Using known numbers to calculate flight speed   Acceleration of gravity = 9.8 meters/second squared (96 meters/sec.) (1 ft = .30 meter) If the rocket flies for upward for 5 seconds the first half of the flight starts at a given speed, decelerates to zero speed and then reaccelerates at the speed of gravity. Divide the flight by 2 to obtain maximum acceleration (eg. 2.5 seconds of upward flight). Multiply maximum acceleration X 96 = 240 meters/second. 240 meters / 30 = 80 ft/second 5280 ft = 1 mile__3600 seconds = 1 hr __3600 seconds / 80 ft/second = 45 miles per hour