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General Topics => RC General Topics => Topic started by: gauravag on September 14, 2009, 10:05:58 AM



Title: Question Dual Rates and Exponential
Post by: gauravag on September 14, 2009, 10:05:58 AM
Hello everyone,
As i had posted earlier, i recently purchased a Futaba 10C radio. Spent the weekend reading through the manual and the features. It seems to be an excellent equipment and has all features to last me a long time, and make me a better pilot too.
Now, though earlier I was using Futaba 6EX , I never used the Dual Rates and Exponential features, and was wondering how many of you use these features. I always seem to have flown on High rates with no exponentials, but would like to use these features if they will make my flying better. Question i seem to have now is :
1. Do you use Dual rates ? If so how much and on what what controls ?
2. Do you use Exponential ? If so how much and on what controls ? ( i believe everyone would be using a -ve exp )

Thanks for sharing your setup details.
-Gaurav


Title: Re: Question Dual Rates and Exponential
Post by: sushil_anand on September 14, 2009, 12:22:48 PM
A lot will depend on the type of flying you do as well as your personal style.

Since I do not fly 3D, and do not have a "hot shot" style, I find that I am better off not using dual rates. For example, Aileron (max) throws are set for the roll rate I like and then a suitable amount of expo dialed in to make the response smooth around neutral. Depending on the airplane and control axis, expo varies from 25 - 40%.

This would be -ve in Futaba & +ve in JR.

Your mileage may vary!


Title: Re: Question Dual Rates and Exponential
Post by: izmile on September 14, 2009, 12:47:48 PM

1. Do you use Dual rates ? If so how much and on what what controls ?
2. Do you use Exponential ? If so how much and on what controls ? ( i believe everyone would be using a -ve exp )

1. Never used dual rates. Would prefer to have full throws.. but I am not a 3d flyer either. If I were to have the dual rates I would have it on the ailerons and the elevators.
2, Yes, have used in some of my models. Especially on my PBF which is full 3D capable. Usually, I start with 30 -40% expo and then add or decrease as necessary.


-Ismail


Title: Re: Question Dual Rates and Exponential
Post by: anwar on September 14, 2009, 04:40:12 PM
Expo seems to be a better way of handling large throws than dual-rates, simply for the fact that larger throws are readily available if you need that extra bit of agility to handle any emergencies (I mean without having to flip switches while you are already under pressure).

That said, I do not use either in general. Just take the first couple of minutes on a any new aircraft to understand the performance characteristics, and it was fine.  That said, there is also no point in struggling at the controls on a plane with really large (3D) throws. If it takes the fun out of flying, it is better to dial in some expo.


Title: Re: Question Dual Rates and Exponential
Post by: sunk? on January 20, 2010, 02:16:10 AM
hi guys,
you explained it well..............for those that know the 'better' tx's.............
dual rates,
this works by 'slowing' the servo and 'shortening' its travel (throw )
can be used on all controls 'it is available for' and depends on the speed of your servos and the agility...or sportiness....
 of your model which control you use it on. this is for the 'full stick movement'.

expotencial.....expo....
is a method of reucing the speed of a certain percentage of the stick movement
ie set 25% on ail and the first 25% of ail stick will be 'very slow' or 'fine' control   ideal for learning    but the other 75% of stick movement will be normal........it makes the stick less sensative around the 'neutral area' for say 'hovering a heli' but give it more stick to turn and FF then away she goes as normal.
regards
don


Title: Re: Question Dual Rates and Exponential
Post by: merog on January 20, 2010, 08:04:50 AM
I got a FUTABA 9C Radio. Am also a noob and trying to use the Dual rates and Expos.

These things are better explained here by RCPowers I think:

http://www.youtube.com/watch?v=_CGS1voU8vY&feature=channel


Title: Re: Question Dual Rates and Exponential
Post by: sushil_anand on January 20, 2010, 09:53:44 AM
Quote
this works by 'slowing' the servo

The speed is not affected by dual rates or expo. It is only the total travel that is limited (dual/triple rate). In the case of EXPO, the servo travel, or throw, is CHANGED around neutral  (an increase or decrease is possible) . The total travel will remain unchanged.

BTW it is possible in many Txs to have dual rates + expo.


Title: Re: Question Dual Rates and Exponential
Post by: anwar on January 20, 2010, 11:59:14 AM
Interesting point about speed. 

If one sets 50% DR, does the servo move that half the distance in half the time as full throws (assuming the stick was moved identically fast in both cases) ? 

BTW, this is just an academic exercise, unless the servos are really really slow.


Title: Re: Question Dual Rates and Exponential
Post by: gauravag on January 20, 2010, 12:04:03 PM
BTW do you ever use DR/expo on helis  If so, how much ? I guess would be only on the cyclic, if indeed used ?


Title: Re: Question Dual Rates and Exponential
Post by: anwar on January 20, 2010, 01:00:19 PM
Now I am flying with no DR and no expo, but when I started, I had EXPO on the cyclics (aileron and elevator).  I think I started at -40% (on Futaba, negative calms the response around neutral), and gradually removed it.

I do have 80% end-points (which is neither DR nor EXPO) on the rudder, since the piro-rate of my helis were too fast at the default 100%.


Title: Re: Question Dual Rates and Exponential
Post by: sushil_anand on January 20, 2010, 03:01:12 PM
Quote
If one sets 50% DR, does the servo move that half the distance in half the time as full throws (assuming the stick was moved identically fast in both cases) ? 

Yes. So it will take the SAME amount of time to reach the SAME position whether on DR or otherwise. This also applies to AFR (Futaba) etc.


Title: Re: Question Dual Rates and Exponential
Post by: sunk? on January 20, 2010, 07:46:51 PM
hi guys,
when I was using dual rates on my futaba 6ex it apeared to slow the sevos as well as limit the throw.......using for two blade flybarless.............. but it was fairly sheap servos and this may just have been lack of throw apeared slower as well.
any it made me able to fly it 'whithout' any 'extra' electronic stabilaty aids.  :)
it is handy for 'sporty' craft to calm them down while you get used to the individual way they handle.
there has been big debates and arguments over here about the two systems 'dual rate and expo'.
with very differing lines of thought.
the answer seems to be to under stand what each one does and try them and use whatever suits your use..............
I now fly with niether  :)
regards
don