A payload launch system includes a launch tube, payload, rocket tube, pressurized motor assembly, and control system. The motor assembly has a launch actuator and an accumulator housing containing compressed gas. The accumulator housing defines a vent opening having a closure. The control system transmits an actuation signal to the actuator in response to a launch request signal to open the closure and cause a discharge of pressure into the launch tube. This causes the rocket tube to launch from the launch tube to a threshold altitude in a single gaseous thrust phase. A method includes deploying a launch system, transmitting a launch actuation signal to the launch actuator via a control system, and opening a closure to allow compressed gas to enter the launch tube, thereby launching the rocket tube from the launch tube to a threshold altitude in the single gaseous thrust phase.