any model rocket using a single motor greater than 160 newton-seconds of total impulse, or multiple motors with a total thrust of 320 newton-seconds, is propelled by a combination of motors having a total of more than 125 grams (4.4 ounces) of propellant weight, or weighs more than 1500 grams (53 ounces) with motors installed, is classified as a high power rocket under national fire protection association standard 1127.