Investigation On Flight Characteristics Of Gyroplane

Autorotation is the rotor operating state of gyroplane in steady flight.The autorotating rotor does not need engine driving,and rotor gets energy from the relative stream to maintain stable autorotation and generates thrust.Simultaneously,autorotation is also an important operate state of helicopter rotor,which directly affect flight safety and the safety of the crew of helicopters.In addition,many compound helicopters will also turn into the autorotation state in high forward speed.Therefore,it is significant to investigation gyroplane flight characteristics for all kinds of rotorcraft.Compared to the traditional helicopters,gyroplane is different on configurations,control and working principle.So that gyroplane flight problems are more specific,and its modeling approach is also more special and complex.For analyzing gyroplane flight characteristics,the modeling approach is carried out in this paper.Free wake method is applied to autorotating rotor aerodynamic characteristics modeling.Auturotating rotor blade flapping motion model and autorotating rotor trim model are introduced into the wake model.The unique rotor speed trim problem of autorotating rotor is solved,and the huge amount of calculation and low efficiency,which bringed by the autorotating rotor speed trim,is solved by accelerated algorithm.An analyze approach of autorotating rotor aerodynamic characteristics is established,and the effectiveness of the method is verified by the comparison with experiment data.Compared with the traditional dynamic inflow model,the wake model improves the precision and accuracy of the aerodynamic characteristics analysis.Autorotating rotor aerodynamic characteristics are analyzed detailedly by using the method.Induced flow distribution and wake geometry characteristics of autorotating rotor are revealed.In order to solve the problem of low accuracy and poor universality for traditional engineering experience method or half experience method,two theoretical modeling methods for analyzing gyroplane flight performance are proposed.The effectiveness of two modeling methods is verified by the comparison with experiment data.Both two modeling methods can analyze the gyroplane flight performance.In order to consider the effects of rotor disk nonuniform induced velocity on power required,the basic analysis method is modified by using free wake model calculation results.The trim analysis method is more detailed and accurate than basic analysis method,and it is suitable for the detailed analysis and calculation of gyroplane flight performance.The flight performance of the autogyro and gyroplane is analyzed by using the method,and the technical scheme which increased wing can improve the maximum forward speed is verified.A trim method which suitable for analyzing gyroplane is established,and the trim problem which bringed by adding wing of autogiro,is solved.Although the flight performance of gyroplane can be improved by adding wing,it has a significant effect on the trim characteristics.Two types of rotorcraft trim characteristics,especially gyroplane which has little research currently,are studied in the paper.The new trim characteristics and the design problem which need to pay attention are revealed.The key technology of the autorotating rotor and wing lift distribution of the gyroplane is studied further based on the model.Gyroplane state space mathematical equations which increased rotor speed degree of freedom are deduced afresh.The mode flight path and the time domain response analysis method are coupled with the model.A method which suitable for analyzing gyroplane control and stability characteristics is established.The control and stability characteristics of autorotating rotorcraft,especially gyroplane are analyzed detailedly.It is found that the increase of the wing is disadvantageous to the rotor speed mode stability.The mode stability can be considered to improve by increasing rotor blade tip distribution blade tip weight.In addition,the longitudinal position of the wing has significant effects on gyroplane longitudinal stability.The longitudinal position of the wing should welcome considering angle stability and the rotation of the rotor speed stability requirements.The wing longitudinal position should be chosen synthetically by considering angle of attack stability and rotor speed stability simultaneously.