CLUSTER BOMBS
- Cluster bombs, incendiaries and fragmentation;
Single incendiary dropped from high altitude were ineffective; fires were too scattered to create the "firestorm effect" that had been observed in Germany. The AN-M76 bomb would still be used, but most incendiary ordnance was to be made of smaller incendiary projectiles, "bomblets", on the principle that many fires are better than one, no matter how big the bomb.
The most used would be the M47 100 lbs chemical bomb;
The body of this bomb is made of 1/32-inch sheet metal rolled and lap welded into a
cylindrical shape 8-inches in diameter. The nose is hemispherical and welded to the body as is
the box type tail fin assembly, which forms the tail taper of the bomb body. The over-all length
is-45 inches excluding fuze. The burster well is screwed into the bomb body by means of pipe
threads to make a gas-tight seal at the nose. It is held in place at the tail of the bomb body by an
attached cone in the inner side of the fin assembly. It is internally threaded to receive a sleeve,
which has a groove in its lower portion to seat the fuze, which is pressed in place. Around the
bomb body are two suspension bands 14-inches apart which provide suspension lugs for
horizontal suspension. One blade of the fixed box type tail assembly is in line with the
suspension lug.(...)
The Bomb may be loaded with an incendiary filler of rubber and gasoline in the field. The
base filling is gasoline supplemented by one of the four different incendiary ingredients as
follows:
1. LA-60. Consists of crude latex or sap in combination with caustic soda, coconut oil, and
water
2. Crepe rubber (CR). This is crude latex but is reduced to a solid by precipitation and
kneading.
3. LA-100. This is crude latex dried until it is approximately 100 percent solid.
4. Smoked rubber sheets (SR) a crude latex, which has been dried over a smoky fire until it is
approximately 100 percent solid.
When loaded with the incendiary filler the Bomb Fuze M108 (Nose) with a 1-pound black
powder Burster Charge M7 is used. This burster charge bursts the bomb and scatters and ignites
the filler. When filled, the body weighs 85 pounds of which 65 pounds is incendiary filler. This
is a typical example of the scatter type of incendiary filler.
(...)
The M47A1 was designed to replace the 100-pound M47. The M47 was found to
have too thin a wall section, and in handling and storage, it developed leaks due to corrosion and
rough treatment. Consequently, the wall thickness was increased from 1/32 inch to 1/16 inch, and
coating inside with acid-proof black paint protected the case. This special inside coat of paint
was to provide a resistance of 100-pound pressure.(...)When loaded with Incendiary Oil, it weighs
94 pounds, of which 65 pounds is incendiary oil.
Anonymous, BOMB, CHEMICAL, 100-POUND M47 SERIES, PDF available
HERE
The bomb had many shortcomings;
(...)The M-47, a 100-pound gasoline jell-filled, could not be carried in economical loads in either the B-17 or the B-24, and it had too much trail to be set into the bombsight with the bombing tables then available. (Trail is the lagging of the bomb behind the plane, caused by the resistance of the air.)
Charles W. McArthur, Operations analysis in the U.S. Army Eighth Air Force in World War II, American Mathematical Society, p. 65, extracts found
HERE
The operations' analysts found ways to compensate trail with a "false disc speed" inserted in the bombsight. Since bombing in Japan was to be done at low altitudes against areas, pinpoint accuracy was not a problem. But their best "invention" was a simple and effective way to bunched together six bombs in a single bomb station;
They (the analysts) worked with the Ordnance and Chemical Warfare Sections to devise ways of loading the bombs to achieve maximum loads. In particular, the subsection succeeded in increasing the loads of M-47 incendiaries. With little help from the States, the Eight Bomber Command , particularly the Chemical Warfare Section, developed and had manufactured its own equipment for increasing the loads of the M-47s by clustering the bombs on their racks.
Charles W. McArthur, Operations analysis in the U.S. Army Eighth Air Force in World War II, American Mathematical Society, p. 65 - 66, extracts found
HERE
This "equipment" is well describe in the following pictures and was extensively used in B-29;
PICRURE HERE; This is the "kit" invented to load one 500 lbs bomb station with six M-47A1 bombs; a marvel of ingenuity and simplicity, all rolled in one. The first bomb was hanging "normally" under the shackle. Ten steel cables (two per bombs) were hanging by a crimped large loop going over the lugs of the first bomb. At the other end of each cable, a springhook to be attached to the suspension lug. Each pair of cables was of a specific length for each bomb. Upon release from the shackle, each loop, until now maintained between the lug of the first bomb and the shackle, was coming loose. The "multi-braids" arming wire was arming each bomb on its way down.
