Propulsion and Propeller Technology for High Altitude Airships (HAA)

Triton Systems, proposes to develop investment cast continuous fiber reinforced aluminum (FRA) materials for an advanced very large, very lightweight high altitude airship propeller. A lightweight, advanced hybrid propeller will be developed that combinesa fiber reinforced aluminum spar with polymer composites. This will eliminate the heavy, large diameter bond joint currently required at the retention end of composite propeller blades. The proposed propeller material will significantly reduce the drag onthe inboard end of the propeller by reducing the frontal area of the chord in this area. The investment cast FRA spar enables efficient load transfer from the FRA inboard end to the PMC outboard end of the propeller. Additionally, the reduced crosssectional area at the propeller root allows thinner propeller blades, increasing aerodynamic propeller efficiency, reduces weight, reduces drag, and opens the design space for the specialized propeller that will be required in the low Reynolds numberregime found at 70,000 feet. Triton Systems, Inc. is teamed with a major manufacturer of composite propeller blades, who will provide technical assistance on the propeller design, the resin systems used, and compatibility with their current processes.The proposed development effort will enable a light propeller with increased aerodynamic efficiency. There exists a significant market for lightweight propellers in both the military and commercial sectors. In the High Altitude Airship application thematerials proposed provide the benefit of lightweight, and increased design flexibility. In larger propellers, with significantly more powerful engines at lower altitudes, the narrowing of the propeller root significantly increases the available air forthe engine and will dramatically improve the thrust to weight ratio for the engine, improving the performance for the entire aircraft. The low-cost production of fiber-reinforced aluminum is applicable to virtually any moving vehicle, and potentially tostructures of large buildings. Military programs such as the Army's Future Combat Systems and the Navy's DDX program are prime areas of DoD application.