Bomb bay

The bomb bay or weapons bay on some military aircraft is a compartment to carry bombs, usually in the aircraft's fuselage, with "bomb bay doors" which open at the bottom. The bomb bay doors are opened and the bombs are dropped when over the target or at a specified launching point.

Bomb bays were born of necessity. Early military aircraft suffered severe aerodynamic drag (which would further slow down the already lumbering bomb-laden aircraft) with bombs hanging from the wings or below the fuselage, so military aviation designers moved the bombs inside the aircraft.

Before the introduction of stealth technology bomb bays were mostly used by dedicated bomber aircraft; in fighters and attack airplanes bombs and rockets were hung from the wings or fuselage on pylons. Notable exceptions are the F-101, F-102 and F-106 interceptor aircraft, all of which had bays used to store missiles, or other weapons stores. Today many designers have moved previously "external" stores into internal multifunction "weapons bays" capable of carrying air-to-air missiles, air-to-ground missiles, drop tanks, and other military "stores" and deploying them rapidly in a battle. The principal reason for the change is to use stealth technology to make aircraft more difficult to detect on radar. Military fighters are now designed to have the smallest possible radar cross-section, which has decreased very substantially since attention was paid to this feature. Large racks of missiles and bombs hanging below the wings return very distinct radar signatures which can be eliminated by bringing the weapons inside the fuselage. This also improves aerodynamic performance and increases the payload which can be carried and the range of the aircraft. Examples of modern U.S. fighters with weapons bays are the F-117 Nighthawk, F-22 Raptor, and F-35 Lightning II. These stealth aircraft such as the Chengdu J-20 use retractable guided missile launchers which move out on rails allowing the weapons bay to be closed while the missiles still hang outside.

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Wikipedia