Editing General-purpose bomb (section)

==Characteristics==
[[File:B-29 Weapons Bay with General-Purpose AN-M64 TNT 500 LB bombs.jpg|thumb|American AN-M64 500-lb general-purpose bomb in [[Boeing B-29 Superfortress]] weapons bay]]

General-purpose (GP) bombs use a thick-walled metal casing with explosive filler (typically [[Trinitrotoluene|TNT]], [[Composition B]], or [[Tritonal]] in [[NATO]] or United States service) comprising about 30% to 40% of the bomb's total weight.  The British term for a bomb of this type is "medium case" or "medium capacity" (MC). The GP bomb is a common weapon of [[fighter bomber]] and [[attack aircraft]] because it is useful for a variety of tactical applications and relatively cheap.

General-purpose bombs are often identified by their weight (e.g., {{cvt|500|lb|kg|disp=or}}). In many cases this is strictly a ''nominal weight'' (the counterpart to the ''[[caliber]]'' of a firearm), and the actual weight of each individual weapon may vary depending on its retardation, fusing, carriage, and guidance systems. For example, the actual weight of a U.S. [[Mark 117 bomb|M117]] bomb, nominally {{cvt|750|lb|kg}}, is typically around {{cvt|820|lb|kg}}.

Most modern air-dropped GP bombs are designed to minimize [[drag (physics)|drag]] for external carriage on aircraft lacking bomb bays.

In low-altitude attacks, there is a danger of the attacking aircraft being caught in the blast of its own weapons. To address this problem, GP bombs are often fitted with ''retarders'', [[parachute]]s or pop-out fins that slow the bomb's descent to allow the aircraft time to escape the detonation.

GP bombs can be fitted with a variety of [[Fuze (explosives)|fuze]]s and fins for different uses. One notable example is the "[[Daisy cutter (fuse)|daisy cutter]]" fuze used in Vietnam War era American weapons, an extended probe designed to ensure that the bomb would detonate on contact (even with foliage) rather than burying itself in earth or mud, which would reduce its effectiveness. (This was not the first instance of such devices. As early as [[World War II]], the [[Luftwaffe]] was using extended-nose fuzes on bombs dropped by [[Stuka]] dive-bombers and other aircraft for exactly the same reason. A blast several feet above the ground is many times more effective and has a far greater radius than one that is delayed until the bomb is below the surface.)

GP bombs are commonly used as the warheads for more sophisticated precision-guided munitions. Using various types of seeker and electrically controlled fins turns a basic 'iron' bomb into a [[laser-guided bomb]] (like the U.S. [[Paveway]] series), an electro-optical guided bomb, or, more recently, [[GPS]]-guided weapon (like the U.S. [[JDAM]]). The combination is cheaper than a true guided missile (and can be more easily upgraded or replaced in service), but is substantially more accurate than an unguided bomb.