Calculates the drag function for a bullet of a given shape

Declared data
Bullet diameter (mm.)
Bullet length (mm.)
Nose length (mm.)
Meplat diameter (mm.)
Drive-band diameter (mm.)
Base diameter (mm.)
Boat-tail angle (degrees)
Boat-tail length (mm.)
Secant radius (calibres)
(Est.) Bullet weight (grains)
Bullet density (gm/cc.)

The outline above is the bullet described by the declared data on the left. Note that the drive-band (if declared) is not shown. If you wish to make changes to the bullet design, change the data fields as required and press the re-calculate button below.

Some of the calculated elements for this bullet are shown to the right. The Centre of Gravity calculation assumes a homogeneous bullet construction. The table gives G1 and G7 Ballistic Coefficients and barrel twists for various Mach numbers. (Mach 1 = 1116 ft/sec. in a standard atmosphere). The recommended barrel twists given are for muzzle velocities at the given Mach numbers and are for a Stability Factor S = 1.5. (The bullet is just stable at S = 1). The length unit for the twist rate is the same as for the declared bullet dimensions data on the left. The calculated curve for the zero yaw Drag Coefficient against Mach number for this bullet design is shown below.

If you would like to calculate ballistics data for this bullet design, press the ballistics button below.

Derived data
Tangent ogive radius (calibres) 3.72
C of G from nose (mm.) 13.154
Mach G1 BC G7 BC Twist
0.5 0.19 0.11 264
1.0 0.06 0.04 246
1.5 0.09 0.04 297
2.0 0.1 0.05 317
2.5 0.11 0.05 326
3.0 0.12 0.05 332
Drag Coefficient CDO -vs- Mach number for GLS PDW II


(Programmed in Perl script by Geoffrey Kolbe - Version: 1.0 June 2010)