Alatron’s Conception – Phase I
Phase I is also known as the Design Inputs phase. This part of the project is focused around concept & prototype development. We began our project by performing market research to find out what UAV customers were looking for from their small Unmanned Systems. We discovered that the market was seeking agile craft with greater range and speeds.
To be fair, the creation of a bi-modal UAV was not immensely revolutionary; there are a number of companies working to solve the problem of a fixed-wing, Vertical Take Off and Landing (VTOL) UAV. Alatron is different, due in large part to its price point. In comparison to some other UAVs with similar capabilities with price tags in the hundreds of thousands of dollars, we decided to build the entire prototype for under $5,000.
In addition to the exceptionally low price point, Ascent developed a list of Project Specifications to determine what would constitute a successful project. The Project Specifications were:
- A complete safety manual and warning labels on the craft
- Vertical Take Off and Landing Capabilities
- Theoretical Fixed-Wing Flight
- Compatibility with a Commercially Available Off-the-Shelf Flight Controller
- Transportable by car
Theoretical Fixed-Wing Flight was left as a constraint, due to limitations imposed by the Federal Aviation Administration (FAA). Unfortunately, regulations prevented us from testing fixed-wing flight outdoors without obtaining a Certificate of Authorization (COA) from the FAA, and due to time constraints, getting a COA was simply not a possibility.
As a group of mechanical engineers with limited experience in non-linear controls, we decided that we would develop a bi-modal UAV that could perform in both rotary and fixed-wing flight, but that we would not develop the transition capabilities. With this idea in mind, we developed three possible concepts.
After some preliminary discussion, it was determined that Concept 2 would be eliminated from the concept pool, due to the complex nature of helicopter controls. We then used a Pugh Chart to choose a concept, with the Datum taken from the Arcturus Jump 20. Concept 1 scored significantly higher than Concept 3, and so it was chosen for further development.
Proof of Concept:
In order to ensure that both of the craft’s wings provided lift in forward flight, flow simulation was performed in MatLab, and validated using the wind tunnel. It was found that for our intended geometries, with a vertical spacing of at least 6 cm, there would be little to no measurable effect on the lift produced by the rear wing.
Vertical offset between the two wings would also equate to a vertical offset between the arms when in rotary-wing mode. We decided that for our proof of concept, we would test a simple quadrotor design with offset arms, using a commercial off the shelf flight controller.
The frame of our proof of concept was constructed from 3D-Printed PLA, and a standard DJI-M Lite flight controller was used, along with a DJI E300 Tuned Propulsion System.
Despite some yawing during takeoff, we determined that the flight test was successful, and we decided to move forward with the project.
Plans, Plans, Plans – Phase II
The main purpose of the design output phase develop the craft design, packaging, labeling, and manufacturing.
In this phase, we developed the drawings and wiring schematics to be used for Alatron. Below you can find some examples of our drawings:
V&V – Phase III
In Phase III, the focus was on Verification and Validation of the project in order to ensure that the project requirement specifications were further developed and met.
We started by calculating the total amount of thrust output from a single motor, and performing Finite Element Analysis in SolidWorks to determine whether the the material was strong enough to withstand the thrust. We then performed a stability test, where the craft was attached to a gimbal at its center of mass, in order to determine whether it was capable of self-stabilizing about its rotational axis.
Once self-stabilization was verified, we moved on to indoor flight testing. Alatron was verified to fly stably in rotary-wing mode; a video of the flight test is below.
In this run, the craft experienced a bit of instability during take off, but was able to maintain a stable flight with a soft landing.
Fabrication – Phase IV
Phase IV is the production and product release phase.
The first step in our fabrication process was to create the molds for the craft’s wings. This was a long and tedious process, which involved cutting the molds from Medium Density Fiberboard (MDF) using a CNC, hand sanding them, sealing them using epoxy, and then polishing the molds to get a smooth finish.
