Effect of Rifling Grooves on the Performance of Small-Caliber Ammunition

A combined experimental and computational investigation was performed to examine the effect of rifling grooves on the aerodynamics of projectiles and determine whether the aerodynamics associated with the rifling grooves are a potential mechanism for in-flight trim angles. The experimental program c...

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Bibliographic Details
Main Authors: Silton, Sidra I, Weinacht, Paul
Format: Report
Language:English
Subjects:
Aerodynamics
Ammunition and Explosives
COMPUTATIONAL FLUID DYNAMICS
IN-FLIGHT SPIN RATES
MAGNUS EFFECT
OVER-SPUN CONDITION
RIFLING GROOVES
ROLL
SMALL ARMS AMMUNITION
SYMPOSIA
TRIM ANGLE
TWIST RATES
WIND TUNNEL TESTS
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Summary:A combined experimental and computational investigation was performed to examine the effect of rifling grooves on the aerodynamics of projectiles and determine whether the aerodynamics associated with the rifling grooves are a potential mechanism for in-flight trim angles. The experimental program consisted of spark-range firings of bullets from the standard twist barrel spanning the range of velocities typically encountered in flight. Additionally, sabot-launched smooth and pre-engraved bullets were fired from oversized barrels with twist rates to match in-flight spin rates and velocities. The computational technique was first validated using existing wind tunnel data for a rifled projectile. Computational results were then obtained to complement the results from the spark-range testing. The results show that the aerodynamic components most sensitive to the rifling grooves are the Magnus force and moment and the roll-damping moment. These effects are relatively small for typical in-flight conditions and are unlikely to produce trim angle effects and can be ignored in future computational and experimental efforts. Presented at the Army Science Conference (26th) in Orlando, FL on 1-4 Dec 2008 and published in proceedings of the same. See also ADM002187. The original document contains color images.