Jetdesign

My Feedback: (8)

I know I'm not supposed to rely on my computer radio to help me fly until I really can fly. However it was suggested to me to use the exponential on my radio at the field. I asked if I should do it, or if I should wait until I gain some experience, and I was told to use it, and that 'everyone's doing it.'

What do you guys think?

Thanks.

BarracudaHockey

My Feedback: (11)

Why would you not want to do something to make the model fly better?

That said, I'd try 15 or 20 percent and see how you like the feel. Spectrum/JR needs positive expo, futaba needs negative to smooth out the center.

MinnFlyer

My Feedback: (4)

Ditto to what Andy said. Keep the percentage down to 15 or 20% and you'll be fine

Jetdesign

My Feedback: (8)

Thanks; I just don't want to get into relying on a radio to make me a better flier, that's all.

Osirisf16

Em...sorry guys but what do you mean by "expo"? And what is this positive ad negative you are talking about? Oh man, i forgot everything since the last time

Jetdesign

My Feedback: (8)

Expo, or exponential, is a setting for the responsiveness of the radio sticks. 0% exponential means that the servo responds exactly to the input of the stick as you control it. Increasing exponential means that the sensitivity around the 'home' position of the stick is limited. As you increase the movement of the stick, you get exponentially increased response from the servo. What this does is eliminate any 'jitters' you might have, i.e. if you are using elevator and your thumb gives just a little bit of aileron, exponential will make it so the receiver didn't really see any aileron.

gboulton

My Feedback: (15)

Expo changes the 'curve' of a control surface.

At "0 expo", which is to say no expo settings, move the stick halfway, the corresponding control surface (say, elevator) will also move 50% of its total travel.

Adding positive expo (usually..there can be exceptions) will 'slow it down'. moving the stick, say, halfway, will result in, for example, only 40% of the elevator's travel. in essence, it "slows down" the responsiveness of the surfaces, and thus the plane.

Negative expo has the opposite effect....a 50% stick movement might move the surface, say, 60% of its travel...making the airplane more responsive or 'twitchier".

There is, of course, a corresponding "spike" or 'flattening" of the curve at the end. If positive expo has the elevator moving only 30% of its travel for 50% of the stick movement, then the remaining 50% of the stick movement will have to produce the last 70% of the eleveator travel...so, near max stick, the surface becomes "hyper" responsive, as it were.

Exactly how much expo translates to how much movement dampening (or increase) depends greatly on the radio.

*EDIT* Sorry, Kat...i gotta type faster.
========================

Must agree with posters above...no reason not to throw some expo in. Saying 'don't mix things until you can fly without them" is, imo, like saying "Don't fly a trainer with dihedral until you can fly a sport plane without it". Ue the tools given to you to make your experience enjoyable and successful, imo.

Osirisf16

Ok, fully understand. Do the radios have that setting? Nice. I'm looking forward for a Futaba 7CH or the 9C but i can't really choose. I'm in the heli world too and i can't really know right now, so i must got some knowledge for everything. I think i'm full of heli knowledge, car no doubt and know, that's why i came here...KNOWLEDGE I must learnd ALL the basics and then go advanced

Jetdesign

My Feedback: (8)

Yeah it's a setting on computer radios. Something to think about (I don't know anything about heli's, so this may or may not matter) is that even if you don't need more than 7 channels, having 9 channels will allow you to mix more servos together.

Osirisf16

Yeah, normally a heli wants 6 channels but i want to leave spares IF I PROCEED TO HELIS for good What do you think? The Futaba 7C 2.4 Ghz or the 9C? Telling the truth, i prefer 2.4 Ghz technology, so i think i will skip the 9C and i will go for a 10C 2.4 Ghz. The bad is that is new, so the price must hurt

BarracudaHockey

My Feedback: (11)

Warning: This is a bit of high level useless info in case you care, not meant to confuse the original issue


The following assumes a FUTABA radio where Negative Expo makes the center LESS sensititive, JR/Spectrum is opposite...

@ gboulton: Actually, round servo outputs already have positive expo built in. The control surface responds more while the servo is centered than than at the extremes. About 22 percent negative expo or so acutally makes the control surface reaction, in relation to the stick movement, linear which is what I prefer.

@Osiris: if you want to fly helis get a heli radio, its easier to fly airplanes on a heli radio than vice versa. A DX7, 9C, or 9303 are all excellent choices, buy the best you can comfortably afford as a good radio will last you a long time.

