Project of anti-tank ACS with recoilless guns L. Zerby (USA)
In the early forties of the last century, Colonel Lee F. J. Zerby was an officer in one of the chemical service units of the US Army and dealt with relevant issues. In his spare time, the officer attempted to analyze the fighting in Europe, based on which he drew some conclusions and even developed his own project for advanced military equipment. In June, 1941, the colonel formed the main ideas, and also made a presentation at a conference. Representatives of the command interested in the original proposal and advised to continue its development.
General view of the "torpedo". You can notice the specific ergonomics of the crew[/ Center]
Later, using the available capabilities and resources, Colonel Zerby developed the ideas and built a prototype of the equipment, later used in field tests. During the tests, various data were collected and several photographs were taken showing both the ACS itself and its work at the test site. Information about the new project was issued in the form of a letter, which 1 of September 1942 of the year went to the army command.
In his letter, L. Zerby described the main features of the recent armed conflicts established during their analysis, and also gave his thoughts on this matter. Further, the document proposed the original method of dealing with the enemy. Finally, a description was given of a prototype of a technique in which new principles were implemented. Thus, the command gained the opportunity to study not only the enthusiast’s general thoughts, but also to get acquainted with their real results.
In the first section of the letter, Colonel Zerby reviewed the results of the fighting in Europe. Thus, the French campaign and the successful offensive of the German troops clearly demonstrated the shortcomings of the existing anti-tank artillery. It became clear that no reasonable and real number of guns in pre-prepared positions can stop a concentrated strike of a large number tanks. In addition, the emergence of new weapons and equipment systems in Germany will make such anti-tank systems simply useless. To maintain the required potential, new anti-tank weapons were needed.
According to the author of the project, the new tool must have high firepower needed to destroy tanks, and also differ from similar equipment with greater speed and maneuverability. Also, the new tool had to be cheap, massive and difficult to defeat. L. Zerby noted that such features of the technique contradict each other, which is why the situation resembles the development of battleships: at one time ships received more and more powerful guns and reinforced armor, and also increased their speed. Nevertheless, in the future, bomber and torpedo bombers appeared, which, without serious protection, could effectively fight battleships. In the case of tanks, in the opinion of Colonel Zerby, it was also required to find a new principle.
Preserving existing ideas at the heart of the project had negative consequences. So, to defeat a protected tank required a powerful weapon with a heavy installation. This artillery unit, in turn, required an appropriate vehicle, which could not be distinguished by high speed and maneuverability, and also turned out to be quite expensive. The way out was to be a light wheeled platform equipped with weapons with the required characteristics. Naturally, the traditional cannon artillery was no longer considered usable.
In search of the most effective way to search and attack tanks, Colonel L. Zerby recalled the generally accepted methods of hunting for various game, namely ducks and deer. In the case of ducks, a “static” or “active” hunting method can be used. Hunters can take a position, use monkey and wait for a bird to fly into the firing sector. This allows you to lure one group of ducks after another, until the game bags are filled. The second method implies a secret advancement by land or by boat with the opening of fire after approaching the desired distance. When hunting for deer, the officer recalled, ambushes were used along the main paths of the beast. Dogs must drive the game, which moves on the usual paths and eventually falls under the fire of hunters.
Tanks, as the colonel rightly pointed out, are not ducks or deer. Having met with anti-tank artillery in a previously prepared position, they will not arrive group by group. In addition, the method of hunting deer with ambushes along the paths is not applicable in this area. Also, we should not forget that tanks, unlike game, have very powerful means for self-defense. As a result, L. Zerby believed that when “hunting” tanks, an “active” method should be applied.
Here, Colonel Zerby recalled the Kansas method of rabbit hunting. He meant the simultaneous work of a large number of shooters who surround the terrain with the game, and then begin to converge. The raised beast tries to leave the encirclement, but gets hunters' eyes with a clear result. At the end of the hunt, all participants meet at one point. It was also proposed to fight with tanks. However, this required a large number of hunting machines, characterized by high speed and maneuverability. In addition to the quantity, it was proposed to use various means, such as smoke curtains, etc.
In the summer of 1942, Lee Zerby and his colleagues brought the original project to the stage of building a prototype of a new technology. Using the materials and resources available at Fort Sam Houston military base, a group of enthusiasts produced a full-fledged sample, which theoretically could even participate in real fights. However, it should be noted that the proposed design of the prototype had a number of characteristic flaws that adversely affected the real prospects of technology.
As a basis for an experimental anti-tank self-propelled gun, a Ford-based half-ton truck with a wheel formula 4х4 was selected. In his letter, L. Zerby mentioned that other vehicles of a similar class with the required characteristics may also carry weapons. To simplify the design and to equip it with new equipment, the car lost most of the body and seats, instead of which they mounted new-designed products. The springs of the front axle were reinforced with two additional plates. The fuel tank was moved to the back of the car. To reduce the frontal projection was used updated driver's workplace.
