BLU-63 Submunition

1. Overview

The BLU-63/B is a United States anti-personnel fragmentation submunition developed as an improved design over earlier bomblets such as the BLU-26. Featuring a distinctive cylindrical body with enhanced fragmentation characteristics, the BLU-63 was designed for deployment from tactical aircraft dispensers to saturate area targets with high-velocity fragments. The weapon represents an evolutionary step in U.S. cluster munition development, incorporating lessons learned from Vietnam War combat experience while maintaining compatibility with existing delivery systems.

2. Country/Bloc of Origin

  • Country of Origin: United States of America
  • Development Period: Late 1960s-1970s
  • Manufacturer: Produced under U.S. Department of Defense contracts
  • Service: United States Air Force and Navy
  • Development Driver: Improved anti-personnel capability and reliability over earlier designs
  • Proliferation: Exported to NATO allies and various partner nations

3. Ordnance Class

  • Type: Anti-personnel fragmentation submunition
  • Role: Area attack against exposed personnel
  • Category: Cluster munition payload element
  • Primary Effect: High-velocity fragmentation
  • Delivery Methods:
    • CBU-52 cluster bomb unit
    • CBU-58 cluster bomb unit (some variants)
    • CBU-71 cluster bomb unit
    • SUU-30 dispenser
    • Various tactical aircraft platforms (F-4, A-6, A-7, F-111, F-16, F-15E, etc.)

4. Ordnance Family / Nomenclature

Primary Designation

  • BLU-63/B – Standard anti-personnel fragmentation submunition
  • Nomenclature Breakdown:
    • BLU: Bomb Live Unit
    • 63: Model number
    • /B: Standard variant suffix

Related Variants

  • BLU-63A/B – Improved variant with fuze modifications
  • BLU-63B/B – Further fuze or construction modifications

Related Submunitions (Same Generation/Role)

  • BLU-26/B – Earlier spherical fragmentation bomblet
  • BLU-59/B – Navy equivalent submunition
  • BLU-61/B – Combined-effects (fragmentation/incendiary)
  • BLU-77/B – Later combined-effects design
  • BLU-97/B – Modern combined-effects bomblet

Parent Munitions

  • CBU-52/B – Cluster bomb unit carrying BLU-63 submunitions
  • CBU-71/B – Alternative dispenser configuration
  • CBU-58/B – May carry BLU-63 or BLU-61 depending on configuration

Functional Position

The BLU-63 represents the progression from first-generation spherical bomblets (BLU-26) toward more sophisticated designs while remaining primarily an anti-personnel fragmentation weapon without the multi-effect capability of combined-effects munitions.

5. Hazards

Primary Hazards

  • Fragmentation: Primary kill mechanism; pre-formed steel fragments or scored casing produces hundreds of high-velocity projectiles
  • Blast Effect: Secondary; explosive charge primarily functions to project fragments
  • Penetration: Fragments can penetrate light cover, foliage, and unarmored surfaces

Sensitivity Concerns

  • Armed Fuze: Impact fuze armed during descent; unexploded items extremely dangerous
  • Fuze Condition: Dud submunitions may have fuzes in precarious partial-armed states
  • Corrosion Effects: Environmental exposure can affect fuze reliability unpredictably
  • Internal Degradation: Explosive fill may deteriorate, creating unstable conditions

Danger Areas

  • Lethal Radius: Approximately 8-12 meters for unprotected personnel
  • Casualty Radius: Fragments effective at 25-35 meters, capable of producing incapacitating wounds
  • Fragment Density: High fragment count creates elevated hit probability within danger zone

UXO Considerations

  • Dud Rate: Historical dud rates estimated at 5-15% depending on delivery conditions, fuze lot, and terrain
  • Persistence: Unexploded submunitions remain dangerous for decades
  • Concealment: Small size allows burial in soil, vegetation, and debris
  • Post-Conflict Hazard: Continues to cause casualties in areas of historical use
  • Scrap Metal Risk: May be collected by scrap gatherers, causing handling casualties

6. Key Identification Features

Physical Characteristics

  • Shape: Cylindrical body with conical or ogival nose section
  • Length: Approximately 100-115 mm (3.9-4.5 inches)
  • Diameter: Approximately 55-65 mm (2.2-2.6 inches)
  • Weight: Approximately 400-450 grams (0.9-1.0 lbs)

External Features

  • Body Construction: Steel casing, typically scored internally or containing pre-formed fragmentation elements
  • Nose Section: Houses impact fuze assembly; striker mechanism may be visible
  • Base Section: Closed base, may show assembly marks or crimping
  • Stabilization: Drag ribbon or fin assembly for orientation during descent
  • Surface Finish: Generally smooth exterior with visible seams

Color and Markings

  • Body Color: Olive drab (OD) is standard; may appear brown, tan, or corroded after exposure
  • Color Bands:
    • Yellow band indicates high-explosive content
  • Stenciled Markings: Nomenclature, lot number, loading date, manufacturer code
  • Standard U.S. Ammunition Marking Convention: Follows MIL-STD marking requirements

