System for lift, propulsion and control of an airborne craft
A system for providing lift, propulsion and control for an aircraft vehicle that facilitates vertical take-off and landing/short take-off and landing operations is described. The system is configured to provide an airfoil that has a leading and a trailing edge, a cross flow fan partially embedded in the airfoil and mounted adjacent to the trailing edge of the airfoil and an exit duct for the cross flow fan to provide distributed flow along the trailing edge of the system to achieve high propulsive efficiency in forward flight and a substantially vertical jet for vertical take-off and landing.
1 . A system for providing lift, propulsion, and control for Vertical take-off and landing (VTOL)/Short take-off and landing (STOL) operations of an aircraft vehicle, the system comprising:
a. at least one airfoil extending from a leading edge to a trailing edge;
b. a cross-flow fan, having a rotation axis and substantially the same length as the airfoil and mounted adjacent to the trailing edge of the airfoil; and
c. an exit duct for the cross-flow fan configured to provide distributed flow along the trailing edge of the system; the airfoil configured to provide vectored thrust; and the system further comprises:
d. a flap arranged rotatable about the cross-flow fan rotation axis, where the flap has an upper face and a lower face, and where the airfoil includes a flexing or morphing lip, with an upper face, wherein the lower face of the flap and the upper face of the flexing or morphing lip forms the exit duct; wherein the flap and the flexing or morphing lip forming the exit duct are further configured to move simultaneously but at different angular rate to deliver a desired change in angle and mass flow of the vectored thrust.
2 . The system in accordance with claim 1 , wherein the exit duct is further configured to eject a longitudinal jet of air required for producing the vertical lift by a combination of a predefined fan speed of the cross flow fan and position of the flexing or morphing lip and the flap.
3 . The system in accordance with claim 1 , where the lower face of the flap is configured to move in concert with and in parallel with the upper face of the flexing or morphing lip.
4 . The system in accordance with claim 1 , wherein the flap and the flexing or morphing lip of the exit duct are mechanically connected and configured to produce thrust that can be vectored from a substantially horizontal direction to a substantially vertical direction.
5 . The system in accordance with claim 1 , wherein the flap and the flexing or morphing lip are configured to be moved through an angle to obtain thrust that can be vectored through an angle to produce change in both magnitude and direction of the thrust.
6 . The system in accordance with claim 1 , wherein the flap and flexing or morphing lip are connected and moved through an angle so that the thrust can be vectored through an angle of more than 70 degrees.
7 . The system in accordance with claim 1 , wherein the airfoil has a thickness to a chord ratio that is greater than 30% and flow separation is limited by boundary layer ingestion into the cross-flow fan.
8 . The system in accordance with claim 1 , wherein the airfoil comprises a curved upper surface that is curved with an upper surface radius between 50% to 60% of the airfoil chord and where the curve extends over at least one third of the upper surface, a lower surface that is substantially flat and extends over at least one third of the lower surface and a rear surface.
9 . The system in accordance with claim 1 , wherein the cross-flow fan is configured with a rotor diameter between 10% to 30% of the chord of the airfoil.
10 . The system in accordance with claim 1 , wherein the system is configured to further provide a distributed flow along the cross-flow fan that has low parasitic drag in the forward flight and the drag decreases with increase in an angle of attack of the airfoil up to a maximum between 5 and 15 degrees.
11 . The system in accordance with claim 1 , wherein the cross-flow fan is configured to ingest the boundary layer of the airfoil to facilitate stall free operation at angles of attack between 5 and 20 degrees.