Experienced SAU received not too powerful booking. In front of the left side of the grille and on the right behind the engine compartment were placed two plates of anti-bullet protection. When developing a full-fledged project, the composition of the reservation could be changed. In particular, it was proposed to take measures to protect the open steering system.
The recoilless gun of the original system was proposed as a weapon for the self-propelled gun of the L. Zerby design. When assembling two experimental products, enthusiasts took as a basis a pair of old and rusty pipes from a certain steam engine. The tubes taken had an 5 inch gauge (127 mm) with an 1 / 4 inch wall thickness (6,35 mm). The length of such a trunk was 11 feet (3,35 m). Tests and calculations showed that the gun can use pipes with less thick walls, up to 1 / 16 inches (1,58 mm).
An experienced anti-tank self-propelled gun received two recoilless guns, which were placed on the sides of the machine. Brackets were used that did not allow the position of the guns to change. It was assumed that the guidance in the horizontal plane will be carried out by turning the whole machine, and the fixed vertical guidance will provide accurate shooting from a given range. Like other units of the prototype, gun mountings were not perfect. Therefore, with the further development of the project should use the product improved design.
The cannons designed by L. Zerby were to use the original separate loading ammunition. As the projectile was used 101-mm (4-inch) mortar mine of the existing type. A TNT charge of 10 pounds (4,54 kg) was to be placed in the metal case of the mine. In the future, it was proposed to use a new special ammunition with less thick body walls. This allowed to reduce the risk of destruction of their troops by fragments, as well as to increase the explosive charge. By analogy with anti-ship weapons aviation, ammunition for self-propelled guns received the name "torpedo".
For the projection of the projectile was proposed to use a sleeve of unusual design, also performing the functions of anti-mass. The barrel of an outdated 101-mm mortar should have been used as a liner. It placed a charge of black powder weighing 2 ounces (56,7 g) in a small cap. The use of smokeless powder was not possible due to the different characteristics of combustion and the formation of gases. As fuses prototype used electric fuses, manufactured for use in mining. Fuse connected to the control systems with wires passing through the trunk.
As an additional weapon, the prototype of the new machine received a rifle caliber machine gun. It was placed on the pivot mounted on the rear wall of the engine compartment.
The car should have been driven by a crew of two. The driver remained in his place at the left side, but now had to sit reclining on the seat of a new design. Instead of the standard steering wheel, a new device of a reduced design appeared, reversed. Also moved back and control knob gearbox. To the right of the driver, right on the floor of the body, was to sit the shooter, whose task was to use a machine gun or personal weapons in self-defense.
The prototype of the anti-tank "torpedo bomber" was not distinguished by the perfection of the design, however, it allowed to establish the prospects for a new development. In addition, under the existing conditions, L. Zerby and his colleagues could only build such a specific prototype. A more accurate and successful version of the machine could be developed later, after receiving the approval of the military and the beginning of a full-fledged project.
Colonel Zerby’s project offered a recoilless weapon that does not use a nozzle block. Instead, to create the required pressure in the barrel should use an anti-mass. This role was played by the mortar barrel, used as a liner. When fired, the powder gases were supposed to push the mortar barrel and the "torpedo" in different directions. Being several times easier, the projectile had to fly to the target. The empty barrel-sleeve, in turn, fell out at a slower speed through the breech breech. In theory, this principle allowed us to achieve acceptable fire characteristics.
The first prototype of an unusual combat vehicle was built in the summer of the 1942 of the year, after which it was tested. A typical test method was as follows. A target shield imitating the enemy’s tank was set up at the shooting range. From a distance of 800-1000 yards (730-914 m) the driver-driver began to move in the direction of the target, trying to preserve secrecy. At a reduced distance, for example, from 100 yards (91 m), a shot was fired, after which the driver had to turn and leave from under the conditional retaliatory strike. In the course of such checks, the firing range, the weight of the propellant charge, etc. were constantly changing, which made it possible to establish optimal parameters.
The surface of the landfill to a certain extent imitated rugged terrain characteristic of real battlefields. At the same time, however, at the last 200-300 yards to the target, the “track” became relatively even, which could somehow affect the outcome of the shooting. However, even in such conditions, the results of the first tests were not satisfactory. Of the nine shots on the target, only two led to the conditional defeat of the enemy. By reducing the shooting distance to 100 yards and less, and also by improving the skills of the gunner, the testers gradually managed to bring the probability of hitting the target to 50%.
Developing the idea of hunting for rabbits, the author of the project proposed a way to work together anti-tank SAU. Since armored vehicles have limited visibility, smoke screens can be an effective countermeasure to them. For this reason, ammunition self-propelled guns were supposed to include both high-explosive and smoke "torpedoes". Thus, approaching the observed target, the “torpedo bombers” were supposed to shoot smoke munitions, with the help of which it was possible to get close to the distance of the shot with a high-explosive projectile. During the tests it was found that the smoke "torpedo" can be launched from 600 yards (548 m) without changing the parameters of the propellant charge and modifications of the gun.
