Optimal Transition of Coaxial Compound Helicopter after Total Propeller Failure
Publication: Journal of Aerospace Engineering
Volume 37, Issue 6
Abstract
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 indicator is proposed to quantify the transition difficulty. Next, the flight dynamics with and without the propeller and the accelerations at the propeller loss instant are discussed from a trim perspective. Finally, dynamic transitions are meticulously analyzed and compared using a multidimensional radar map to identify an effective strategy. Contrary to the static trim analysis, dynamic simulation results highlight the critical importance of pitch attitude control, longitudinal speed stability, and incidence instability. The potential threats include blade tip collision, significant height increase up to 300 m, and reverse longitudinal stick control regarding pitch attitude. To mitigate these risks and reduce pilot workload, we recommend gradually pitching up to enter the quasi-autorotation state. Additionally, slightly lowering the position of the propeller and maintaining a positive pitch attitude during normal flight can help improve aircraft transition stability.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
This study was supported by A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
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Published In
Journal of Aerospace Engineering
Volume 37 • Issue 6 • November 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Aug 10, 2023
Accepted: Mar 14, 2024
Published online: Aug 24, 2024
Published in print: Nov 1, 2024
Discussion open until: Jan 24, 2025
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