One unexpected benefit of this

One unexpected benefit of this analysis was that it order BLU9931 illustrated the precision of the AFVA method to measure projectile orientation. Previously, it was determined that AFVA measurements were within 0.1° of on-board electronic measurements [5], but clearly the data from this test smoothly show fluctuations in pitching motion much smaller than 0.01°.
Discussion of results As described by McCoy [2], the magnitude of the wobble motion (tricyclic arm) for a dynamically imbalanced but gyroscopically stable projectile iswhere is the inertia along the projectile spin axis, is the transverse moment of inertia, and is the product of inertia resulting from. It would follow that a linear relationship would exist between the wobble amplitude and the measured product of inertia for each of the projectiles in this test. Unfortunately, the four projectiles that had their mass asymmetries corrected were not re-measured before firing. Since their true products of inertia are unknown, typical values for the M110A2E1 projectile are used for the projectiles that were restored to normal levels of mass asymmetry [6]. The comparison between the product of inertia and the measured amplitude of wobble motion is shown in Fig. 6. From the data in Figs. 5 and 6, it is obvious that two distinct groupings of wobble amplitudes were measured. One group corresponds to the four projectiles with significant mass asymmetries and the other is the group of four projectiles that were returned to normal conditions. Since the products of inertia were not measured for the four rounds that were restored to normal conditions, it is difficult to truly assess the validity of the relationship between the wobble magnitude and the measured product of inertia. When compared to the expected relationship which was generated using Eq. (3) and typical inertial properties for the M110A2E1, it is clear that the wobble amplitudes measured using AFVA are roughly 32% lower than would be expected for projectiles exhibiting such large mass imbalances. This is believed to be attributed to residual settling of the WP during launch, effectively reducing the product of inertia to some degree before the projectile leaves the weapon muzzle. This possibility is being investigated in a separate study.
Conclusions
Introduction Two areas where significant weight reduction could be achieved are the weapon system and the ammunition. In order to reduce the weight of the ammunition, several concepts are being investigated and reached a high technology readiness level. Among these, polymer cased ammunition, caseless ammunition (CL) and cased telescoped ammunition (CT) are the most promising. Using these technologies, ammo/link weight reduction of the order of 37% and 12% volume reduction could eventually be achieved [1]. In order to reduce the bias and the dispersion associated with the aerodynamic jump and the lateral throw-off, the gun\'s twist rate can be reduced to lower the spin rate of the projectile at the muzzle. However, for the projectile to remain gyroscopically stable, the spin rate must be kept high enough such that the gyroscopic stability factor, , remains above 1 for all firing conditions. Lateral throw-off of a projectile was first studied by Mann [2] using statically unbalanced projectiles having a center of mass off the axial axis. The aerodynamic jump was also investigated by Mann [2] using dynamically unbalanced projectile. Murphy [3] studied a yaw induction technique for spin-stabilized projectiles using mass asymmetry. He developed a mathematical relationship that relates the size of the tricyclic arm and the dynamic unbalance due to a slight mass asymmetry. More recently, Ritter [4] and Beyer and Ritter [5] used a custom made small caliber gun breech to quantify the initial motion of unmodified small caliber projectiles. In studying videos of the projectile at the tube exit, they observed considerable off-axis motion. Additional experiments to study and understand the implications of this motion are being developed by the authors.