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.