Centuri Rocketry Exploration Set (Approximate?) Altitude

The Centuri Rocketry Exploration set was introduced in the 1977 catalog.
Two "base" models were included, a one or two stage ST-7 based model and a ST-16 based rocket.
The manual guided you through different launch scenarios using both models.







Centuri had sent me this set for review. I didn't remember that a ping pong ball was included in the box.
This page showed the suggested X-16 model flights.
The ping pong ball used to get the approximate altitude.





"When the parachute ejects at the peak of flight, a ping-pong ball is also released. As it fall to the ground it accelerates (for less than a second) to a speed of 30 ft/sec. The ball is very light and offers so much air friction that at 30 ft/sec. it reaches "terminal velocity" and descends at this constant rate.

To measure this atltitude it is necessary to observe how long it takes from the parachute ejection to when the ball hits the ground.
Multiply the number of seconds by 30 and that product is the altitude in feet, even in a breeze."