Southern touch 99 is correct in observing that airplanes designed for aerobatics usually have little or no dihedral. There are two reasons for this, maneuvers involving inverted flight, and knife edge flight. With no dihedral, the airplane flies the same inverted as right side up. In knife edge flight, dihedral effect tries to roll the airplane away from the side slip and requires constant correction to resist the roll. In no case does dihedral affect rate of roll. Maximum rate of roll is determined by something called “roll damping” which is a function of wing area and span. To increase rate of roll, you can reduce wing span/area (clipped wing) or increase control forces (larger surfaces or greater deflection) but taking out dihedral won’t effect it. The airplane may feel like it’s more responsive due to the fact that you are busier on the sticks to fly the less stable airplane.

Another modification toward aerobatic characteristics is to move the cg a little aft. This will lessen the longitudinal stability, and make the craft more responsive in pitch. Seriously aerobatic planes are balanced just forward of the neutral point which makes them quite responsive but require a careful thumb not to over control.

As far as performance goes there are only two ways to achieve it, reduce weight or add power.

To make your trainer fly like a more advanced bird do the following:

1. Reduce the dihedral. This will make inverted flight and knife edge a little easier.
2. Clip one bay off each wing. This will increase the roll rate. It will also increase the stall speed, so be prepared to land a little faster. It also reduces available lift so what you gain in roll rate you will lose in loops and such.
3. Move the cg aft a little at a time until the pitch response is like you want. Go slow here. Too far and it might not be controllable.
4. If possible increase deflection of all control surfaces (up to about 45 degrees)
5. Get rid of all unnecessary weight. If you have used lead for balance, try shifting the batteries and servos around instead.

If you do all this you will be surprised at what a different airplane you have.