a fluid pressure actuated launching system for aircraft or other articles having a piston assembly with an exterior portion that engages the aircraft or article to be launched and an interior portion disposed within and adapted to move within a plurality of connected cylinders to provide a long working stroke and controlled acceleration of the piston and article to be launched . the cylinders are hinged to one another so that the launching system is collapsible to form a compact unit and facilitate portability and ready accommodation on a launch vehicle of limited size . the cylinders are provided with a longitudinal slot to permit passage of a web between the exterior and interior portions of the piston assembly . the slot is adapted to be sealed by a tensioned flexible closure ribbon that is operatively connected to the piston assembly and is restrained at both ends so that it does not travel . as the piston travels within the cylinder , the closure ribbon passes through a cavity in the piston assembly that guides the ribbon away from its sealing engagement with the cylinders as the piston moves . the fluid pressure may be applied to the cylinder at one end to drive the piston during the launch stroke and at the opposite end to return the piston assembly . the closure ribbon tensioning means may be selectively operated to permit one end of the closure ribbon to be unfettered and thereby enable the cylinders to be folded on their hinges to form a compact unit while re - engagement of the closure ribbon tensioning means may be quickly restored when the cylinders are again opened to the operational launch position .