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Raging Rotors: Expo, anyone?

Another week, another fun time here in Raging Rotors! With the DIY and Bind-n-Fly helicopter/multirotor market booming, I am seeing more and more of this question popping up: What is Exponential (aka Expo), and how does it help me?

DX9 with 0percent exponential

Exponential is more than just another name for a fair or trade show, but is also the relationship between Controller/Transmitter and subsequent output reaction from the RC vehicle. With an exponential set at 0% (shown on the above image as seen on a radio), or ‘linear curve’, any minute input from the controller will generate a response proportional to the input. In the helicopter/multirotor spectrum, it makes the aircraft very responsive to the point of being ‘twitchy.’ In RC cars, it would make steering ultra reactive, though expo is seen on more advanced radios (like the DX4s we just reviewed) and not RTR radios.

DX9 with 50percent exponential

With a higher exponential level (shown above is 50% expo for better visual), there is little to no response from minute input from the controller. This logarithmic curve provides great control when massive correction is used, and requires more than tiny changes in radio input to generate any noticeable response. This smooths out the flight of the aircraft to make it more manageable for first time pilots or to work out the bugs in your new toy to better ‘dial it in’. I have been experimenting with expo for the last two weeks, and it definitely makes a big difference, considering I tend to try and over correct and more expo keeps me from becoming my own worst enemy.

As we speak I’m wrapping up Part 2 of the Great Multirotor Build (check out the first part here). I have 2 quads running smoothly, so the whole thing will be wrapping up faster than it has been (I promise). Until next week, Stay Shiny and Keep Flyin’!


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Posted by in Columns, rc helicopter on Thursday, May 1st, 2014 at 11:30 am