BC003 — QUICK USER GUIDE

1. PURPOSE

BC003 determines BC from velocity V1 and a measured POI at a known distance. BC is fitted numerically so that the calculated trajectory matches the impact measurement.

2. TERMINOLOGY

• V1 — velocity at the initial measurement point.
• POI — measured vertical impact position; “+” is above and “−” is below the line of sight.
• V1 TO POI DISTANCE — distance from the V1 point to the POI measurement.
• BC — fitted result for the G1, G7, GA/RA4 or GS model.
• POI RANGE — interval for which a valid BC solution can be found.
• ZERO 1 / ZERO 2 — fitted trajectory intersections with the line of sight.
• CLICK — turret correction; positive means UP and negative means DOWN.

3. FUNCTIONS

• NAME / DESCRIPTION, UNITS and DRAG MODEL — identify the measurement and select the model.
• V1, MEASURED POI and V1 TO POI DISTANCE — main fitting inputs.
• SIGHT HEIGHT and ZERO — required to determine BC from POI.
• POI RANGE — automatically displays the permitted interval. A value outside this interval cannot be fitted to a valid BC.
• PROJECTILE MASS — enables energy and velocity calculation at the POI point.
• MAX. RANGE, STEP and ATMOSPHERE — calculation range, interval and conditions.
• TURRET SCALE and CORRECTION DISTANCE — optional single CLICK correction.
• RESULT — fitted BC and velocity/energy at V1 and POI.
• V / E / POI CHARTS and TABLE — full prediction using the fitted BC.
• SAVE / SAVE AS — save a TXT report; LOAD — opens a BC001–BC004 report.

4. EXAMPLE

1. Select metric units and the G1 model.
2. Enter V1 = 920 m/s, 4 cm sight height, a 100 m zero and a 200 m distance from V1 to the POI measurement.
3. Check POI RANGE, then enter the measured POI, for example −10 cm, if it is inside the displayed interval.
4. Read the fitted BC, velocity at POI, chart and table.
5. Save the report with SAVE AS.

5. NOTES

The POI measurement cannot be taken at the ZERO point because POI there is always 0 regardless of BC.