Flight dynamics model of convertible rotary-winged aircraft with automatic control system

Аuthors

Myasnikov M. I.^*, Il’in I. R.^**

National Helicopter Center Mil & Kamov, 26/1, Garshina str., Tomilino, Moscow region, 140070, Russia

*e-mail: m.myasnikov@nhc.aero
**e-mail: irilyin@mi-helicopter.ru

Abstract

Light vertical takeoff and landing (VTOL) are being regarded in many countries as basic means of rectifying the tasks of urban air mobility. Rotary-winged aircraft may be employed as both aero-taxis for passenger transportation and by various city services including police, ambulance and fire-fighting service. Conventional helicopters, quadcopters, multicopters, including those with aerodynamic surfaces for the flight range and endurance increasing, as well as transformable (convertible) in flight aerial vehicles were being proposed as aerodynamic configurations. Scientific studies in the field of design, flight dynamics and control systems of convertible aircraft or tilt rotors with 90° swiveling rotors, are in full strength all over the world (predominantly in the USA) since 1950s. As of now, the tiltrotors are widely applied in the military-oriented aviation (Bell/Boeing V-22 Osprey, V-280 Valor) and being prepared for application in civil aviation (AgustaWestland AW-609). In the article being presented the tiltrotor scheme with two swiveling rotors was selected as an aircraft scheme for urban air taxi, as the one combining the advantages of both helicopter and airplane. Its main advantages are:

– the ability performing hovering mode, vertical takeoff and landing;

– high speed of horizontal flight;

– higher flight endurance and range.

The presented article considers nonlinear mathematical model of light convertible rotary-winged aircraft flight dynamics with a view to this aerial vehicle application for solving the task of urban air mobility. This flight dynamics mathematical model development was being accomplished with the MATLAB/Simulink software package. The alike VTOL is being supposed to be equipped with a traditional power plant, such as internal combustion engine and gas turbine engine, or electrical (hybrid) one. A system of differential equations of solid body motion was used for the flight dynamics model description. Mathematical modeling of the tiltrotor main rotors was being performed employing the blade element theory. For the modeling accuracy enhancing of energetic maneuvers with drastic changes of the flight parameters, such as overloads, as well as translational and angular VTOL velocities, the mathematical model accounted for both angular and translational displacement of the main rotors. The algorithm for aerodynamic calculation of the airframe elements, such as wing, fuselage and empennage, of the convertible aircraft using analytical models was proposed. Synthesis of automatic control system (autopilot) for all flight modes (“helicopter”, “airplane” and transitional) was accomplished. Tiltrotor trajectories computing for the main flight stages (hovering and a flight with low translational velocity, transitional modes from “helicopter” to “airplane” and back, the flight along the rectangular route, steady turns, as well as upward and downward spirals) was performed.

Keywords:

twin-screw tiltrotor of a transverse scheme, mathematical model of flight dynamics, automatic control system, control system algorithms, urban air mobility

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