Nonlinear modeling and transition corridor calculation of a tiltrotor without cyclic pitch

Yourong Fan,Xinhua Wang,Kai Zhang,Zhe Hu,J Zhu

doi:10.1051/matecconf/202235501022

Yourong Fan, Xinhua Wang + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/202235501022

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Abstract

In order to solve the problem of rotor airflow interference to the wing of tiltrotor UAV, the lift and drag in the slipstream area and the free flow area were calculated respectively according to the hydrodynamics theory and CFD simulation. The longitudinal nonlinear dynamics model of tiltrotor UAV is established by Newton-Euler method. In order to solve the problem that the lift and thrust are difficult to balance the body gravity in the transition flight mode, a method for calculating the transition corridor of a tiltrotor UAV without cyclic pitch is proposed. The boundary of the transition corridor is restricted by the Angle of attack of the wing and the thrust of the rotor. Considering the requirements of UAV cruise speed, flight safety and minimum energy consumption, the optimal transition curve is selected. The result show that the designed transition curve can ensure that the lift and the rotor thrust can balance the gravity completely and the Angle of attack is in a reasonable range, and the rotor force has enough margin of safety.

Highlights

Tiltrotor UAV has the advantages of long endurance and fast speed of fixed-wing UAV, it can hover and take off and land vertically like a helicopter, so it has a wide application prospect in various fields
Four tilting rotor systems are mounted on the wing and one vertical rotor system is mounted between the fuselage and the tail; all the rotors are operated without cyclic pitch
The calculation model of slipstream area and relative airspeed is derived by fully considering the interference of rotor flow on the wing

Summary

Introduction

Tiltrotor UAV has the advantages of long endurance and fast speed of fixed-wing UAV, it can hover and take off and land vertically like a helicopter, so it has a wide application prospect in various fields. During the transition from copter mode to fixed wing mode, the gravity of the aircraft is balanced by the transition from the thrust of the rotor to the lift of the wing [2]. According to hydromechanics and rotor aerodynamics theory and CFD simulation, the area of the slipstream area and the relative airflow velocity in the whole tilting process were obtained, and the total lift, drag and pitching moment of the UAV are calculated. = Vout Va cosα sin βM + vss where T is the thrust of one rotor, m is the air mass passing through any section of slipstream in unit time, αα is the angle of attack of the UAV, and ββMM is the nacelle angle. Based on the above constraints, the tilting transition corridor is divided into a high-speed section and a low-speed section [12]

Angle of attack constraint

Rotor thrust constraint

Findings

Conclusion