Mechanic of Advanced and Smart Materials
Quarterly

Design and weight optimization of a manned hybrid octocopter

Document Type : Original Article

Authors

Sirwan Farhadi 1
Mostafa Sanjari Sarmad 2

1 Department of Mechanical Engineering, University of Kurdistan

2 Department of Mechanical Engineering, University of Kurdistan, Sanandaj, Iran

https://doi.org/10.66224/masm.4.3.425
Abstract
This research aims to conceptually and optimally design a hybrid-electric octocopter to carry cargo or passengers. The drone uses a Wankel engine connected to an electricity generator to drive the brushless motors or charge the batteries. A genetic algorithm is employed to optimize the total weight and thrust force. The design variables include the engine power, fuel tank capacity, capacity and number of battery cells, brushless motor speed constant, speed controllers’ amperage, arm length, arms cross-section diameter, propeller radius, and propeller angular velocity. The engine’s mass-to-weight ratio is considered a key input parameter of the algorithm used to study the effect of technology on the final design. Two optimization objective functions are used: 1. maximizing the fuel-to-gross weight ratio and, 2. maximizing the thrust-to-weight ratio. Numerical results show that long flight ranges of order 1000 km are achievable with the designs presented by the first objective function, thanks to their large fuel capacity. According to our calculations, the overall performance of the octocopter configurations obtained by the second objective function with engine mass-to-power ratios of a=0.3 and a=0.6 (kg/kW) is very close. In other words, further advancement in Wankel engines’ mass-to-weight ratio does not result in considerable improvements in short-range VTOL vehicles.

Keywords

Hybrid octocopter
Weight optimization
Genetic algorithm
Wankel engine
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Mechanic of Advanced and Smart Materials
Volume 4, Issue 3
Autumn 2024
Pages 425-448

  • Receive Date 29 December 2024
  • Revise Date 15 March 2025
  • Accept Date 05 April 2025

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