Liaoning General Aviation Research Institute

Traditional aerodynamic design faces significant limitations in modeling and computational efficiency during conceptual design stage. A phased collaborative aerodynamic design strategy for eVTOL aircraft was established, by combining the OpenVSP platform for rapid parametric modeling and evaluation, a Kriging surrogate framework with an improved differential evolution algorithm for optimization, and the SUAVE platform for propeller reverse design. In the wing-body (WB) optimization phase, 23 configuration parameters such as the wing shape and location were adjusted. The aerodynamic evaluation was conducted using the Vortex Lattice Method (VLM) in OpenVSP, resulting in a 9.3% increase in the lift-to-drag ratio (L/D). During the wing-body-propeller (WBP) coupling optimization phase, the Actuator Disk Theory (ADT) was incorporated into WB model to quantify the slipstream effects. After optimizing the key geometric parameters such as disk diameter and location, the comprehensive propulsion efficiency and lift-to-drag ratio (η·/L/D) was increased by 14%. Relative performance parameters were then transferred to SUAVE to reconstruct the propeller based on the Betz-BEM theory. The RANS high-fidelity verification of the optimized WBP model shows high consistency in the trends of lift coefficient Cl and L/D calculated by VLM, with the propeller thrust error 5.2%, and the Cl error 9.7%, which confirms the engineering reliability and efficiency of the proposed strategy.

In order to strengthen the hovering precision of a small unmanned helicopter with a manipulator for completing a hovering operation, in this study, a double-loop control strategy of position and attitude is designed. In the position loop, a sliding mode controller is proposed. It attains high precision and strong robustness under continuous disturbance. With the manipulator continuously operating during helicopter hovering, the overall center of gravity and the moment of inertia of the system will also change. Therefore, a backstepping sliding mode controller is proposed in the attitude loop for controlling the hovering attitude of the helicopter. The high precision and strong robustness of the control system are proven. The digital simulation presents a position steady-state error of less than 2% under constant disturbance, and the hovering attitude angle fluctuation amplitude of the helicopter is less than 0.05 rad.

The electric seaplane, designed for take-off and landing directly on water, incorporates additional structures such as floats to meet operational requirements. Consequently, during the take-off taxiing phase, it encounters significantly higher aerodynamic and hydrodynamic resistance than other aircraft. This increases energy demand for the electric seaplane during the take-off phase. A mathematical model for energy consumption during this stage was developed by analyzing resistance, using the propeller pitch angle as an optimization variable. This study proposes a coupled energy efficiency optimization method for the take-off phase of an electric seaplane’s electric propulsion unit (EPU). The method aims to determine an optimal propeller pitch angle configuration aligned with the seaplane’s design criteria. This ensures that the propeller output thrust meets minimal requirements during take-off while enhancing energy efficiency. Experimental validation with the two-seater electric seaplane prototype RX1E-S has demonstrated that selecting the optimal propeller pitch angle can effectively reduce energy consumption by approximately 10.4%, thereby significantly enhancing flight efficiency.

The takeoff process of a seaplane is different from that of a conventional land-based plane owing to the influence of hydrostatic, hydrodynamic, and aerodynamic forces. As a result, more energy will be consumed by the electric propulsion unit (EPU) of a seaplane during takeoff. Given the limited energy density of contemporary batteries, the energy consumed by the seaplane during its flight mission profile was minimized in this study by improving the efficiency of the EPU using a proposed optimization method. To meet the performance requirements of the seaplane EPU, the pitch angle of the propeller was taken as the optimization variable and the system loss was mathematically modeled. The performance of the EPU was thereby optimized, its consumption during flight was reduced, and the seaplane endurance was increased accordingly. The proposed optimization method was subsequently verified using a prototype test of a two-seat electric seaplane. The results show that the proposed method can reduce the energy consumption of the EPU by more than 5% during a single flight.

Abstract Composite materials are more and more widely used in aircraft structural design, and impact damage is the most serious defect/damage form of aviation composite structures in service. Therefore, it is of great significance to study the impact resistance of composites with different materials and structural forms for aircraft structural design. In this article, the damage of reinforced fiber/resin composite laminates with unidirectional carbon fiber prepreg (UIN23100), carbon fiber woven fabric (W-3021FF), and carbon fiber-aramid fiber blended fabric (W-38211) under the same impact energy were studied. The impact damage area was scanned and analyzed by ultrasonic C-scan, and the impact resistance of the three laminates were obtained. Finally, the compression bearing capacity of carbon fiber laminates after impact was tested, and the compression failure mode of each material has been analyzed. The results show that the impact resistance of carbon fiber unidirectional prepreg was stronger than that of carbon fiber woven fabric; the compression bearing capacity of carbon fiber laminate after impact was higher than that of carbon fiber unidirectional prepreg; the post impact bearing capacity of W-38211 was higher than that of W-3021FF.

Prediction of relative permeability is important to avoid dry spots or micro voids in the liquid composite molding process. Most of previous studies focused on plain and twill, but few are about stain and none of them provide explicit equation to calculate accurate values of unsaturated permeability. The main purpose of this work is to first propose a new model which is proposed mainly based on fractal theory and has no empirical constant in the expression, to calculate the permeability of satin fabric. And then we employ a new experimental method to calculate the unsaturated permeability. Finally, a contrast experiment of 5-harness fabric and 8-harness fabric is designed at different injection pressures, and the accurate values of permeability are obtained. The results show that unsaturated and saturated permeabilities are in the same order of magnitude; furthermore, unsaturated permeability is 77% of saturated permeability in 5-harness fabric and 73% in 8-harness fabric.

Electric propulsion system of two seat electric aircraft used permanent magnet synchronous motor as the main drive, combined with vector control system. The aircraft is suffered impact of airflow with a certain chaotic characteristics while the vector control system ignores the chaotic characteristics of airflow impact force. Permanent magnet synchronous motor according to the two seat electric aircraft was established by chaos mathematical model. The use of the method of time delayed feedback chaos anti control are a reflection of the permanent magnet synchronous motor. The system is simulated using Simulink, and the lyapunov value and simulation image are given. Validity of the control algorithm is proved, On the basis of chaos anti control provides the theory of PMSM used for electric two seat aircraft.