Originally Posted by
SrTelemaster150
The rudder is used to keep the nose from pointing high or in other words to keep the tail from sinking. Most non-trainer type airfcraft will need the rudder to keep the axis of the fuselage poniting straight in relationship to the path of flight. As mentioned, it is not to prevent loosing altitude, that is the elevator's function. In a scale aircraft, it take ailerons, rudder & elevator for a coordinated turn.
For those that say the rudder is not for turning. Have you ever flown a 3-channel ship? A rudder that is roll coupled will also bank the aircraft when used. My Sr Tel;emaster had so much roll couple in the rudder, I used full cross control rudder/aileron for knife edge & just released the aileron & keep the (up) rudder in to roll out level.
I don't think anyone will disagree that you can use rudder to turn, as it will change the direction of aircraft flight.
You can also use the secondary effect of rudder very effectively to bank an aircraft. (3 channel aircraft without ailerons work this way)
As a training exercise, in real aircraft I would get the student to fly back to the airport and line up on final using nothing except rudder, elevator trim wheel and throttle. IE hands totally off the joystick (This was simulating a total loss of elevator and aileron control ). It was entirely possible to fly the aircraft that way and is easier than one might expect.
I also agree there are many applications where you deliberately would fly out of balance. But if we are talking about performing a smooth balanced 'efficient' turn in an aircraft the rudder is primarily there to balance adverse yaw and the turn is achieved by tilting the lift vector into the direction you wish to turn. IE Banking.
Yes you need more elevator to stop the nose from dropping as the lift vector is no longer vertical. The greater the bank the more elevator you need for a level turn. At 60 degrees bank you need to sustain 2 G for a level turn. That means twice the angle of attack you have in 1 G level flight assuming a constant airspeed, IE that's a lot of elevator,