Editing Model rocket (section)

===First number===

The number that comes after the letter indicates the motor's average thrust, measured in [[newton (unit)|newton]]s. A higher thrust will result in higher liftoff acceleration, and can be used to launch a heavier model. Within the same letter class, a higher average thrust also implies a shorter burn time (e.g., a B6 motor will not burn as long as - but will have more initial thrust than - a B4). Motors within the same letter class that have different first numbers are usually for rockets with different weights. For example, a heavier rocket would require an engine with more initial thrust to get it off of the launch pad, whereas a lighter rocket would need less initial thrust and would sustain a longer burn, reaching higher altitudes.