Yes your plane will turn just fine without rudder. After all. Roll is the primary effect of aileron.

Rudder just provides that last ounce of finesse by balancing adverse yaw. In most RC models you will never notice the difference.

You do notice it in real aircraft by the seat of your pants and the balance ball.

In slow flying aircraft such as a scale ww1 bi-plane you really notice a big improvement in how they roll into and out of turns if you use rudder to counteract the adverse yaw.

Thanks, glad it helps, I fly a corporate Global Express, Sydney based but currently in the USA.

I still have a valid flight instructor rating though don't use it in my current job and have 3500 hours instructing aerobatics.

Good signature. From Flight of the Phoenix, one of my favourite movies when growing up.

I notice it when I fly R/C & see it in many YouTube videos too.

Of the races I have watched there wasn't any real prolonged knife edge flight. 99% of what I saw had the airplanes pulling positive G while 90 degree banked so I would have to say no top rudder was needed.

On most R/C models if the aileron differential has been worked out correctly there will be no adverse yaw. Please read that I said MOST models so please don't come back telling me your Cub, SE5, Curtis Jenny and such has to have rudder in the turns, there are exceptions to every rule. If your typical Kaos, Extra, ugly stick type airplanes have adverse yaw it's cure is aileron differential.

My Parkzone Albatros doesn't seem to want to bank at all with rudder only; maybe this is because it's got little to no dihedral. In fact, the top wing seems to have a little anhedral.

"Absolutely all of my model aircraft bank/turn just fine with no rudder input whatsoever."

I'm pretty sure that statement is accurate, within the context of the models a person has. I have five right now, and 60% of them can't turn at all without a rudder-the are 3 channel and don't have ailerons!!!!

I addressed aileron diferential already & as I stated, many ARF instructions have the servo arm @ 90° to the aileron control horn @ neutral W/the control horn coupling rotating concentrically about the hinge line. That does not achieve aileron differential.

Funny how all of the aircraft you cite as needing rudder input are scale while the all but 1 of those you cite as not needing rudder input are not scale & even that one is a short coupled aerobatic airframe.

Indeed, it seems that (at least for the aircraft you cited) scale R/C airframes that don't require rudder input are the exception.

I didn't mean to infer that all R/C aircraft need rudder input for a coordinated turn, but many do. It seems that a lot of post on this thread infer that rudder input is not needed W/O qualifying that many airframes do need rudder input.

As far as turning W/rudder only, where did that idea come from? On 3-channel (sans ailerons) the dihedrel & rudder geometry enhance rudder roll couple. My Sr Telemaster had rudder roll couple even after nearly all of the dihedrel was eliminated.

Most of what I have flown are IMAA legal giants & most of them are scale. I have yet to see any of them that won't turn better in a moderate banked turn W/@ least a small amount of rudder input.

Aileron differential certainly helps & yes they can be turned W/aileron only.

As a couple of us have pointed out before, rudder makes a plane bank because, when the rudder induces yaw, that yaw makes the plane bank because of the plane's dihedral. That's how three-channel planes turn. It doesn't look quite right, but it works, but that's because of the dihedral. Without dihedral, yawing won't create the bank and you'll get a skid. Whether a plane with ailerons needs rudder input to make a turn that looks good from the ground depends in large part on size (larger models tend to need rudder), on whether it has aileron differential, and on how much dihedral it has. My club has a plane which, before I built a new wing for it, had so much dihedral that giving it aileron input with no rudder would make it turn the wrong way (i.e. left aileron would make it turn right.) We call it the trainer from hell, and we use it only as a paintball target. As a rule, three-channel trainers have more dihedral than similar four channel trainers.

I don't think anybody in this thread is trying to discourage you from learning to use the rudder. We are trying to discourage you from getting into the habit of making ordinary turns unnaturally flat by using rudder and opposite aileron, because someday, if you routinely do that, it will cost you a plane. Once you've learned the right way to turn, you can play around with skidding turns, slips (useful at times) and lots of other things. But that video you watched is dead wrong.

You can set up an experiment very easily to test your if you plane benefits from a little rudder to counteract adverse yaw.

The Parkzone Albatross is a perfect model to try it with.

In your radio, set up an Aileron / Rudder mix - about 35%.

Note, its an Aileron / Rudder mix, so when you move the Aileron stick, the rudder will also move.

When you move the rudder stick, the ailerons should not move.

Assign the mix to a switch so you can disable it.

Take off as normal (mix disabled) fly a few circuits, then enable the mix and try the same. (your roll response will be faster and more precise)

Let us know what you think.

My friend has the Albatross and we both agree it flies much nicer with this mix.

Note - if you want to fly inverted disable the mix as it will be counterproductive when the wing is developing negative G.

Is this the video you are referring to?

https://www.youtube.com/watch?v=uUWZ1M9BxbA If so, I totally agree it is dead wrong. Very bad advice for beginners. Don't heed it.

Yeah, that's the one. Just crazy.

That's the one!!!!

Just after seeing it I made the post and said "after seeing that I thought I never know how to make a turn!"

And now after these 3 pages I'm completely convinced that I didn't!!

