When flying my plane I have trouble turning it. When I try to turn the plane it wants to drop down and lose altitude. How can I keep it from doing that?

All plane lose altitude during a turn. When you bank the wings the planes loses some of its vertical lift. To correct for this you have to use some up elevator to keep the plane level during the turn. Try making very shallow turns and experiment with how much elevator you have to use to keep the airplane at the same alititude throughout the turn. Hope this helps!

If using aileron and elevator to turn....add a smidge of rudder to hold the nose up through the turn.

As has been said the use of elevator is required to maintain altitude during turn. You will find during experimentation the more you bank and the more elevator you use the tighter the turn will be. Some will mention using rudder for cordinating the turn, true but not really necassary.

The rudder will be used to cancel out adverse yaw so you will need it to lower the nose. Mostly in a right turn. The nose will want to move in the opposite direction of the tunr due the drag of the raised wing.

Besides the stated above, look at a turn like this:

Gravity is ALWAYS pulling your plane straight down.

The wings of your plane are ALWAYS lifting in a direction perpendicular to them. That lifting force is proportional to the speed of the air and to the angle of attack (AOA).

When the wings get banked to turn, that SAME lifting force (perpendicular to the wings) is divided between one force pulling to the center of the turn, and one force pulling straight up and fighting the force of gravity.

Hence, this force pulling straight up and fighting the force of gravity is now less strong that it was before initiating the turn. As the force of gravity (weight of the plane) remains the same, the plane starts descending.

If you don’t want that to happen, which is good piloting practice (to achieve a turn without loosing any altitude), one of two things (or both) needs to be done by the pilot:

1) To feed up elevator (in order to increase the AOA and the lifting force of the wings)

2) To feed throttle (in order to increase the speed of the air and the lifting force of the wings)

The way each model looks while turning will tell you what to do with the rudder.

Regards!

What plane & transmitter are you using.

I have the mini super cub from E-Hobbies. It has a three channel transmitter. No ailerons. Only rudder and elevator and throttle. I will have to practice with my turns and giving it a little up on the elevator when turning.

With rudder-only control, beware of flying very quickly and using large deflections and angles of bank.
There is a coupling between yaw (the effect caused by the rudder) and roll (normally caused by ailerons).
The coupling is increased by having dihedral in the wings (ie the wings are not in a straight line).
If you have a large angle of bank and keep rudder applied then it will br trying to turn the nose downwards. If you apply up elevator to counter then you have the beginnings of a spiral dive.
Until you are really confident about the behaviour of the plane, apply gentle, but progressive, rudder inputs until you get to about 30 degrees of bank; then ease off the rudder until the bank angle stabilises. A touch of up should be all that's required to keep the plane level.