PICTURE HERE; Two views of the M47A1 cluster, almost ready to go, hanging from the rack. Release station is on "lock" and safety pins are still in place. We can clearly see why no cluster could be hanged on the central rack, the cluster is almost three bombs wide. Central rack mounted cluster would "overlap" side ones.
PICTURE HERE; Testing the M-47A1 clusters. The lines you see on the pictures were made intentionally to measure dispersion and distribution. Clusters disintegrate upon release and are scattered evenly on the target.
I have stumbled recently on a site dedicated to the B-29 in Korea "police action" where it is mentioned that the maximum load of a B-29 carrying 100 lbs bombs was 192 bombs. (
HERE) If you get all the side racks, minus the central racks, loaded with a cluster of six, you'll get 32 stations by six bombs; 192. I suspect that a "kit" similar to the one used for the M-47 was created for normal 100 pounders. But I doubt that it was used during WWII, since only one mission reports the drop of hundred pounders.
So, if we assemble all the information available on the M47, we can approximate that 6 bombs x 32 stations x 94 pounds = 18,048 lbs. Lets round it up to 18,100 lbs to take into account the "kits" used.
One last remark about the M47; when you see a picture of hundred of 100 lbs bombs standing on their tails near a B-29, you can almost bet that they are M47 waiting to be filled with gasoline before being fused and clustered in the bomb bay, not American propaganda making a show of strength.
Even though clustered, M47 were still bombs, not bomblets, or "sub-munitions" in modern parlance.
These incendiaries devices would be much lighter and were never intended to be release singly. British incendiaries were first being used, for testing and because Americans had none, but they soon started making their own. The first to be produced in mass was the M50 bomblet.
The 4 lbs AN-M50A1 was weighing 3.7 lbs. It was an hexagonal tube of magnesium alloy 21.3 inches long and 2.9 inches wide across the flats. AN-M50A2 and AN-M50A3 would follow and were identical. They where filled with Magnesium/Thermite and were tail fuzed.
PICTURE HERE; M50 bomblets (second starting from the top). Thermite (called "Thermate" in the picture, a variety of thermite with additives) needs high temperature to ignite while magnesium, as anyone old enough to remember flashbulbs will know, ignites quite easily. M54 bomblets (under the M50s on the above picture) are using thin steel tubing instead of magnesium. Thermite quantity is proportionally bigger but shape, size, and weight are approximately the same.
Thermite bomblets would burn furiously at temperature capable of melting, even igniting, steel. Thermite was, and still is, being used to destroy enemy guns and tanks, melting breeches and engine blocks. Being mostly made of rust powder, it can't be extinguished by oxygen deprivation. Water and wet tatami, the main tools of Japaneses firefighters, were useless. Only a shovel and a large sand bucket could do the job, the bomblet being left to burn until sand had vitrified all around it. But even that option was not for the faint hearted; many bomblets had explosives charges to injure or kill firefighters and passerby.
PICTURE HERE
But the M50-M54 bomblet was only burning at one place and, although the fire was quite intense and "plumes" of ignited thermite would fly around, it could be contained if swiftly attended to. The British equivalent were superior in that respect; small thermite or white phosphorus (WP) "pellets" charges would be scattered while the body was being consumed. ( see
HERE )
Many bomblets were "duds", as they needed to impact nose first. An empty portion (±1/3th) of the tube was acting as a drag tail but the "thermals", wind up-drifts, caused by already burning ground fires would toss and turn them all around. In fact, thermals would toss B-29 as well, enough to be reported at debriefings ( see
HERE ,
HERE , and
HERE ).
This personal account is even more colorful;
One of the best stories to come out of the Twentieth Air Force relating to the dangers of the thermals was told by the crew of aircraft number 21, whose commander was Captain William "Buck" Senger of the 61st Squadron. After bombing Tokyo on this attack, all the men swear that their plane did two loops over Tokyo Bay before it was righted at an attitude of about 4,000 feet. Some of the people say that a B-29 cannot be looped under any circumstances, but the men of Senger's crew think otherwise. They said they did it!
