Projectiles currently used for the M203/M320 gun launcher devices include the M433 High Explosive Dual Purpose Round, M406 High Explosive Round, M583A1 Star Parachute Round, M585 White Star Cluster Round, M713 Ground Marker Round, M781 Practice Round, M651 CS Round and M576 Buckshot Round. The M203 is not a stand-alone gun. It must be attached to an M16 or M4 rifle, for instance, and fires a family of 40 mm low velocity projectile rounds. In order to load a 40 mm round into an M203, the forward sleeve of the gun tube is slid forward, and a 40 mm round is pushed into the sleeve. The sleeve is then slid backwards and locked into position, ready to fire. The barrel of the M203 is rifled, which spins up the projectile as it travels down the barrel tube, and the projectile leaves the gun tube with a high spin rate.
The 40 mm cartridge case is typically not reused or recycled after firing. If the cartridge case becomes stuck in the gun tube, there is a tool to help the war-fighter push it from the tube. The M320 gun launcher device fires the same 40 mm low velocity ammunition as does an M203. There are several improvements that the M320 has compared to the M203. The M320 has stand alone single shot capability and may be fired by a war-fighter without attaching to a gun. It also has the capability to be attached to and fired from an M16/M4 rifle, similarly to an M203 gun launcher device. A major improvement of the M320 is the ability of the firing tube to open sideways. By opening sideways, longer ammunition can be loaded into the M320 gun tube as compared to loading into an M203. While the approximate maximum length of the projectile is approximately five inches in the M203, projectiles several inches longer can be loaded into an M320. Both M203 and M320 have rifled barrels which induce spinning in the projectile as it travels through the gun tube.
There exists a great need to develop a new family of 40 mm projectiles that can have extended range through increased velocity and projectile shape to over 1000 meters; can provide capability for an add-on optional guidance-navigation and control (“GN&C”) subsystem; can increase lethality through enhanced precision and accurate strikes; can increase projectile length which can accommodate more fragments and an increased amount of explosives and/or energetics; and can provide a novel system with much longer rear end fins, that can allow for greater stability, in applications which will no longer need any appreciable, or no, projectile spin for flight accuracy.
Currently, low velocity (“LV”) 40 mm projectiles are length restricted by the presence of the loading system that is in the M203 gun. The 40 mm LV projectiles do not fly as well as desired, due to the inability to add fins for providing stability. Instead, 40mm LV projectiles are spin stabilized, which both do not fly as well as desired and also can not employ guidance systems due to these projectiles' extensive pitch, yaw and drag. Current guidance-navigation and control (“GN&C”) subsystems can't function in a spin environment. Guided ammunition would need to have no spin (or very little spin) so that the seeker or camera therein, e.g., can see the target clearly while in flight. However, the conventional M203 or M320 grenade launcher guns do have spin since they have internal rifling intended to spin up the projectiles (at approximately 1800 revolutions per second) for stabilization of flight. Clearly then, a way must be found to avoid the spin which is inherent in conventional M203 or M320 grenade launcher guns when optional guidance is desired to be added to the projectile.
Recently developed new 40 mm projectiles of several varieties provide better performance, extended range, with reduced or no spin at all, and have the ability to have added on guidance and control systems to hit stationary targets. These novel technologies all allow for better performance, yet while reducing pitch, yaw, and/or drag. The stability of these projectiles are still somewhat limited by the length and area of their fins. These projectiles will fly well and have the ability to add guidance and control with small canards added in the front of the projectile, in a canard actuating system (“CAS”). Smaller (width and/or length) canards however would mean less control authority or less of an ability to make large course corrections while in flight. The projectiles' center of gravity (“CG”) and center of pressure (“CP”) needs to be a certain distance apart in order to provide a needed stability margin. In the case of fin stabilized projectiles, the CG needs to be in the front of the projectile while the CP needs to be in the rear of the projectile. Larger canards, and changing the position of the canards away from the front of the projectile, move the CP forward and begin to compromise or reduce the stability margin. By incorporating longer fins on a projectile with more surface area however, the CP is moved back and the projectile gains a better stability margin. With this greatly improved stability margin, larger canards can be positioned where needed. This improvement now allows for a projectile to have larger course corrections and hit harder targets such as moving targets. Optional guidance and control can now be added to the front or side of a projectile utilized for battle. The optional guidance and control provides increases accuracy and precision hits on targets up to and beyond 1000 meters (a goal which is sought). The obturator on the projectile prevents gases from blowing past it; it seals in the gases allowing a projectile to move with a constant rate push as it travels down the barrel of a gun launcher. The obturator must be positioned immediately behind of the cartridge case. This is because the M320 and M203 have both a section to seat the cartridge case, and then also enough room still, for the obturator before the rifling part of the gun tube is encountered. The obturator is higher than (near the end of) the projectile and therefore is found at the top of the gun tube. If the obturator were made too long in dimension, then the cartridge could not be loaded. This is since the obturator cannot be pushed into the rifling just by hand. Currently, there is an approximately one inch long of space in between the back of the obturator and the front of the (inside of the) cartridge case. This can only allow for fins that are one inch long therefore. The projectile continues on past the obturator by a distance of approximately 1/16 inch (press fit into the cartridge case) and then slopes down at an angle of 15 degrees, toward the end of the projectile. There is currently provided a housing for the fins at the end of the projectile, which housing functionally attaches the fins to the projectile. The fins physically now extend from the housing and up until the beginning of the interference fit with the cartridge case. Therefore the fins are approximately one inch long. The fins open up after exit from the gun. These finned projectiles have tested with excellent flight results, however, to add in a guidance and control (G&C) canard system as desired, the fins would not allow for larger and more aggressive canards and positioning. These projectiles are good for stationary targets. To hit moving and stationary targets, fins that are two inches or longer are needed. Therefore, what is greatly needed is to provide a low velocity 40 mm projectile with two or more inch long fins to allow for aggressive guidance and control CAS systems. In addition, aeroballistic modeling shows that the rear end of the projectile will have less drag with slopes on the projectile that are less than eight degrees, rather than the currently mentioned fifteen degrees, and this type of projectile is also greatly needed.