Aerodynamic air gun projectile
First Claim
1. In a projectile for an air arm molded as a body of revolution about a longitudinal axis comprising a head portion dimensioned for free sliding in the bore of an air arm and a skirt portion of frusto-conical form of which the rearward end is dimensioned to be in interference fit with said bore and the forward end is joined with the head portion in a reduced diameter waist, the frustum being shell-walled and having a central recess opening to the rear and extending forwardly into the head portion, an improvement wherein said projectile has an external surface form characterized by a parabolic head which smoothly transitions axially into a hyperbolic skirt,said projectile further comprising one or more vanes formed substantially symmetrically on the outer surface of said head portion, each vane extending axially in a helix configuration with a characteristic pitch which varies along the axial extent thereof.
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Abstract
A projectile for an air arm is integrally formed from a single piece of dense malleable material formed as a body of revolution about a longitudinal axis having a head portion dimensioned for free sliding in the bore of an air arm and a skirt-like portion of frusto-conical form. The rearward end of the skirt portion is dimensioned to be in slight interference fit with the bore and the forward end is joined with the head portion to define a reduced diameter waist. The frustum is shell-walled, having a central recess opening to the rear and extending forwardly into the head portion. The head portion has a parabolically shaped outer surface which transitions smoothly into a hyperbolically shaped outer skirt surface for aerodynamic efficiency. Vanes are formed on the head portion to enhance in-flight spiraling rotation.
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Citations
21 Claims
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1. In a projectile for an air arm molded as a body of revolution about a longitudinal axis comprising a head portion dimensioned for free sliding in the bore of an air arm and a skirt portion of frusto-conical form of which the rearward end is dimensioned to be in interference fit with said bore and the forward end is joined with the head portion in a reduced diameter waist, the frustum being shell-walled and having a central recess opening to the rear and extending forwardly into the head portion, an improvement wherein said projectile has an external surface form characterized by a parabolic head which smoothly transitions axially into a hyperbolic skirt,
said projectile further comprising one or more vanes formed substantially symmetrically on the outer surface of said head portion, each vane extending axially in a helix configuration with a characteristic pitch which varies along the axial extent thereof.
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19. A projectile for an air arm molded as a body of revolution about a longitudinal axis, said projectile comprising:
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a head portion dimensioned for free sliding in the bore of an air arm; a skirt portion of frusto-conical shape integrally formed with said head portion from common homogeneous material, said skirt portion including a rearward end dimensioned to be in interference fit with said bore and a forward end joined with said head portion in a reduced diameter waist, the frustum being shell-walled and having a central recess opening to the rear and extending forwardly into the head portion, wherein said head portion has a parabolic outer surface and said skirt portion has a hyperbolic outer surface, said head portion outer surface and said skirt portion outer surface having a common nominal diameter dimension at a point of transition there between to effect a smooth transition in a direction along said longitudinal axis; and means for inducing rotation of said projectile about its longitudinal axis as it traverses a line of trajectory after being discharged from said air arm, said means for inducing rotation comprising one or more vanes formed substantially symmetrically on the outer surfaces of said head portion and the reduced diameter waist portion of said skirt portion, each vane extending axially in a helix configuration which varies in pitch along its axial extent, and at least some of said vanes incused within said head portion, wherein said projectile has a characteristic center of gravity located within the head portion along the longitudinal axis at a point intermediate the forwardmost and rearward most ends of said vanes formed on the outer surface of said head portion, and wherein the axial length of said skirt portion equals or exceeds the axial length of said head portion.
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20. In a projectile for an air arm molded as a body of revolution about a longitudinal axis comprising a head portion dimensioned for free sliding in the bore of an air arm and a skirt portion of frusto-conical form of which the rearward end is dimensioned to be in interference fit with said bore and the forward end is joined with the head portion in a reduced diameter waist, the frustum being shell-walled and having a central recess opening to the rear and extending forwardly into the head portion, an improvement wherein said projectile has an external surface form characterized by a parabolic head which smoothly transitions axially into a hyperbolic skirt,
said projectile further comprising means operative to induce continued rotation of said projectile about its axis as it traverses a line of trajectory after being discharged from said air arm, wherein said means operative to induce continued rotation comprises one or more vanes formed substantially symmetrically on the outer surface of said head portion, each vane extending axially in a helix configuration, and wherein one or more of said vanes extend axially along at least a portion of the outer surface of said skirt portion.
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21. In a projectile for an air arm molded as a body of revolution about a longitudinal axis comprising a head portion dimensioned for free sliding in the bore of an air arm and a skirt portion of frusto-conical form of which the rearward end is dimensioned to be in interference fit with said bore and the forward end is joined with the head portion in a reduced diameter waist, the frustum being shell-walled and having a central recess opening to the rear and extending forwardly into the head portion, an improvement wherein said projectile has an external surface form characterized by a parabolic head which smoothly transitions axially into a hyperbolic skirt,
said projectile further comprising means operative to induce continued rotation of said projectile about its axis as it traverses a line of trajectory after being discharged from said air arm, wherein said means operative to induce continued rotation comprises one or more vanes formed substantially symmetrically on the outer surface of said head portion, each vane extending axially in a helix configuration, and wherein said vanes have a characteristic pitch which varies along the axial extent thereof.
Specification