In this paper, the unsteady effect of airflow is introduced into the calculation of aircraft maneuver load, and the results are compared with those obtained by quasi-steady method. Taking the steep pitch maneuver of a...In this paper, the unsteady effect of airflow is introduced into the calculation of aircraft maneuver load, and the results are compared with those obtained by quasi-steady method. Taking the steep pitch maneuver of an aircraft as an example, two methods are used to calculate the aircraft response after the rudder input is given according to the specifications. The calculation results show that if the peak overload of the aircraft is the same, the horizontal tail load increases by about 1% when the unsteady effect of the airflow is taken into account. If the rudder input of the two methods is the same, the unsteady calculation method will increase more. At the same time, the calculation shows that the bigger the deflection speed of rudder surface is, the bigger the difference between them is. Therefore, in order to improve the design quality of aircraft, it is necessary to introduce the unsteady effect into the calculation of loads in the detailed design stage of aircraft.展开更多
A nonlinear and time-varying gyroplane jump takeoff dynamics model considering the unsteady ground effect and the rapid blade-pitch increase(RBPI) is developed and validated against the experiment data.The precisions ...A nonlinear and time-varying gyroplane jump takeoff dynamics model considering the unsteady ground effect and the rapid blade-pitch increase(RBPI) is developed and validated against the experiment data.The precisions of the proposed model,an experienced Hollmann model and three other simplified models are compared by displaying the height and rpm time histories of those models and the experimental data.The mean square errors(MSE) of the height histories and maximum height errors(MHE) between those models are calculated and given out.The statistics provide a kind of evaluation method of importance of the unsteady ground effect,RBPI,and the induced velocity on jump takeoff performance in vertical phase.The impact of the unsteady ground effect and RBPI on the thrust and induced velocity of the experimental rotor of a small scale platform is analyzed.The study indicates that the proposed model agrees better with the experimental data than other models.It is useful for predicting the gyroplane jump takeoff performance for design.展开更多
文摘In this paper, the unsteady effect of airflow is introduced into the calculation of aircraft maneuver load, and the results are compared with those obtained by quasi-steady method. Taking the steep pitch maneuver of an aircraft as an example, two methods are used to calculate the aircraft response after the rudder input is given according to the specifications. The calculation results show that if the peak overload of the aircraft is the same, the horizontal tail load increases by about 1% when the unsteady effect of the airflow is taken into account. If the rudder input of the two methods is the same, the unsteady calculation method will increase more. At the same time, the calculation shows that the bigger the deflection speed of rudder surface is, the bigger the difference between them is. Therefore, in order to improve the design quality of aircraft, it is necessary to introduce the unsteady effect into the calculation of loads in the detailed design stage of aircraft.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51505031)
文摘A nonlinear and time-varying gyroplane jump takeoff dynamics model considering the unsteady ground effect and the rapid blade-pitch increase(RBPI) is developed and validated against the experiment data.The precisions of the proposed model,an experienced Hollmann model and three other simplified models are compared by displaying the height and rpm time histories of those models and the experimental data.The mean square errors(MSE) of the height histories and maximum height errors(MHE) between those models are calculated and given out.The statistics provide a kind of evaluation method of importance of the unsteady ground effect,RBPI,and the induced velocity on jump takeoff performance in vertical phase.The impact of the unsteady ground effect and RBPI on the thrust and induced velocity of the experimental rotor of a small scale platform is analyzed.The study indicates that the proposed model agrees better with the experimental data than other models.It is useful for predicting the gyroplane jump takeoff performance for design.
