Dual Rates & Exponentials
 

I apologize if this has alredy been done to death, but let me see if I have it right...

Dual rates are two different throw rates for the same plane/rx/servos/tx, set at the tx?

Exponential... I understand the term and the implication. My question is whether this is for digital radios only? Dual rates take a digital as well?

Are these setups widely used?

I must admit that I haven't done a search. But I've been here a while and haven't seen any posts on this subject.

Dual Rates and Exponential
 

Your definition of Dual Rates is correct. The use is for flying more precisely and 3D type of manuvers. Low rates for precision and high for 3D.

Exponential is used to "soften" the feel around center. Most rotary servos by design move more (laterally) in the center of the stick than at the ends of travel. Over controlling aroung center is a good thing to avoid especailly when landing. Before programmable radios exponential and differential (more movement in one direction than the other) was accomplished by the placement of the pushrod on the servo wheel.

All radios are digital so I'm not quite sure what your question refers to unless you mean does it require digital servos. It does not require digital servos. A computer radio (transmitter) is needed however.

These set ups are widely used and more as well. I fly a JR radio with 5 flight modes. One filp of a switch and all functions can be changed. It comes in real handy when switching from level flight to snap rolls and then into rolling circles as an example.

EXCAP232

Dual Rates & Exponentials
 

Just to give an example, as EXCAP232 noted, the control throw off a servo is non-linear because the servo arm is moving on a circular path.

If you have a computer transmitter that lets you set exponential, you can set it to -18 to -20% exponential and have a servo output that is linear. Note that you put exponential in as a negative % (at least on my equipment). If you go to a +%, you are sharpening up control right around the center of the stick travel - not normally advised.

I had a friend I was instructing once who just couldn't keep from making big throws of the aileron stick. Finally, set his transmitter up with about -50% exponential and finally got him where he solo'ed his trainer.

Take care,

Dual Rates & Exponentials
 

You can get dual rates in some non-computer radios, but with the constant lowering prices of computer radios I'd recommend you get one to take advantage of expo and mixing.

Follow-up question...
 

So as a beginner without a computer radio, what can I do with setup to help give reasonable center-section throws?
BTW, I can really see the difference with exponential setup on the FSM.

Dual Rates & Exponentials
 

I find with expo I never use the low rates.

Dual Rates & Exponentials
 

To be honest 90% of the time i dont think you need either, for general sport flying just set the CG slightly nose heavy and set the throws so you are comfortable.

Dual rates comes in handy for planes that need big throws for wild manouvers but you want better control say durring landing or 4 point rolls.

expo comes in handy for planes that have big throws and/or rearward CG

Re: Follow-up question...
 

I have both a computer radio, and an old 6 channel Futaba non computer radio. Both have dual rates. I use dual rates a lot, but have been advised by many veteran pilots to not use the expo or any form of mixing etc. until I have mastered conventional. Their thinking is that although it will make things easier when flying close to center position, it will also be a crutch to a learner, and make him dependent on it. I am heeding their advise. Now one thing that I did do that seemed to help me a lot was extend the length of the sticks approximately 1/2 to 3/4 of an inch. This in effect makes you move your thumbs more distance to get a given reaction. But it is not expo as it is the same throughout the range. It just seems to help "slow things down" a bit, and I progressed much quicker once I did this. I guess this is still a crutch in a way, but it works for me.
As they say on commercials, (your results may vairy :)

Dwight Hayden

Perspective
 

. I use dual rates a lot, but have been advised by many veteran pilots to not use the expo or any form of mixing etc. until I have mastered conventional. Their thinking is that although it will make things easier when flying close to center position, it will also be a crutch to a learner, and make him dependent on it. I am heeding their advise.

The above from "secondchildhood" post is one way to look at this situation. I frankly don't agree with not using expo and will have a student use it from the beginning. The reasoning is that radios don't give linear response (particularly around center) and make controlling the plane more difficult and much more likely to be to over controlled when landing. I don't see this as a "crutch" but as a tool to make the plane fly better (and as it should) from the beginning since it is used as part of setting up a new plane.

EXCAP232

Dual Rates & Exponentials
 

Thanks for all the replies. I think for now I'm just gonna follow the motto in my sig.