Base bleed

Simplified diagram of a base-bleed artillery shell reducing turbulent vortices
Diagram of a base bleed unit. The top diagram shows the bottom of the shell and the location of the gas vents. The bottom diagram is a cut-away view showing the gas generator mechanism.

Base bleed or base burn (BB)[1] is a system used on some artillery shells to increase range, typically by about 20%–35%. It expels gas into the low-pressure area behind the shell to reduce base drag (it does not produce thrust; if it did it would be a rocket-assisted projectile). Since it extends the range by a percentage, it is more useful on longer-range artillery where an increase of approximately 5–15 kilometres (3.1–9.3 mi) can be achieved, and it also was found that the reduced turbulence gave the projectiles a more consistent trajectory, resulting in tighter grouping, and efficient shelling more than 40 kilometres (25 mi) away.

Base bleed technology was developed in Sweden in the mid-1960s but took some time to spread and find its niche between cheaper classical ordnance and even more expensive rocket-assisted projectiles. It is now a fairly common option.[2][3]

  1. ^ Nguyen, Ductri (30 August 2011). "M1128 Insensitive Munition High Explosive Base Burn Projectile" (PDF). Department of the Army. Office of the Project Manager for Combat Ammunition Systems. Archived from the original on 13 May 2015. Retrieved 7 April 2023.{{cite web}}: CS1 maint: bot: original URL status unknown (link) (Public domain Public domain)
  2. ^ "155 mm HE ER FB-BB (OFd M3-DV)". MSM GROUP. Retrieved 29 July 2022.
  3. ^ YAKOUT, HASSAN; ABDEL-KADER, MOHAMED S. (14–16 May 1991). ASSESSMENT OF ERFB-BB PROJECTILE (PDF). FOURTH ASAT CONFERENCE. CAIRO, EGYPT: MILITARY TECHNICAL COLLEGE. MF-366. Archived (PDF) from the original on 2019-04-29.