Conceptual Modeling of Novel Configurations for UAS Applications
Sponsors: Army, Navy and NASA sponsored University of Maryland Vertical Lift Research Center of Excellence
Increased demand for unmanned aerial systems for both military and civilian applications has sparked interest in novel configurations using conventional rotors as well as out-of-the-box solutions such as cycloidal-rotors and flapping wings. However, most of these novel vehicle prototypes are developed through extensive experimentation and not by utilizing traditional aircraft design techniques. Based on our preliminary research, even quad-rotors, the most popular UAV configuration today, are heavily over-designed with poor rotor performance leading to very low endurance. The reason for this is primarily the lack of design tools for these types of small-scale unconventional systems. Proper modeling techniques and systematic design are needed to develop more efficient next generation small-scale vehicles. A good example for this is the 45-gram quad-rotor helicopter developed by the PI and his students demonstrating 31 minutes of hover endurance, which is more than double the endurance of any micro-helicopter at this scale.
The objective of this project is to develop a design code which will provide the capability to model some of the novel UAS concepts, namely (1) Multi-rotor, shrouded-rotor helicopters, (2) Cyclocopter, and (3) Flapping-wing aircraft, over a range of scales. This involved developing analytical methods to predict thruster (conventional rotor, cyclorotor, flapping wing) average performance (lift, thrust and power), blade aerodynamic/structural loads and hub loads, methods to calculate component weights and geometry, modeling of propulsion system. In order to obtain the blade aerodynamic/structural loads and thruster performance a blade element momentum theory (BEMT) based unsteady aerodynamic model was coupled with a geometrically exact finite element based beam/plate large deflection structural model and thoroughly validated with in-house experimental data. Obtaining component weights for such unconventional configurations is not a trivial task. A combination of fundamental structural principles-based methods and empirical models were developed to calculate the weights for different components which include thrusters, vehicle structure, electronics and propulsion system.
A demonstration of a long-endurance flight by a quadrotor vehicle
Students: Atanu Halder, Xuan Yang