Designed, fabricated, and tested a three-stage turbocompression system for a high-altitude, long endurance, unmanned aerial vehicle (HALE UAV). This turbocompression system included three turbochargers in series with the associated intercoolers, piping, and wastegates, and a space frame for mounting within the vehicle. There were many challenges in this project, including an overall pressure ratio in excess of 120:1, ensuring the proper matching of all three turbochargers throughout the flight envelope from sea level to 65,000 feet, and the requirement for flight-weight hardware. Turbo Solutions completed cycle analysis to properly match the turbocompression system to the hydrogen-fueled piston engine, aerodynamic and structural design of the turbochargers, solid modeling of the entire turbocompression system, and a full set of dimensioned and toleranced manufacturing drawings for all of the components. We then worked with our subcontractors to fabricate two sets of flight hardware, and assembled both complete systems in our shop. The complete turbocompression system was tested successfully in an altitude chamber up to a simulated 65,000 feet, followed by iron wing endurance testing. The system is now undergoing on-aircraft flight testing at Edwards Air Force Base.