I've started to play around with aircraft dynamics.. I am new to all this .. I have my craft hovering and controls are more like a helicopter.

here's a sample of code

function FlyForward (){
if (Input.GetButton("Forward")){ energy = Time.deltaTime * 50; rigidbody.AddRelativeForce (10,0,0);
rigidbody.AddRelativeTorque (0,0,-4); // tilt forwards print (" Forward Thrust Active "); }

I am trying to achieve stable turns. Currently my craft tends to yaw rather than bank. Is it ok to use rigidbody.AddRelativeForce as apposed to rigidbody.AddForce ??

AddForce is based on world coordinates. For a spaceship or airplane, it makes more sense to use AddRelativeForce, because the ship will move in its local direction - a jet will push the airplane to its forward direction, for instance. For an airplane, the gravity is the only world related force; for a spaceship, usually there are no world based forces.
But if you apply a relative force and a relative torque, the airplane may behave like an untied party balloon when we release its neck - the force will push it forward, but the torque will make the forward direction change.
A better alternative is to make the airplane model a child of the actual rigidbody: create an empty game object, add a suitable collider (box or capsule) and a rigidbody - this will be your actual airplane. Child the airplane model to it, and when necessary fake the banking by modifying the model's transform.localEulerAngles. Applying torque to a rigidbody usually isn't a good idea: the rigidbody spins instead of just turn to the desired direction. To turn left or right, for instance, it's better to rotate the transform with transform.Rotate - the rigidbody follows the transform, thus it will go in the new direction.