Small Arms Projectile with Blunted Nose and Step Transition
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Solution Overview
Problem
Current small arms ammunition projectiles face challenges in achieving high precision long-range firing due to increased aerodynamic drag and initial disturbances, particularly at supersonic velocities, which result in trajectory deviations and dispersion, especially under unfavorable conditions like dust, fog, or rain.
Innovation Solution
The design of a projectile with a head portion featuring a blunted nose surface, a cylindrical central leading portion, and a boattail that tapers towards the base, incorporating a step transition between the central leading portion and the boattail, with specific diameter and angle configurations to minimize aerodynamic drag and initial disturbances, ensuring symmetrical separation from the barrel rifling and reduced interaction with the rifling lands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a smooth transition is made between the cylindrical central leading portion and the boattail, then manufacturing precision is improved and initial disturbances are decreased, but the length of asymmetrical effect of the rifling is increased thus increasing initial disturbances
Solution Approach 1:
The projectile is divided into three distinct portions: a head portion with blunted nose surface, a cylindrical central leading portion, and a boattail. This segmentation allows each portion to be optimized independently - the head portion for aerodynamic performance, the central portion for rifling interaction, and the boattail for drag reduction, while the step transition provides a clear separation point that prevents the boattail from experiencing prolonged rifling asymmetrical effects.
2Loss of energy
If the head portion length is increased to reduce aerodynamic drag, then ballistic characteristics are improved, but the projectile nutation in the barrel is increased thus increasing initial disturbances
Solution Approach 1:
Different portions of the projectile are given different geometric properties optimized for their specific functions. The head portion has a blunted nose surface with specific curvature radius (0.05D-0.15D) to minimize wave drag. The cylindrical central leading portion provides stable rifling engagement. The boattail has a specific taper angle (10-20 degrees) to reduce base drag. This local optimization of geometric properties allows the projectile to achieve low aerodynamic drag without excessive nutation.
3Device complexity
If the projectile exits the barrel with asymmetrical clearance, then the circular clearance formation is simplified, but the gunpowder gas breaks through asymmetrically increasing initial disturbances and trajectory deflection
Solution Approach 1:
The invention intentionally introduces a controlled asymmetry in the form of a step transition between the cylindrical central leading portion and the boattail. This step creates a specific clearance pattern at the muzzle that, while asymmetric in form, provides predictable and consistent gas flow characteristics. The step transition ensures that the clearance between the projectile and muzzle face is well-defined, preventing chaotic asymmetrical gas breakthrough that would cause trajectory deflection and increased dispersion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances ballistic characteristics by reducing aerodynamic drag and initial disturbances, leading to improved trajectory stability and reduced dispersion, as demonstrated by experimental tests showing increased muzzle velocity and decreased dispersion at various ranges compared to existing projectiles.
Implementation Method 1
the projectile aerodynamic drag depends on the wave resistance, surface friction drag and vortex (base) drag
Implementation Method 2
Wave resistance depends on the geometry of the projectile head portion and can amount to 60-70% of the total aerodynamic drag at supersonic projectile velocities
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to small arms ammunition and can be used in the designs of projectiles intended for high precision long-range firing at supersonic and subsonic muzzle velocities of a projectile. A projectile of small arms ammunition comprises a head portion with a blunted nose surface, a central leading portion, and a boattail, which tapers towards the projectile base, wherein the largest diameter of the cross-section of the central leading portion is equal to "D", wherein a caliber of the projectile is within the range of 5.45-14.5mm, wherein a length of the head portion is equal to 1.9-2.9D, wherein a caliber of the projectile is within the range of 5.45-14.5mm, wherein a the diameter at the interface between the nose surface and the lateral surface of the head portion is equal to 0.15-0.3D. Between the central leading portion and the boattail a step transition is made so that the largest diameter of the cross-section of the boattail is equal to 0.94-0.97D and is less than the diameter of the barrel bore measured at the rifling lands. The invention provides an increase in the ballistic characteristics of projectiles on the trajectory and a decrease in projectiles dispersion.