Originally Posted by
Bob Pastorello
Add to this that if you are using approx. 1" standard arms, with maximum deflection of 60* either side of center, the "early" movement off neutral at the servo with ZERO expo is significantly over-sensitive. Please measure one...you'll see immediately what I'm explaining. As the servo arm moves, it becomes less linear because of the arc of movement. On JR, Hitec, Airtronics, Futaba, ANY flavor of radio, this is absolutely true. For Hitec, getting to 28% expo makes the movement of the control surface actually "linear", that is, the percentage of control movement will match the amount of stick movement, proportionally.
This isn't a magic function...it is simple rotational geometry of radial movement against a linear goal.
It is absolutely accurate, also....SOME amount of expo to "de sensitize" neutral WILL be required simply to get the linkage system to be truly linear and proportional.
Doubters, fire away, but please do so AFTER you've actually measured amounts of travel at the servo arm takeoff point both WITH expo and without.
Folks who already know this to be true - please help clarify my explanation, as it's a little bit about explaining Ackerman...
I haven't measured, but:
Per Hitec
It is a radio function that will allow you to change the control response of the control sticks from being a linear response to what is known as an increasing response curve, or exponential. An example of how this feature is commonly used would be the pilot on an extremely responsive aerobatic aircraft using full servo throw travel and does not need much servo input to control the plane in level flight but wants to take full advantage of it's aerobatic capabilities. Therefore, exponential is programmed such that very little servo response is provided when the control sticks are near centered, or neutral. As the sticks are moved farther from the neutral point, more servo response is generated at a rate greater than a straight linear response, allowing for quick and precise maneuvers. Exponential values are available from -100% to +100%.