Aeronautics and astronautics – Missile stabilization or trajectory control – Externally mounted stabilizing appendage
Reexamination Certificate
1999-11-18
2002-04-09
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Missile stabilization or trajectory control
Externally mounted stabilizing appendage
C089S047000
Reexamination Certificate
active
06369373
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to projectiles launched from a gun barrel or cannon, and more particularly to a ramming brake for gun-launched projectiles.
BACKGROUND OF THE INVENTION
When launching projectiles out of large military guns or cannons, a typical loading technique is to first ram the projectile into the breach of the gun, and then to ram a propelling charge in a shell casing behind the projectile. The propelling charge is typically positioned in the breach by a shell casing rim that is similar to the rim on a bullet cartridge used with a handgun. This rim is larger than the diameter of the breach and is prevented from being inserted into the barrel of the gun. Alternatively, the propelling charge and the projectile may be contained in a single unit that is inserted into the breach of the gun.
Projectiles launched from military guns are typically rear obturated. The aft end of the projectile has a protruding ring or flange of material called an obturator or a rotating band. The obturator has a diameter smaller than the diameter of the breach, but larger than the diameter of the bore of the gun barrel. The bore is the section of the barrel that typically contains a series of rifling grooves used to impart a spin on the projectile.
During loading, the projectile is rammed into the breach in a manner similar to putting a bullet in a gun chamber. However, unlike a typical bullet, the projectile does not have a cartridge rim to stop it (only the separate propelling charge has a cartridge rim). Therefore, the aft end or rear obturator is used to stop the projectile once it has traveled an appropriate distance into the barrel. Because the rear obturator has a diameter larger than the bore diameter of the gun, the obturator is stopped during loading of the projectile in an area of the gun barrel where the inside diameter decreases from the breach diameter to the bore diameter. This area of inside diameter change is called the forcing cone. Because the obturator is located at the rear of the projectile, when the obturator stops at the forcing cone, most of the projectile is positioned in the bore of the barrel.
When the propelling charge is ignited, the rear of the projectile is forced into the bore of the gun barrel. The obturator, which has a diameter larger than the bore of the gun, is forced to extrude into the rifling grooves. This extrusion helps to prevent the charge gases created by the ignition of the propelling charge from flowing past the projectile in the rifling grooves. By preventing the charge gases from blowing by the projectile, the obturator causes the charge gases to drive the projectile out of the gun at the optimal velocity. In addition, since the rifling grooves spiral down the barrel, the grooves impart a spin to the projectile to increase flight stability. It should be noted that the term “rotating band” is often used to denote a device that provides obturation (the obstruction of gas flow) as well as imparting a rotation to the projectile. The term “obturator” typically refers to a device that only performs the obturation function. However, for the purposes of this application, the term “obturator” will be used generically to refer to both rotating bands and obturators.
Advanced projectiles (“smart” projectiles) are capable of being fired from the same guns that are used to fire the standard unguided projectiles described above. An example of an unguided projectile is a standard artillery shell, which is basically a large bullet. On the other hand, advanced projectiles have enhanced features such as electronic guidance and extended range rocket motors. For example, certain advanced projectiles are launched from a gun using a propelling charge, but then use a rocket motor and a guidance system to propel them to a selected target. These advanced projectiles must be designed to be loaded and fired in the same gun barrels that were designed to fire the standard unguided projectiles. However, advanced projectiles are often longer than standard projectiles due to their increased complexity. In addition, in order to increase the range of advanced projectiles, a relatively thin rocket motor wall is used. Because of the increased length and the thin rocket motor wall, if a standard rear obturator is used on such projectiles, the launch pressures created when the charge is ignited would buckle the aft portion of the advanced projectile.
An obturator or related device must be used in order to stop the charge gases from blowing by the projectile. This function is important in the case of advanced projectiles due to the sensitivity of the guidance electronics. Any blow-by could potentially destroy the projectile's operability. Additionally, a brake is needed to stop the projectile when it is rammed into the gun. Traditionally, both of these functions have been performed by the rear obturator or rotating band, as described above. However, since the obturator cannot be located at the rear of the projectile on an advanced projectile, the standard rear obturator/rotating band design used with unguided projectiles must be replaced by one or more components that serve the functions of stopping the advanced projectile when rammed into the gun barrel.
SUMMARY OF THE INVENTION
Accordingly, a need has arisen for apparatus to position an advanced projectile in a gun barrel during loading of the projectile. The present invention provides a ramming brake for use with a gun-launched projectile that addresses shortcomings of prior apparatus.
In accordance with the present invention, there is provided a ramming brake for use with a projectile launched from the barrel of a gun having a tapered portion. The ramming brake includes a braking ring that has a tapered surface configured to wedge into a tapered portion of the gun barrel. In a particular configuration, the braking ring wedges in the tapered breach of the gun barrel. The ramming brake further includes a retaining mechanism that is used to couple the braking ring to the projectile. This retaining mechanism restrains and controls the movement of the projectile after the braking ring wedges into the tapered portion of the barrel.
Embodiments of the present invention provide numerous technical advantages. For example, in one embodiment of the invention, a ramming brake is provided that stops the aft end of a mid-body obturated projectile from entering the bore of a gun barrel during loading of the projectile into the barrel. Furthermore, ramming brakes incorporating teachings of the present invention are typically fabricated from a material that disintegrates once the projectile is fired from the gun. Such disintegration prevents the ramming brake from damaging the inside of the gun barrel during launch.
Additional technical advantages include a ramming brake having a configuration that allows the brake to be stopped in the breach of the gun instead of the forcing cone. Because typically unguided munitions are stopped in the forcing cone during loading, this area typically experiences high wear. By providing a ramming brake for use with advanced projectiles that stop in the breach (which experiences little wear) additional wear of the forcing cone is minimized. However, ramming brakes incorporating teachings of the present invention also function when stopped in the forcing cone instead of the breach (which may occur once the inner surface of the gun barrel wears after many uses). Moreover, a ramming brake is provided in one embodiment of the present invention that is not rigidly attached to the projectile. For example, semi-elastic cords are used to attach the braking ring to the projectile. In such instances, the force needed to stop the momentum of the moving projectile is greatly decreased.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.
REFERENCES:
patent: 910935 (1909-01-01), Meyer
patent: 1861522 (1932-06-01), Brandt
patent: 2454801 (1948-11-01), Himmer
patent: 2699094 (1955-01-01), Musser
patent: 3687079 (1
Henderson James A.
Liggett G. Michael
Tepera Joseph E.
Baker & Botts L.L.P.
Best Christian M.
Jordan Charles T.
Raytheon Company
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