Colonel Zerby thought out not only the overall appearance of the vehicle, but also the method of its combat use during the combined arms battle with the massive attack of enemy tanks. In his letter to the command, he described the combat work of the ACS in comparison with the current situation at Stalingrad, where German and Soviet troops fought fierce battles with extensive use of armored vehicles of all kinds.
L. Zerby offered the reader to imagine himself on the site of the Red Army, but given the presence of anti-tank self-propelled guns of his development. The defending side has 10 thousand "torpedo bombers" hidden in forests and various shelters along a front a hundred miles long. The equipment is organized into platoons of six units headed by a commander’s vehicle. Aerial reconnaissance reports the start of a German attack. The platoon commanders begin to monitor their area of responsibility. When tanks appear, the commander orders to start moving in the direction of the target. Approaching the enemy armored vehicle under the cover of smoke, six self-propelled guns were supposed to surround it and fire from different sides from distances of no more than 100 yards. In doing so, from 6 to 12 shots could provide an acceptable probability of hitting.
The massive use of smoke projectiles disorients tanks and does not allow them to fully perform the task. It also makes it difficult to manage units and formations, as a result of which the “torpedo bombers” get the opportunity to continue the attack and fire at the enemy. A large number of light vehicles, even with limited ammunition, should have given the troops the opportunity to fight off even massive tank attacks.
The letter of L. Zerby clarified that the original proposal should be kept secret so that the enemy could not meet the American troops with his version of "torpedo bombers". It was also proposed to continue the development of existing ideas and develop a complete draft of a combat vehicle suitable for use by the troops, and in addition, a list of necessary improvements and improvements to the existing project was given. After sending the letter, the further fate of the original project was in the hands of specialists of the military department.
Army experts familiar with the development of anti-tank weapons, studied the proposal of Colonel Zerby and made their verdict. They noted that the project has several noticeable flaws. One of the main recognized rigid fastening recoilless guns. This seriously hampered the guidance of weapons, which negatively affected the accuracy rates. In addition, the accuracy of the shooting could be affected by the terrain, the operation of the springs and other various factors. Other problems, such as insufficient protection or mobility characteristics, could be corrected with the further development of the project.
The plan of a normal attack with the participation of "torpedo"
However, no one became involved in improving the project. Experts who studied the materials of L. Zerby indicated that the proposed “torpedo bomber” in its current form cannot be an effective means of fighting enemy tanks. The main claim in this regard was the lack of guidance systems. Soon L.F.J. Zerby received a response to his letter. The army did not need to develop it. The colonel continued work in the chemical service and, as far as is known, no longer dealt with the subject of anti-tank weapons.
The project of anti-tank "torpedo bomber" with recoilless guns, built on the basis of the automobile chassis, is of great interest from the point of view stories technology. And it is interesting, first of all, as a curious historical curiosity. The ideas of Colonel Zerby turned out to be so original and bold that they even went beyond the limits of the possibilities of real practical application. In addition, it is hardly possible to say about this project that it had both positive features and disadvantages. With the exception of mobility and ease of operation of the wheeled chassis, all the main features of the Zerbi torpedo bomber can be considered flaws, including those that can lead to fatal consequences for the vehicle and its crew.
The project was based on a clear and logical desire to increase the mobility of anti-tank artillery. With great reservations, this problem was solved. Nevertheless, all the successes of the project were limited to this. To increase mobility, it was proposed to use a recoilless cannon with a high-explosive projectile, as well as the maximum lightweight chassis with the smallest possible silhouette. Naturally, with the fulfillment of such requirements, the project simply did not have room for guidance systems and any sufficient crew protection. Finally, the main armament also failed, which could show acceptable accuracy of hits only at distances less than 100 yards, and it was proposed to destroy armored targets using high-explosive shells with a charge of the order of 4,5 kg of TNT. Armor-piercing ammunition, which is interesting, was not developed.
Because of all these problems, "10 of thousands of combat vehicles in forests and shelters" could hardly fight off the attack of the enemy tanks. The lack of protection led to an extraordinary risk for the crew and main units, because of which not only the tank, but also the infantrymen accompanying it could withdraw the torpedo bomber from the battlefield. A smoke screen and a machine gun would not reduce the risks to an acceptable level.
Given the few advantages and multiple drawbacks of the project, one should not be surprised at the decision of the American military department. Experts noted the fundamentally inherent flaws of the L. Zerby project, which eventually became decisive. In its current form, the "torpedo bomber" was of no interest to the army, and its refinement with the elimination of the main problems was considered inexpedient. The project was closed as unnecessary. Subsequently, designers from the United States returned to work on anti-tank SAUs with recoilless weapons, but in new projects more advanced components and other principles of combat use were used.
On the materials of the sites:
- Ryabov Kirill
- Worldoftanks.com, Strangernn.livejournal.com
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