Ye Yuan

• Doctor of Engineering
• Lecturer at Swansea University

The research explores transition strategies of a coaxial compound helicopter transitioning to pure coaxial-rotor mode following a complete aft propeller failure. For that, a flight dynamics model is developed to predict the transition path, which is formulated as a multiphase trajectory optimization problem. Additionally, a revised aggressiveness i...

This study assesses the influence of engine dynamic characteristics on helicopter handling quality during hover and low-speed forward flight. First, we construct the helicopter–engine coupling model (HECM) based on the power-matching relationship between the engine and the rotor. The impact of the engine is evaluated by comparing HECM with a helico...

This paper studies the pilot control strategy and workload of a tilt-rotor aircraft dynamic conversion procedure between helicopter mode and fixed-wing mode. A nonlinear flight dynamics model of tilt-rotor aircraft with full flight modes is established. On this basis, a nonlinear optimal control model of dynamic conversion is constructed, consideri...

This paper focuses on the optimal takeoff of a coaxial compound helicopter, considering the possibility of engine failure. When one engine fails during takeoff, a twin-engine helicopter must either reject the takeoff (RTO) before reaching the takeoff decision point (TDP) or continue the takeoff (CTO) after the TDP. This study aims to determine the...

This paper studies the pilot control strategy and workload of tilt-rotor aircraft dynamic conversion procedure between helicopter mode and fixed-wing mode. A nonlinear flight dynamics model of tilt-rotor aircraft with full flight modes is established. On this basis, a nonlinear optimal control model of dynamic conversion is constructed, considering...

Although a coaxial compound helicopter can takeoff without propeller in the normal condition, the distance should be as short as possible for obstacle avoidance when the vehicle operates in a confined area with heavy loads. Therefore, a suitable propeller control is required to improve the takeoff performance while the total power consumption is no...

This work was focused on the conversion and reconversion maneuvers of XV-15 tilt rotor aircraft between helicopter and airplane modes. To alleviate pilot workload and improve safety, we proposed a multi-objective optimization method. Firstly, an augmented dynamics model has been developed and validated. Then, the transition maneuver was formulated...

The tiltrotor has unique flight dynamics due to the aerodynamic interference characteristics. Multiple aerodynamics calculation approaches, such as the CFD method, are utilised to characterise this feature. The calculation process is usually time-consuming, and the obtained results are generally varied from each other. Thus, the uncertainty quantif...

The aerodynamic interference between the different components of quad-tiltrotor (QTR) aircraft were considered to analyze its influence on trim characteristics. A comprehensive method with the fixed-wake model was developed for multiple aerodynamic interactions, improving the accuracy of the flight dynamics analysis. Additionally, a more general co...

The tiltrotor aircraft has unique flight dynamics characteristics because of the extensive aerodynamic interference and the unique control strategy. Inverse simulation offers an opportunity to study a vehicle's performance during manoeuvring flights. In this paper, an improved inverse simulation method is developed with an Automatic Differentiation...

The tiltrotor aircraft has unique flight dynamics characteristics and handling qualities due to its multiple unique designs. However, these designs may lead to additional manufacturing errors, and these uncertainties may play a significant effect on the flight dynamics and handling qualities. Therefore, this article combines a validated flight dyna...

The paper will review the development and application of the mathematical modelling of the advanced rotorcraft configuration, including compound helicopter configurations and tilt-rotor vehicles. The mathematical model is the basis for the design of the flight control system and an essential tool to assess the flying and handling qualities for heli...

The tiltrotor aircraft has the capability to extend its performance characteristics compared to the conventional helicopter. However, the performance features, namely the maximum flight duration and flight range, are determined by a series of factors, such as the nacelle angle, the aerodynamic interference, and the effect of the fuel consumption. I...

The coaxial compound configuration has been proposed as a concept for future high-performance rotorcraft. The co-axial rotor system requires no anti-torque device, while the longitudinal thrust is provided by a propeller. A well-designed propeller can ensure both the performance and the cruise efficiency. The propeller design also influences the fl...

The coaxial compound helicopter with lift-offset rotors has been proposed as a concept for future high-performance rotorcraft. This helicopter usually utilizes a variable-speed rotor system to improve the high-speed performance and the cruise efficiency. A flight dynamics model of this helicopter associated with rotor speed governor/engine model is...

Coaxial compound helicopters adopt the lift-offset (LOS) strategy to improve the rotor performance in high-speed flight, which influences the flight dynamics characteristics of the vehicle. Thus, a flight dynamics model and an inverse simulation method are developed to assess the effect of LOS on this helicopter. The trim results demonstrate that L...

The coaxial compound helicopters have obtained a lot of research interest due to their outstanding performance, especially in high speed flight. This rotorcraft could use the longitudinal cyclic pitch and the elevator to control the pitching moment during the flight. In order to investigate the effect of different longitudinal control strategy on t...

The coaxial compound helicopters have obtained a lot of research interest due to their outstanding performance, especially in high speed flight. This rotorcraft could use the longitudinal cyclic pitch and the elevator to control the pitching moment during the flight. In order to investigate the effect of different longitudinal control strategy on t...

The coaxial compound helicopter has two possible strategies for heading control: collective differential and rudder deflection. A flight dynamics model is developed to assess the effect of different heading control strategies. This includes the trim characteristics, steady flight performance, controllability, and manoeuvrability. The trim study dem...

The coaxial rigid rotor helicopter has been proposed as a future high-performance rotorcraft concept. However, the aerodynamic interference of this helicopter is complicated because it couples with the unique flapping feature of the rigid rotor, which further alters the trim characteristics of coaxial rigid rotor helicopters. Thus, a multi-point vo...

The coaxial compound configuration has been proposed as a concept for future high-performance rotorcraft. The co-axial rotor system does not require an anti-torque device, and a propeller provides axial thrust. A well-designed control strategy for the propeller is necessary to improve the performance and the flight dynamics characteristics. A fligh...

In order to research on the effect of lateral cyclic pitch differential and rotor control phase angle on the flight dynamic characteristics of coaxial rigid rotor high-speed helicopter. By using the validated flight dynamic model of XH-59 helicopter, analyze the influence of lateral cyclic pitch differential and rotor control phase on the trim char...

The rotor spacing of coaxial rigid rotor helicopter is relatively small and lead to more complex aerodynamic-interference, which could affect the flight dynamic characteristics. Aiming at this problem, this paper utilized the vortex ring dynamic wake method to build the aerodynamic model of the coaxial rotor. The accuracy of this aerodynamic model...

Adopting the flight dynamic model of coaxial rigid rotor helicopter, this paper sets the XH-59A coaxial rigid rotor helicopter as research object and analyzes the influence of rotor control phase angle on longitudinal trim characteristics, helicopter power required and hub bending moment of upper and lower rotor. Based on the analysis results, this...

Adopting the flight dynamic model of coaxial rigid rotor helicopter, set the XH-59A helicopter in copter mode as object, analyze the influence of rotor control phase angle on longitudinal trim characteristics, helicopter power required and hub bending moment of upper and lower rotor. The result shows: with increasing forward speed, enhancing the ro...

Aiming at the difference between the coaxial rigid rotor and the conventional rotor, the aerodynamic models of coaxial rigid rotor are built in terms of rotor flapping, pitch control and induced velocity. The flapping movement function of the coaxial rigid rotor is introduced based on the concept of equivalent flapping. The pitch control motion fit...