@fatcat: If you paid for it, use it! Most of us don't drive automatics and go around manually shifting the gears up and down Learning how to take advantage of the features of your radio is part of learning.

Osirisf16

Em...i already made a thread about that man, if you can, copy it there but i want more info if you can, from you and from all of you Thanks, anyway

gboulton

My Feedback: (15)

True enough. I was trying to keep it simple. Should have pointed out that i was using a generalization, however, instead of spreading inaccurate info. Good catch.

flyX

well if you don't wanna rely on the Tx...just move linage closer to the center of servo.
What's suckie about that is...there's only so many holes on the servo arm.

ChuckW

It really depends on the plane. For a trainer, I see no need. With the throws set right, most of them are plenty docile. For a fun fly plane with monster control surfaces, on the other hand, it is almost a must for me. I know some really, really good pilots with years of experience who hate it though and refuse to use it on anything.

Charlie P.

I'm with ChuckW. A beginner shouldn't be trying a model so twitchy it needs negative exponential to tame the stick's midranges. That's also introducing radio alterations that take every bit as much understanding as the aerodynamic basics and a good start with the basics is, IMHO, preferred to jumping into "fancy" features before the simple ones are fully grasped. Most beginners lack the finesse of tiny stick movements anyhow and hit the stops in the control inputs.

Installing a servo so the control rod is perpendicular to the control movement axis at full extension (as opposed to perpendicular at neutral as most of us do for looks) also helps reduce that effect without programming.

RCKen

My Feedback: (9)

I'm with Charlie and Chuck here. At this level that we're talking about in this forum I think that expo should be avoided like the plague. If an experienced pilot uses expo he does it as an aid to his flying skills, but if a beginner at this level uses expo he's using it as a crutch to make up for lack of skills. One of the biggest things that a new pilot needs to learn to do is not over-control the plane. When expo is added it gives the pilot a false sense of knowing that he's properly controlling the plane. If a beginner is using expo he's going to more than likely need to us it the rest of the time he flies and will never really develop fully as a pilot. This is one of the biggest reasons why I recommend that beginners stay away from computer radios when they learn how to fly, so they can avoid the temptation to "cheat" like this. Without "cheating" a pilot will develop better skills by simply learning to fly the plane with the sticks, and they'll be a better pilot for it in the long run.

Ken

Jetdesign

My Feedback: (8)

Believe it or not I was hoping to hear this and NOT use the expo. I don't want to learn with training wheels. I'm not going to use it, at least on the first plane. The reason I asked is because my plane really wants to fly into the ground with the slightest bit of rudder, it's really insane, but now that I'm thinking about it my instructor used my radio and didn't have a problem with my plane. So the latter are right, I need to learn how to fly my plane w/o computerized help.

Thanks guys.

Cyclic Hardover

My Feedback: (3)

What about me?

To me, Expo makes the plane feel sloppy. I keep it around 10-20% neg. Whats happening is I like to have my plane respond when i move the sticks. The more expo you dial in the farther over the stick needs to go to have an effect on the control surfaces. If you were to fly a plane at zero for a while, then dial in 50% you'll be over controlling like a mama until you get use to it. Your making a right turn and you keep moving the stick right and right and right and nothing until wham-there it is.

ChuckW

This is very true. I think confusion is another big factor. Some of the programming available on high end radios can get pretty complicated. If you are still trying to figure out the basics, an added layer of complexity just makes it that much harder. I've seen people accidentally reverse a channel, screw up an end point adjustment, put the radio into mode one or something like that and not remember how to undo it. Their flying day can be ruined unless they remember to bring the manual or someone else is around who knows that radio. I have nothing against a computer radio, I typically use my DX-7 and love it. You just gotta take things one step at a time in my opinion.

Bob Mitchell

I can give you a good example of what you are talking about.

When assembling my Alpha 60 I needed to reverse the throttle servo. I took a look at the manual, saw a reference to "throttle reverse" and adjusted the radio per the instructions. As a result, when I got to the field to have the plane checked and maidened the throttle trim and throttle cut-off would not work. It took someone with decent knowledge of Futaba radios to un-do this and show me how to choose a specific servo and reverse it, for that model only. I don't know if I would have ever figured out why I couldn't kill my engine or adjust throttle trim without his help.

I too can fly my G4 simulator with ease on most of the planes, and land 'em. Big differrence between the PT-40 and the P51 in terms of throttle requirements on final. Even so, I welcome the assistance of our instructors. You never know when you might learn something.