Influence of propeller configuration on propulsion system efficiency of multi-rotor Unmanned Aerial Vehicles

Abstract

Multi-rotor Unmanned Aerial Vehicles make use of multiple propellers, mounted on arms, to produce the required lift. This article investigates the influence on propulsion system efficiency in hover due to the configuration of these propellers. Influence of pusher or puller configuration of the propeller, number of blades, shape and dimensions of the arm, coaxial and overlapping propellers, is presented. A dedicated test bench that allows testing of various experimental setups is designed and built in order to realistically represent multi-rotor arms. Test results show that a two-bladed pusher configuration is most efficient and slenderness of the arm has more influence on efficiency than shape. A coaxial propulsion system approaches the efficiency of a single-prop system at high disk loadings. Finally, interference effects due to overlapping propellers are discussed.

An Empirical Study of Overlapping Rotor Interference for a Small Unmanned Aircraft Propulsion System

“…Even greater efficiency losses (~14%) were recorded by Heyson [25] and Sweet [26]. Theys et al's [17] experiments using SUAV components showed no decline or increase in propulsion system performance at 0.85 < d/D < 0.9, however, there is a lack of information on their test setup in regards to the torque balance of the rotors.…”

“…Full-sized helicopter rotors achieving trim by changing rotor pitch and fixing rotational velocities were investigated by [15,18,19]. Some of the higher fidelity tests on overlapping rotor systems closer to the sizes of small UAV rotors used in this research (D = 0.406 m) could be seen in [15,17]. Ramasamy [15] has used twisted variable pitch rotors of 1.314 m in diameter.…”

“…Most of the early research in this area was done using blades greater than 1.5 m in diameter. Only recently were smaller rotor tests put forward with the research carried out by McAlister [16], Bohorquez [13], Ramasamy [15], and Theys et al [17]. Most of this research was conducted when both rotors are operating in torque equilibrium.…”

“…Ramasamy [15] has used twisted variable pitch rotors of 1.314 m in diameter. Theys et al [17] have conducted overlapping rotor tests using fixed pitch off-the-shelf Graupner 9 inch × 5 inch rotors which have a diameter of 0.229 m.…”

Chattering-Free Tracking Control of a Fully Actuated Multirotor with Passively Tilted Rotors

“…There are a few papers [3,4] that deal with configuration parameters important for the design of multirotors intended to perform different tasks such as disaster site observations or search and rescue missions [5,6].…”