Aerodynamic projectile
A projectile has a front portion, a divider and a cylindrical portion. The front portion has a wall defining an interior cavity, which is closed by the divider. The cylindrical portion comprises a cylindrical sidewall having an outer surface and an inner surface. The projectile also has a plurality of depressions in the cylindrical sidewall. The depressions have an outlet adjacent the second end, an inlet toward the first end and a neck area between the inlet and the outlet. A width of the inlet is smaller than a width of the outlet. The depressions at the neck area have a curved sidewall, but a generally straight sidewall between the neck area and the outlet. The surface of the depression extends at a ramp angle from the outer surface of the sidewall at the inlet of the depression toward the inner surface of the sidewall at the outlet.
1. A projectile comprising:
a generally hemispherical portion having an inner surface and an outer surface forming a generally hemispherical wall and a generally hemispherical interior volume;
a divider engaging the generally hemispherical wall to close the hemispherical interior volume of the generally hemispherical portion;
a cylindrical portion comprising a cylindrical sidewall adjacent the divider, the cylindrical sidewall having a first end adjacent the divider and a second end distal the divider, the cylindrical sidewall formed by an inner surface and an outer surface and having a wall thickness between the inner surface and the outer surface of the cylindrical sidewall;
a plurality of depressions formed in the cylindrical sidewall, the depressions having an inlet distal the second end of the cylindrical sidewall and an outlet adjacent the second end of the cylindrical sidewall, wherein a width of the inlet is smaller than a width of the outlet, and a neck area between the inlet and the outlet, wherein an outer surface of the depression has a ramp surface extending at a ramp angle gradually from the outer surface of the cylindrical sidewall at the inlet to the depression toward the inner surface of the cylindrical sidewall at the outlet of the depression; and,
a chamfer at the second end of the cylindrical portion, the chamfer generally extending from a bottom wall at the second end proximal the inner surface toward the outer surface of the cylindrical sidewall and toward the first end of the cylindrical sidewall.
2. The projectile of claim 1 , wherein the depressions at the neck area have a curved sidewall.
3. The projectile of claim 1 , wherein the depressions have a generally straight sidewall between the neck area and the outlet.
4. The projectile of claim 1 , wherein the ramp angle is between 1° and 15°.
5. The projectile of claim 1 , wherein the ramp angle is about 3.5°.
6. The projectile of claim 1 , wherein the depressions are provided at a transverse angle to a longitudinal axis of the projectile about the outer surface of the cylindrical sidewall.
7. The projectile of claim 6 , wherein the depressions are provided at an angle to the longitudinal axis of the projectile of between approximately 5° and approximately 15°.
8. The projectile of claim 6 , wherein the depressions are provided at an angle to the longitudinal axis of the projectile of approximately 9°.
9. The projectile of claim 1 , wherein the plurality of depressions are symmetrically spaced around the outer surface of the cylindrical sidewall.
10. The projectile of claim 1 , further comprising a plurality of geometrically shaped recesses in the cylindrical sidewall between the depressions.
11. The projectile of claim 10 , wherein the recesses are v-shaped.
12. The projectile of claim 1 , wherein the width of the inlet is approximately ⅓ of the width of the outlet.
13. The projectile of claim 1 , further comprising an open rear cavity between the inner surface of the cylindrical sidewall.
14. A projectile comprising:
a front portion having a wall defining an interior cavity;
a divider closing the interior cavity;
a cylindrical portion comprising a cylindrical sidewall having an outer surface and an inner surface, the cylindrical sidewall having a first end adjacent the divider and a second end distal the divider; and,
a plurality of depressions formed in the cylindrical sidewall, the depressions having an inlet distal the second end of the cylindrical sidewall and an outlet adjacent the second end of the cylindrical sidewall, wherein the outlet of the depression is open through the second end of the cylindrical portion of the projectile, wherein a width of the inlet is smaller than a width of the outlet, and a neck area between the inlet and the outlet, wherein the depressions at the neck area have a curved sidewall, and wherein the depressions have a generally straight sidewall between the neck area and the outlet.
15. The projectile of claim 14 , wherein an outer surface of the depression has a ramp surface extending at a ramp angle gradually from the outer surface of the cylindrical sidewall at the inlet of the depression toward the inner surface of the cylindrical sidewall at the outlet of the depression.
16. The projectile of claim 14 , wherein the depressions are provided at a transverse angle to the longitudinal axis of the projectile.
17. The projectile of claim 14 , wherein the plurality of depressions are symmetrically spaced around the outer surface of the cylindrical sidewall.
18. The projectile of claim 14 , further comprising a plurality of geometrically shaped recesses in the cylindrical sidewall between the depressions.
19. The projectile of claim 14 , further comprising a chamfer at the second end of the cylindrical portion, the chamfer generally extending from a bottom wall at the second end proximal the inner surface toward the outer surface of the cylindrical sidewall and toward the first end of the cylindrical sidewall.
20. A projectile comprising:
a front portion having a wall defining an interior cavity;
a cylindrical portion adjacent the front portion, the cylindrical portion comprising a cylindrical sidewall having an outer surface and an inner surface; and,
a plurality of depressions formed in the cylindrical sidewall, the depressions having an inlet distal a second end of the cylindrical sidewall and an outlet adjacent the second end of the cylindrical sidewall, wherein a width of the inlet is smaller than a width of the outlet, and a neck area between the inlet and the outlet, wherein the depressions at the neck area have a curved sidewall, wherein the depressions have a generally straight sidewall between the neck area and the outlet, and wherein a surface of the depression has a ramp surface extending at a ramp angle gradually from the outer surface of the cylindrical sidewall at the inlet of the depression toward the inner surface of the cylindrical sidewall at the outlet of the depression such that the outlet of the depression is open through the second end of the cylindrical portion of the projectile.
21. The projectile of claim 20 , further comprising a chamfer at the second end of the cylindrical portion, the chamfer generally extending from a bottom wall at the second end proximal the inner surface of the cylindrical sidewall toward the outer surface of the cylindrical sidewall and toward a first end of the cylindrical sidewall.