Once the molds were finished, we laid up the top and bottom halves of the wing separately, each with 4 layers of carbon fiber, two for lateral stiffness and two for torsional stiffness. Once cured, we then placed the foam core between the two wing skins, and epoxied them together.
The pieces of the fuselage frame were laser cut from balsa wood, and assembled using CA Glue. The fuselage was strategically wrapped with carbon fiber tape for added torsional rigidity, then wrapped in plain weave, biaxial carbon fiber for added strength overall.
Once all of the composites were cured, holes were cut in the fuselage to feed the wings through, and panels were strategically placed at the wings and center of the craft for wiring and electrical component placement.
We also used additive manufacturing to create the motor mounts for the ends of the wings, as well as brackets to secure the wings inside the fuselage. We chose 3D printed nylon for its good strength properties.
She Flies! – The Final Prototype
The project was a success! Alatron flew successfully in rotary-wing flight, and as a team we are proud to share our photos with you: (Think of them like photos of your loved ones’ babies. We do.)
- Larger wingspan for increased lift in forward flight
- More aerodynamic fuselage for less drag
- Fully transitional between fixed and rotary wing flight
As a team, we would like to thank our sponsors and mentors, including Dr. Richard Kelley and the Nevada Advanced Autonomous Systems Innovation Center, Dr. Logan Yliniemi, Jake Mestre, and Abaris Training Resources.
Who is team acent
Sierra Adibi – Project Lead
Sierra is a graduating senior with a passion for Aerospace Engineering. She served as the President of both the UNR Chapter of the American Institute of Aeronautics and Astronautics and the Nevada Alpha Chapter of Tau Beta Pi. Sierra’s interests lie in the dynamics and controls of air and spacecraft, and she will be spending the summer of 2016 working in the Aeromechanics Department at the NASA Ames Research Center. Following graduation, Sierra will be pursuing a PhD in Aeronautics & Astronautics at the University of Washington. In her free time, Sierra enjoys traveling, snowboarding, and performing in the circus arts.
Keith Scott – Task Support
Keith is a graduating mechanical engineer who loves learning how the world works. His involvement with AIAA, and ARLISS led to his interest in UAVs, autonomy and aeronautical engineering. After college he hopes to explore these areas of interest in the workforce and to never stop learning. In his free time he enjoys playing soccer, doing backflips on the beach and snowboarding.
Jeremy Fries – Mechanical Design Lead
Jeremy is a senior with a passion for design. During his time at UNR, he has been an officer of AIAA, Human Powered Vehicle Challenge, and Nevada Rocketry team; as well as being an active member in ARLYSS. He has interned at Hamilton Company and is currently an undergrad researcher. Jeremy’s interest lie in controls and design. After graduating he plans to continue his education. Jeremy enjoys Rock climbing, backpacking and prototyping.
Adam Larson – Head of Engineering Analysis
Adam is a graduating senior who enjoys solving problems, spending time with his family, and distance running. During his time at UNR, he has been a member of ASME, Human Powered Vehicle Challenge, and Tau Beta Pi. He also worked as an intern at the Nevada Terawatt Facility. Adam is now an R&D Engineer at Innovative Drive Corporation in Reno, where he works with a team that develops medical devices. Now that school is over, he plans to spend his evenings and weekends taking his family outside and continually training to meet his next running goal.
Anna Cameron – Head Reporter
Anna is a graduating senior, whose experience playing for the University of Nevada, Reno’s Women’s Basketball Team, has influenced her to pursue further education/ experience in the field of Biomedical Engineering. Along with being an athlete, Anna was also an officer for the UNR chapter of Society of Women Engineers, and an active member of UNR’s Human Powered Vehicle Team and American Institute of Aeronautics and Astronautics. Anna is interested in design and development in biomedical engineering. She hopes to enter competitively into the workplace, via a Master’s degree or employment opportunity, in the area of biomedical product development. Anna enjoys competitive running, hiking and triathlons.