H-Force of Rigid Rotor in Forward Flight of Multi-rotor

Multi-rotors have certain outstanding features, such as VTOL (Vertical Take-Off and Landing) ability and a simple mechanical system. However, they tend to lack endurance performance. Several types of fixed-wing VTOL have therefore been studied and proposed to minimize this drawback. Our proposal of a novel fixed-wing VTOL is one of these. It has a simple mechanism and has low drag because it is not equipped with control surfaces and stabilizers. Like a multi-rotor, this VTOL is controlled only by the speed of the rotors. In a previous study of our novel VTOL, we conducted a fundamental wind tunnel test of the multi-rotor with and without wings, and acquired data on the drag of the multi-rotor under condition of forward flight. In this paper we describe the results of theoretically examining the drag caused by the rotor. The paper is set out as follows. Section 1 introduces the novel VTOL and the purpose of this research, Sect. 2 describes the wind tunnel tests and the drag measured during forward flight, Sect. 3 describes the theoretical examination of the H-force caused by rotor spin and Sect. 4 verifies the experimental results based on the results of our theoretical study. We draw our conclusions in Sect. 5.