A propulsion system configured to be coupled to a vehicle, the system comprising: an ejector comprising an outlet structure out of which propulsive fluid flows at a predetermined adjustable velocity; and a first control surface having upper and lower surfaces and a leading edge: wherein the first control surface is located directly downstream of the outlet structure such that at least a portion of the leading edge is within the planes: (a) occupied by the surfaces outlet structure that are parallel with the leading edge; and (b) extending in a direction axial to ejector, whereby the propulsive fluid from the ejector flows over the upper and lower surfaces; the first control surface being positioned close enough to the outlet structure such that, during operation of the system, only propulsive fluid from the ejector flows over the upper and lower surfaces; and the ejector further comprising: a diffusing structure; at least one conduit coupled to the diffusing structure and configured to introduce to the diffusing structure a primary fluid produced by the vehicle; and an intake structure coupled to the diffusing structure and configured to introduce to the diffusing structure a secondary fluid accessible to the vehicle, wherein the diffusing structure comprises the outlet structure, and the propulsive fluid comprises the primary and secondary fluids; characterized in that the ejector further comprises a convex surface, the diffusing structure is coupled to the convex surface downstream of the convex surface, and the at least one conduit is coupled to the convex surface upstream of the convex surface and configured to introduce the primary fluid to the convex surface. an ejector comprising an outlet structure out of which propulsive fluid flows at a predetermined adjustable velocity; and a first control surface having upper and lower surfaces and a leading edge: wherein the first control surface is located directly downstream of the outlet structure such that at least a portion of the leading edge is within the planes: (a) occupied by the surfaces outlet structure that are parallel with the leading edge; and (b) extending in a direction axial to ejector, (a) occupied by the surfaces outlet structure that are parallel with the leading edge; and (b) extending in a direction axial to ejector, whereby the propulsive fluid from the ejector flows over the upper and lower surfaces; the first control surface being positioned close enough to the outlet structure such that, during operation of the system, only propulsive fluid from the ejector flows over the upper and lower surfaces; and the ejector further comprising: a diffusing structure; at least one conduit coupled to the diffusing structure and configured to introduce to the diffusing structure a primary fluid produced by the vehicle; and an intake structure coupled to the diffusing structure and configured to introduce to the diffusing structure a secondary fluid accessible to the vehicle, wherein the diffusing structure comprises the outlet structure, and the propulsive fluid comprises the primary and secondary fluids; a diffusing structure; at least one conduit coupled to the diffusing structure and configured to introduce to the diffusing structure a primary fluid produced by the vehicle; and an intake structure coupled to the diffusing structure and configured to introduce to the diffusing structure a secondary fluid accessible to the vehicle, wherein the diffusing structure comprises the outlet structure, and the propulsive fluid comprises the primary and secondary fluids; characterized in that the ejector further comprises a convex surface, the diffusing structure is coupled to the convex surface downstream of the convex surface, and the at least one conduit is coupled to the convex surface upstream of the convex surface and configured to introduce the primary fluid to the convex surface.