influences your center stick movement, and the Super Rate impacts the furthest throws of your sticks.  Which is where the outlines on my gimbals come into play. The yellow outline is about where the RC Rate stops and begins to be influenced my the Super Rate.  That area is also called 'Mid Stick.'  Once you move a little further out on your stick you are in the Super Rate portion of stick travel. 




If your quad feels twitchy at center stick.  You might be like me and shake a little on your sticks, and you might consider using a lower RC Rate. That will soften the feel of your quad at center stick.  If you want a quicker motion at center stick, consider using a higher RC Rate. 

The same principle applies to the end of your stick travel.  The Super Rate gives you a faster response on the edges of stick travel.


Final thoughts:
Its less about what others are running, but what feels comfortable to you. Your rates should be set for what gives you predictable and consistent responses from your quad.  No matter where you are as your sticks travel. 

For racing, I have been told and I agree with starting your overall rates around 350 deg/s.  Then altering them to fit your personal taste.  Be aware that the more linear your rates are the more predictable your sticks inputs will be reflected in your quad.

Comments

  1. I liked this read and find in interesting how race pilots rates seem lower than freestyle, 300-500 vs 800-1200. A note that might interest some people, Dr. Robert Woods said something along the lines of wanting linear response from his control input in the Formula SAE race cars. If you don't know what FSAE is, you should look it up because it's awesome. I believe it translates in most things that a linear response is easily predictable and thus desirable in many race situations.

    ReplyDelete
    Replies
    1. I agree, most racers I know do fly very linear rates. I prefer a slightly more curved line than most. But keeping them predictable is the most important in my mind.

      The best way I've heard rates for racing explained is from Justin Skinner, and he says you're not running and gunning, you want to fly like a sniper, slow and smooth.

      It sounds backwards, but to go fast you have to go slow.

      Delete

Post a Comment

Popular posts from this blog

Building on the Panda Cavity

Noise In Your Quad? Hot Motors?