Patent Application
20170046542
The present invention relates generally to long range shooting of bullets and to determining and compensating for deflections due to wind speed and wind direction.
It is well known that for an accurate long range shot that the shooter must take into account a number of variables. It is known in the art to determine a “known solution” which is the set of parameters that produce a deflection amount known to be correct for the ballistic and atmospheric factors affecting the bullet. Shooters often compile a table of such “known solutions” on a card commonly known as a “dope card” which typically records data such as ballistic parameters, atmospheric conditions, range, and sight corrections values for elevation, wind deflection, and gyroscopic drift or spin drift.
Because it is not practical to chart all deflection amounts for all possible combinations of speeds and directions, a dope card typically only recorded with “full value” wind deflections for only one or two wind speeds. Full value means that the wind direction is perpendicular to the line of fire. Wind direction relative to the line of fire is typically referenced by the origin of the wind as it would relate to a standard clock face, with the clock's center representing the shooter's position, and 12 o'clock representing the position of the target. Wind originating from either the 3 o'clock position or the 9 o'clock position is perpendicular to the line of fire.
The present invention provides a simple, light weight apparatus for determining deflection due to wind speed and wind direction, starting with one “known solution”. The analog calculator of the invention has a first series of indicia of deflections relative to wind direction, and an indicator with a scale of wind speeds. The calculator is calibrated using the known solution. Then deflection values at other speeds may be read. The calculator, which is preferably two sided, has a second series of indicia to additionally correct for wind direction relative to full value.
Other objects, features and advantages of the invention will become apparent as this description proceeds.
Referring to
On the side of disc 12 shown in
The concentric sets of indicia 18 are arranged so that the values reflect the linear relationship that exists between the correct deflection values for each wind speed. The indicator member 14 has a transparent central section with a radial indication line 22.
To start calculating a typical solution, a shooter starts by calibrating the apparatus using a “known solution” from a “dope card” or other source of such information. The known solution has a specified deflection for a specified wind speed. The indicator member 14 is rotated until the indicator line is on the known specified deflection at the known wind speed. Now using the wind speed the shooter encounters, deflection for the current wind speed may be read at indicator line 22. The value found is “full value” wind deflection for the chosen current wind speed.
Deflection values for wind speeds not listed in wind speed indicia 20 may be found by adding or subtracting values to equal the unlisted wind value.
To complete a deflection determination, the shooter takes the deflection value determined for wind speed from
After a complete wind solution has been readily determined according to the invention; other minor adjustments known in the art may be made. One such external factor is gyroscopic drift, also known as spin drift. The indicator number 14,
Applicant claims the priority of Provisional Application No. 62/036,586 filed Aug. 12, 2014, for Analog Calculator for Wind Deflections of Rifle Bullets, inventor, William Thomas Pifer.
