M118 (T55) Demolition Bomb
Project Combat Trap
The M118, originally designated as the T55, was a 3,000 pound demolition bomb developed in the 1950s as a weapon for the first and second generation of high performance jet fighter and attack aircraft. Compared to weapons from World War II, the weapon had an aerodynamic design intended to produce lower drag when carried externally. The weapon continued to serve into the 1970s, until it was completely replaced with newer types of bombs in its weight class, like the Mk 84 2,000 pound bomb.
The M118 was also used at the beginning of Project Combat Trap, a program intended to develop a means of rapidly clearly helicopter landing zones in Vietnam of foliage and traps. On 20 November 1967, the Military Assistance Command, Vietnam (MACV) Scientific Adviser Office requested assistance from the Southeast Asia (SEA) Mobile Explosive Ordnance Disposal (EOD) team at Tan Son Nhut Air Base in South Vietnam in helping to design a method for explosively clearing helicopter landing zones in heavy jungle terrain. Under what became Project Combat Trap, it was decided to try the M118 bomb for this purpose.
On 9 December 1967 the bomb, together with the necessary equipment, was flown to Dak To, in northwestern II Corps Tactical Zone, and placed nose-down on a wooden rack 20 inches above the ground. Later in the day, an Army CH-47 helicopter airlifted the platform and lowered it onto the selected site in heavy jungle near Dak To, while EOD personnel set up booby traps at distances of 10, 50, 100, and 150 feet from the bomb. On 10 December 1967, when the EOD team detonated the weapon, the jungle was cleared for an area about 150 feet wide, and all booby traps were either detonated or disabled by the blast.
As a result of this evaluation, MACV directed Seventh Air Force to develop the capability of delivering specialized ordnance for clearing such heavily-jungled areas. Use of the Ml fuze extender on Mk 84 and M118 bombs gave Seventh Air Force a partial capability in this direction. The 10,000 pound M121 was later determined to be suitable for the Combat Trap mission and eventually the 15,000 pound BLU-82/B was developed for what had by then become Project Commando Vault.
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