HERE
Magnesium was, and still is, a costly material. Natural rubber was also becoming scarce after the fall of producing countries into Japanese hands and stocks were better used for making tires, gasket seals and hoses, to name some. Americans scientific and industrial communities put their noses to the grindstone;
(...) Army Air Corps officers went to England and studied the Nazi blitz. The Chemical Warfare Service, which had been urging the Air Corps to adopt incendiary weapons, sent one of its expert, Colonel J. Enrique Zanetti, a Columbia University chemistry professor on active duty, to London in June 1941 to analyze fire raids, then put him in charge of its own incendiary program. A few days after Pearl Harbor it set up an incendiary laboratory at the Massachusetts Institute of Technology. The National Defense Research Committee, established in 1940 to coordinate the military work of American scientists, created an incendiary weapons section. NDRC specialists worked with the Arthur D. Little Company, the E.I. du Pont Corporation, Eastman Kodak, the Standard Oil Development Company, and other chemical suppliers and users to develop fire weapons. The Standard Oil group soon devised a small, extremely efficient bomb, designated the M-69, which ejected napalm from its tail. This was the jellied gasoline product created chiefly by Harvard University chemist Louis F. Fieser, a leading figure in the NDRC program.
Ronald Schaffer, "Wings of judgment: American bombing in World War II", Oxford University Press, p. 108
Professor Louis F. Fieser and his team at Harvard University created a brownish powder substance (
HERE), made of coprecipitated aluminium salts of naphthenic and palmitic acids (
HERE), hence the name;
Na-Palm.When mixed in appropriate quantity with gasoline, it would make a sticky jelly, which would also be known as napalm by extension.
The powder, very stable, could be shipped to operation theaters and used instead of natural rubber, although it is not certain that it was done since rubber-producing territories were back under Allied control and stocks of latex and natural rubber could be replenished.
But the mixture powder-gasoline proved stable enough to pack it into weapons stateside, seal it, and send it "ready to use". The most popular container would be the M69 bomblet. The M69 was again an hexagonal tube, most compact and stable geometric form for clusters, of 19.5 inches long and 2.9 inches wide across the flats, made out of steel, much cheaper than magnesium. They each contained 2.8 lbs of napalm in a cheesecloth pouch. Contact detonator and a delay fuse were in the nose of the bomb, the ignition and expulsion being performed by to black powder/magnesium/oil bags.
PICTURE HERE
Planning for the testing of new-generation U.S. incendiary bombs began in February 1943 and by May the tests were underway at Dugway Proving Ground, Utah. The designs under comparative test included the M-47 (...); the M-50 (...) and the M-69 (...).
(...)
The thorough tests at Dugway, which ran for four months, left little to the imagination. B-17s and B-24s flying in combat formations released live bombs from normal bombing altitudes over carefully replicated residential structures in two prototypes "enemy villages" built by the Army's Chemical Warfare Service. The Japanese village consisted of 12 two-story row houses and the German town included six assorted-design houses. Cost had been no object and the structures were as authentic as the builders could erect. They were of the same construction and furnished as they typically were in Japan and Germany, including the same woods, same dimensions, even the same paints, interior and exterior. For example, the Japanese residences had smooth plastered walls and sliding paper screens to divide the rooms; included were tatami mats, sitting pillows, low tables, charcoal braziers, even chopsticks on the tables. The Japanese homes were lined up on narrow streets, precisely 8 feet wide, as in Japanese cities.
Records were kept on each bomb hit; where it entered the building, the path it followed through the structure, where the incendiary action took place, and the fire result achieved. The comparative effectiveness of the bombs was categorized as follows; Class A, a fire that burned out of control after six minutes of attempts by trained fire guards to put it out; Class B, a fire that was ultimately destructive if unattended; and Class C, a fire that went out when unattended, with no destruction resulting. The M-69 proved to be the clear winner, creating far more Class A fires than its competitors. They would be manufactured by the millions and delivered by ship to the Marianas for the B-29 raids in 1945.
