Advantages and Disadvantages

Aircraft built with two main wings (or three in a triplane) can usually lift up to 20% more than can a similarly sized monoplane of similar wingspan. Biplanes will therefore typically have a shorter wingspan than a similar monoplane, which tends to afford greater maneuverability. The struts and wire bracing of a typical biplane form a box girder that permits a light but very strong wing structure.

On the other hand, there are many disadvantages to the configuration. Each wing negatively interferes with the aerodynamics of the other. For a given wing area the biplane generates more drag and produces less lift than a monoplane.

Now, one may ask what is the specific difference between a biplane and monoplane? The answer is as follows.

A biplane has two (bi) sets of wings, and a monoplane has one (mono) set of wings. The two sets of wings on a biplane add lift, and also drag, allowing it to fly slower. The one set of wings on a monoplane do not add as much lift or drag, making it fly faster, and as a result, all fast planes are monoplanes, and most planes these days are monoplanes.