The original program Logic was done in 2001 by Rick Robinson as a MS-DOS program (ZIP Archive with executable + source). In 2024, I decided to convert it to an in-browser HTML5/Javascript format with ChatGPT into version 1.1b. In this form, it works a lot better than the original MS-DOS program; as well as being accessible "on the go".

Per Rick's notes, this program is a rather quick kludge, based on an iterative model of ballistic travel and a penetration model based on tensile strength of steel, originally worked out for a space weapons sim.

Original estimated penetration formula - 1 kg moving at 20 km/s = 95.24 lbs TNT equivalent energy, requires 96.11 cm (37.84") radius of 5 cm (2") steel armor to stop it (assuming 200,000 psi ultimate strength; 238,000 lbs force later inferred from 16"/50 penetration).

Gun Caliber (Inches) (millimeters)

Shell Weight (lbs) (kilograms)

Typical muzzle velocities (NOTE: Some excellent guns had 'slow' muzzle velocities)

19th Century (1860s-70s): 1100-1400 fps
19th Century (1880s): 1900 fps
20th Century 'Slow': 2400 fps
20th Century 'Fast': 2850 fps

Muzzle Velocity (ft/sec) (m/sec)

Gun Elevation (Degrees)

Target Armor Belt Inclination (Degrees)

Relative Armor Quality

Shell Form Factor

The Shellform Factor adjusts for ballistic performance of different shell types. Typical ranges are:

• 19th Century: 0.5 - 0.55
• 20th C (WW1): 0.6 - 0.80
• 20th C (WW2): 1.0~ (Average for everyone)
• 20th C (WW2): 1.1 (Germany)

Time of Flight Table

Terminal Results