Application and Advantages
A twin tail arrangement is generally used in aircrafts having twin engines for their propulsion. When a rudder operates behind a propeller, which is moved by twin engines, it requires an additional authority to set the aircraft along a specific course. This higher authority requires an additional control surface area which can come in direct control with the slipstream. Thus, the higher the surface area of the rudder, the better will be the rudder control especially at lower airspeeds.
Also “taxing", which is the movement of aircraft on land (or the runway), where the airplane uses its own power, is highly benefited by twin tails as they improve control and facilitate smooth turning of the aircraft by the pilot. Apart from this, a twin rudder also helps in solving issues related to hangar construction, and lateral firing area constraints in war planes.
In some of the fighter airplanes, where high speed is an utmost requirement, twin rudder design helps to reduce the overall weight of the aircraft. Also, if due to any unfavorable circumstances one of the two rudders fails, the aircraft can be controlled using only one rudder; however this is possible only up to a certain degree.
Many aircrafts during the world war era were made with the twin rudder arrangement. In fact, some of the aircrafts even had more than two rudders; but their usage and application were very limited. However, it is important to note that a twin rudder arrangement was only used for fighter aircraft and not for passenger or cargo planes.