The results of the combat use of barreled artillery directly depend on the range and accuracy of fire. To improve these characteristics, various measures are taken, affecting both the weapon and its ammunition. In particular, guided and active-rocket projectiles are used. This year, the Norwegian company Nammo presented for the first time an original concept of a promising ammunition capable of showing outstanding characteristics of range and accuracy. It is proposed to obtain such results through the use of unusual components.
A new concept project of a guided active-rocket artillery projectile was developed recently, and was first presented in June this year. The platform for the first public display was the French military-technical exhibition Eurosatory-2018. As part of this event, the Nordic Ammunition Company / Nammo company demonstrated to specialists and the public a model of a promising projectile, and also spoke about its main features and design characteristics.
Projectile model at Eurosatory-2018
During the first demonstration, it was noted that so far we are not talking about a finished sample of an artillery shot, but only about a concept that can be further developed. In particular, for this reason, the shown sample so far has a specific working title. The mock-up bore the inscription "155mm Solid Fuel RamJet", indicating the caliber and specific equipment of the product. Perhaps, in the future, the projectile will receive a more convenient name.
The main goal of the so far unnamed project is to increase the firing range of existing artillery systems - and at times. Also, the designers of Nammo plan to ensure high accuracy of hitting the intended target. To solve such problems, they propose to use several well-known principles, but one of them looks extremely unusual and can draw special attention to the project. The fact is that the Norwegians propose to build a guided active-jet projectile with a ramjet engine.
At an exhibition in Paris, the development company showed a layout, and also talked about the device of a promising ammunition. The expected characteristics were also announced - and this information is of particular interest. According to the calculations of the authors of the concept, the new projectile in terms of flight range can surpass not only other artillery weapons, but also some missile systems.
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The demonstrated layout, as well as other information from the manufacturer, allows you to draw up a fairly detailed picture. The product presented at the exhibition was at the same time similar to an artillery shell and a rocket. It received a large elongation case with a diameter of 155 mm. Instead of a head fairing, the projectile has a frontal air intake with a protruding conical central body. Near the front edge, on the tapering part of the hull, rudders that can be folded in flight are provided. The tail section has a leading belt, behind which there is a second set of planes. From the point of view of aerodynamics, the projectile is built according to the "duck" scheme. The bottom of the projectile is virtually absent - the rear section of the body is shaped like a nozzle.
The layout depicts the projectile in flight configuration
The new projectile has a caliber of 155 mm. The total length appears to be slightly more than 1 m. The mass of the product and the weight of the payload are still unknown. Perhaps the finished projectile will be slightly lighter than the existing 155-mm ammunition. The parameters of the entire shot are also unclear. However, given the current stage of the project, such information should not be required from Nammo.
Due to the use of an unusual propulsion system, the projectile has a specific layout. Its outer casing is a metal shell capable of absorbing existing loads and containing other components. The front half of the body is occupied by a cylindrical inner body, the head of which is shaped as a central body of the air intake and protrudes from the projectile. The engineers left a gap between the walls of the two housings, sufficient for the passage of air, as well as for its compression before entering the engine. The engine is located in the tail section of the projectile and takes up just under half its length.
Norwegian gunsmiths proposed to make the projectile an active-rocket, and equip it with an unusual propulsion system for such a product. For additional acceleration after exiting the barrel, the projectile must use a solid-fuel ramjet engine with sufficient thrust parameters. In fact, the only element of such a propulsion system is a solid fuel charge made in the form of a cylindrical block with a longitudinal channel. It is placed in the tail part of the body, directly at the nozzle cut. The supply of atmospheric air to the solid fuel is provided by an annular channel between the two housings.
According to information from the developers, the engine needs a special solid fuel. It should ignite spontaneously at a high temperature of the incoming air from the air intake and use atmospheric oxygen as an oxidizing agent. In the tail of the 155-mm projectile, you can place a charge of solid fuel sufficient to run the engine for 50 seconds. During this time, the ammunition can receive a large impulse, sufficient to significantly change the trajectory and increase the firing range.
Side view, planes unfolded
Obviously, long-range artillery shells by themselves cannot show high accuracy. Consequently, the Nammo project proposes the use of control systems. In the inner case, the designers provide for the installation of a seeker using inertial and satellite navigation. This equipment must calculate the relative position of the projectile and the target, and then, based on these data, generate commands for steering machines. In-flight control is assigned to a set of four aerodynamic rudders mounted on the outside of the head of the hull. The tail stabilizer, in turn, should only be responsible for maintaining the required trajectory.
Together with the control systems, it is proposed to place a warhead in the inner hull. What charge the projectile can carry was not specified. At the same time, there is reason to believe that the concept implies the creation of high-explosive fragmentation ammunition. Taking into account the proportions of the product and its layout, it can be assumed that no more than 8-10 kg of explosive will fit in the inner case - approximately at the level of other modern ammunition.
An active-reactive guided projectile must be equipped with a propellant charge that meets the requirements of a particular weapon. Perhaps, in the future, charges will be created for him in a sleeve or cap. However, exact data on this part of the artillery shot are not yet available.
Another issue that has not yet been officially commented on concerns shooting controls. Obviously, a gun or self-propelled gun using guided munitions must be equipped with devices for entering data into its guidance system. However, the presence of fundamentally new features and functions imposes special requirements on the equipment of the tool. In particular, new calculation algorithms are needed for aiming when shooting in new modes.