Stewart Halsey Ross, "Strategic bombing by the United States in World War II: The Myths and the Facts", McFarland, pp. 107 - 108, extracts available
HERE
For information about Dugway Proving Ground, go see a slide show
HERE
PICTURE HERE: HERE
A version, the M-69WP, had a sealed WP (white phosphorus) plastic container at the base that was shattered during its expulsion, forming a dense cloud and spreading around chard of incandescent white phosphorus igniting the napalm. The M-69WP was not differentiated from ordinary M-69. The M69X was "booby trapped" with half a pound of TNT or Tetryl set to explode about six minutes after impact to deter firefighting. They where all externally similar and of the same weight.
Another bomblet, the M74, was being developed as an improvement over the M-69. But it saw very limited operational use and, in fact, the M-69 and its variants - M-69W (WP) and M-69X (TNT) - were still predominant during the Korean war. Weighing 8 lbs, of which two were for the "pyrogel" (known as "PT1" by the War Department) incendiary substance. It was 19.4 inches long (tail retracted) and 2.8 wide across the flats. The streamer was replaced by a telescopic shrouded tail fin assembly. The "Popular Science" magazine of May 1945 report that;
The fuse in this bomb is described by a conservative former professor of chemistry (???) as "super-instantaneous." It is an all-ways fuse, which means that it goes off regardless of the angle or direction from which the bombs hit the target.
Volta Torrey & al., "How we fight Japan with fire". Popular Science, p. 108, ailable
HERE
This article is certainly very informative, but the information herein is to be taken into context. This was a document published in wartime and, most certainly, read by "not-so-friendly" people. To take only one example, the M69 is described as being "always" explosive - we know it wasn't the case and that only M69X were.
The superlatives arguments made for the M74 over the M69 appear to be a blend of facts and fiction. For example, if the fuse was to be triggered from any angle, what is the need for an elaborate extensible tail? The triggering mechanism described just after that seems perfectly maladapted to aerial transport. In fact, the triggering could be done from different angles, but it was preferable to hit nose or tail first. Hitting sideway could do the job, but only if the shock has violent enough. Other discrepancies are revealing; in one line, it is said that pyrogel is shot out by the tail while picture caption says that it is by the nose! The same caption talks of a "dome-shaped" nose and, fortuitously, the G.I. is holding the M-74 bomblet in such a way as to hide that nose. We now know that the nose of the M74 was as flat as any other bomblet! I can imagine frightened Japaneses staying away from unexploded bomblets having lost their dome-shaped noses! In fact, the "goop" was exiting by the tail, being pushed by a dome-shaped piston
inside the tube.
Pyrogel is, incidentally, a "beefed-up" version of napalm in which magnesium, metal oxides and tar, to name a few ingredients, are added to intensify the heat and prolong the burning. It was more often dubbed "goop" by G.I.s, and "PT1" by official documents. But it never replaced napalm. It doesn't even has a "stub" at Wikipedia, which says a lot (lol!). I will have to conjecture here that this "goop" was unstable due to its composition. If you know more on the subject, why not share with the rest of us?
Although many bomblets were tried by the USAAF, these were the "mainstay" of the firebombing campaign against Japan.
CLUSTERS
It must be stressed here that bomblets and clusters nomenclature is in itself very confusing. Many works are confounding one with the other, calling a bomblet by its cluster's name or designating a cluster as being the bomblet itself. To add to this confusion, many cluster pictures are mislabeled, often being used to represent another type of cluster. And, finally, as if it was not complicated enough, Army nomenclature would go at variance with rules and regulations. If you know better, please do not hesitate to correct what follows.
AN-M50 bomblet was packaged in two quick-opening clusters; AN-M6 100 lbs (34 bomblets) and AN-M7 500 lbs (128 bomblets). The AN-M17 was an aimable 500 lbs cluster, containing 110 bomblets.
