A rotary propulsion system, comprising: a fan arranged along a rotation axis; an electric motor having windings and a permanent magnet arranged along the rotation axis and operatively connected to the fan; and a reduction gear set extending about the rotation axis and coupling the electric motor to the fan, wherein the permanent magnet is rotatable relative to the windings and the fan to rotate the fan using the electric motor at a rotational speed that is lower than a rotational speed of the permanent magnet; wherein the fan is a first fan and further comprising a second fan , the second fan coaxially supported for rotation about the rotation axis with the first fan; and further comprising a shaft supporting the fan and coupled to the fan by the reduction gear set, wherein the winding or the permanent magnet is fixed relative to the shaft, wherein the shaft is a first shaft and further comprising a second shaft, the second shaft arranged coaxially with the first shaft along the rotation axis and supported for rotation relative to the first shaft; wherein the electric motor is a first electric motor , the winding is a first winding , and the permanent magnet is a first permanent magnet , the rotary propulsion system further comprising a second electric motor with a second winding and a second permanent magnet , the second winding fixed relative to the first winding and the second permanent magnet rotatable relative to the first permanent magnet and the second winding; and wherein the reduction gear set is a first reduction gear set and further comprising a second reduction gear set , the second reduction gear set axially offset from the first reduction gear set along the rotation axis, wherein the second reduction gear set arranged axially on a side of the first reduction gear set opposite the electric motor. a fan arranged along a rotation axis; an electric motor having windings and a permanent magnet arranged along the rotation axis and operatively connected to the fan; and a reduction gear set extending about the rotation axis and coupling the electric motor to the fan, wherein the permanent magnet is rotatable relative to the windings and the fan to rotate the fan using the electric motor at a rotational speed that is lower than a rotational speed of the permanent magnet; wherein the fan is a first fan and further comprising a second fan , the second fan coaxially supported for rotation about the rotation axis with the first fan; and further comprising a shaft supporting the fan and coupled to the fan by the reduction gear set, wherein the winding or the permanent magnet is fixed relative to the shaft, wherein the shaft is a first shaft and further comprising a second shaft, the second shaft arranged coaxially with the first shaft along the rotation axis and supported for rotation relative to the first shaft; wherein the electric motor is a first electric motor , the winding is a first winding , and the permanent magnet is a first permanent magnet , the rotary propulsion system further comprising a second electric motor with a second winding and a second permanent magnet , the second winding fixed relative to the first winding and the second permanent magnet rotatable relative to the first permanent magnet and the second winding; and wherein the reduction gear set is a first reduction gear set and further comprising a second reduction gear set , the second reduction gear set axially offset from the first reduction gear set along the rotation axis, wherein the second reduction gear set arranged axially on a side of the first reduction gear set opposite the electric motor. <EOS>