Bomber

A bomber is a type of airplane that is used to attack ground targets, mainly by dropping bombs. The first bombers were made at the start of World War I.

Bombers often fly low to the ground to confuse enemy radar. Most cannot fly very fast. Because of this, bombers are not outfitted to fight other airplanes. To make up for this, bombers in the past had many machine guns for defense. 

 World War II 
Dive bombers were numerous in World War II. They attacked surface targets including tanks and ships.
Strategic bombing became important. Bombers had large crews, sometimes as many as 12 people. Usually a bomber had a pilot, a bombadier, a co-pilot/navigator, and many machine gunners all around to shoot at enemy fighter aircraft defending the target. Friendly fighters often came along to help fight the defenders.

 Modern day 
Bombers now have one or two people in them. The other positions have been replaced by computers. Bombers have very few guns on them partly because they are much faster. In bombing missions now, the pilot drops a bomb and leaves as quickly as possible. During the Cold War, a few bombers were made that could travel supersonic, so a nuclear bomb could be dropped without killing the people in the airplane. They were never used that way, however.

 Other websites 
 WW2-era Bombers
 Bomber aircraft -Citizendium