SELF-SPINNING BULLET AND RELATED METHODS OF USE
A bullet may have its base shaped such that explosive from the cartridge or chamber causes the bullet to spin. A bullet may have any shape to the base that causes spinning that closely or exactly matches the rifling of a particular rifle. The base may be structured to achieve an impellor or turbine action to angularly accelerate the bullet while the bullet is being acted upon by an axial force from a propellant explosion during free travel within the gun or while travelling along the rifling.
This application claims the benefit under 35 USC 119(e) of U.S. provisional application Ser. No. 62/337,775 filed May 17, 2016.
TECHNICAL FIELDThis document relates to self-spinning or propeller bullets and related methods of use.
BACKGROUNDBullets are propelled by a controlled explosion through a rifled barrel of a firearm. The rifling in the barrel induces the bullet to spin to gyroscopically stabilize the bullet as it exits the muzzle end of the barrel and travels toward a target. In some cases, rifling may be configured to have a twist rate that progressively increases down the length of the barrel.
SUMMARYBullets are disclosed whose bases are shaped such that explosive from the cartridge or chamber causes the bullet to spin.
Bullets are disclosed having any shape to the base that causes spinning that closely or exactly matches the rifling of a particular rifle.
Bullets are disclosed whose base achieves an impellor or turbine action to angularly accelerate the bullet during free travel.
A bullet is disclosed comprising: a cylindrical body; a tip; and a base shaped to cause the bullet to spin, in a rotational direction about a flight axis defined by the body, on exposure to an axial force from a propellant explosion adjacent the base.
A combination is disclosed comprising a gun and the bullet loaded in the gun, the gun having a barrel with a rifling path defined on an interior surface of the barrel, in which the rotational direction matches a twist direction of the rifling path.
A combination is disclosed comprising a gun and the bullet loaded in the gun, the gun having a barrel with a rifling path defined on an interior surface of the barrel, in which the rotational direction matches a twist direction of the rifling path, and each vane surface is sloped to form an angle of ninety degrees or less, with respect to a longitudinal leading edge of the rifling path, the angle being defined moving in the rotational direction from the longitudinal edge to the vane surface.
A method comprising initiating a propellant explosion adjacent a base of a bullet loaded in a gun to propel the bullet down a barrel of the gun, in which the propellant explosion creates an axial force that acts upon a vane surface defined by the base of the bullet to generate a torque that causes the bullet to spin in a rotational direction about a flight axis defined by the bullet.
In various embodiments, there may be included any one or more of the following features: The base is shaped to cause the bullet to spin in a clockwise direction when viewing a base end of the bullet down the flight axis. The base is a closed circular end of the cylindrical body. The base defines a vane surface radially spaced from the flight axis and sloped relative to a plane defined perpendicular to the flight axis such that exposure, on the vane surface, to the axial force imparts a torque on the bullet in the rotational direction. The base defines a plurality of vane surfaces angularly distributed about the flight axis relative to one another and each being respectively sloped relative to the plane defined perpendicular to the flight axis such that exposure, on each vane surface, to the axial force imparts a torque on the bullet in the rotational direction. The plurality of vane surfaces are angularly distributed about at least a periphery of the base. A circumferential edge, defined between the base and the cylindrical body, follows the sloping of the plurality of vane surfaces. The plurality of vane surfaces connect radial end to radial end in a stepped fashion. Each vane surface forms a circular sector. The plurality of vane surfaces comprises two semi-circular sectors. Each vane surface is sloped with a helical shape. Each vane surface is sloped with a planar shape. Each vane surface is sloped with the shape of a cylindrical wall. The cylindrical body has a boat tail shape adjacent the base. Each vane surface is sloped to form an angle of ninety degrees with respect to the longitudinal leading edge of the rifling path. The barrel comprises a rifling path whose twist direction matches the rotational direction. The barrel is a smoothbore barrel.
These and other aspects of the device and method are set out in the claims, which are incorporated here by reference.
Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:
Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.
