expo for beginners yes or no ?

[SONNY MONKS]

Do i use 30% expo on all control surfaces,control throws im told off one to keep at 100% while training with a boomerang 2,or should you have a second rate at 65%,while the instruction booklet states 3/8s elevator/aileron,HELP PLEASE!!

[Denis Watkins]

NO expo

A beginner should not even knows what it means Sonny

And warn any helper whatever you may have dialled in

Learn to fly without it first, then add a little if needed

[john stones 1 - Moderator]

Pet hate for me, you don't want too much movement as a learner, if/when you get into difficulties it can/will make things worse, expo nope.

Ah but.

[Dave Hopkin]

I think you might be confusing EXPO and RATES....

Rates limits the total movement of the Servo from end to end, which limits the control surface movement

Expo alters the sensitivity of the servo in the centre stick area but does not alter the total movement

Rates are highly suitable for learners who tend to over control - setting rates reduced the violence of a full stick movement (though do try to treat the stick like a womans t.. not a Gorilla's throat)

Expo can land learners in trouble as it tends to encourage over control as "nothing seems to happen when i move the stick a bit"

[Geoff S]

I always use expo - usually about 30% - particularly on elevator and aileron. As a mode 2 flyer who came to aeromodelling after a spinal injury stopped me from sailing (and cycling seriously) my right hand doesn't work as well as it should and I find it helps a lot. I also use it on rudder because I like a lot of rudder when in the air (stall turns and co-ordinated with aileron) but not so much on the take off run.

Can't see why it would be a problem for a beginner to have it, particularly with a buddy lead.

Geoff

[Jon H]

no expo. Most trainer models are docile enough to not need it and even more exciting models rarely require it if set up correctly.

I use 10% expo on only two of my models. One is my 1/4 stampe biplane and one is a small hand launch thing that zips about at high speed. Both have expo on the ailerons as both are too sensitive around the middle stick. In the case of the stampe, I need high deflection when the speed bleeds off in a roll, this makes level flight twitchy so 10% expo cures it. On the missile, its roll rate is mental at all speeds and that's part of the fun. However its easier to fly 3 inches off the ground with 10% expo on the ailerons.

In general, if you find yourself using less than 75% of the available stick travel during your flight then your rates are probably too high and you should lower those instead of using expo.

Expo is a useful and powerful tool but if used on a trainer it is likely to make you lazy and will mask inaccuracies in the movement of your sticks. When I instruct, loops and rolls are part of what I teach beginners as they are good as a circuit planning exercise and it reveals if the student is moving the stick straight without accidentally mixing the controls. A loop will soon show if they are tugging some aileron in there with the elevator.

And sorry to disagree Geoff but I would never use rudder mixed with aileron on any model. Its far better to do it manually as the controls are often used in opposition and you don't want them interacting with each other.

[Martin Harris - Moderator]

I think there's a matter of degree here...I have certainly seen beginners' control improved when a little "nervousness" is removed by a reasonable amount of expo being added. I believe it can reduce the tendency to over correct and chase a model at a time when the learner needs to be able to concentrate on learning to place the model in the correct attitudes and directions.

I've never put it to the test but I suspect that control effectiveness is not linear as the deflection away from the designed aerofoil shape progresses (BEB might be able to add something here?) so some expo may even make response more linear?

[Keith Berriman]

Untill my first transmitter with expo I was always twitchy with input on the sticks. With expo I was suddenly

a smoother flyer. Being mode 1 it's the better thing to have on the rudder input so as not to over egg turning on airleons

[Allan Bennett]

Interesting thoughts there: A couple of weeks ago I had my first experience of teaching someone with an Eflite Apprentice. In beginner mode it is terrible for an experienced flyer -- even with the stick full over it requires about a full football pitch to make a turn. Ideal for our beginner because he can bang the stick full over and not come to much harm, but how do we then wean him onto smaller stick movements? Dialling in a load of rates will allow him to make large stick movements, but at the expense of loss of manoeuverability, so how is he going to learn that he should only need small movements? Expo, on the other hand, would allow him to make relatively large stick movements most of the time, without jeopardising the model, and leave full deflection available for emergencies. It can then be reduced as his skills progress.

[Denis Watkins]

Its little wonder that Sonny is smiling so broadly at us,

[Former Member]

[This posting has been removed]

[Geoff S]

Posted by Jon - Laser Engines on 02/07/2018 20:41:47:

And sorry to disagree Geoff but I would never use rudder mixed with aileron on any model. Its far better to do it manually as the controls are often used in opposition and you don't want them interacting with each other.

I don't use coupled aileron/rudder. I add it in as necessary manually. I just like plenty of movement. You misunderstood what I wrote which is probably my fault for not making it clear.

