Open-Architecture Composite Structure
Most amateur high-powered rocket airframes are typically made
up of a composite material. Many make use of fiberglass due to its low
weight and compressibility strengths. Others use the heavier, and
albeit stronger, carbon fiber material. Both work well with the typical
amateur rocket; however, Project Aquila recognized that both had
weaknesses in terms of the design aspects required for the teams
rocket. Fiberglass alone would not provide sufficient strength to
overcome the thrust and drag loads experienced during ascent. Carbon
fiber would be able to handle all loads, but is difficult to fabricate,
expensive, and would decrease the mass margin from design to final
In collaboration with Auburn University's Department of Mechanical Engineering, Center for Polymers and Advnaced Composites (CPAC), and sponsorship by Highland Composites, Project TIGRIS has developed a solution to overcome both problems: the open-architecture composite structure (O-ACS). O-ACS makes use of the maypole braiding process, a weaving method that uses meshed gears arranged in a circle to carry packages of yarn in an interlaced pattern. This pattern creates a composite lattice structure using yarns comprised of multiple prepreg carbon fiber (CF) cord pregs, which when cured, become a rigid skeletal structure.
The O-ACS will act as the skeleton of the Project TIGRIS rocket. It's enhanced compressive resistance, compared to that of the typical carbon fiber or fiberglass tube, means increased strength with decreased weight. The O-ACS will be wrapped in a fiberglass and foam core that will provide the exterior surface of the rocket. This design decreases weight by almost 30-40% compared to a carbon fiber tube of the same size.
If you would like to learn more about O-ACS, please check out "The Design of Optimal Lattice Structures Manufactured by Maypole Braiding", by Austin Gurley, Ph.D., as well as the corresponding patent application.
Last Updated: 18 September 2018