Design and Control Studies for the VectoRotor Hybrid VTOL Heavy Lift Vehicle

There has been a resurgence of interest in both lighter than air vehicles and hybrid designs that combine buoyant lift with powered or rotorborne propulsion. While the potential of such vehicles to undertake short range heavy lift functions has been long understood, many concepts have been found to lack the control capability necessary for precision vertical flight or easily controllable forward flight. This paper describes initial design work on a novel concept – denoted VectoRotor – that bypasses these problems; VectoRotor combines buoyant and dynamic lift in a hybrid, rotary-wing aircraft that employs a unique joined-rotor design. The resulting configuration provides vertical thrust and direct lateral force control for precision hovering in a structurally efficient manner. Preliminary analysis suggests this concept offers reduced fuel burn, lower noise, and lower operating costs than heavy lift helicopters conducting similar missions. This paper will outline the design history of the concept and results of preliminary scaling analyses on sizing for practical flight vehicles. It will also describe the application of a comprehensive rotorcraft model to define key performance issues for hover and forward flight, in particular engine power and flight control requirements and estimated limits on trimmed forward flight.