JBM - Calculations - Maximum Distance Terms

Input Data

Muzzle Velocity

The velocity of the bullet as either (1) measured at some distance from the muzzle or (2) as estimated from reloading data.

Ballistic Coefficient

The ballistic coefficient for the bullet being used. It is almost always obtained from the manufacturer, but can also be measured. The ballistic coefficient is represents the ratio of the drag of the standard (e.g. G1 standard bullet) bullet to that of the bullet you are shooting. A ballistic coefficient of 0.100 means that your bullet has 10 times the drag of the standard bullet.

Bullet Library

A drop down list showing all the buttons in the library. If a bullet is selected, the trajectory is run with the selected bullet. If "None" is selected, the entered BC, drag function and bullet weight are used.

Bullet Weight

The weight of the bullet

Drag function

A drag function (or G function) provides the forces on a standard bullet for which the drag function was derived. A bullet's ballistic coefficient then relates the drag on any bullet to that of the standard bullet.

Temperature, Pressure and Relative Humidity

The measured or estimated air temperature, the barometric pressure and the relative humidity at the firing position. These are required to calculate the air density and correct bullet drag.

Altitude

Used in estimating the atmospheric conditions. This value is not used unless the Standard Conditions at Altitude checkbox is checked.

Standard Conditions at Altitude

When checked, the temperature, pressure and humidity for standard atmospheric conditions at the entered altitude (always 0% at standard conditions) are entered in the calculation. The standard used is the ICAO standard atmosphere.

Output Data

Maximum Distance

Maximum distance achieved.

Initial Angle

The angle of the barrel relative to the ground.

Terminal Range

The distance achieved by the bullet for the elevation.

Maximum Height

The maximum height above the ground that the bullet achieved, in feet.

Terminal Angle

The angle at which the bullet strikes the ground. Ninety degrees is straight down.

Terminal Velocity

The final speed of the bullet in feet per second

Terminal Energy

Really the "Kinetic Energy" of the bullet. The kinetic energy is a measure of the maximum amount of work (force time distance) an object can do. [It is also a measure of the work done by the firearm/case/primer/powder on the bullet.]

Time of flight

The time of flight of bullet in seconds.