Abstract: The disclosed invention comprises a spring-based launch device, and method of using the device within a system for launching an unmanned aerial vehicle (UAV) using constant torque springs to pull a carriage to accelerate a UAV to the necessary launch speed. A torque frame holds multiple constant torque springs attached to an adjustable power system, enabling a selectable number of springs to connect to a spool. The adjustable power system enables the launch speed of the UAV to vary based on its launch requirements. The spool is used to move a carriage at constant acceleration. The carriage holds the UAV and is pulled along rails until it hits a stop spring system, which stops the carriage, causing the aircraft to be launched off the carriage. Re-tensioning of the system occurs through a retraction mechanism which pulls the carriage back to a spring box, where it is positioned in tensioned configuration.