Design and Testing of the Joby Lotus Multifunctional Rotor VTOL UAV

The development of a wingtip-mounted electric lift propeller concept to enable quiet, efficient VTOL aircraft has yielded a promising UAV design employing two-bladed propellers that lock into a fixed position during horizontal flight to become wingtip extensions, resulting in a low-drag cruise configuration. The desire to reduce dependence on high-fidelity computational simulations which would increase the development timeframe for this concept led to the adoption of a spiral development model in which a series of six increasingly large and complex subscale prototypes were built and tested. Results from these tests were used to validate and update the computational models and led to various modifications of the aircraft configuration. A fully-functional 55-pound airframe designed to demonstrate mechanical feasibility, desired aerodynamic properties, full mission profiles including quiet VTOL and efficient forward flight operations, automatic stabilization, pilot workload mitigation and fully autonomous control was also constructed and is undergoing early stage testing. Static and flight test results as well as conceptual design studies are presented, including aerodynamic and structural simulations. The impact of these results on the design of the aircraft is examined. The feasibility and current performance predictions of this concept as applied to larger scale UAV systems is also touched upon.