THE EFFECT OF SHAPE FACTOR ON THE DRAG COEFFICIENT OF SPIN STABILIZED BULLETS BY EXPERIMENTAL AND NUMERICAL ANALYSES

In the present study, 7.62 x 51 mm NATO bullet has been taken as an example and drag coefficients (C-D) of the bullets at different geometric forms have been examined experimentally and numerically, in an attempt to minimize them. A G3 infantry rifle, a B481 Doppler Radar and a data gathering system have been employed for the experiments. The PRODAS program, which is capable of implementing numerical calculations by carrying out geometric optimisation and is used frequently in ballistic calculations, has been utilized for numerical calculations. Reference values, which are utilized for the existing bullet geometry, have been verified in experimental and numerical terms. Subsequently, different forms of the bullet samples have been designed and manufactured by varying the certain geometric parameters predetermined on the bullet which had been verified as mentioned above. These samples have been filled with the same amount of the gunpowder each and turned into cartridges and tested in ballistic experiments. While designing the bullet samples, the basic dimensions consisting of the bullet diameter, the longitudinal length from the starting point of the bullet radius to the starting point of the bullet nose, and longitudinal length from the starting point of the bullet radius to the point where the cartridge starts have been maintained on the existing bullet model. The drag coefficients (C-D) of the new bullets have been experimentally measured both at the subsonic and the supersonic speeds and they have also been numerically calculated with PRODAS program.