Description
This projectile is fired from 155mm howitzers for battlefield illumination at night or during other conditions of reduced visibility.
The projectile is a hollow steel shell containing an illuminant canister, an ejection charge in the nose, and a parachute in the base. A threaded nose cavity is provided for an MTSQ fuze, and a lifting plug in installed in the fuze cavity for shipment and handling. The base of the projectile is closed with a steel plug retained by twist and shear pins. A center wire connecting the parachute suspension lines and the illuminant canister runs through the illuminant charge within a tube and is secured at the forward end by solder attachment to a release sleeve. The release sleeve is imbedded in the forward end of the illuminant assembly behind a first fire charge. A rotating band encircles the projectile near the base and is protected by a grommet for shipment and handling.
The projectile is gray with white markings. Later manufactured rounds also had a white band.
Functioning
When the weapon is fired, the burning propellant charge generates rapidly expanding gases to propel the projectile through the barrel to the velocity required to reach the function point. The rotating band engages the barrel rifling to impact spin to the projectile for stability in flight and provides a seal to prevent leakage of gas pressure past the projectile. Functioning of the fuze detonates the ejection charge. The ejection charge ignites the first fire charge and the illuminant while blowing out the base plug to eject the parachute and the illuminant canister. The parachute does not open until the burning illuminant has melted the soldered center wire from the release sleeve. Release of the center wire frees the parachute risers, permitting the parachute to open fully. This delay permits the canister and parachute to decelerate to a safe deployment speed. Suspended from the parachute, the illuminant burns for approximately 60 seconds with a maximum of 400,000 candlepower.
Hazardous Components
Filler - Illuminant composition (4.3 lb, 1.95 kg)
Propelling charge - M3, M4
Primer - Mk 2A4, M82, M199
Physical Data
Length, without fuze (M118A2) - 18.95 in, 481.3 mm
Length, without fuze (M118A2B1) - 18.9 in, 480 mm
See Also
Source(s)
TM 9-1300-203, Artillery Ammunition (1967)
