US 4,311,902 A · Lead calculator for moving targets

Abstract

A calculating device and a method of use thereof for determining the lead required to shoot a projectile at a moving target such as game including cooperating logarithmic scales with parameter indicia corresponding to the range of the target, the speed and direction of movement of the target, the speed of the projectile and the required lead displayed on a fixed and a slide member. Markers representative of various projectiles are disposed on the projectile velocity scale at locations corresponding to their normal speed and words descriptive of game speed are disposed at appropriate locations along the target speed scale so that calculations may be made by persons not having knowledge of game and projectile speeds in numerical terms. The lead is calculated from a knowledge of the parameters in a two step process of moving one member relative to the other. In accordance with one embodiment of the invention, the scales are arcuately disposed on members which may be rotated about a common axis.

Claims18

Dependent claims

A device for calculating the required lead when shooting a projectile at a moving target, as a function of target speed, target range, projectile speed and the direction of movement of the target, comprising:

five scales including:
a first logarithmic scale having indicia associated therewith representing the speed of the target;
a second logarithmic scale having numerical indicia associated therewith representing the required lead;
a third logarithmic scale having numerical indicia associated therewith representing target range;
a fourth logarithmic scale having indicia associated therewith representing projectile speed;
and
a fifth logarithmic scale having indicia associated therewith representing the direction of movement of the target relative to the direction of movement of the projectile;
said first, second, third, fourth and fifth scales being formed on at least one member and disposed in physical proximity with each other so that they are correlated, the correlated numerical value associated with one of the scales being readily determinable if the correlated numerical value associated with each of the other four scales is known.

5 more elements

A method for calculating the required lead when shooting a projectile at a moving target, as a function of four parameters, the parameters being target speed, target range, projectile speed, and the angle between the line of defining the flight line of the projectile and the line defining the direction of movement of the target, utilizing a calculator comprising at least five scales including a first scale having corresponding indicia of target speed, a second logarithmic scale having corresponding indicia designating quantitative representations of target range, a third logarithmic scale having corresponding indicia of projectile speed, a fourth logarithmic scale having corresponding indicia designating quantitative representations of required lead and a logarithmic sine scale having quantitative representations of the angle of movement of the target;

the calculator further comprising a first member and a second member slidable in relation to said first member, two of said first through fifth scales being disposed on said first member and the remaining three of said first through fifth scale being disposed on said second member, said first through fifth scales being structurally correlated;
said method comprising the step of:
sliding said second member in relation to said first member twice in order to determine the product of the target speed, the target range and the sine of the angle of movement of the target divided by the projectile speed.

Dependencies are inferred from the claim text.

Lead calculator for moving targets

Life of this patent

Lead calculator for moving targets

Life of this patent

Abstract

Claims18