Abstract: A fluid dynamic device (100) for directing fluid flow to generate thrust comprising a thrust control shroud (130) disposed about a central axis (210) of said fluid dynamic device (100) for directing a fluid flow between an upstream fluid intake region (220) and a downstream fluid exit region (222), forming a fluid exit area, of said shroud (130) to generate thrust wherein a displacement of said fluid exit region (222) of said shroud (130) with respect to said central axis (210) results in a translation of said fluid exit area (222) such that the level of shear stress induced in that part of the shroud (130) disposed laterally to the direction of translation of the shroud (130) is minimized.

Abstract: An airborne craft is provided comprising an aerodynamic lifting device having a radial drum fan and a thrust vectoring shroud. The radial drum or vertical axis fan comprises a fan with a rotor, the rotor having a rotational axis and comprising a plurality of rotor blades disposed in an annular ring about the rotational axis and a driving means for the rotor such that, on operation of the driving means, lift is generated.

Abstract: A fluid dynamic device (100) for directing fluid flow to generate thrust comprising a thrust control shroud (130) disposed about a central axis (210) of said fluid dynamic device (100) for directing a fluid flow between an upstream fluid intake region (220) and a downstream fluid exit region (222), forming a fluid exit area, of said shroud (130) to generate thrust wherein a displacement of said fluid exit region (222) of said shroud (130) with respect to said central axis (210) results in a translation of said fluid exit area (222) such that the level of shear stress induced in that part of the shroud (130) disposed laterally to the direction of translation of the shroud (130) is minimised.

Abstract: An airborne craft is provided comprising an aerodynamic lifting device having a radial drum fan with an operating region intermediate the power loading (“y”) asymptotic region and the disc loading (“x”) asymptotic region of a power loading—disc loading characteristic for the lifting device. The radial drum or vertical axis fan comprises a fan with a rotor, the rotor having a rotational axis and comprising a plurality of rotor blades disposed in an annular ring about the rotational axis and a driving means for the rotor such that, on operation of the driving means, lift is generated.

Abstract: A fluid dynamic device including a shroud disposed about a central axis and having an upstream fluid intake region and a downstream fluid exit region, the shroud directing fluid flow between the upstream fluid intake region and the downstream fluid exit region. The shroud is configured so that, at least during some operating conditions of the fluid dynamic device, at least a portion of fluid exiting the fluid exit region is directed towards the central axis.

Abstract: An airborne craft is provided comprising an aerodynamic lifting device having a radial drum fan and a thrust vectoring shroud. The radial drum or vertical axis fan comprises a fan with a rotor, the rotor having a rotational axis and comprising a plurality of rotor blades disposed in an annular ring about the rotational axis and a driving means for the rotor such that, on operation of the driving means, lift is generated.