Black Powder Charge Calculator

πŸ’₯ Ejection Charge Sizing

Formula: grams = (volume_inΒ³ Γ— PSI) / 350.
Always ground test before flying.

Motor Reference

ClassTotal Impulse (NΒ·s)Typical Use
A1.26 – 2.50Low-power, small models
B2.51 – 5.00Low-power, small models
C5.01 – 10.00Low-power, standard models
D10.01 – 20.00Mid-power entry
E20.01 – 40.00Mid-power, BT-50/55
F40.01 – 80.00Mid-power
G80.01 – 160.00Mid-power max (SPAAR field limit)
H160.01 – 320.00HPR β€” L1 cert minimum
I320.01 – 640.00HPR β€” L1 range
J640.01 – 1,280.00HPR β€” L2 cert range
K1,280.01 – 2,560.00HPR β€” L2 range
L2,560.01 – 5,120.00HPR β€” L3 range

Quick-Look: Fleet Specs

RocketDiameterMotor MountAltimeterNotes
LOC IV Γ—22.63"29mmEggtimer QuarkL1 cert Β· J350W sims to 3,900'
LOC Hi-Tech2.63"38mm (29mm adapter)Eggtimer QuantumJ350W sims to 5,310' Β· 2.03 cal stability
Estes Cherokee-EBT-55 (1.31")24mmCustomRetired Sept 2025

Useful Links