Design, Build, Fly - OTIS Aerodynamics

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Team Member(s) 
Roger Castaneda
Trey Eckstine
Rashed Hayajneh 

Mentor(s) 
GWU Design, Build, Fly
American Institute of Aeronautics and Astronautics

Instructor(s) 
Professor Mitch Narins, MAE, GW Engineering
Dr. Peng Wei, MAE, GW Engineering

This project tackles the design and fabrication of the aerodynamic and payload subsystems of the RC aircraft OTIS. Effective designs of these three subsystems are integral to providing OTIS with the ability to clear three missions of a competition hosted by the American Institute of Aeronautics and Astronautics (AIAA) involving teams from across this nation and others. This involves designing and integrating an aerodynamically efficient wing that can maintain flight throughout the duration of the missions. Additionally, designing and implementing an effective tail is essential to aiding the stability and control of the entire aircraft. Finally, the payload aboard the aircraft's wings must be secured with structurally sound and reliable pylons that can support the loads without failure. In all three missions of the competition, the aircraft must be able to fly a minimum of three laps around a designated path in five minutes or less. The second and third missions also involve carrying a payload of bottles attached to the pylons on both sides of the wing, as well as a testing glider on the bottom of the fuselage.

Who experiences the problem?

Our project addresses issues in the aviation industry related to weight and range. Airlines and courier aircraft constantly balance payload and fuel weight to ensure efficient flights and prevent losing money. The military also contends with this issue when balancing fuel weight and performance using external fuel drop tanks. Although our project will not have a direct industry application, our iterative design process might help others view the physical limitations of flight at a model scale.

Why is it important?

With the development of flight, weight has always been an underlying issue. If you follow a free-body diagram of an airplane, you will see that the opposing force for lifting is weight. This issue still affects most aspects of modern aviation and the future of it. With the development of sustainable aircraft propulsion technologies, issues with the weight of supporting technology arose. Hydrogen requires heavy storage tanks, while electric motors require many heavy batteries. To develop the future’s airplane designs, we must balance structural integrity with aerodynamic efficiency.

What is the coolest thing about your project?

Undeniably, the most remarkable thing about working on this project was gaining first-hand experience in designing and manufacturing an aircraft, even if it may be on a smaller scale. Leading up to the prototype’s first test flight, we all frantically worked to complete the manufacturing and integration of OTIS on time. Although the test led to our prototype crashing down thirty seconds into its flight, watching OTIS gain speed and lift off the ground was enough to make all of the time spent worth it. In the aftermath of that first failed test flight, we were excited for the next time that we would be back in that park, flying an even better, more streamlined iteration of OTIS. The work required for this project has tested us on much of the knowledge we accumulated during our undergraduate years at GWU.

What sustainable design considerations drove your solution?

In our Design, Build, Fly (DBF) capstone project, sustainable design considerations primarily influence material selection, weight reduction strategies, and aerodynamic efficiency. Given that weight directly impacts an aircraft's performance, we prioritize lightweight yet structurally sound materials, such as 3D-printed nylon for pylon components and potentially polystyrene for the payload container. These choices help minimize material waste while maintaining necessary strength. Additionally, by optimizing the design for manufacturability and reducing excess material, we lower energy consumption during production. The focus on aerodynamic efficiency also aligns with sustainability, as reduced drag improves fuel or energy efficiency in full-scale applications. These principles ensure our design meets competition requirements while reflecting broader industry trends toward more sustainable aviation.

What were some technical problems?

Many of the team’s challenges arose during manufacturing, primarily related to 3D printing tolerances. While 3D printing offers design flexibility, it also has many limitations in layer deposition, resulting in dimensional inaccuracies. During the manufacturing process of the prototype phase, components like the pylon hardpoint, control motor mounts, and landing gear support did not fit on the spar or longerons due to tolerancing. The team attempted to counter this by sanding down components or reprinting a part with a more significant hole tolerance. However, this resulted in uneven holes and loose components. The team innovated a snap-fit arc design, replacing circular holes with flexible arc clamps. These Lego-hand-looking clamps can stretch without fracturing, providing a secure and consistent connection. Reprinting different toleranced parts could’ve solved our initial challenge; however, that would only waste PLA and the team’s available resources.