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Posted on 07/25/2003 3:43:11 AM PDT by snippy_about_it
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 are acknowledged, affirmed and commemorated.
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 The 4.2-Inch Chemical Mortar History Weapons available to American ground troops for delivering toxic agents included Livens projectors, grenades, land mines, mortars, rockets and artillery shells. If gas warfare had broken out, the burden would have fallen chiefly on the 4.2" chemical mortars of CWS mortar battalions.  The 4.2" mortar descended from the old Stokes mortar of the British Army. Britain invented the Stokes in World War I to overcome the disadvantages of gas cloud attacks. Gas clouds could be tremendously effective under the proper conditions, but they required considerable labor, were wholly dependent on the weather, could only be used with a few gases and, by their color and odor, sometimes warned the enemy. The Stokes had a smooth-bore barrel and therefore could not fire shells with pin-point accuracy. On the other hand, it had certain advantages. Troops could easily move it and fire shells at the rapid rate of twenty a minute. Each shell held more than two quarts of toxic agent. Because of these factors a mortar could suddenly overwhelm an enemy position with a large amount of poison gas.
The First Gas Regiment of the CWS obtained Stokes mortars from the British in 1918 and employed them along the western front. In July 1918, the Army contracted with American firms for the manufacture of these mortars. More than 400 were turned out but they did not reach France in time for battle.  The CWS found the Stokes mortar a versatile, useful weapon, and in the early 1920s set out to lengthen its range. The objective, as laid down by Maj Gen Fries [then the Chief Chemical Officer of the U.S. Army], was to double the WWI range of 1100 yards. Early experimentation showed that heavy powder charges could hurl the shell only a few hundred yards beyond the normal range. This was dangerous since the higher pressure within the mortar at the instant of explosion could burst the barrel. The designers attached fins to the shell, enabling it to fly through the air like a dart, and shot it 2,600 yards. But the shock from the exploding propellant generally damaged the fins, and the shell's flight was short and erratic. In 1924, Captain McBride and Dr G.S. Maxwell rifled several barrels with varying pitches and numbers of grooves. During machining operations, metal was gouged out of the bore, increasing its diameter from four to four and two-tenths inches between lands. This marked the end of the old smooth-bore Stokes mortar and the beginning of the new 4.2" chemical mortar. On 7 June 1924, one of the experimental barrels sent three shells through the air on accurate, spin-stabilized flights of almost 2300 yards.  Adoption of a rifled barrel made it necessary for engineers to redesign each component of the mortar, from baseplate to shell fuze. WWI shells had an all-ways fuze to make certain that the tumbling shell would explode no matter whether it landed on its base, side or nose. Fuzes of this type could not be used on a spinning shell since centrifugal force would activate the fuze and cause the shell to burst as it left the muzzle of the mortar. After considerable experimentation, engineers developed a safe, dependable fuze that could be set for impact or time. Something had to be done to prevent liquid fillings, such as mustard or phosgene, from surging around inside the shell, unbalancing it and causing it to tumble and yaw in flight. This characteristic had not mattered with the Stokes mortar since its shells had tumbled anyway, but it affected the accuracy and range of the rifled mortar. Technicians solved this problem by fastening vanes inside the shell to swirl the fillings as the shell spin through the air.  To seal the bore against loss of explosion gases, and to force the shell to rotate as it sped up the barrel, the men had to devise a driving mechanism for the base of the projectile. This consisted of two round plates, one of brass and one of steel, the brass disk designed so that its edge could be forced outward by pressure. When the powder exploded, gas pressure rammed the steel plate up against the softer brass plate, forcing its edge out and into the grooves, sealing gases in and forcing the shell to spiral out of the barrel. For the baseplate of the Stokes mortar it had been feasible to have a steel cup, bolted to an oak plank. But recoil from the new 4.2" barrel soon pounded this type of baseplate into splinters, and a forged steel baseplate had to be produced. Finally, in 1928, after several years of experimentation, model M1 of the 4.2" chemical mortar was ready for service. During the next decade CWS engineers put considerable thought into improving the standard model. The practice of digging an emplacement, which took time and reduced the mobility of the mortar, was abandoned and the base was placed directly on the ground. The two-legged support inherited from the Stokes mortar was improved and retained for a time, but it proved to be so awkward that it gave way to a single leg. Engineers then found it necessary to place connecting rods between the baseplate and barrel support to keep the recoil from forcing base and support apart. The barrels, hitherto obtained from the old Stokes mortars, were made specifically for the new model from seamless drawn-nickel steel tubing. A spring shock absorber was placed on the barrel to prevent the force of recoil from breaking the connection between support and the barrel. At last, after seven years of work, the CWS completed a greatly improved mortar, model M1A1, with a range of 2400 yards. This mortar was in the hands of chemical troops at the time of Pearl Harbor.  