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Inert bombs -Spears, Tridents and Darts.

Updated 29-3-11

        Inert bombs have been suggested to minimise collateral damage. The RAF has experimented with the field expedient of filling bomb casings with concrete but this is neither the most efficient or cheapest way to make an inert bomb. Inert bombs can be classed as Spears, Tridents and Darts.

        The Spear is nothing more than a steel girder or length of railway line fitted with a seeker head and some stabilising fins. It will be long and narrow in cross section and probably look more like an AAM than a bomb. This sort of bomb will be used against the hardest targets such as bunkers.

        The Trident is made of three projectiles like the Spear but with one seeker head. There are two modes of use. The first is for the three sub units to stay together and just break apart on impact, helping transfer their energy to the building that they hit. The second mode is for them to separate at a pre-programmed altitude. Ideally this altitude is calculated so that the components have dispersed just enough so that the shock areas produced by their impacts overlap.

        Darts are finned projectiles the size of a pencil held in a plastic capsule. At a preset altitude the casing opens allowing the darts to disperse. These are a simple but effective weapons for use against personnel and lightly armoured or soft-skinned vehicles.

FEEDBACK
My Friend Ed Sackett writes:

        You can build a better inert heavy "bomb" than a length of railroad iron (although that's an ingenious field expedient) by visiting any large foundry and buying some cylindrical billets of steel. These will cost much less per pound and will have better secional density. All foundries produce them as raw material for manufacturing. I believe the Ford foundry in Inkster would gladly ship as many tons as the RAF can use.


        Ed also points out that the proposed Dart system is essentially a Cluster Bomb of inert submunitions.

        How about inert bomblets? Say 50-lb billets of steel w/ fins on them: container opens, projectiles scatter just enough, and impact w/ a whump. If you accelerate the cluster w/ a small rocket booster just before it opens, you can hit a target at ~2500 fps imho. No unexploded munitions afterward, no peasants blowing themselves up years later, no clever gooks extracting TNT from duds and using it on us.

UPDATE
        During Nam, the Rand Corp. persuaded the USAF to try dropping "bomblets" (a term later applied to cluster munitions) from B52s. These were also called “Lazy Dogs”. These were solid steel gizmos shaped exactly like WW II general-purpose 500 lb models, blunt body, tail fins, and all. They were about 2” long, weighed a few ounces and achieved a terminal velocity somewhat slower than a .45 ACP. The idea was to leave Uncle Ho wondering fearfully why people were dropping dead when there was just a whisper of engines in the sky far above. Didn't work worth a goddamn.

         Half of the problem is no doubt once dropped from a B52's altitude they'd be so dispersed that there was only a randon chance of being hit. This article indicates that Lazy Dogs were used from more practical platforms than B-52s. Lazy Dogs can still be found for sale on ebay. (right)



        The models used in WW1 seem far better designed. A typical one would be 3-5” in length and about 8mm diameter -a velocity of 150m/sec is quoted if dropped from 2000m and 100m/sec if dropped from 1000m.

        The book Winds of destruction: the autobiography of a Rhodesian combat pilot By Peter J. H. Petter-Bowyer on page 301-2 describes experiments with darts made from 6” nails. Two cansisters, each of 4,500 darts released at 450kts resulted in 9,000 darts landing in a 900 metre long by 70 metre wide area. A projectile density in one second equivalent to the fire of 450 .303 Browning Machine Guns.

        Flechette rockets such as the M255 2.75” FFAR containing 2,500 28gr (1.8gm) or 1,180 60gr (3.9gm) Flechettes will be familiar to many readers. A not so well known variation on this idea were the 68mm SNEB and 100mm rockets produced by the French company Thomson-Brandt (later Thomson-CSF). These contained heavier darts or fleché designed to destroy lightly armoured and soft skinned vehicles. Types marketed included:-

68mm SNEB rockets

Multi-Dart ABL 261-8: Each of the 8 dart sub-munitions is 13.5mm dart (0.53”) in diameter and 270 mm (10.63”) long with a weight of 190 g (6.7oz). Range 1,500-2,200m. Dart velocity at 1,800m is 500m/s. Penetration up to 15 mm (0.59”) of armour.

Multi-Dart 261-36 AMV: Each of the 36 darts is 9mm (0.35”) in diameter and 132 mm (5.2”) long with a mass of 35 g (1.23oz). Range 1,500-2,200m. Dart velocity at 1,800m is 400m/s. Penetration up to 8 mm (0.315”) of armour.

Thomson-Brandt 100mm rockets

Multi-Dart 100mm AB 24: Uses 6 darts each 24mm (0.94”) in diameter and 548mm (21.57”) long, 1.65 kg (58.2oz) weight. Capable of penetrating up to 80 mm (3.15”) of armour.

Multi-Dart 100mm ABL (Light Anti-Armor): Uses 36 darts each 13.5mm (0.53”) in diameter and 270mm (10.63”) long, 190gm (6.7oz) weight. Capable of penetrating up to 15 mm (0.59”) of armour.

Multi-Dart 100mm AMV (Anti-moving vehicle): Uses 192 Darts each 9mm (0.35”) in diameter and 132mm (5.2”) long, 35gm (1.23oz) weight. Capable of penetrating up to 8 mm (0.315”) of armour.

        A 22 round pod of 68mm AMV rockets each with 36 darts would in 4.5 seconds blanket an area 1,000m x 70m with 792 darts. Maximum speed of a 68mm AMV rocket is 760 m/s (2 493 ft/s). No reason why a properly designed dart would not remain lethal after punching through the average roof.

         On the original subject, which was full sized “solid” bombs, the only drawback I can see is that these would need to be dropped from altitude so would be the weapon of high flying bombers rather than the tree top hoppers. The Germans made some use of the Röchling anticoncrete round fired from a battlefield 210mm gun . Tests on captured French and Belgium forts proved it could go through earth cover, concrete burster plates, concrete roof (often 10m thick), the room below and through the floor before detonation. It may be that our solid bombs are too good at penetration and will need to be designed so they break up on impact to transfer some of their energy.

CBU-107 Passive Attack Weapon
CBU-107 PAW

        Payload: 3,750 non-explosive steel and tungsten penetrator rods of various sizes:-

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