Conceptual Design Studies of a Mono Tiltrotor
Leishman, J. Gordon
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The Mono Tiltrotor (MTR) has been proposed by the Baldwin Technology Company as an innovative VTOL concept that integrates a tilting coaxial rotor, an aerodynamically deployed folding wing, and an efficient cargo handling system. The MTR has been targeted to meet heavy-lift, long-range mission objectives for which there is growing demand from military planners. This thesis describes a series of conceptual design studies aimed at determining the potential value that the MTR concept would possess, if it were to be technically realized. A versatile rotorcraft sizing analysis was developed to perform sizing and weight predictions for conventional single rotor and coaxial helicopters, as well as the MTR concept, based on key input mission and design requirements. This analysis was partly based on historical trends used in the rotorcraft and fixed-wing aircraft industries. These methods were expanded upon to include the capability for sizing the unique MTR concept. As presented, the results of this design analysis include a detailed weight budget of any number of potential aircraft point designs. The sizing methodology was validated against legacy helicopter sizing and component weights data, with good overall agreement. Comparisons, in terms of sizing and potential performance, between the MTR concept and conventional and coaxial helicopters sized to perform the same heavy-lift, long range mission are then presented. Key mission and design trade studies are also detailed, which were performed to study and refine the design concept and analytical methodology. The optimization of two key design points is also presented. These design points include a heavy-lift, long-range (20 ton payload, 1,000 nm range) MTR, and an MTR Scaled Demonstrator (2 ton payload, 700 nm range). Detailed performance studies are reported for each optimized point design. Overall, it was found that the MTR concept, if technically realized, offers unprecedented performance capability in terms of payload, range, and mission versatility. This comes in a very compact package relative to the size of a helicopter that would be required to complete the same mission.