An Interference-Free Quad-Tilt Design

The rotor blade vorticity roll-up phenomenon is reviewed, including quantitative estimation of characteristic distances. A four-rotor tilt-wing configuration that overcomes unfavorable wake impingements by close-coupling fore-and-rear propulsors to form counter-rotating pairs is presented and described. This is accomplished without the need for an added degree of variable geometry by allowing the rotor planes to pass through one another during the transition maneuver. To ensure that blade collisions cannot occur, constraints regarding (1) component dimensions and (2) gearing schemes must be observed. These are described in moderate detail. A candidate shaft-in-geared-sleeve arrangement for driving both wing tilt and rotor motion from within the fuselage is offered, as is a whole-aircraft schematic utilizing this approach. A brief survey of the design degrees-of-freedom available to the engineer is made.