RC Slope Soaring in Hong Kong

What is the advantages of V-tails over T / inverted T tails? I saw many "high class" gliders using V tails.

V-Tail is lighter and less drag than the other designs, and so it is usually used in competition gliders.

T-Tail is widely used in real gliders (and so the scale models). The main advantage is the good ground clearance. The bad thing is the heavier structure because of the bell-crank and the stronger vertical fin to hold the horizontal plane. Some said T-tail also has lower induced drag than the tradition cross tail but I am not sure about this.

(Inverted-T?!?) is the strongest in structure as the horizontal plane sits firmly on the fuselage. However it is not commonly found in gliders. Gliders have slim fuselage and so the main and the tail will probably be on the same plane. This will cause the tail works under the wash of the main wing, especially when the brakes or flaps are deployed. A modification of this design is the "cross-tail", that the horizontal plane is moved up to the middle of the vertical plane.

Thank you for your very "in-depth" explaination. Does V tail type glider roll faster?

Though the light weight and low drag V tail can benefit the overall maneuverability of an aircraft, but I think the roll rate depends very much on the moment of inertia about the roll axis and the efficiency of the ailerons.

So to have a fast roll, what you need is a pair of short and light wings with generous aileron surface, but not a V-tail!