After 25+ years, I am returning to this hobby. Things have changed. Trying to learn as much as I can.

Recently, read an article in Model airplane News.

Control Throws:

Elevator plus/minus 2 in.: expo: 50% (high); plus/minus 1.5 in. (low); expo:50%
Aileron plus/minus 1>5 in; expo; 50%(high); plus/minus 1 in. (low); expo 50 %
Rudder plus/minus 2.5 in.; no expo: (high); no low rates

AAAh, What?
Help please !!!

LOL, welcome to the future!

It's not as bad as it sounds.

Most radios nowadays have a feature called "Dual Rates". It is usually turned on and off with a switch (Or two) on the transmitter. You usually set them up so that on "High" you have full throws and on "low" you have less sensitive control.

This is a handy feature for very areobatic planes so that when landing or taking off you don't have an overly sensitive plane.

"Expo" is short for "Exponential". This is a feature found on most computer radios and it's similar to dual rates but it doesn't have to be turned on and off.

You set the amount you want (30%, 50%, etc) and it "Softens" the control exponentially. An example would be:

Without expo, you move the stick 1/4 and the servo moves 1/4 - move the stick 1/2, the servo moves 1/2 etc

WITH expo, you move the stick 1/4 and the servo moves 1/16 - move the stick 1/2, the servo moves 1/4 - move the stick 3/4, the servo moves 5/8 move the stick to 100%, the servo moves 100%

So you still have full control, it is just "Softer" around the center of the stick travel - It's a very nice feature!

But neither of these are needed to fly!

you can also use them them enhance the stick movenet i use MinnFlyer example you move the stick a 1/4 you can get 1/2 out of the controll. also a fact to kept in mind this is only around the center of the sticks once you go so far it's the same as the input ( at least jr dont fly futaba) it is a nice thing to have but as said it's not needed


welcome back

Thanx Guys,
Another point, I recently read a post that expo and d/r can be crutches. Getting back into this hobby, should I stay away or employ them?

harmsway, I'd recommending using them, and I do (expo). Expo is a great tool for softening a plane's response around neutral. For example, you have a plane that is very sensitive to control inputs and you want a gentle-handling plane on final approach and during level flying. Expo will do this for you. Dual rates are similar in the effect. You have a plane that is violent on full rates. So, for landing and takeoff - you switch in, let's say, 50% rates. Now you have the same plane but with half of the control response. When you're ready for the aerobatics, switch the rates off.

Dr.1

Hi guys,
I think I understand expo and d/r. However, what is high, low, and plus/minus xxin. mean or stand for?
Thanx again

With regard to rates, maybe this will help. Say the radio is set for low rates. The ailerons/elevator/rudder will move a max of 25 degrees (assuming that's what it's set for). When you flip the switch and use high rates, they will now max at 50 degrees (again, depending on the setting). It basically just gives you multiple levels of maximum throw on the servos.

You have to be kiding

Live Wire,
Don't want to start trouble here, but "kidding" about what?

Dual rates (d/r) are usually referred to as high rate and low rate, or just "High" and "Low".

Plus/minus 1.5" on low rate elevator would mean that with the d/r switch down, full throw on the elevator would be 1.5" up and 1.5" down. Sometimes there will be an aileron recommendation for more throw up than down. With the d/r switch flipped up (on high rate), the elevator travel might be 2" up and 2" down (plus/minus 2" ).

Good luck,
Dave Olson

Scar,
Thank-you very much. That cleared up a lot of questions.
In addition, thanx to all who replied, I learned a lot tonite.

Hey Scar, I assume your talking about deflection from the neutral position, I hope !!!

High rates are 100% throw. Low rates can be whatever the TX allows you to set, typically from 50% to 100% of the high rate. Expo: a (-) expo softens the control movement around center. A (+) setting softens control movement at the end points.

Dr.1

IMO, if you're just getting back in, I wouldn't worry too much about dual rates or expo on the planes you'll start out with. One thing I noticed after being out for many years is the increase in radically areobatic aircraft--stubby wings, monster engines, huge throws. No doubt expo and DR come in handy with planes like that. For a standard sport or scale plane, and certainly for a trainer, ordinary proportional controls work fine.

As far as being a crutch? I couldn't disagree more. These are tools that allow you more flexibility with your airplane.
An example: My Showtime 90 has high rates set at 100% and low rates at 70%. I use low rates for takeoff, landing or just lazy circuits around the field, I flip on the high rates to tare up the sky.
When you put together a kit or ARF the instructions will usually show how much deflection is recommended for high or low and after you fly for a while you will be able to make adjustments to the throws to suit your flying style and comfort level.

LOL. When I look to assign low rates to modern models I dig out my old 1970's Contender 60 manual and check out the rates.

Aileron: low 3/8" up/down, high 5/8" up/down
Elevator: low 3/16" up/down, high 5/16" up/down
Rudder: low 5/8" left/right, high 1" left/right

Nowadays if you don't have 2" in any surface you ain't jack spit.

And this is on a 60 size model that used to be considered a hot performer! I use the highs listed above as my default lows for .40 and .60 size models if the instructions seem a little crazy to me. I don't care what model it is there are days when I just want to fly it smooth and in large, expansive maneuvers. What you can do is copy the model settings (if your transmitter has the feature) and rename it, then tone it way down. That will be like having quadruple rates on a model. Trouble is you can't go from mild to wild in a single flight.

I am a newer to the hobby, i have yet to use expo's, but I do use dual rates. I feel expo "reduces" your feel for the plane and control, i like to think of it this way, when you drive a new car the steering wheel is very tight, but if you drive a car that has a lot of miles on it, you can just about turn the wheel all the way around before it turns, both will get you to turn but one will be a bit more jerky, especialy to a new driver.

hope that helps

Jon

harmsway don't feel bad, I'm in the same boat. I also have been away for about 20+ years only to come back and find this fine site and be completely thrown for a loop. So I have been reading quite a bit here and learning heck of a lot. There are some knowledgeable and informative people here, and some even make me laugh from time to time..
I still have my old Falcon 56 I never finished and the old AM radio which I will never use for fear of embarrassment.[] I will finish up the Falcon and maybe purchase one of those new fangled radios that fly the plane for you, but in the meantime I will keep learning. So stay positive.

Teran, Welcome to RCU (And all the crazies that hang out here )

Jon, actually, using a small amount of expo will make your controls MORE linear. Because, if you think about it, your servo is actually providing you with REVERSE expo.

How so?

Look at how the pushrod travels as the servo rotates in the illustration below.

This shows six, 10-degree rotations. You can see how the servo moves the pushrod MORE at the center of stick movement than it does at the end.

So a rotating servo wheel actually gives you the OPPOSITE of expo

There you are !
MinnFlyer nailed it. The key here is to use expo correctly and not over do it and have poor control around neutral. The - or + depends on brand. I like -20 (futaba) on an everyday sport model such as a four star and up to -35 or -40 on my Pro Twister.
The first time I had a radio with expo I was flying a Sig 4* 60 and thought it was like cheating because flying smoothly was suddenly easy[8D] IT is fun to play with so enjoy!

Hey guys,Thanks again for all the help. Teran 54, you are absolutely correct. This is a terrific site and I have learned alot. A great group of guys, more than willing to help. It's to bad we all don't live i n the same area. However, that would probably lead to a lot of divorces, and I,ve been there!

Thanx again guys