Skin As Radiator-Passive Thermal Management for High Altitude Long Endurance-UAVs 1999-01-2501

This Paper reports a recently completed Phase I SBIR program which showed that Loop Heat Pipe (LHP) condenser tubing can be embedded into the composite skin of a UAV, essentially turning the aircraft skin into a radiator. Test panels were fabricated by Teledyne Ryan Aeronautical which incorporated processed LHP condenser tubing into the composite skin material of the Global Hawk. The thermal characteristics of the composite structure as heat rejection fin were experimentally determined. The overall system was modeled and calculated that the upper wing of the Global Hawk would be capable of rejecting more than 50 kW under MIL-STD-210B, 1% Hot Day conditions. Phase II is underway; it will demonstrate the system operation and could lead to all-composite LHP radiator panels.