A bullet is a projectile that is propelled toward a target by a controlled explosion within a firearm (gun). The bullet is loaded in the gun, often at the tip end of a cartridge full of gun powder, which is then ignited to propel the bullet in an axial direction. Immediately after the explosion, the bullet travels axially through the gun barrel, which may have rifling grooves to induce spin in the bullet. Rifling includes lateral projections or grooves, such as helical grooves, in the barrel of a gun to impart a spin to the bullet around its long axis. After leaving the muzzle end of the barrel, the bullet continues to travel toward a target while spinning. The resulting spin serves to gyroscopically stabilize the bullet, improving its aerodynamic stability and accuracy.
A rifle barrel may gradually burn out by erosion of the throat and bore caused by continual firing. Initially, the rifling in the throat may start to round off rather than have sharp corners. The rifling may gradually continue to disappear until the user can no longer contact the rifling with the loaded but unfired bullet. At some point the bore may start to heat check, evidenced by tiny shallow cracks that start to appear all over the throat area and a few inches down the barrel, sometimes having the appearance of mud flats in a dry lake bed. Once heat checking has begun, continual firing may cause small parts to pop out causing the bore to get rough and become more difficult to clean. Performance will deteriorate to greater and greater degrees throughout this process, eventually leading to a need to replace the barrel.
The erosion to the barrel is caused by both the extreme temperatures created by the propellant explosion, and physical contact with the bullet. Temperature and heat erosion is understood as follows. Every time a bullet is fired the propellant explosion creates a blow torch effect of powder gasses and solids that strikes the rifling. Superheated powder travels down the barrel at high speeds, weakening the barrel wall over time.
The effect of physical contact between the bullet and barrel is understood as follows. Every time a bullet is fired, the bullet will strike the rifling and undergo an angular acceleration over a fraction of a second from zero or nominal spin to a maximum spin rate (revolutions per length of axial travel) dependent on the dimensions of the rifling path. The actual rotation speed is dependent on the characteristics of the particular rifling and the breech velocity of the bullet among other factors.
The force acting on the bullet is matched by an opposing force of equal magnitude acting on the rifling, and the opposing force may gradually erode the barrel over time. A bullet may be slightly larger in diameter than the bore diameter of the corresponding barrel, or may expand (obturate) into barrel contact when fired, and as a result, a rifled barrel may impress a negative impression of itself on the sides of the bullet. The contact between the bullet and the barrel may also act to remove energy from the bullet, reducing the muzzle velocity of the bullet relative to the same bullet fired from a wider, smoothbore barrel.
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The slope of the vane surfaces may be adjusted, alone or in combination with adjustments to other variables such as amount and type of propellant, and barrel dimensions, in order to tailor the magnitude of angular acceleration acting on the base 14 from the propellant explosion as desired. As the angle 40 decreases, the vane surface slope may become steeper, resulting in relatively larger torque on the bullet 10. Steeper sloping may also compensate for pressure on the sides of the boat tail section 30 of the base 14, and for the fact that in the boat tail configuration shown the vaned part of the base has a smaller surface area for conversion of axial force to torque. In some cases, the slope or slopes are adjusted to minimize or otherwise reduce the demand on the rifling path 20 to bring the bullet 10 to a spin rate equal to the twist rate of the rifling path 20. In cases where a non-zero free-travel clearance jump distance 46 is defined, the sloping and dimensions of the vane surfaces may be adjusted such that the bullet 10 achieves a spin rate commensurate with (for example equal to) the twist rate of the rifling path 20 prior to or on entering contact with the rifling path 20.
Angles 40 greater or less than ninety degrees (acute angles) may be used, for example an angle that is within twenty percent of (plus or minus) ninety degrees. Referring to
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The base 14 of the bullet 10 may be initially mounted to sit within a cartridge 22 mounted in a chamber 50, for example if the bullet 10 sits within a cartridge sleeve 28. The cartridge 22 may contain a suitable amount and type of propellant (not shown), which may be ignited to propel and spin the bullet 10. A primer 24 may be located adjacent a cartridge base rim 26, the primer 24 being positioned to be struck by a hammer (not shown) connected to a trigger system to initiate the propulsive explosion of the propellant.
The nose or tip 16 of the bullet 10 may be seated in a mouth 48 of the gun 47, and in some cases the mouth 48 may taper or otherwise reduce in diameter toward the barrel 18. A free travel clearance jump distance 46, representing the distance the bullet 10 must travel before engaging the rifling path 20, may be defined between the cylindrical body 12 and the rifling path 20. However, in some cases, particularly with newer barrels, the body 12 may abut the rifling groove or path 20 when the bullet 10 is loaded and ready to fire.