Distinctive Identification Points

  • Cylindrical shape with pointed nose
  • Visible fuze well at nose
  • Possible attached fabric ribbon stabilizer
  • Olive drab color with potential yellow band
  • Size approximately larger than a beverage can
  • Heavier than appearance suggests (dense steel construction)

7. Fuzing Mechanisms

Primary Fuze Type

  • Type: Mechanical impact fuze, all-ways-acting
  • Designation: M219 series or equivalent
  • Function: Detonates on ground impact; designed to function regardless of impact angle
  • Mechanism: Inertial striker released by deceleration forces on impact

Arming Sequence

  1. BLU-63 secured in cluster bomb dispenser during aircraft carriage
  2. Dispenser opens at pre-set altitude, releasing submunitions
  3. Submunitions separate and begin free-fall descent
  4. Stabilization ribbon deploys, orienting submunition nose-down
  5. Arming mechanism activates (spin-out rotor or inertial device)
  6. Fuze fully armed during descent
  7. Ground impact initiates striker, firing explosive train

Safety Features

  • In-Dispenser Retention: Mechanical systems prevent function while stored
  • Arming Delay: Time or distance delay ensures separation from dispenser and other submunitions
  • Arming Wire/Pin: May retain arming mechanism until removed by ejection forces

Self-Destruct/Neutralization

  • Standard BLU-63: Does NOT incorporate self-destruct mechanism
  • Critical Implication: Dud submunitions remain armed and dangerous indefinitely
  • UXO Consequence: Significant contributor to post-conflict unexploded ordnance burden

Failure Modes

  • Soft Surface Impact: Mud, water, sand, deep snow may fail to provide sufficient deceleration
  • Oblique Impact: Extreme angles may prevent proper striker function
  • Arming Failure: Insufficient descent time or distance
  • Manufacturing Defects: Fuze component defects preventing function
  • Environmental Degradation: Corrosion or moisture affecting mechanical components

8. History of Development and Use

Development Background

The BLU-63 emerged from U.S. Air Force and Navy requirements for improved anti-personnel submunitions based on Vietnam War combat experience. While the BLU-26 proved effective, its spherical design had limitations in certain tactical scenarios. The BLU-63’s cylindrical configuration offered different fragmentation characteristics and improved compatibility with newer dispenser systems.

Design Objectives

  • Enhanced fragmentation effectiveness
  • Improved reliability over earlier designs
  • Compatibility with evolving dispenser technology
  • Cost-effective mass production
  • Optimized fuze performance across delivery conditions

Combat Employment

The BLU-63 saw extensive combat use:

  • Vietnam War (late period): Area attacks against personnel, logistics, and defensive positions
  • Middle East Operations: Various conflicts involving U.S. and allied air power
  • Gulf War (1991): Used against Iraqi military positions and logistics
  • Later Operations: Continued use where cluster munitions remained authorized

Tactical Applications

  • Suppression of air defenses (SEAD)
  • Attacks on troop concentrations
  • Airfield denial and suppression
  • Logistics and supply point attacks
  • Area denial missions
  • Close air support (with appropriate clearance)

Comparison to BLU-26

The BLU-63 represented evolution from the BLU-26:

  • Shape: Cylindrical vs. spherical
  • Size: Slightly larger
  • Fragmentation: Optimized pattern for specific effects
  • Fuze: Improved reliability in some variants
  • Dispenser Compatibility: Designed for newer CBU systems

International Response and Treaties

  • BLU-63 use contributed to humanitarian concerns about cluster munitions
  • UXO contamination from BLU-63 and similar weapons documented in multiple countries
  • Convention on Cluster Munitions (2008) addressed such weapons (U.S. not a signatory)
  • Continued subject of humanitarian demining operations

Current Status

  • U.S. Inventory: Reduced stockpiles; older lots being demilitarized
  • Replacement: Superseded by more modern designs and guided alternatives
  • UXO Presence: Remains significant hazard in areas of historical use
  • Training Relevance: Essential knowledge for EOD and demining personnel

9. Technical Specifications

SpecificationValue
DesignationBLU-63/B
TypeAnti-personnel fragmentation submunition
ShapeCylindrical with conical nose
Length~100-115 mm (3.9-4.5 in)
Diameter~55-65 mm (2.2-2.6 in)
Weight~400-450 g (0.9-1.0 lb)
Explosive FillComposition B or Cyclotol
Explosive Weight~70-85 g
Fragment TypePre-formed steel or scored casing
Fragment Count~250-350 fragments
Fuze TypeM219 series all-ways impact
Lethal Radius~8-12 m
Casualty Radius~25-35 m
Self-DestructNone (standard variant)
Primary CBUCBU-52/B, CBU-71/B
Submunitions per CBU217-254 (varies by dispenser)

10. Frequently Asked Questions

Q: How does the BLU-63 differ from the earlier BLU-26 submunition? A: The primary differences are shape and design generation. The BLU-26 is spherical (“guava” shape), while the BLU-63 is cylindrical with a conical nose. The BLU-63 is slightly larger and heavier, with an optimized fragmentation pattern. The BLU-63’s cylindrical shape requires ribbon stabilization for proper orientation, while the BLU-26’s spherical design ensures function regardless of orientation. The BLU-63 also incorporated fuze improvements based on field experience with earlier designs. Both serve the anti-personnel fragmentation role without self-destruct mechanisms.

