Course Setting Bomb Sight

The Course Setting Bomb Sight (CSBS) is the canonical vector bombsight, the first practical system for properly accounting for the effects of wind when dropping bombs. It is also widely referred to as the Wimperis sight after its inventor, Harry Wimperis. The CSBS was developed for the Royal Naval Air Service (RNAS) in order to attack submarines and ships. It was introduced in 1917, and was such a great advance over earlier designs that it was quickly adopted by the Royal Flying Corps, and the Independent Air Force. It has been called "the most important bomb sight of the war".

The design found widespread use around the world after the war. A US version, the Mark III, was used by Billy Mitchell on his famous attack on the Ostfriesland in 1921. Similar designs were adopted by almost all air forces and used well into World War II. It was eventually replaced in British service by more advanced designs like the Mark XIV bomb sight and the Stabilized Automatic Bomb Sight. The US and Germany introduced advanced designs as well. Most other forces continued using vector bombsights throughout the war.