Amateur rocket motor classificationとは 意味・読み方・使い方

Motors for model rockets, high powered rockets, and amateur rockets are classified by total impulse into a set of letter-designated ranges, from A (the smallest, though 1/2, 1/4, and 1/8-A motors are also available), up to O as the largest. A is from 1.26 newton-seconds to 2.5 N·s, and each class is then double the total impulse of the preceding class, with B being 2.51 to 5.00 N·s. Engines classified beyond O are in the realm of amateur rocketry. In this context, the term amateur refers to the rocketeer's independence from an established commercial or government organization.