Thanks for all the input it's been useful. I need to tag this thread to come back to it some day

Regards

The R2160 is my favourite light plane, I have many happy hours doing aerobatics or flying over to France in it. I have even more hours in the R2112A but the extra power of the 160 transforms it. The Robins are lovely to fly, it's such a pity that most PPLs have only flown Pipers or Cessnas and have never known what it is like to fly a plane with such control response or view from the cockpit. Many years ago I was asked if I would take a chap up for a flight for his 80th birthday, it turned out he had flown Hurricanes in the Battle of Britain, he was so keen to handle a plane again, he gave the stick a little stir and exclaimed how responsive it was.

I am not a fan of aileron differential, believing it to be a model pilots' myth! Full size don't bother with it, because they found out decades ago it doesn't work well enough. A great example is the Tiger Moth which has a clever bellcrank system so that the downgoing aileron only moves down a little bit and then comes back upwards towards neutral. Despite this the adverse yaw is so bad that Pilot magazine said the term adverse yaw could have been invented just for the Tiger Moth. Huge differential, yet huge adverse yaw, showing the differential makes no practical difference. Full size designers then learned more and realised that aileron differential isn't a cure and they pretty much gave upon it, but like many things it persists in model flying. Many times model fliers have shown me their "adverse yaw" making a roll look uneven and then proceed to cure it with differential. But it wasn't adverse yaw, it was an offset roll axis. The roll looked uneven, they had heard the term "adverse yaw" so they put the two ideas together and claimed it as adverse yaw when actually the model had no adverse yaw and they didn't actually know what adverse yaw looks like! Differential then cured the off-centre roll axis so they claimed it had cured adverse yaw, which it hadn't because it wasn't! But it had now cemented in their minds that differntial cured advesre yaw. They also claim that the tail low in a turn is adverse yaw despite the fact they are not holding on any aileron, and adverse yaw by definition can only happen while the aileron is applied, which just shows they didn't understand what adverse yaw is. I can't say that differntial hasn't cured your adverse yaw, maybe it has, but my experience of what model fliers say has made me very doubtful because so many don't know what adverse yaw really is or looks like! Like the vast number of model fliers that say you hold in constant rudder towards the wind when coming in to land in a side-wind, far too many model fliers have not had the benefit of proper pilot trainin and have just learned bad myths and misconceptions from other similarly untrained model fliers. That video on youtube is a great example, someone who hasn't a clue is teaching innocent beginners everything wrong, indeed downright dangerous.

If I get a model with adverse yaw, and the lovely little Parkzone Albatross is a good example of it, I always program an aileron to rudder mix and adjust that until i can waggle the wings and the plane goes straight instead of wallowing.

The rudder is a very powerful control and it is easy to use far too much when trying to make small adjustments for slip/skid etc and you then over-control and change a slip onto a skid instead of getting it straight. In full size power planes the rudder control is very heavy and demands a lot of push, and that it makes it easy to control just small amounts of travel. So on my models I set a huge amount of expo on the rudder so that it is easy to control a small amount of travel and not over-control.

Not so, the rudder causes the same roll response no matter which way up the plane! You can, and I have often, fly a 3 channel model doing inverted circuits and the rudder behaves the same, right rudder means roll right. If the rudder's roll effect reversed at negative AoA then it would also reverse when upright and pushing well forward on the stick. Dihedral effect works the same whether AoA is +ve or -ve.

WOW, that's NUTS!

Just the opposite of what I learned, use ailerons to make the turn W/just enough rudder (in the same direction) to keep the tail from sagging (when needed) & just enough elevator to maintain altitude.

Think it through.. Apply left rudder and hold left rudder deflected.

Now freeze the plane inverted. When the plane is inverted and has negative G - (that is the key - negative G) the rudder is pointing to the right side (viewed externally)

Another way to think about it.. If you built a plane with a rudder underneath and an anhedral wing.. and you flew that aircraft normally.

Applying left rudder in this plane the rudder would move to the left. viewed externally.

But in our inverted scenario, the rudder was left (viewed externally, when upright, but when inverted, it is now deflected right, viewed externally) There is a difference.

yes the Robin is a sweet plane to fly. I owned one for 12 years and operated it with this flying school. http://www.redbaron.com.au

It was called "Sydney Aerobatic School" back then. The plane I owned was VH DXY http://jetphotos.net/showphotos.php?regsearch=VH-DXY

Lots of jokes from ATC when the 'red red robin comes bob bob bobbin along"

Some random video of Aerobatics in a Robin 2160

http://www.youtube.com/watch?v=A68tYY9AA9Q&feature=c4-overview&list=UUwIYggrxOH5IcBJm-QWfSlQ

That is a perfect way to describe it. I have the Parkzone SE5a and it flies beautifully with the Aileron / Rudder mix.

http://www.youtube.com/watch?v=swJO1aYo_YA

Harry, you crack me up. First off aileron differential does indeed work on models. To state that it does not just tells me you have not progressed into advanced R/C flying. Same goes for rudder application in a cross wind. There are several reasons why it may not work for full scale but does for models. I have stated time and time again to you well read full scale guys that flight characteristics between full scale and models is vastly different because of wing loading and power to weight ratios being so different. Others have not listened so i don't expect you to either. Imagine a world class R/C aerobatics guy walking up to Patty Wagstaff and telling her she is doing it wrong. Wouldn't go over very well I'm sure. I honestly don't see the difference between that and a full scale guy telling accomplished R/C pilots that we are doing it wrong. Some things work well with some models while not so much for others.

