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Figured that this was the better site to ask than drone SE, but if I'm wrong just let me know.
I'm making a spitfire model and was just wondering how do I do a roll? I have elevator, rudder, and two connected ailerons.
What control surfaces do I move to do a roll?
The ailerons should be connected so that they move opposite each other. When one aileron moves up, the other one must move down, and vice versa. In fact, in full-size aircraft, the ailerons are connected so that it's actually impossible to move them in the same direction*. So, to answer your question, to roll to the right, the right aileron must move up and the left must move down.
*Well, certain airplanes have "drooping ailerons": when the flaps are deployed, it causes both ailerons to tilt downward slightly. But this is about increasing lift at low airspeeds, it doesn't affect how the ailerons control.
To perform a roll maneuver in flight, there are essentially three choices.
The easiest is an aileron roll. For this, a small reserve of airspeed is needed above stall; the nose is raised and elevator neutralized, then full (or for some models, partial) aileron is applied in the direction of the desired roll. Elevator and rudder are kept neutral as the aircraft rolls, and if the roll rate is correct, the nose will have dropped about as far below horizon as it was lifted before the maneuver at the time the wings come level. Roll is then stopped with reversed aileron (not much is needed with a stable model), and the nose returned to level flight at nearly the same speed as entry. A variant of this, the barrel roll, carries up elevator through the entire maneuver, thus keeping positive G loading on the airframe.
Next is the snap roll. This is a stalled maneuver, essentially a spin in a horizontal direction rather than vertically descending. At 2x stall speed, the nose is raised sharply with rudder is applied in the direction of the desired spin. The wing will undergo accelerated stall at about 1.5G, the rudder input will cause the aircraft to autorotate. Rudder is reversed briefly to stop the roll when the wings approach level, and the elevator released to unstall the wing.
Most complex, and hardest to perform well, is a slow roll. This requires a similar reserve of airspeed to the aileron roll, but the nose is kept on the horizon. Aileron is used to roll the aircraft at significantly less than maximum roll rate, while rudder and elevator are coordinated to keep the nose level throughout the maneuver. Opposite aileron halts the roll (with elevator and rudder back to neutral) when the wings are level and aircraft upright once again. In order to keep the nose level, progressively increasing, then decreasing rudder inputs (toward the high wing), combined with progressively increasing and decreasing "down" elevator input as the aircraft passes through inverted flight, are required. When done well, the aircraft will appear to roll around an invisible string passing from the nose through the tail.
