Designing a high speed, stealthy, and payload-focused VTOL UAV

Traditional intelligence, surveillance, and reconnaissance (ISR) missions conducted by the military and intelligence community typically are associated with high costs, slow response times, and inflexible designs. Current UAV technology has the potential for use in ISR, but typically copters are limited in speed, endurance, and payload capacity. As the technology develops, there is a growing interest in developing small-scale UAVs with vertical take-off and landing (VTOL) capability. A VTOL-capable UAV with autonomous and high-speed payload delivery will prove useful in ISR missions. The goal of this project is to develop a proof of concept design for a fixed-wing UAV with these capabilities along with improved endurance and stealth. An additive manufactured airframe and commercial off-the-shelf (COTS) components allow for low cost and rapid re-configuration. The completed design will incorporate multiple servos for a variety of control surfaces, a rear tilting motor for forward and vertical flight, an embedded lift fan system for vertical flight stability, and an Android-based control system for autonomous flight. Within this cross-disciplinary, multi-year project, the objectives for the 2015-16 year are: to begin understanding the flight controls and algorithms required for VTOL flight, to design the aerodynamic shape and final airframe, to understand how to integrate the software and hardware with the airframe, and to develop a flight rig to test VTOL transition capabilities using RC. Results presented in this paper include details behind the design and layout of electronic components and the building and testing of the flight rig. Hardware decisions for this aircraft were based on the following design requirements: control system allowing for both fixed wing and tri-copter airframes, ability to transition between vertical and horizontal flight within three feet after vertical lift off, sufficient battery power to allow for reasonable flight endurance, ease of packaging within the fixed wing airframe, compatibility with servo requirements, and a total system cost of less than $5K. The team found suitable COTS components that satisfied the program objectives at low cost. Functional testing of vertical and horizontal flight transitions with the rig is currently underway and autonomous flight capabilities are under development.