Dual rates and expo - how to ?

Hello again,

Some time ago when I first got my 6 channel “real heli” the Esky Belt CPX, many guys on the forums told me the best upgrade I could do

would be getting a programmable digital transmitter. Instead of that suggestion, I was planning to mainly upgrade to metal components in the rotor head.

Some time later, I finally got a Walkera Devo 10 transmitter, and now I realize what a huge difference there is compared to the non-programmable TX from Esky.

Because I will make a review of the TX later on, I just want to explain about the most important, maybe, settings that can help a beginner into Rc flying, whether

this would mean helicopter, plane or glider : Dual rates and exponential…

So, what does dual rates mean ? As you probably know already, all the stick movements we make into the transmitter, go into the receivers from our rc models, and

get translated into servo movements… Of course the servo arm that in our case is connected to the heli swash plate or the plane ailerons/elevators will move to maximum

positions for the maximum stick movement, right ? I hope it’s simple and understandable so far…The problem for a beginner is that maximum servo arm movement moves the

swashplate to the maximum position, and then the heli moves so fast, that for a beginner might take too much time to counter it, and crash….

Here the dual rates come into play…On the transmitter you can set the maximum travel of the servo arm, for example 70 or 80 % usually….This means that for the same

full stick movement the servo arm will move only 70 or 80% of his maximum travel, making our model move a bit less than with normal 100% servo travel…

On the Devo 10 you can set aileron dual rates, elevator dual rates and also rudder dual rates which is all you really need.

I hope you could understand my explanation so far…now let’s move on to the exponential settings…

For this one we should go back some time during the math lessons, because this is basically what the expo curve is…

It works very simple: in the defined area in the transmitter, the sensitivity can be increased by adding “-“ or negative expo, like world champ pilots use,

or in our case we want to reduce sensitivity for usually aileron and elevator by adding positive expo values, and then we have a curve like below…

Important thing is that after the stick gets ouside of the expo area, it will still move linear like you can see, only difference is that it is less sensitive in the

central area…For example I use my servo dual rates travel on my 450 helis to 80% and I set-up also exponential curve values to 15 or 20%.

On smaller size helis, like micro helis, many people use dual rates of 70% servo travel and expo values between 30-40%, but it depends on personal preferences.

Positive expo to reduce sensitivity around center stick

Negative expo that increase sensitivity around center stick

I hope I really made it simple and easy to understand...If you have any questions, please post your comments below.

Happy flying and see you next time