The current propulsion and power requirements for small unmanned air systems (UAS) are limited by the power density of current battery chemistries (e.g, Lithium Ion). The roadmap to improve endurance relies on transition to fuel cells for UAS that are have high energy-density, such as gaseous hydrogen. However, current storage technologies are heavy, bulky and expensive which lead to less capable UAS as payloads are substituted for less efficient hydrogen storage tanks. Composite Technology Development, Inc. (CTD) is proposing an all-composite fuel tank leveraging a novel manufacturing method developed by CTD using novel high-strain resin systems that offers an extremely lightweight, thin and lower cost alternative to existing Type IV liner technologies (e.g., HDPE, Nylon, etc.). This new technology is cheaper to produce than a typical Type IV tank but with similar lined tank performance relative to permeability and pressure performance in a Type V (linerless) solution. CTD expects to utilize this technology in the design of this tank to improve the tank mass / hydrogen volume storage ratio for this solution. This technology has the added benefit of enabling conformal designs where traditional Type IV liners cannot be utilized; the tank dimensions can be modified in an iterative manner. Traditional Type IV tank fabrication requires new molds every time the tank geometry is modified for each novel UAS application, which can significantly impact non-recurring engineering and schedule considering the current lead times to fabricate these molds. CTDs approach doesnt require special tooling and allows for rapid redesign and prototyping to achieve novel tank designs on a much more reasonable timeline. The expected pressure vessel solution will enable increased UAS range and endurance through weight reduction and increased internal volume through composite manufacturing techniques, and improved economics through the integration of best-manufacturing practices. As the design matures, CTD will also explore novel conformal fabrication methods to improve the overall storage efficiency within the UAS.
Benefit: The improvements that will be delivered include weight reduction of the hydrogen storage tank structure, increased volume through unique construction techniques enabled by high-strain composites, and overall program improvements that improve UAS range and endurance. While this solution is focused on the specific military application, the techniques and outcomes can be applied to other unmanned vehicles and breathing applications (e.g,. SCBA) that would benefit from the use of composite materials to construct efficient, high storage density, lightweight pressure vessels.
Keywords: Gaseous Hydrogen, Gaseous Hydrogen, conformal, Composite, pressure vessel, Fuel tank, Unmanned Air Systems