AN-M54 bomblet was packaged in two quick-opening clusters; AN-M8 100 lbs (34 bomblets) and AN-M9 500 lbs (128 bomblets). It may have been used in aimable cluster similar to the AN-M17 but it is not sure, especially since the M54 was phased-out rapidly when it was observed that it had too much penetration and ignited fewer fires than the M50 and the M69. (see
HERE)
AN-M69 bomblet was packaged in one quick-opening cluster; M-12 100 lbs (14 bomblets). The bomblet was mostly packed in a 500 lbs (38 bomblets) aimable cluster officially known as the AN-M19, but the mention only starts to appear on the beginning of August 1945, a few days before Hiroshima and Nagasaki atomic bombing. (see
HERE) Before that, mention was made of "E46" or "E-46", and I believe that it was an interim nomenclature, "M" prefix was reserved to approved standard equipment ("E" for experimental maybe?). This is an educated guess based on personal accounts (
HERE), third party research (F J Bradley, "No Strategic Targets Left", Turner Publishing Company. p. 34, extracts available
HERE), reports on chemical plants (HISTORY OF ROCKY MOUNTAIN ARSENAL COMMERCE CITY, COLORADO, found
HERE, and disposal of dangerous material site (
HERE), but I would venture to say that the E46 was a 500 lbs aimable cluster of 38 bomblets with an E6R2 cluster adapter (
HERE).
AN-M74 bomblet was only packaged in aimable cluster. It was officially going to be the M31 cluster but this nomenclature never appears in 20th Air Force Mission Summaries. But mention of a certain "E48" or "E-48" (see
HERE) lead me to believe that it was an interim designation for a 500 lbs cluster of 38 M74 with the E6R2 adapter (see above paragraph).
Quick-opening clusters were only an expedient to pack more bomblets in bomb bays. They were suspended from 100 or 500 lbs bombing stations, their functioning was purely mechanical;
(...) When the cluster is released from an aircraft, the arming wire is withdrawn, freeing the clusters buckles. The cluster buckles open, releasing the strapping bands. The adapter opens, allowing the bomblets to fall individually to the target.
Department of the Army and the Air Force, May 1957, "TM 3-400 TO11C2-1-1", p. 41, available
HERE.
This description of the M12 cluster applies to all other quick-opening clusters. It was a major problem for the 8th AF;
(...)the M-50, a four-pound magnesium bomb in 100- or 500-pound quick-opening clusters was not sufficiently aimable. Furthermore, its quick-opening clusters endangered other aircraft in the formation.
Charles W. McArthur, Operations analysis in the U.S. Army Eighth Air Force in World War II, American Mathematical Society, p. 65, extracts found
HERE
The "quick-opening" clusters talked about were the AN-M6 (100 lbs) and M7 (500 lbs).
This was not an American-specific issue;
(...) The mainstay of the Command throughout the war was the 4-lb. magnesium I.B. The main (and very serious) difficulty met in the use of this weapon was its lack of aimability when dropped from small bomb containers, which resulted in incendiary attacks being widely dispersed and tending to fall downwind from the target with consequent great risk to our own aircraft froms showers of loose bombs over the target area.
Sir Arthur Travers Harris, "Despatch on war operations, 23rd February, 1942, to 8th May, 1945", Routledge, p. 94 , extracts available
HERE.
Americans and British worked arduously to develop an "aimable" cluster that would not open on release. They were still experimenting when war in Europe ended;
(...) The story of the development of clustered incendiary projectiles makes a sad reading, and there can be no doubt that the failure to produce a satisfactory cluster before the end of the war enormously reduced the efficiency of our incendiary attacks.
Sir Arthur Travers Harris, "Despatch on war operations, 23rd February, 1942, to 8th May, 1945", Routledge, p. 95 , extracts available
HERE.
Americans faired better. An "aimable" cluster, the AN-M17, was developed for the M50 bomblet, overcoming the difficulties. By reducing slightly the number of M50 bomblets in a cluster, from 128 to 110, it was possible to encase the bundles and attach a tail and a nose to the casing, giving the whole ensemble ballistic characteristics.
PICTURE HERE; CAPTION- An inspector with the Chemical Warfare Service's New York Procurement District writes a birthday greeting to Adolf Hitler on a cluster of M50 incendiary bombs at the Unexcelled Manufacturing Company. REMARKS- This M17 cluster is still missing its tail.
photo from
HERE.
The M17 cluster were used in Europe see
HERE, as an example among many, and were the mainstay of the incendiaries used along with the M47. Some M69 were probably used, but it was done piecemeal and only on an experimental basis, if ever.
