On the possibility of human-powered vertical flight

This paper reviews critically the history of human-power vertical flight, from the speculative ideas of Leonardo da Vinci to the AHS Human-Powered Prize. Basic helicopter performance theory is used to analyze single and co-axial rotor performance in hover flight, as well as single-rotor configurations in forward flight. The paper presents hover calculations in- and out of ground effect, low Reynolds number effects on the blade sections, the effects of more than one crew member, and co-axial rotor analysis. It is proved that most configurations with more than one crew member do not add any benefit, except when the operating empty weight of the rotorcraft is comparable to the weight of the crew members. The configurations examined lead to conclude that human-powered hover out of ground effect and forward flight are not possible. However, hover in ground effect is possible for a limited amount of time if the essential rotorcraft stability can be ensured. In all cases the optimal rotor diameters are in excess of 25 m.