I am surprised you have fallen for that! Dihedral as viewed from the rudder is the same dihedral regardless of whether it is at a +ve or -ve AoA. Whether the plane is upright, knife edge or inverted is irrelevant. From the point of view of the rudder and yaw, dihedral is the same whether at a +ve or -ve AoA. Those of us who have flown circuits with a 3 channel model can confirm it!

Which proves to me you haven't been taught to fly if you apply rudder into cross winds, and the moment anyone says models are piloted differently proves they have lost!

Happy to discuss further, and yes, after reading this article I see your point. A few other factors I'd like to mention but unfortunately tied up now with work for the next 24 hours.

You are right in describing the effect of rudder with anhedral, but my case was the use of rudder to compensate adverse yaw, and the adverse yaw from the down going aileron changes when you change from positive to negative G. (and becomes more pronounced if you have differential ailerons.

http://www.aeroexperiments.org/dianposneg.shtml

Harry, you are missing the point. Models are piloted differently because they are piloted from the ground. If you are a competition pilot such as myself you want to keep the airplanes track parallel to the runway. Using rudder to do this will not result in a downgrade from the judges. Leaning the wings into the wind will result in a downgrade. So now I suppose the entire IMAC judging guide is wrong? Again. we are talking MODELS with less wing loading, more power, higher G loads in operation. Not everything full scale can me laterally applied to our models and vice versa. Please sir DO NOT tell me I am piloting my MODELS wrong, I have a wall full of trophies that would imply I am not.

Ah I see, and agree. I thought you were saying that the rudder yaw-roll effect reversed at -ve G.
As well as that, aileron differential reverses at -ve G and would multiply up rather than reduce adverse yaw, yet it is surprising the number of people with aerobatic models who claim the differential helps when inverted, or at zero G like keeping the plane straight in a vertical climb! People convince themselves of what they want to see!

You're wrong!
And here's why.
The fact that you are piloting it from the ground is irrelevant, a full size pilot in the same situation would do the same as you have done, and in that situation I would also do the same as you whether I was flying a model or in the full-size..
But... you are not doing a turn as discussed here. you are doing a deception for the sake of the ground based judges. You are off line and want to turn to regain the line but don't want it to be obvious to the judges, which it would be if you banked for a proper turn. So you do a "flat" or "control-line turn" yawing the plane out of balanced flight and holding the wings level. That's an aerobatic manoeuvre in its own right, it is not a proper turn and you would never normally do a turn like that. It's not a turn, it's a deception for the ground based judges. It's a result of the judges' rules, if they changed the rules not to downgrade you for it, you would bank.

On a separate point, the misunderstanding of rudder and side winds amongst model fliers is stupefying. One day at my model club a full-size Piper Warrior flew directly overhead in a cross wind. I knew that because it was not pointing exactly the same way it was travelling, it appeared to be crabbing. The Chairman of our club looked at it and announced that the pilot must be having to hold on a lot of rudder against that crosswind!!! The Chairman of the club, a chap who had taught, or rather mis-taught, lots of innocent beginners with such rubbish. he seriously believed the pilot was holding in rudder all the time!!!! And since the beginners have been told it by no less than the Chairman, the chap who "taught" them to fly, they believe it like a religion and you just can't do anything to show them it is wrong. Sadly every model club has lots of instructors who haven't a clue, like the one in the youtube video, but they pass on their rubbish and the beginners cling to it so hard they just can't be shown it is wrong. They will tell you if you hold on rudder you can do a flat turn, but that magically if you hold on rudder during approach to landing the model will go straight and they just can't accept they are contradicting themselves, they think that planes have some magical knowledge that they are coming in to land rather than just flying by and that somehow the plane's reactions to the rudder control magically changes. They will argue quite vehemently that you hold on rudder into a crosswind when on approach to land, and model clubs and internet forums are full of that nonsense which is clung to like a cult religion.

As to those who claim "models fly different to full-size" what tosh! Every model I have flown has handled the same way as every full-size I have flown. How does an aeroplane know it is a "model" or "full-size"? Answer - it doesn't!!! There are full size planes so small and models so big that the models are bigger than the full-size. But if models fly differently then the model which is bigger than the full size will fly like a model, differently to the full-sze that is smaller! Tell me, at what point does an aeroplane know it is a model so that it knows to use some mythical set of handling laws that apply only if it is a model even if it is bigger than a full-size? There is no such thing. Size matters due to things like reynolds numbers, mass, wing loadings but at no time does a plane ever know that it is a model or full size, it has no way of knowing, there is no such distinction in the laws of physics or the rules for piloting a plane, it is word applied purely by humans to denote the plane's use