The M69 was certainly earmarked for Japan and, from the first mention of E-46 to the M19, it was always being used in aimable clusters, at least from Marianas' B-29. The M74, if it was used, came in the form of the E-48 cluster.
Here comes the basic question (some will say "finally"
); how much were these clusters weighing?
They were all quoted as being "500 lbs" clusters, but, as we have seen with GP/HE bombs, ordnance seldomly equals any given number. Many documents are using the "#" symbol instead of "lbs". This is only a "caliber", to use military parlance, a nominal charge simply stating that XYZ ordnance can be treated as 100, 300, 500, 1600, 2000, or 4000 lbs loads. A good example is the M47 which, when made of six 94 lbs, was approximately 564 lbs, but was often referred as a "500 pound cluster".
The M19 is the best documented when it comes to weigh;
The cluster is approximately 59½ inches long, 14¾ inches in diameter, and weighs approximately 435 pounds.
Department of the Army and the Air Force, May 1957, "TM 3-400 TO11C2-1-1", p. 42, PDF available
HERE.
PICTURE HERE; REMARKS; The M19 and M21 clusters are indistinguishable one from the other as they share the same M23 cluster adapter set, the only difference is that the former carry AN-M69 and the latter AN-M69X. We can see the two arming wires going to the rear where the two fuses are.
PICTURE HERE; REMARKS; This diagram shows how the M23 adapter is being fuzed. If the LONG fuse does not do the job, the SHORT one will!
Others will have to be deduced since the TM 3-400 I found dated from 1957. If you have earlier copies, I would appreciate having one.
The E46 was probably about the same weigh since it is reported (see mentions above) that it was carrying 38 M69 bomblets as well.
PICTURE HERE; REMARKS; This cluster adapter, an interim A6R2, was certainly inspired from the M17. Only one fuse, and only one arming wire, is visible.
The E48, carrying 38 M74 weighing 8.5 lbs each, we have to add 38 x (8.5 - 6.1) = 91.2 lbs. This gives us 526.2 lbs.
The M17 is the hardest to evaluate since we have no direct data. It was made of two bundles of 55 M50 bomblets, each weighing 3.7 lbs, so 110 x 3.7 = 407 lbs. We have to add the weigh of the adapter cluster itself. This should not be more than 200 and less than 150 lbs, for a cluster weighing between 607 and 557 lbs.
PICTURE HERE; REMARKS; This is a view of the belly of a M17 cluster, the detonating cord v-channel running under is clearly visible.
PICTURE HERE; REMARKS; As this view shows, the M17 cluster had a nose fuse, here not installed. Like the A6R2, the rear of the second bundle is not entirely covered. This lead me to believe that both clusters were not tail fuzed, as the detonating cord would have damaged the unprotected bomblets.
PICTURE HERE; REMARKS; Drawing diagram showing the M17 workings.
PICTURE HERE; REMARKS; This earlier version extract of TM 3-400 would suggest that the M23 adapter was used with the M74 bomblets. According to the same document, it would have weighed 323 + 190 = 513 lbs. No M20 cluster was ever mentioned in missions summaries.
Of all these clusters, only the M17 could be significantly heavier than the M64 GP bomb. In theory, all 40 bomb stations could carry one of these clusters. But we know that it was never the case. The M50 bomblet was a "filling gap" ordnance because of M69 insufficient stocks. The second highest average load of the XXI , 19,979 lbs, was attained by "E48, 500# incendiary clusters to open 5,000 feet above Target" (
HERE), the first being a load of M64 (
HERE).
Even if the following precisions are not essential to the comprehension of the topic being discussed, the bomb loads of the B-29 during WWII, it is an intriguing aspect of bombing that I find worthy of mentioning, if only to satisfy my own, and maybe your, curiosity; how do these aimable clusters could open at a given altitude?
