Visitors fill either rocket with compressed air. They can select any pressure up to 90 psi. When released, the rocket shoots up a guide wire with a great whoosh of escaping air. The two rockets shown here have equal air capacities but one is twice as heavy as the other. They reach a height that depends upon the pressure of the air in them. The lighter rocket reaches a height of 40 feet but this can be adjusted up or down depending on the building. Within seconds of launch, the rocket falls back to a spring loaded landing pad. The cycle time is short enough that visitors quickly can try a variety of air pressures. These are true rockets because they are propelled by gas escaping from the rocket throughout its flight. Some exhibits sold as air rockets are really projectiles because they are launched by a blast of air from below.