US 5,349,853 A · Apparatus and method for measuring and calculating exterior and interior ballistics

Abstract

An apparatus and method for measuring ballistics in a firearm is disclosed. The apparatus comprises (a) a device for measuring pressure in a firearm-firing-chamber disposed at least in part at the strain sensitive region, and for producing analog signals indicative of the pressure, and connected to digitizing circuits which record the amplitudes of the signals representing pressure as a function of time; (b) a plurality of muzzle bullet sensors for measuring the relative times at which the bullet passes the plane of each sensor and for producing analog signals indicative of these times, the analog signals being converted to digital signals and connected to digital timing circuits; and (c) an acoustic target located downrange and including (i) sensors arrayed at corners of a triangle for sensing acoustic energy emitted by a passing bullet and (ii) a device for generating analog signals representative of the acoustic energy sensed at the triangle corners. The pressure in the firing chamber is measured according to the formula: ##EQU1## and where PSI.sub.Max is Maximum expected PSI, N is the gain port setting which is a digital setting to an amplifier gain port and is expressed as an integer from 20 to 255, G is the gage factor, D is the outside diameter of the firing chamber at the gage, and d is the inside diameter of the firing-chamber at the gage. Optionally, a plurality of bullet sensors may be located downrange in lieu of the downrange acoustic target. Analog signals are converted to digital signals which in turn are connected to timing circuits. Signals from the timing circuits are connected to a processor which calculates external and internal ballistics such as for example, velocity and time-of-flight using the common time-zero reference, and determines the location of "hit" at a target plane. The processor can be interfaced with a personal computer.

Claims28

Dependent claims

An apparatus for measuring ballistics in a firearm comprising in combination:

(a) an outside-surface-mounted means for measuring pressure in a firearm firing-chamber according to the following formula:
##EQU5## where the voltage amplifier gain equals 32500/N and N is computed by:
##EQU6## and where
PSI.sub.Max is Maximum expected PSI,
N is the gain port setting which is a digital setting to an amplifier gain port and is expressed as an integer from 20 to 255,
G is the gage factor,
D is the outside diameter of the firing chamber at the gage, and
d is the inside diameter of the firing chamber at the gage;
and producing an analog signal indicative of said pressure;
(b) a target means located at a predetermined point producing an analog signal indicative of time;
(c) means for receiving separate streams of analog signals from said means for measuring pressure and from said target means, and for converting said separate streams of analog signals from analog to digital form and for outputting said separate streams as digital signals:
(d) signal receiving means for receiving said separate streams of digital signals as a data output set;
and
(e) means for computing an estimated velocity and ballistics from said digital output set.

11 more elements

A method for measuring exterior and interior ballistics of a bullet fired from a firearm having a muzzle and a firing chamber by detecting energy imparted to a bullet at its exit from the muzzle of the firearm, comprising the steps of:

(a) measuring firearm-firing chamber pressure as a function of time wherein the pressure is calculated according to the following formula:
##EQU11## ##EQU12## and where
PSI.sub.Max is Maximum expected PSI,
N is the gain port setting which is a digital setting to an amplifier gain port and is expressed as an integer from 20 to 255,
G is the gage factor,
D is the outside diameter of the firing chamber at the gage, and
d is the inside diameter of the firing-chamber at the gage;
(b) placing velocity detector means at a known distance d downrange from the muzzle of the firearm;
(c) determining the velocity of the bullet at said distance d;
(d) computing bullet muzzle exit time form the distance d and the velocity, and
(e) computing impulse imparted to the bullet as a time integral of the pressure in the chamber from the onset of pressure until the bullet exits the muzzle.

8 more elements

A method for measuring ballistics of a bullet fired from a firing arm having a muzzle, comprising the steps of:

(a) measuring the pressure in the firing chamber of the firearm using the following formula:
##EQU13## ##EQU14## and where
PSI.sub.Max is Maximum expected PSI,
N is the gain port setting which is a digital
setting to an amplifier gain port and is expressed
as an integer from 20 to 255,
G is the gage factor,
D is the outside diameter of the firing chamber at the gage, and
d is the inside diameter of the firing chamber at the gage;
measuring the bullet muzzle velocity (V.sub.o) at a set of muzzle sensors located at a first predetermined location near the muzzle, wherein said bullet muzzle velocity (V.sub.m) is measured directly from the time of flight between each of said muzzle sensors and the known distances between the sensors;
(b) approximating the time of flight from the set of muzzle sensors at said first predetermined location by measuring the time difference between passage of the bullet at the muzzle sensors at said first predetermined location and the arrival of the acoustic energy generated by the bullet's passage at a set of downrange acoustic sensors located at a second predetermined location;
(c) calculating the velocity at the target in accordance with the formula:
V.sub.t =2 V.sub.a -V.sub.m
where
V.sub.t =velocity at the target
V.sub.m =velocity at the muzzle, and
V.sub.a =average velocity and is calculated by dividing the approximated time of flight by the distance from the muzzle sensors to the downrange sensors;
(d) computing an apparent hit location at a plane of the downrange acoustic sensors using the difference in arrival times of the acoustic energy generated by the bullet's passage at the downrange acoustic sensors, the location of the downrange acoustic sensors, the ambient conditions, and the V.sub.t from step (c);
(e) correcting the approximated time of flight to compensate for passing of the bullet through the plane of the downrange acoustic sensors before the acoustic energy generated by the bullet's passage reaches said downrange acoustic sensors;
and
(f) determining a ballistic coefficient that is consistent with the velocity at the muzzle (V.sub.m), the distance from said muzzle sensors to said downrange acoustic sensors, the approximated time of flight, and the distance from the muzzle sensors to the downrange acoustic sensors.

18 more elements

Dependencies are inferred from the claim text.

Apparatus and method for measuring and calculating exterior and interior ballistics

Life of this patent

Apparatus and method for measuring and calculating exterior and interior ballistics

Life of this patent

Abstract

Claims28