Geoff

[Ron Gray]

On my Laser 260 (3D) I have 70% expo on high rates! But then the control surfaces are moving quite a bit............

Nowt wrong with it if it helps flying imo, a bit like gyros and TX mixes (ducks head down).

[Gary Manuel]

No expo for beginners.

Maybe later when they crank the rates up or start using dual / triple rates.

[alex nicol]

in my humble opinion. it should be learn to fly with the basics first........no expo or mixing. There's nothing wrong with a little rates but be wary of dialling in too much as you could lose control surface authority as you slow up on landing approach.

thing is its a matter of opinion ( said the man with the wooden leg) if it works for you great........at the end of the day there's no one size fits all

[Jon H]

Posted by Geoff Sleath on 02/07/2018 22:14:05:

Posted by Jon - Laser Engines on 02/07/2018 20:41:47:

And sorry to disagree Geoff but I would never use rudder mixed with aileron on any model. Its far better to do it manually as the controls are often used in opposition and you don't want them interacting with each other.

I don't use coupled aileron/rudder. I add it in as necessary manually. I just like plenty of movement. You misunderstood what I wrote which is probably my fault for not making it clear.

Geoff

fair enough, sorry for the misunderstanding

[Martin Harris - Moderator]

Agreed Alex, but my feeling is that a well sorted and predictable trainer helps beginners to progress better. If I, as an instructor, notice the model has handling quirks that can be sorted with expo, airframe tweaks such as thrustline or incidence mods or even mixes then I'm happy to help with modifications or program the learner's transmitter if it has the capability. There is such variety in models and their handling characteristics used by beginners that it's inevitable that some need fine tuning to get the best from them.

Edited By Martin Harris on 02/07/2018 23:55:45

[Rich too]

Interesting topic. I have been flying for nearly 40 years on and off and have never used rates - I can’t find the switches when flying! I have recently started using expo as it’s recommended in the manuals for the models I am flying.

My question is, why not use lots of movement with high expo? Is it necessary to use dual rates?

[andyh]

Posted by Rich too on 03/07/2018 05:47:25:

My question is, why not use lots of movement with high expo? Is it necessary to use dual rates?

I do both. Low rates with low expo & high rates with high expo. The rates are fairly similar up to around 50% & then obviously then diverge markedly.

The way I see it is that most mechanical linkages give a non-linear response, usually *more* sensitive around the mid-point, so a small amount of expo just brings it back to somewhat more linear for normal flying. I don't think this amount of expo is bad for beginners.

I'm really never sure whether the expo %age values are comparable between radio vendors - ie whether it refers to some real mathematical variable, or whether it's just some arbitrary weighting set by the manufacturer. I use 70% on some of my models on high rates & it's progressive & predictable (on FrSky/OpenTX), but on some other radios it can be a case of nothing .. nothing .. huge deflection, which can be a bit alarming!

[Kevin 216]

I learned to fly recently and did not use expo on aileron and elevator. However, I found I had a tendency, when advancing the throttle for take-off to feed in a little rudder input. 30% expo on the rudder mitigated the problem and my small stick errors were damped out - result straight take-offs. I still fly in this configuration zero expo on aileron & elevator, 30% on rudder.

As for rates I set them and usually maiden my model on low rates once satisfied all is well I use full rates.

[Jon H]

Posted by Kevin 216 on 03/07/2018 08:33:31:

I learned to fly recently and did not use expo on aileron and elevator. However, I found I had a tendency, when advancing the throttle for take-off to feed in a little rudder input. 30% expo on the rudder mitigated the problem and my small stick errors were damped out - result straight take-offs. I still fly in this configuration zero expo on aileron & elevator, 30% on rudder.

As for rates I set them and usually maiden my model on low rates once satisfied all is well I use full rates.

With all respect to Kevin (this is not a personal criticism) this is exactly why you shouldnt use expo when learning. Instead of learning to move the throttle accurately the error is being masked by the expo and by his own admission that state is set to continue, most likely for the rest of the time he is a model pilot.

Its a far better bet to learn to move the sticks accurately in the first place. All of my students do the same with the throttle/rudder interaction so you arent alone in that, but within a handfull of takeoffs and some dedicated rudder training they soon kick the habit.

Rich, i use rates a reasonable amount but in general they are only few % apart. For example my WWII fighters tend to need slightly more elevator movement on landing but that makes them a little too sensitive in normal flight. many of my models only have one setting. When setting rates i work on the basis that if i only need X deflection for a normal flight then X+10% is all i need and that is where i set them. If i feel i need more for landing i set a high rate 10% over that. I never measure any of this, its all done by feel. I totally ignore recommended deflections these days as they are often much too large and they then recommend high expo to counter it. The problem with this is when you get to a certain point on the curve deflection increases very rapidly and makes models very hard to fly. A friend had this with a spitfire. 60% rates and 65% expo. He started at 30% expo, as the manual, but found it too sensitive so added more and more expo. As he was unable to land it he asked me for help and I came down to 30% travel and no expo, after that it was on rails when trying to land.