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In accordance with the idea of the designers of Nammo, the promising projectile should be compatible with all existing 155 mm artillery systems. The principles of its operation should also not depend on the tool used. At the same time, two modes of operation of the onboard equipment are proposed, providing a change in characteristics in a fairly wide range. One of these modes actually turns the artillery shell into a kind of guided missile or guided bomb.
View from a different angle
The projectile and the cartridge case / cap must be placed in the gun chamber like other ammunition, after which the gunners can fire. In the barrel, the 155mm Solid Fuel RamJet projectile must pick up speed and start spinning. The muzzle velocity of the product, according to calculations, should reach M = 2, 5. At the same time, atmospheric air entering the frontal air intake should pass through the longitudinal channels of the body, compress and heat up to the design temperature. The latter is necessary for the ignition of solid fuel.
The task of the ramjet engine is to maintain the speed at the muzzle level throughout its operation. Thus, for 50 seconds, the projectile is on the "active part of the trajectory" and can move almost in a straight line. After running out of fuel, the ammunition continues to fly by inertia. The onboard electronics, in turn, proceeds to perform their tasks in one of the two proposed modes.
The first mode provides for a simple flight along a ballistic trajectory with correction as needed. Using signals from navigation satellites, the projectile must correct its trajectory up to falling on the target. In this mode, in its principle of action, it is similar to existing guided projectiles. At the same time, the development of Nammo is distinguished by increased characteristics. According to calculations, a projectile in ballistic mode will be able to hit a target at a distance of up to 100 km.
The second mode provides for the abandonment of the ballistic trajectory in favor of gliding flight. With the help of an impulse from a propellant charge and its own engine, the 155mm Solid Fuel RamJet product should rise to a height of several tens of kilometers, and there go into planning. Due to this, it is argued, the firing range at a ground target can be increased to 150 km. Thus, the artillery projectile in its flight characteristics will be equal to the rocket armament.
Presentation of a new projectile at an exhibition in Paris
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Norwegian gunsmiths from the Nordic Ammunition Company have proposed an extremely interesting version of the artillery shell, capable of showing outstanding combat characteristics and solving special tasks. This development, as expected, attracted the attention of specialists and the public, and became one of the most interesting "premieres" of the Eurosatory-2018 exhibition. However, you should not overly admire the proposed shell and overestimate this proposal. The fact is that a guided active-jet projectile with a ramjet engine is still only a concept.
At the time of the first demonstration, the product with the inscription 155mm Solid Fuel RamJet existed only as a model, roughly demonstrating the general provisions of the original concept. There is no talk of a full-fledged artillery shot, at least ready for testing. In fact, the engineers from Nammo just took an original idea and worked it out using modern technologies and solutions. The result of this preliminary "design" was presented at a military-technical exhibition, where everyone could get acquainted with it.
Among other things, during the Eurosatory-2018 exhibition, Nammo could get acquainted with the reaction of potential customers and, on its basis, determine whether to create a full-fledged project that could interest buyers and find a place in the arsenals. If this or that country shows real interest in a promising guided missile, the concept will be developed. Otherwise, even the layout will no longer be shown at exhibitions.
While the military of different countries are trying to determine whether they need new projectiles, and the development company is waiting for future orders, it is possible to analyze the presented concept project and draw some conclusions. First of all, it should be noted that the presented version of the artillery ammunition looks very interesting. However, upon careful study, various questions and doubts arise.
The concept caught the attention of visitors
The advantages of the proposed projectile are obvious - it is a uniquely high range, accuracy and compatibility with serial artillery systems. In addition, two flight modes are of great interest, one of which provides for gliding over most of the trajectory. All these functions significantly increase the combat qualities of such a projectile in comparison with other ammunition. It can be considered that the timely detection of weapons using shells from Nammo, and a retaliatory strike against their position turns out to be an extremely difficult task. In particular, counter-battery artillery fire will only be possible if ammunition with similar characteristics is available.
The disadvantages of the proposed concept can also be noticed without much difficulty. First of all, this is the high cost of real ammunition. Apparently, it will be much more expensive than any existing guided projectiles, which should be associated with the presence of new devices and other principles of operation. In addition, to develop all new technical solutions - from a compact ramjet engine to new flight modes - a long design and refinement process is required, which can also affect the cost of the program.
Also, the scope of the proposed shells is not entirely clear. Ammunition with a range of more than 30 km is indeed capable of positively affecting the combat potential of artillery guns, increasing their area of responsibility. However, increasing the range only makes sense in a certain range. The fact is that a projectile capable of flying 100-150 km "invades" the range of operational-tactical missile systems. Obviously, the 155-mm product, in terms of its combat qualities, cannot be a full-fledged competitor to a larger and heavier missile. Whether there is any sense in the simultaneous existence of missiles and projectiles with a similar range is a big question.
Thus, the proposed active-rocket projectile with an outstanding range can only be an addition to the existing artillery and missile systems. However, due to its special characteristics, it turns out to be a highly specialized development, in practice suitable only for solving certain problems. Combined with the high cost, this makes Nammo's development of little value and not very attractive to potential operators.
The new Norwegian concept project has two main features. It is more than interesting from a technical point of view, but at the same time it seems to be futile in practical terms. All this does not allow us to evaluate the future of the concept in an optimistic way and gives reason to doubt the further development of the proposed ideas. Apparently, the product marked 155mm Solid Fuel RamJet will remain a purely exhibition model to demonstrate original solutions. However, for now, one should not exclude another development of events, in which the concept will nevertheless reach, at least, the stage of technical design.
