Solid Rocket Grain Thrust Profile Calculator
Aerospace propulsion & solid rocketry: Model propellant grain burn geometry ($A_b$), web fraction, chamber pressure ($P_c$), and progressive/regressive/neutral thrust curves.
Grain Geometry & Dimensions
Casing internal diameter
Initial center port hole
Total propellant column length
Individual grain cylinders (ends burn)
Propellant & Nozzle Properties
APCP composite propellant ~7–12 mm/s
Critical sonic throat aperture
BATES Grain Neutrality Criterion
A BATES (Ballistic Analysis and Testing of Evaluation Sections) grain burns simultaneously on the cylindrical core (progressive: area grows with radius) and on the annular ends (regressive: length shortens). When length-to-diameter ratio $L/D_o \approx 1.5$, the progressive and regressive area changes cancel, yielding a constant flat chamber pressure.
Motor Performance & Thrust
Average Thrust (F_avg)
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Burn Duration (t_burn)
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Combustion Chamber Conditions
Mean Chamber Pressure (P_c)
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Steady-state operating pressure
Initial Kn (A_b / A_t)
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Burning area to throat area ratio
Grain Balistics & Total Impulse
Propellant Web Thickness (w):
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Total Propellant Mass (M_p):
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Total Delivered Impulse (I_tot):
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TRA / Tripoli Motor Class:
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