ESM WWII models were a nightmare for incorrect elevator recommendations and so many crashed because of it. Most people assumed the c/g was wrong but in my experience its just been excessive elevator rate causing the problem.

[simon barr]

I use expo when training, I don't see anything wrong with that.

This is just a hobby and is supposed to be enjoyable, so why force a student to struggle with a model when we have the technology available to make it easier to learn. We are trying to encourage newcomers into the hobby, so we need to help them, not put them off by making them fly a model that is twitchy, when it could be smoothed out for them.

[Jon H]

Posted by simon barr on 03/07/2018 09:04:32:

I use expo when training, I don't see anything wrong with that.

This is just a hobby and is supposed to be enjoyable, so why force a student to struggle with a model when we have the technology available to make it easier to learn. We are trying to encourage newcomers into the hobby, so we need to help them, not put them off by making them fly a model that is twitchy, when it could be smoothed out for them.

I think you misunderstand. A trainer should not be twitchy in the first place if it is set up correctly. Most trainers are really benign.

While i fully agree that the objective is not to make students lives stupidly difficult its also a mistake to make it really easy for them as, frankly, they wont learn anything. There is also little reward when you get something for free and a bit of a challenge, backed up with clear instruction, gives them a sense of achievement once they have mastered whatever it is. Also when they upgrade to a new model that is likely to be even more sensitive than their trainer, they have to learn to fly all over again without their instructor and that is far more likely to put them off.

[Geoff S]

Posted by Jon - Laser Engines on 03/07/2018 08:53:56:

Posted by Kevin 216 on 03/07/2018 08:33:31:

I learned to fly recently and did not use expo on aileron and elevator. However, I found I had a tendency, when advancing the throttle for take-off to feed in a little rudder input. 30% expo on the rudder mitigated the problem and my small stick errors were damped out - result straight take-offs. I still fly in this configuration zero expo on aileron & elevator, 30% on rudder.

As for rates I set them and usually maiden my model on low rates once satisfied all is well I use full rates.

With all respect to Kevin (this is not a personal criticism) this is exactly why you shouldnt use expo when learning. Instead of learning to move the throttle accurately the error is being masked by the expo and by his own admission that state is set to continue, most likely for the rest of the time he is a model pilot.

Its a far better bet to learn to move the sticks accurately in the first place. All of my students do the same with the throttle/rudder interaction so you arent alone in that, but within a handfull of takeoffs and some dedicated rudder training they soon kick the habit.

Rich, i use rates a reasonable amount but in general they are only few % apart. For example my WWII fighters tend to need slightly more elevator movement on landing but that makes them a little too sensitive in normal flight. many of my models only have one setting. When setting rates i work on the basis that if i only need X deflection for a normal flight then X+10% is all i need and that is where i set them. If i feel i need more for landing i set a high rate 10% over that. I never measure any of this, its all done by feel. I totally ignore recommended deflections these days as they are often much too large and they then recommend high expo to counter it. The problem with this is when you get to a certain point on the curve deflection increases very rapidly and makes models very hard to fly. A friend had this with a spitfire. 60% rates and 65% expo. He started at 30% expo, as the manual, but found it too sensitive so added more and more expo. As he was unable to land it he asked me for help and I came down to 30% travel and no expo, after that it was on rails when trying to land.

ESM WWII models were a nightmare for incorrect elevator recommendations and so many crashed because of it. Most people assumed the c/g was wrong but in my experience its just been excessive elevator rate causing the problem.

Unfortunately, Jon, some people have less control over their fingers and hands than is the norm. I'm one of them and a centre dead zone helps me a lot. In my case it's mostly my right hand (I'm also right-handed) so I don't have too much trouble with throttle/rudder interaction but flying 100% tail draggers I use rudder quite a bit on take off anyway. Expo has it's uses even if only for creating a centre dead-band thus helping to isolate different functions for people like me. The non-linearity doesn't affect me at all. In fact I don't notice it. I just watch the model in the air and adjust the controls as required.

I built my own trainer (those were the days! ) which is probably the last time I flew anything with a tricycle undercarriage but passed my 'A' with a trail dragger I'd built (Precedent Funfly)

Geoff

[Jon H]

Geoff, in cases like yours then i can see the advantage and its fair enough, but the op didnt mention anything like that so i am working under the assumption that its not an issue for him.