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The rifling path 20 may have a suitable shape and style, such as conventional or polygonal rifling, indents, grooves, projections, or other features. The location and dimensions of the vane surfaces may be selected to balance the torque on the bullet to avoid wobble. The bullet may have a single vane surface, for example indented in an otherwise planar base end, which forms a plane perpendicular to the flight axis 38. The tip 16 may have a suitable shape such as a closed circular end, a cone, a bicone, an ogive, or others. The base 14 may have the shape of a stepped cam disc. The vane surfaces may be arranged in a ring form about the axis 38. The bullet 10 may be fired in a smoothbore barrel and still achieve a spin rate analogous to that attainable with rifling. A smoothbore barrel embodiment may be visualized by taking
In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.
Claims
1. A bullet comprising:
- a cylindrical body;
- a tip; and
- a base shaped to cause the bullet to spin, in a rotational direction about a flight axis defined by the body, on exposure to an axial force from a propellant explosion adjacent the base.
2. The bullet of claim 1 in which the base is shaped to cause the bullet to spin in a clockwise direction when viewing a base end of the bullet down the flight axis.
3. The bullet of claim 1 in which the base is a closed circular end of the cylindrical body.
4. The bullet of claim 3 in which the base defines a vane surface radially spaced from the flight axis and sloped relative to a plane defined perpendicular to the flight axis such that exposure, on the vane surface, to the axial force imparts a torque on the bullet in the rotational direction.
5. The bullet of claim 4 in which the base defines a plurality of vane surfaces angularly distributed about the flight axis relative to one another and each being respectively sloped relative to the plane defined perpendicular to the flight axis such that exposure, on each vane surface, to the axial force imparts a torque on the bullet in the rotational direction.
6. The bullet of claim 5 in which the plurality of vane surfaces are angularly distributed about at least a periphery of the base.
7. The bullet of claim 6 in which a circumferential edge, defined between the base and the cylindrical body, follows the sloping of the plurality of vane surfaces.
8. The bullet of claim 6 in which the plurality of vane surfaces connect radial end to radial end in a stepped fashion.
9. The bullet of claim 5 in which each vane surface forms a circular sector.
10. The bullet of claim 9 in which the plurality of vane surfaces comprises two semi-circular sectors.
11. The bullet of claim 4 in which each vane surface is sloped with a helical shape.
12. The bullet of claim 4 in which each vane surface is sloped with a planar shape.
13. The bullet of claim 4 in which each vane surface is sloped with the shape of a cylindrical wall.
14. The bullet of claim 1 in which the cylindrical body has a boat tail shape adjacent the base.
15. A combination comprising a gun and the bullet of claim 1 loaded in the gun, the gun having a barrel with a rifling path defined on an interior surface of the barrel, in which the rotational direction matches a twist direction of the rifling path.
16. A combination comprising a gun and the bullet of claim 4 loaded in the gun, the gun having a barrel with a rifling path defined on an interior surface of the barrel, in which the rotational direction matches a twist direction of the rifling path, and each vane surface is sloped to form an angle of ninety degrees or less, with respect to a longitudinal leading edge of the rifling path, the angle being defined moving in the rotational direction from the longitudinal edge to the vane surface.
17. The combination of claim 16 in which each vane surface is sloped to form an angle of ninety degrees with respect to the longitudinal leading edge of the rifling path.
18. A method comprising initiating a propellant explosion adjacent a base of a bullet loaded in a gun to propel the bullet down a barrel of the gun, in which the propellant explosion creates an axial force that acts upon a vane surface defined by the base of the bullet to generate a torque that causes the bullet to spin in a rotational direction about a flight axis defined by the bullet.
19. The method of claim 18 in which the barrel comprises a rifling path whose twist direction matches the rotational direction.
20. The method of claim 18 in which the barrel is a smoothbore barrel.
Type: Application
Filed: Feb 3, 2017
Publication Date: Feb 22, 2018
Inventor: Todd Ronald Schwark (Kaslo)
Application Number: 15/424,626