but why the use of this extended metal tube? I read something about vibrations/pressure which set the fuze to go off in the air (above ground).
So, this kind of bomb should be dropped at high-pass speed, low attitude?
The Tail Retarding Device will slow it down travelling towards ground target. The metal extended tube....must have effect on the fuze to go off?
Developed for United States military forces in the 1950s, it was first used during the Vietnam War. The bomb consists of a cast steel case with 96 lb (44 kg) of Composition H6, Minol or Tritonal explosive. The power of the Mk 81 was found to be inadequate for U.S. military tactical use, and it was quickly discontinued, although license-built copies or duplicates of this weapon remain in service with various other nations.
Mark 81 Snakeye fitted with a Mark 14 TRD (Tail Retarding Device) to increase the bomb's drag after release. The bomb's increased air-time, coupled with its (relatively) forgiving safe drop envelope, allowed for very low-level bombing runs at slower speed. Used commonly in the close air support role in Vietnam (prior to wider availability of GBU-series precision ordnance). Nicknamed "snake", as in the typical Vietnam support loadout of "snake and nape" (250-lb. Mk-81 Snakeye bombs and 500-lb. M-47 napalm canisters).
hmm...why the purpose??
- internet: steel casing with a unitary "cast ductile iron" warhead and reconfigured burst height
The BLU-82 produces an overpressure of 1,000 pounds per square inch (psi) (7 MPa or 70 kg/cm²) near ground zero, tapering off as distance increases. It is detonated just above ground by a 38-inch (970 mm) fuze extender. This results in a maximum destruction at ground level without digging a crater.