For several years now, scientists in the United States of America have been working on a rail gun project (also referred to as the English term railgun). A promising type of weapon promises good indicators of the initial velocity of the projectile and, as a result, the firing range and penetration indicators. However, on the way to creating such weapons there are several problems, primarily associated with the energy part of the gun. To achieve such indicators of firing, at which the rail gun will significantly exceed the firearm, such an amount of electricity is required that the railgun has not yet left the laboratory. Or rather, outside the test facility: both the gun itself and the power supply systems occupy huge rooms.
At the same time, in just five years, the Pentagon and the designers are going to install the first prototype of a practically applicable rail gun on the ship. The test results of this complex will be able to show the features of the operation of railguns on mobile platforms such as ships. In the meantime, another issue is of interest, which has recently been attended by the customers and authors of the project. A projectile from a rail gun - including a metal blank - can be launched at hypersonic speed and will have enough energy to hit a target at a considerable distance. However, during the flight, the projectile is exposed to a number of influences, such as gravity, air resistance, etc. Accordingly, with an increase in the range to the target, the dispersion of projectiles also grows. As a result, all the advantages of the rail gun can be completely "eaten" by external factors.
In recent years, a transition to guided munitions has been outlined in barrel artillery. Guided shells have the ability to correct their trajectory to maintain the desired direction of flight. Thanks to this, the accuracy of the fire increases significantly. Recently it became known that American rail guns will fire precisely corrected ammunition. The United States Navy's Office of Marine Research (ONR) has announced the launch of the Hyper Velocity Projectile (HVP) program. Within the framework of this project, it is planned to create a guided projectile that can effectively hit targets at long ranges and at high flight speeds.
At the moment, it is only known for sure that ONR wants to see a control system based on a GPS positioning system. This approach to trajectory correction is not new for American military science, but in this case the task is complicated by the specifics of the acceleration and flight of a projectile fired from a railgun. First of all, the contractors of the project will need to take into account the monstrous overloads that affect the projectile during acceleration. A barrel artillery projectile has a few fractions of a second to reach a speed of 500-800 meters per second. One can imagine what kind of overloads act on it - hundreds of units. In turn, the rail gun must accelerate the projectile to much higher speeds. It follows from this that the electronics of the projectile and its course correction systems must be particularly resistant to such loads. Of course, there are already several models of adjustable artillery shells, but they fly at significantly lower speeds than a railgun can provide.
The second difficulty in creating a controlled "rail" projectile lies in the method of operation of the gun. When fired from a rail gun, a magnetic field of enormous power is formed around the rails, the accelerating block and the projectile. Thus, the electronics of the projectile must also be resistant to electromagnetic radiation, otherwise an expensive “smart” projectile will become the most common blank even before it leaves the cannon. A possible solution to this problem is a special shielding system. For example, before firing, a projectile with electronic equipment is placed in a kind of pallet of sub-caliber ammunition, which will protect it from electromagnetic "interference" when moving along the rails. After exiting the muzzle, the shielding pan, respectively, is separated and the projectile continues its flight on its own.
The projectile withstood the overload, its electronics did not burn out and it flies to the target. The "brain" of the projectile notices the deviation from the required trajectory and issues the appropriate commands to the rudders. This is where the third problem arises. To achieve a firing range of at least 100-120 kilometers, the muzzle velocity of the projectile must be at least one and a half to two kilometers per second. Obviously, at these speeds, flight control becomes a real problem. Firstly, at such a speed, the control of the aerodynamic rudders is very, very difficult, and secondly, even if it is possible to debug the aerodynamic control system, it must work at a very high speed. Otherwise, a slight deviation of the rudder, even by a few degrees within hundredths of a second, can greatly affect the trajectory of the projectile. As for gas rudders, they are also not a panacea. Hence, quite high requirements for the control mechanics and speed of the projectile computer follow.
In general, scientists are faced with a far from easy task. On the other hand, there is still enough time - ONR wants to get a prototype of the projectile only in 2017. Another plus of the terms of reference concerns the general appearance of the projectile. Due to its high speed, it does not have to carry an explosive charge. The kinetic energy of the ammunition alone will be enough to destroy a wide range of targets. Therefore, you can give slightly larger volumes for electronics. Some specific figures from the requirements were freely available, although there was no official confirmation yet. A shell about two feet long (~ 60 centimeters) will weigh 10-15 kilograms. In addition, according to unofficial information, the new guided projectiles can be used not only in rail guns, but also in “traditional” barrel artillery. If this is true, then we can draw conclusions about the caliber of the promising ammunition. Currently, US Navy warships are equipped with artillery systems ranging from 57 mm (Mk-110 on ships of the LCS project) to 127 mm (Mk-45, installed on destroyers of the Arleigh Burke project and the Ticonderoga cruisers). In the near future, the lead destroyer of the Zumwalt project should receive an AGS artillery mount of 155 mm caliber. Of the entire spectrum of US naval artillery calibers, 155 mm is the most probable and convenient for a guided projectile. In addition, the existing American guided artillery shells - Copperhead and Excalibur - have a caliber of exactly 6.1 inches. Just the same 155 millimeters.
Perhaps the already created guided projectiles will to some extent become the basis for a promising one. But it is too early to talk about it. All information about the HVP project is limited to just a few theses, some of which, moreover, have no official confirmation. Fortunately, a number of features of rail guns allow you to make an approximate judgment about the project and already at the stage of its beginning to imagine the difficulties that the developers of the projectile will have to face. Probably, in the near future, the Marine Research Administration will share with the public some details of its requirements, or even the full appearance of a promising projectile in the form in which they want to receive it. But for now, it remains to use only the available scraps of data and fabrications on the topic.
