Projectile M1A1 Illumination

Projectile M1A1 Illumination (illuminating) is a 155 mm artillery projectile designed to illuminate terrain at night or in conditions of limited visibility. Its use improves observation of the battlefield, helps to detect targets and to support combat operations.

Projectile HE M1A1 Illumination ERFB BT (Boat Tail) — belongs to the ERFB (Extended Range Full Bore) type, which means extended range thanks to the aerodynamic shape of the projectile body. The BT (Boat Tail) version (literally: boat tail) has a tapered rear section, which helps to reduce air drag, further improving range and flight stability.

Design:

1. Projectile body:
   • A strong steel body containing the illuminating charge and the parachute.
   • Equipped with special openings for even distribution of the light.
2. Illuminating charge:
   • Consists of combustible substances that provide an intense and long-lasting light flow.
   • Burning occurs without significant smoke in order to preserve visibility.
3. Parachute:
   • Made of heat-resistant material, it ensures a smooth descent of the illuminating charge.
   • Descent speed: about 5 m/s.
4. Fuze:
   • Installed in the nose of the projectile.
   • The fuze ensures functioning at the height required for effective illumination (usually 400–600 m).

Principle of operation:

1. After firing, the projectile climbs to the set height.
2. The fuze initiates opening of the body.
3. The illuminating charge is ejected together with the parachute.
4. The charge ignites and descends on the parachute, illuminating the terrain.

Application:

• Provides illumination at night for infantry operations.
• Detection of enemy positions.
• Coordination of fire of artillery and other units.

Advantages:

• Effective illumination of a large area.
• Ease of use.
• Can be used with various types of 155 mm guns.