Abstract:
This paper explores the conceptual design and proof-of-concept demonstration of an unmanned rotary wing Unmanned Aerial Vehicle (UAV) for logistics at high altitude areas. An iterative design methodology is developed using sizing formulas to carry out trade-off study for conceptual design of an unmanned helicopter based on the specified mission requirements. The key mission scenario involves taking off with 25 kg payload at an altitude of 5500 meters above mean sea level (AMSL), climbing 500 m above ground level (AGL), cruising to the delivery target, dropping of the payload while hovering, returning, and descending 500 meters for final landing. Two distinct mission profiles are explored for design: one with a total hover endurance of 40 minutes and the other with complete mission comprising of takeoff, climb, cruise, descent and landing. The methodology employed evaluates key design factors, including component weight allocation using empirical approaches. Hover Out of Ground Effect (HOGE) power is determined using Blade Element Momentum Theory (BEMT) and uniform inflow based aerodynamic model is used for climbing, descending, and forward flight power calculations. A blade optimization study is also carried and selection of high lift airfoil, reduction of number of blades and use of −15° linear twist, results in 14% reduction in hover power. The final design choice is driven by trading-off between tip speed and control bandwidth availability. The design is experimentally validated by fabricating an approximately half-scaled prototype which is flight tested at 5000 m altitude. This paper demonstrates the feasibility of an electric powered tandem rotor UAV for high-altitude payload missions, offering a framework for precise design in this challenging environment.