http://en.wikipedia.org/wiki/Adverse_yaw

Assume we are turning aircraft to the right.
Rolling an aircraft right, causes phenomenon known as adverse yaw of aircraft.

Cause is the disturbance in lift forces on both wings, also the rolling of wings.

Adverse yaw means that the nose of the aircraft keeps wanting to yaw towards the opposite direction of the roll.

This is bad because we want to turn to the same direction as the roll. (obviously)

Adverse yaw is bad news for turn rate, turn radius, and speed, it sounds like that to me.

We use rudder to counteract the effects of adverse yaw. And by using rudder right, when turning right, we are counteracting the adverse yaw because the rudder turns the nose to the same direction to the inside of the "curve", instead of nose being outside the curve.

Also, if you want to turn better, don´t do it at full RPM's. Plane will become much more stable, and less prone to get into a spin.
The YAW effect Laurwin describes, is better noticed when trying to turn in ROF with a Focker Dr I. If you master turning with that plane, you will do it automatically on il-2.

Also the effect described affects you if you are not with your wings perpendicular to ground. If you put your plane in that angle, you won´t suffer the climbing forces differential, but you will be loosing altitude very fast.

Also, if you try to correct the yaw effect with a high RPM, on the direction where the rudder instead of countering torque will add to its effect, you are far pone to enter into a spin, or be forced to loose more speed on the turn.
Every plane have a better turn direction, unless they are like the P38 with counter rotating engines.

usually best idea in IL-2 combat is to turn both in vertical and horizontal at same time. This kind of turning makes the most difficult target for enemy (oftentimes) and it gives good turn rate.

Either downwards diving turning, or climbing turn (or simply quick immelman, climb quickly to utilize vertical turning room)

Adverse yaw is because wing you raise has greater drag from higher AOA along the aileron portion of the wing.

First drop the nose a bit to reduce loading, drop prop speed to reduce gyro, then rudder and roll but even before halfway into the turn, once the turn is established bring the power up smoothly as you level off and bring the nose up so half the turn is dropping and the next half is rising unless you want to stay lower.

Non-horizontal turns are done at less wing load than horizontal turns because gravity orients down and the less perpendicular you cross gravity the less wing load you got.

It is good to learn how to get the most out of your aircraft in every situation it and you are in, but if you sit there staring at your balls in combat you are dead.

If you have a natural knack for flight sims then you should just be able to fly around and discover what is right on your own. If you have to think about what you have heard and read during combat you will never be an ace, your aircraft has to work for you as your limbs do, and your eyes have to be nowhere but on your opponent.

For a large extent this is true. In game for practical purposes, the ball slip indicator matters the most when you are shooting guns and aiming. But it was more of a flight physics idea to keep the ball centered. So it's like a theoretical idea.

If you fight 1v1 with both planes being exact copy, like 109 vs 109, then you get advantage from "flying pure" because flying pure with ball centered minimizes drag, and maximizes energy, for energy fighting purposes.

In theory at least... In practical terms you always have to spend energy to kill people in air combat so you cannot simply accumulate energy like money savings in the bank, you must spend that energy wisely and not let it sit hidden in bank vault!:grin:

Especially long range shots it's best idea to have ball centered. because side slip affect aiming point.

More side slip (yaw) creates more change in aiming point. Of course it would be a good idea to learn also particular aiming with the rudder use also!
Sometimes you have to use the rudder like that durring snap shot. Sometimes with focke wulf for example, you only need one good snap shot.

If you spend time practicing nothing but flying you will be able to only need to check once in a while. The rest of the time you will be able to tell from cues and the habits of your training will see you through.

How often do you check the speedometer when you drive? When I ran old VW's, the engine noise and gear told me most of the time. Those are cues.

Practice just flying to get good, get better and stay better. When you are concentrating on many other things, good flying needs to be done without much thinking --- it can be poor flying more easily by not practicing.

So practice flying where the enemy to watch for is everything that slows you down and find ways to lose less or not lose at all. Find out if you've fallen into making nose high mushy turns or skidding around. Find out what you're too busy to see in combat that leaves you thinking the others cheat.