Increasing the Range in World War II The next step in the development of the mortar came about as a result of an addition to the mission of CWS troops. Up to the time of America's entrance into the war, the mortar had been considered as a weapon for firing toxic agents, smoke and incendiaries at the enemy. In April 1942, General Porter [then the Chief Chemical Officer] asked the Services of Supply for permission to use high explosive ammunition in the mortar. Chemical troops had fired HE in WWI and, if allowed to do the same in WWII, it would broaden their usefulness in the theaters of operation. The SOS gave its consent, thereby giving the CWS impetus in lengthening the range. The mortar had been developed under the pre-war doctrine that chemical shells would be employed only within a range of 2400 yards. This concept did not apply to HE, and the CWS set about increasing this distance before the mortars saw action. Engineers could have lengthened the range by redesigning parts of the mortar, but such a step would have taken time. When tests demonstrated that 50% more powder hurled the projectile an additional 800 yards, bringing the total distance up to 3200 yards, a larger charge was adopted. The higher explosion pressure imposed more strain on the barrel and baseplate than they had been designed for. To prevent accidents, the service adopted a tougher barrel and baseplate. To prevent mortar squads from using the old barrel and perhaps blowing themselves up the CWS designated all mortars with the new barrel as model M2. The CWS carried the M2 into all theaters and some were still in action at the end of the war. The 4.2" mortar first saw action [with the 2nd and 3rd Chemical Mortar Battalions] in the taking of Sicily in the summer of 1943. Mortar squads were among the first waves of troops to hit the beach, and they went into action a few minutes after landing. During the 38-day campaign, they shot 35,000 rounds of ammunition in crash concentration, harassing, interdictory and counter-battery fire, and in tactical smoke screening missions. The mortar made an excellent impression on commanders of infantry, ranger, armored and airborne units. Thereafter there was no question that the CWS had taken the right course in turning the chemical mortar into a HE-delivering weapon.  After troops tried out mortars in Europe, they began calling for a longer range. Back in the U.S., the CWS had already anticipated the demand and had succeeded in adding another thousand yards to the flight of mortar shells. It had achieved the increase by changing the form of the propellant so that it burned slowly, gave off gas more evenly, and thereby became more efficient. Lt. Arthur Denues had experimented with the propellant, trying different shapes, arrangements and types, and had finally found out that with disks of powder of a certain thickness, the range depended upon the number of disks. The minimum charge, which lobbed the shell only 340 yards, could be lengthened to 4400 yards simply by adding more disks. The maximum gas pressure did not become excessive and there was no disturbance in the ballistics of liquid-filled shells. The disks were cut square, with a hole in the center to allow the disk to slip on the cartridge container. Sufficient disks, sewn together in bundles of different thickness, were placed on each shell before shipment to give a range of 4397 yards. Before the shell was fired, the mortar squad could remove one or more disks to shorten the range. Notwithstanding that the range of the mortar had almost doubled by 1944, troops in the field were still not satisfied. They wanted the weapon to hit targets 5000 or more yards away. One means of accomplishing this was to devise a jet accelerator that would fit on the base of a shell and give it a boost after it left the barrel. The CWS started work on such a device but soon canceled the project after a survey showed that development would take too long, and men with the know-how could not be spared from other mortar projects.  Infantrymen of the Heavy Mortar Co., 1st Platoon, 35th Infantry Regiment, 25th U.S. Infantry Division, fire the 4.2-inch Heavy mortar on Communist hill positions in the Mung Dung-ni Valley. 10 August 1952. Korea. Two other courses lay open to the CWS, a long-term project to completely redesign the mortar from baseplate to standard, and a short-term project, which might not work, of again modifying the propellant. Experiments with the propellant began after calculations and preliminary experiments indicated that the velocity of the shell could be increased 100 feet per second and the range jumped to more than 5000 yards if the chamber volume of the mortar and the weight of powder were doubled. Engineers set up an experimental mortar and made test firings, but to their surprise the shells had an unexpectedly short range. They carefully checked all possible sources of error and at last discovered that the high pressure from the explosion had deformed the rotating disk on the base of the shell and this had increased air resistance. Development of a new rotating mechanism proved to be the major task in extending the range, but when the job was finished the mortar shell carried distances of 5600 yards in firings at Edgewood in June 1945. These results obtained in the shop and on the test field occurred too late in the war to be transmitted to the battlefield. Regardless of demands for longer ranges, a complete redesign of the mortar was necessary by 1944. By this time, both the M1A1 and M2 had been used extensively, particularly in mountainous regions where artillery found it difficult or impossible to operate. The terrain in which mortars operated in Italy and the Southwest Pacific was at times so rugged that standard mortar carts or jeeps could not be used, and the CWS had to devise a mule pack.  This constant use of mortars took its toll in worn and damaged parts, much harm being caused by attempts to get more service out of the mortar than it had been designed to deliver. The CWS Technical Division set out to produce an entirely new mortar that would be free from the limitations inherent in the basic design of the M2 model which had been intended originally to fire a range of 2400 yards. By the end of the war, an experimental model, E37, had been constructed and test fired at Edgewood. After the war, the service continued development until 1949 when the War Department, feeling that the mortar was now a legitimate weapon of the infantry, transferred the responsibility for development to the Ordnance Department. The Ordnance Department made a few final modifications and standardized the mortar as model M30 in 1951. American troops who saw the chemical mortar in action in the Pacific and in Europe had a high opinion of the weapon. German and Japanese troops respected its fire power and accuracy. Generalleutenant Ochsner of the chemical warfare branch of the German Army stated that "from the technical point of view the American 4.2" chemical projector is very good; the construction is simple, it is a very handy weapon in battle and its firing efficiency is high."  A 4.2-inch mortar crew of the Heavy Mortar Company, 179th Regiment, 45th U.S. Infantry Division, fires on Communist positions, west of Chorwon, Korea. 5 May 1952. Korea      |
"tragedies" for the Kennedy's And a godsend for America.
It's always so sad to hear that there are either no or so few flyable planes left.
Same problem here, always getting canteens or some pouch caught up in the netting. I hated messing with that stuff.
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