Q: What cluster bomb units carry the BLU-63? A: The BLU-63 is primarily carried by the CBU-52/B (carrying approximately 254 submunitions) and the CBU-71/B. Some CBU-58 variants may also accommodate BLU-63 submunitions. These dispensers were carried by a wide range of tactical aircraft including the F-4 Phantom, A-6 Intruder, A-7 Corsair, F-111, F-15E Strike Eagle, and F-16 Fighting Falcon. The CBU design opened at preset altitude, dispersing submunitions across the target area.

Q: Why doesn’t the BLU-63 have a self-destruct mechanism? A: The BLU-63 was developed before self-destruct technology was incorporated into U.S. submunition designs. Design priorities at the time focused on effectiveness, reliability, simplicity, and cost. The long-term humanitarian consequences of high dud rates were not driving requirements during the weapon’s development. Recognition of this problem—partly from BLU-63 and similar weapons’ UXO burden—eventually led to requirements for self-destruct in later designs and contributed to international restrictions on cluster munitions.

Q: What is the estimated dud rate for the BLU-63? A: Historical dud rates for the BLU-63 are estimated at 5-15%, though actual rates varied significantly based on delivery conditions, altitude, terrain type, fuze lot, and age of ammunition. Soft surfaces (mud, sand, snow) produced higher dud rates due to insufficient impact force for fuze function. These rates meant that in typical employment, hundreds or thousands of unexploded submunitions could contaminate target areas, creating persistent UXO hazards.

Q: How should unexploded BLU-63 submunitions be handled? A: Unexploded BLU-63s must be treated as extremely dangerous. They should never be approached, touched, or moved by untrained personnel. The armed impact fuze may be in a precarious state, and any disturbance could cause immediate detonation. Standard procedures require evacuation of the area, marking the location if safely possible, and reporting to military EOD or humanitarian demining organizations. Disposal typically involves destruction in place through controlled demolition rather than movement.

Q: Is the BLU-63 still in active U.S. military service? A: The BLU-63 has been largely superseded by more modern submunitions and precision-guided alternatives. U.S. cluster munition policy has evolved, with various restrictions on use and requirements for improved reliability. While some legacy stocks may technically remain, operational preference has shifted to weapons like the CBU-87 (with BLU-97 submunitions) or precision-guided alternatives. International pressure and humanitarian concerns have accelerated the transition away from older submunition designs.

Q: What are the key identification features to distinguish BLU-63 from similar ordnance? A: Key BLU-63 identification features include: cylindrical body approximately 100-115mm long and 55-65mm in diameter; conical/ogival nose section housing impact fuze; olive drab color with possible yellow HE band; visible fuze well at nose; possible attached fabric ribbon stabilizer; and overall size similar to a small beverage can but notably heavier. Stenciled markings in English with U.S. nomenclature format confirm American origin. Positive identification should only be attempted by qualified personnel from safe distances.

Q: Where has the BLU-63 contributed to UXO contamination? A: BLU-63 contamination exists in multiple regions where U.S. air operations employed cluster munitions. Significant contamination exists in Southeast Asia (Vietnam, Laos, Cambodia) from the Vietnam War era. Middle Eastern countries affected by various conflicts (Iraq, Kuwait) also contain BLU-63 UXO. Kosovo and other Balkan areas from 1990s operations, and other locations where U.S. or allied air power employed such weapons, may contain unexploded BLU-63 submunitions. Humanitarian demining organizations continue clearance operations in many of these areas.

Q: How does the BLU-63 compare to the modern BLU-97 submunition? A: The BLU-97 represents a significant advancement over the BLU-63. The BLU-97 is a true combined-effects munition incorporating shaped charge (anti-armor), fragmentation (anti-personnel), and incendiary effects—making it effective against a much broader target set. The BLU-97 also incorporates self-destruct and self-neutralization features intended to reduce UXO rates (though reliability remains imperfect). The BLU-63 is solely a fragmentation weapon without self-destruct. The evolution from BLU-63 to BLU-97 reflects both expanded capability requirements and humanitarian concerns.

This lesson is intended for educational purposes in professional ordnance training contexts. All ordnance should be considered dangerous until assessed and rendered safe by qualified EOD personnel. Never approach, handle, or disturb suspected unexploded ordnance.