Well, in fact, they weren't! All WWII American aimable clusters depended on timed vanes-type fuses. Here is the general way it worked;
1- Cluster is released from the aircraft and starts free falling;
2- The arming wire(s) is retained by the shackle and the vane(s) start to spin, eventually arming the fuze;
3- A timer clockwork mechanism, preset by the ordnance officer in the bomb bay, explode a primer charge at the end of the set period of time;
4- The primer charge activates a detonating cord. This explosive device was already well known in the mining and demolition industry. It is a very fast acting cord used to detonate many charges almost simultaneously. Its explosive nature is also used as a "quick cutter". The detonating cord, running in a v-shaped "gutter" along the cluster, cuts the steel bands maintaining the container, It can also blow-out the nose and/or the tail fairings;
5- In the case of the M23 cluster adapter, a "fail safe" device, if the detonating cord has not worked, will ignite a second detonating cord that will sever the tail. As the tail fly away, it will pull a wire that was holding straps buckles, opening them and liberating the container;
6- Bomblets fly away from the container and are dispersed in the air stream turbulence. Their safety plunger springs out or the safety pin is ejected, arming the bomblets;
7- Depending on the type;
- M50 or M54: they fall and hit nose first with the help of their empty tube tail. On impact, a firing pin hits the primer cap by inertia. This primer ignites the first-fire mixture, and this mixture ignites the thermite (or thermate) which burns and, in the case of the M50, ignite the magnesium casing.
- M69: they fall and hit nose first with the help of a gauze streamer. On impact, a firing pin hits the primer cap by inertia. This primer set fire to a slow-burning compound, acting as a 3 to 5 second delay fuse, which ignite two bags of black powder/magnesium/oil mixture. The explosion of these bags eject the cheesecloth bag up to a hundred yards, along with a WP shattered cup in some case, and set fire to the globs of napalm scattered around up to fifty yards around.
- M74: they fall nose first with the help of a metallic shrouded tail that springs out in flight, but can hit at any angles, providing that the shock is hard enough. If they hit nose first, the primer is projected againts the firing pin, if they hit tail first, the firing pin is projected against the primer and, if they hit sideway, the funnel-shaped interior of the fuse gets pin and primer in contact. The primer explosion ignites the first-fire mixture, which ignites the exploding charge that throws away the PT1 mixture (pyrogel) up to fifty yards around as well as a WP shattered plastic cup which ignites the mixture.
All these bomblets may be containing small explosive charges aimed at slowing firefighting response.
Mankind really has a gift when it comes to hurting or killing each others...
Most cluster munition was incendiaries, but some was fragmentation, again to make firefighters think twice before entering a bombed zone.
One type of fragmentation bomb was extensively used; the M41.
PICTURE HERE
The M41 fragmentation bomb (...) has a charge-weight ratio of approximately 15 percent. (...) The overall length of the bomb is 22.2 inches and its diameter about 4 inches. A long rod of square wire 0.44 x 0.44 inch is tightly wrapped about a light cylindrical casing 0.11 inch thick to form the main body of the bomb. The cylinder is filled with TNT or other explosives. The ends are sealed with steel plugs. The nose plug contains a cavity for an instantaneous fuse, and the tail plug has a threaded hole to take the tail fins.
(...)
When an M41 bomb falls, 250 revolutions of the propellerlike blade, on the nose of the bomb, are required before the bomb is armed. This process permits the collarlike safety block located just ahead of the propeller to fall away, which in turn permits the striker head to be driven into the fuse upon impact.
(...)
The effect of wrapping the bomb cylinder with square wire is to produce a large number of fragments, each of which is a piece of rod 0.4 inch to 1 inch long (...). These fragments are much more effective per pound of metal than the usual long, narrow shell fragments.
Found
HERE.
PICTURE HERE
Twenty of them were suspended under a steel pole, maintained in place by spacers and held together by steel straps with the same buckle release system as describe above for the M23 adapter. This cluster was called M26 or T4E4, it was 52.6 inches long and weighed 416 lbs. The AN-M26A1 was a quick-opening cluster while the AN-M26A2 could be fuse-delayed to release the bombs nearer to the ground in a more compact grouping. Both could be suspended on a 500 lbs station.
PICTURE HERE
A very useful document, from which most of the information not directly quoted comes from, is "AMERICAN AIRCRAFT BOMBS 1917 - 1974", author unknown, found
HERE.
Some "exotic" loads were not mentioned here, such as leaflets' bombs (also called "bull**** bombs"), or photoflash bombs. Same thing with "500#" clusters dubbed "E-28" or "E-36". Maybe in some future thread about uncommon loads.
NEXT TIME: MINES AND CONCLUSION
-, but they probably had a ±500lbs bomb in their arsenal.