The Vertical Take-off and Landing (VTOL) unmanned aerial vehicles (UAVs) with the tilt-rotor mechanism also known as hybrid UAVs have a lot of challenges in designing and controlling concerning their use in harsh weather for surveillance and access to remote areas. This review paper presents a review of the preliminary design of hybrid aircraft and control systems. The tilt-rotor mechanism and tilt wings of a hybrid UAV are analyzed. The paper provides an outline of technical advances in UAVs in hybrid configuration concerning their constraint analysis, propulsion sizing, and design evaluation. Furthermore, the flight dynamics modeling is described with the control system and dynamics of the hybrid UAV. This paper lists various software for simulations and analysis such as SOLIDWORKS and CATIA for CAD modeling, MATLAB and SIMULINK for mathematical modeling and flight control, and XFLR5 for stability analysis of aerofoils, wings, and planes. In addition, certain control strategies are executed and scrutinized in terms of the theory, the linearity, and the implementation of the model.

A Review on Vertical Take-Off and Landing (VTOL) Tilt-Rotor and Tilt Wing Unmanned Aerial Vehicles (UAVs)

Electric unmanned aerial vehicles consume a significant portion of their stored propulsion energy in gaining altitude. The analysis of shortfall in cruise range as a function of climb altitude confirmed that, if the energy required for climbing is conserved, then cruise range of the UAV would improve significantly. In this paper, we present a conceptual design of a High Endurance Relocatable Crewless Aircraft on Reconnaissance Aerostat, a novel system that would enable electric UAVs to operate continuously from an aerostat deployed at the cruising altitude of the UAVs. The three subsystems of HERCARA - the aircraft carrier (aerostat), aircraft and the ground station are also discussed. 

Project HERCARA: High Endurance Relocatable Crewless Aircraft on Reconnaissance Aerostat

School of Mechanical Engineering, Vellore Institute of Technology (VIT), Vellore 632014, India Department of ­ermal and Energy Engineering, School of Mechanical Engineering, Vellore Institute of Technology (VIT), Vellore 632014, India Department of Manufacturing Engineering, School of Mechanical Engineering (SMEC), Vellore Institute of Technology (VIT), Vellore 632014, Tamil Nadu, India School of Mechanical Engineering, Dilla University, SNNPR, Gedeo, Dilla, Ethiopia

AReviewonVertical Take-Off andLanding ( VTOL ) TiltRotor and Tilt Wing Unmanned Aerial Vehicles ( UAVs )

Unmanned Aerial Vehicles (UAVs) are utilized in various fields such as aerial shots, transportation, spraying chemicals in agriculture and surveys of plant growth in forestry. It is necessary to consider the ground effect when operating UAVs/AAVs. The lift coefficient changes and significantly affects the controllability when operating sharp turns within the range of ground effect. So, it is essential to attend to safety-based takeoff and landing as the risk of accidents. In this paper, we propose a fuzzy control for the attitude control of a quadrotor based takeoff. 

A Fuzzy Theory Based Attitude Control for Takeoff of Quadrotor

This paper presents the development of an hybrid Unmanned Aerial Vehicle that combines the capabilities of Vertical Takeoff and Landing (VTOL) as well as the hover flight of an helicopter, with the autonomy, load capacity and speed offered by an airplane. We start from an aircraft concept that uses the Tilt-Rotor configuration to perform the transition phase from one flight mode to another and simultaneously we used Ducted-Fans for increasing the flight performance during the vertical flight phase. The aerodynamic design is developed using computational tools, such as XFLR5 for preliminary design and ANSYS FLuent®for the verification of the preliminary fixed wing design. While for the vertical flight, experimental tests were conducted in order to determine the lift system requirements by using Ducted-Fans. Afterwards, the manufacturing process derived from the aerodynamic design is presented. The avionics developed is described for handling the control surfaces during the airplane mode and the main lift system during the vertical flight as well as the integration of mechanism and sensors used. Finally, the obtained results from the conducted vertical flight tests at outdoors environments are presented in order to show the effectiveness of the aircraft concept.

Design and Construction of a UAV VTOL in Ducted-Fan and Tilt-Rotor Configuration

One of the pivotal aspects in aircraft design and manufacturing is the definition of airfoils. This activity can be addressed with software such as Plane Maker and Airfoil Maker, two applications bundled with the X-Plane flight simulator, which allows the design of airfoils or use of predefined ones to build aircraft lifting elements. However, such airfoils can only be selected from a folder included with X-Plane, where, as stated, either default or custom airfoils designed with Airfoil Maker can be found. The design of airfoils using this program is done based on their desired aerodynamic characteristics, which is a tedious and time consuming task if they are meant to be designed for the whole range of angles of attack. For this reason, designers prefer using the provided default airfoils in a preliminary design, but choosing them arbitrary is far from a correct decision due to the variation in the aerodynamic performance. In this article we present a strategy for selecting suitable default airfoils to build the aircraft lifting elements in Plane Maker such that their aerodynamic performance is not considerably affected. The proposed strategy consist on conducting a geometric comparison between software-provided default airfoils and user-defined airfoils in order to select the ones with the best aerodynamic performance for a specific aircraft. To validate the effectiveness of the proposed strategy, we used the XFLR5 software to compare the aerodynamic behavior of same-shape wings generated by similar airfoils in a fixed wing Unmanned Aerial Vehicle.

Juan M. Bustamante

Papers

Design and Construction of a UAV VTOL in Ducted-Fan and Tilt-Rotor Configuration

A Strategy for Airfoils Selection in the Design of Customized Aircraft Models for Flight Simulation Testing