I still work the flaps and throttle in combat, just not the rudder. I never learned how to do it, and what it DOES.
It's pretty simple... there are three primary flight controls:
1> Elevators (pitch)... this pitches the plane upwards or downwards
2> Ailerons (bank/roll)... this rolls the plane clockwise or counter-clockwise
3> Rudders (yaw)... this turns the plane left or right.. kind of like how a car turns
What flaps do is create turbulence which helps the plane fly more controllable at slower speeds, and can help to 'pull up' with more force (and could help with a last-ditch effort to increase the turn rate during a dogfight)... BUT at the cost of increased drag on the plane which means you'll lose E more quickly with flaps deployed which is why they are so useful for landing. They allow you to maintain control at the slower speeds required for landing, and also help you to slow down enough for touch-down.
Rudder control is actually used to turn the airplane on the ground (however some models have wheels that can turn left/right like a car as well). Flying without rudder control, while possible, makes it difficult to maintain fine control of the aircraft... such as lining up for landing, and pointing your nose in the proper place to get a good shot off on an enemy, or on a strat.
Although not really modeled in this game, it is not wise to fly in real life without rudder control, as turns require a combination of all three surfaces to keep the g-force fluctuations to a minimum, to make a more comfortable flying experience for passengers. A rudder only turn would force everyone in the plane to to left or to the right (like a hard turn in a car). Moving only the ailerons would cause everyone to fall to the left or to the right, and if you were to make a turn using only elevators and ailerons, everyone would be pushed down into their seats which while fun for some people, isn't exactly comfortable for everyone. Adding a bit of rudder into a turn not only makes the turn faster, but it also helps to stabilize the forces felt by the passengers.
Here's a pretty good 'novice' article about it all at wikipedia
HERE