Flying a cluster? Calculate combined total impulse across multiple motors. See the aggregate FAA class, combined certification requirement, and whether your configuration crosses the Class 2 threshold.
Add each motor in your cluster. The calculator combines their total impulse and determines the aggregate FAA classification and certification requirement.
Under 14 CFR § 101.1, the FAA adds the total impulse of all motors in the rocket — regardless of whether they fire simultaneously or in sequence — to determine the rocket's FAA classification. Four E motors (max 40 Ns each) total up to 160 Ns, staying just within Class 1. Four F motors (max 80 Ns each) total 320 Ns, placing the configuration firmly in Class 2 — requiring a COA waiver and Level 1 certification. Propellant weight across all motors also adds up for the 125g Class 2 threshold.