Is it possible to control an airplane with a 40" or less wingspan with ailerons ONLY for turning and having a fixed rudder?

Yes, you can fly all day without needing any rudder. The rudder (for beginners) is mainly to keep the plane pointed straight while taking off. You can't really steer with ailerons on the ground. But if you have a plane that takes off really quickly or is hand-launched, you don't need the rudder.

It was my understanding that ailerons were for rolls only and that rudder was for turning. Guess I was mistaken.

crank the aileron so that one wing is lower than the other, and pull back on the elevator at the same time and you can do a nice turn......the aileron can be used for more than just rolling, and the rudder can be used for more than just turning whe u get into more advanced aerobatics

Parkzone P51D has no rudder, it is a option.

No rudder use? How would you manage crosswind landings?

Models made without rudder for simplicity normally lack landing gear and land on the belly against the wind.
Combat RC planes fly with no rudder.

In general, they are also fast models with low drag, so the non-coordinated turns are not too ugly.

Ailerons are used for turns. Elevator is also used due to the fact that some of the lift is now being used to turn the A/C. Rudder is only used to compensate for some of the side effects of maneuvering, such as adverse yaw and P-factor. In most smaller planes these side effects are subtle and don't need to be corrected for successful flight. Your best course of action is to read up on the basics of flight before you get into the air. It can be the difference between a good experience and a bad one.

A lot of the answer to your question depends on what plane you are talking about. Some planes turn better with ailerons only than others do. The big limit you'll see by not having a rudder is you can't handle nearly as much wind. When turning from upwind to downwind, the wind pushes your tail out of the turn, forcing you to roll nearly sideways and use the elevator to get through. That works, but it makes for such nicer turns (and far less stall prone) to be able to horse it around with the rudder.

Gusts can do what you describe as can turbulence, but a turn from upwind to downwind will not affect the plane in any way. The amount of wind makes no difference unless you have to land and T.O. in a certain direction forcing a crosswind landing. Rudder does not help avoid a stall, but can make the stall less likely to develop into a spin. The key to flying a plane without rudder is to keep the speed up and T.O. and land into the wind. Aircraft designed to fly without a rudder will tend to have a larger vertical surface and some washout in the wings to increase low speed stability. Aileron differential is also advisable.

Turns should be done with coordinated rudder and aileron otherwise you are "skidding" around a turn. When I was taking flying lessons, I got to know exactly what "step on the ball" meant. Rudder management is essential in take-offs and landings as well....to fly with ailerons only is just lazy sloppy flying.

aileron VS rudder?? That makes a knife edge. LOL

The type of A/C the OP is talking about are generally hand launched and don't usually have a rudder to save weight, space, and limit complexity. They don't carry passengers and are intended to be for fun at small fields, so the whole rudder thing is really not necessary. Small .049 powered rudder and elevator only planes have been flow for decades, and you would never operate a full scale that way either. These small planes are for fun on a budget, or when you just want to throw it in the car and go, don't take it to seriously.

cfircav8r - What I was talking about was how in the middle of a gentle turn at the end of the upwind leg of an oval pattern the wind pushes on the vertical stabilizer producing some adverse yaw. It can be overcome by simply rolling more and yanking the elevator, but the right response is to use the rudder. The stall I'm referring to is a sideslip which I have seen happen on training nights multiple times when pilots over roll their planes to tighten up a turn and their airspeed is low because they've just been flying into the wind. Using the rudder helps to avoid that situation and will let the pilot make a nice graceful turn instead of the bank and yank that ends in a 10-15 foot dive and recovery. Obviously, more speed oriented planes and planes designed to be flown without a rudder aren't nearly as prone to this, which is why I said that the answer to the OP's question is plane dependent.

Gusts and turbulence affect an airplane in flight as you described, no matter what turn you are making. Wind only affects ground speed and track, nothing more. A stall in a turn without proper coordination can result in an incipient spin/spin, but the stall would happen with or without rudder if you get too slow. It doesn't have to be an inherently fast plane, you just need to mind your speed. At that sized wingspan just about any plane can be set up without a rudder some just need a little tweaking.

I believe the original thought here from a poster that has yet to fly RC, let alone solo, is in the theory of what would happen if a plane was flown without a rudder.

All the advanced theory is great information, but is not going to help him learn to fly. And, there are plenty of planes with under 40 inch wingspan that have all four controls - rudder, aileron, elevator and throttle, including most glow powered trainers.

The point I am making here is that if a student pilot has a plane with all four controls, he/she should learn to fly with all four controls, including the rudder. Once the student has learned the basics, has solo'ed, and has gained a little wing time, then it's time to experiment.

I fly with only aileron input at times, and at times, I do flat turns with only the rudder with opposing input using the ailerons to keep the turn flat. It's fun and entertaining, but useful? I don't know about that.. it can be "dangerous" if the pilot isn't careful.

But, for a new person to fly without the rudder is something that I wouldn't teach them to do, at least not until the person has had the advantage of quite a few successful flights.

CGr.

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If you look a his profile he has a standard .40 sized trainer but shows he has an interest in .049 scale. I was guessing he was asking in anticipation of working on a project. It is nice to know what to do before you start. As you said all of this will be of benefit after he has some stick time on a good 4ch trainer.

I am following your thread and have the opposite question. I am just finishing up a PT-20 trainer kit. There is an option to include the ailerons or lock them. The ailerons are to installed, but the servo is left out and the ailerons are fixed in a neutral position. The servo can be installed and the lock removed at any time.  I have zero hours of flying time and intend to start to learn. Would it be better to go ahead and install the servo when I start or go ahead and learn as a three channel plane?

Thanks for your advice

Jim

Yes!

If you plan to move ahead and flying more, youll eventually use ailerons.

BTW, my first solo was with a PT-20 and the worst kit I ever built. [X(]

Important! If you have not already built the wing check to see if it has the option of a smaller dihedral angle with ailerons or greater for use without ailerons. I would strongly suggest, if you have help, using the ailerons from the start. If you don't have help I would strongly suggest getting help and using ailerons. If you build it with a greater dihedral angle it will not perform as well later when you progress into more advanced maneuvers. With an instructor the smaller dihedral will still be sufficiently stable to learn easly.

Jim

YES!!!!!! Definitely.

Learn all four channels. It just makes sense to learn how to control it now with ailerons. You can always leave the aileron in the center position and fly with rudder only if you so desire, but learning all four channels now is definitely the way to go.

CGr.

Interesting discussion!

One thing I didn't see mentioned is the fact that rudder is the first and last control surface to be effective.

The rudder is the primary control for spin recovery to stop the rotation while down elevator is used to break the stall condition; this is particularly important with aircraft that are dynamically unstable ( not wanting to easily recover from spins). During approach and landing rudder is used to perform both side and forward slips; a primary control in aerobatics. Rudder is used to perform coordinated flight while turning and useful in other flight regimes. Such as sluing gun sights on target during aerial combat or strafing in military applications.

So yes, rudder is far more important than just a control for takeoff and landing ground handling.

IMHO using the a ailerons only in turns is a bad habit. Most advanced models- like scale love rudder for the turns. The rudder is not just for ground control. Get in the habit in using your rudder in flight, you will become a better pilot if you do.

I once did some of my turns in a full scale plane by aileron and elevator and my instructor yelled at me. He said " This ain't a radio controlled plane!" I got in the habit ever since using both aileron, rudder and elevator on all my turns for both R/C and full size ever since then.


Pete

I asked basically out of curiosity and you have answered my question and I thank you. I will not be switching any of mine over to aileron only. Thank you again.