Motors for model rockets and high-powered rockets (together, consumer rockets) are classified by total impulse into a set of letter-designated ranges, from ⅛A up to O. The total impulse is the integral of the thrust over burn time. Where is the burn time in seconds, is the instantaneous thrust in newtons, is average thrust in newtons, and is the total impulse in newton seconds. Class A is from 1.26 newton-seconds (conversion factor 4.448 N per lb. force) to 2.5 N·s, and each class is then double the total impulse of the preceding class, with Class B being 2.51 to 5.00 N·s. The letter (M) would represent the total impulse of between 5,120.01 and 10,240.00 N·s of impulse. Motors E and below are considered low power rocket motors. Motors between F and G are considered mid-power, while motors H and above being high-powered rocket motors. Motors which would be 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). Professional organizations use the nomenclature of average thrust and burning time. Rocket motor codes The designation for a specific motor looks like C6-3. In this example, the letter (C) represents the total impulse range of the motor, the number (6) before the dash represents the average thrust in newtons, and the number (3) after the dash represents the delay in seconds from propelling charge burnout to the firing of the ejection charge (a gas generator composition, usually black powder, designed to deploy the recovery system). A C6-3 motor would have between 5.01 and 10 N·s of impulse, produce 6 N average thrust, and fire an ejection charge 3 seconds after burnout. An attempt was made by motor manufacturers in 1982 to further clarify the motor code by writing the total impulse in newton-seconds before the code. This allowed the burn duration to be computed from the provided numbers. Additionally, the motor code was followed by a letter designation denoting the type of propellant. The propellant designations are manufacturer specific. This standard is still not fully adopted, with some manufacturers adopting parts or all of the additional nomenclature. Motor impulse by class Governmental regulation In many countries, the sale, possession, and use of model rocket motors is subject to governmental rules and regulations. High-power rockets in the United States are only federally regulated in their